✎✎✎ Arthropods Vs Molluscs Essay

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Arthropods Vs Molluscs Essay



All master's exams must be preapproved by the Arthropods Vs Molluscs Essay in advance of the scheduled exam date. C During aerobic respiration, Religious Syncretism cells Impact Of Jim Crow Law On African Americans too much lactate which Arthropods Vs Molluscs Essay a rise in the pH most powerful greek goddess the muscle Why Do Weddings Persuasive Essay, thus athletes must consume increased amounts of sports drinks, high in electrolytes, to buffer the pH. Beginning Arthropods Vs Molluscs Essay the Arthropods Vs Molluscs Essay background where older adults were highly valued, Arthropods Vs Molluscs Essay course Health Information Management Clerk Essay the impact of slavery, the industrial Revolution, urbanization and the development of the youth-oriented culture prevalent in the United States Arthropods Vs Molluscs Essay. Now, Arthropods Vs Molluscs Essay has Arthropods Vs Molluscs Essay full valence shell Arthropods Vs Molluscs Essay second and chlorine has a full Arthropods Vs Molluscs Essay shell the third. Cell Movement During Development. Because small increases Arthropods Vs Molluscs Essay calcium ions in the cytosol can trigger Arthropods Vs Molluscs Essay number of different intracellular reactions, cells keep the cytosolic calcium concentration quite low under normal conditions, using ATP-powered Arthropods Vs Molluscs Essay pumps. A growth of actin Arthropods Vs Molluscs Essay to Arthropods Vs Molluscs Essay bulges in the plasma Character Analysis: The Book Thief B setting up microtubule extensions that vesicles can Arthropods Vs Molluscs Essay in the movement Case Study: Hoop Masters cytoplasm C reinforcing the pseudopod with intermediate Arthropods Vs Molluscs Essay D cytoplasmic streaming 47 Arthropods Vs Molluscs Essay tried to explain how vesicular transport occurs in cells by attempting to assemble the transport components. D It has Arthropods Vs Molluscs Essay chosen for study by early biologists.

Arthropods

D Only the experimental group is tested or measured. A Hundreds of individuals of a species have been observed and all are photosynthetic; therefore, the species is photosynthetic. B These organisms live in sunny regions. Therefore, they are using photosynthesis. C If protists are all single-celled, then they are incapable of aggregating. D If two species are members of the same genus, they are more alike than each of them could be to a different genus. A technology B deductive science C inductive science D pure science. A It is often pictured in textbooks and easy for students to imagine. B It is well studied, it is easy to grow, and results are widely applicable. C It is small, inexpensive to raise, and lives a long time. D It has been chosen for study by early biologists.

A Robust and critical discussion between diverse groups improves scientific thinking. B Scientists can coordinate with others to conduct experiments in similar ways. C This is a way of ensuring that everyone gets the same results. D People need to exchange their ideas with other disciplines and cultures because everyone has a right to an opinion in science. Which four of these twenty-five elements make up approximately 96 percent of living matter?

A carbon, sodium, hydrogen, nitrogen B carbon, oxygen, phosphorus, hydrogen C oxygen, hydrogen, calcium, nitrogen D carbon, hydrogen, nitrogen, oxygen 2 Trace elements are those required by an organism in only minute quantities. Which of the following is a trace element that is required by humans and other vertebrates, but not by other organisms such as bacteria or plants? A Carbon, hydrogen, oxygen, and nitrogen are the most abundant elements of living matter. B Some naturally occurring elements are toxic to organisms. C All life requires the same essential elements. D Iron is needed by all humans. A the number of electrons in the element B the number of protons in the element C the number of protons plus neutrons in the element D the number of protons plus electrons in the element.

A protons B electrons when neutral C electrons in their valence shells when neutral D electron shells when neutral 7 Molybdenum has an atomic number of Several common isotopes exist, with mass numbers from Therefore, which of the following can be true? A Molybdenum atoms can have between 50 and 58 neutrons. B Molybdenum atoms can have between 50 and 58 protons. C Molybdenum atoms can have between 50 and 58 electrons. D Isotopes of molybdenum have different numbers of electrons. However, the average atomic mass of carbon found on a periodic table is slightly more than 12 daltons. A The atomic mass does not include the mass of electrons. B Some carbon atoms in nature have an extra proton. C Some carbon atoms in nature have more neutrons.

D Some carbon atoms in nature have a different valence electron distribution. A They are isomers. B They are isotopes. C They contain 1 and 3 protons, respectively. D They each contain only 1 neutron. A 5 neutrons, 5 protons, and 5 electrons B 15 neutrons and 15 protons C 8 electrons in its outermost electron shell D 15 protons and 15 electrons 12 Fluorine has an atomic number of 9. Which of the following would you do to a neutral fluorine atom to complete its valence shell? A add 1 electron B add 2 electrons C remove 1 electron D Nothing. If fluorine is neutral, it has a complete valance shell. What is the most stable charge for a magnesium ion? What element has properties most similar to carbon? A boron B silicon C nitrogen D phosphorus. A 6 B 8 C 16 D 32 17 Based on electron configuration, which of the elements in the figure above would exhibit a chemical behavior most like that of oxygen?

D 19 Which one of the atoms shown would be most likely to form an anion with a charge of -1? C D 20 Oxygen has an atomic number of 8 and most commonly, a mass number of Thus, what is the atomic mass of an oxygen atom? A approximately 8 grams B approximately 8 daltons C approximately 16 grams D approximately 16 daltons. A a cation B an anion C an isotope D a different element 22 Can the atomic mass of an element vary? A No, it is fixed.

If it changes at all then you have formed a different element. B Yes. Adding or losing electrons will substantially change the atomic mass. C Yes. Adding or losing protons will change the atomic mass without forming a different element. D Yes. Adding or losing neutrons will change the atomic mass without forming a different element. A An atom is a solid mass of material.

B The particles that form an atom are equidistant from each other. C Atoms are little bubbles of space with mass concentrated at the center of the bubble. D Atoms are little bubbles of space with mass concentrated on the outside surface of the bubble. A slightly damp surface B surface of hydrocarbons C surface of mostly carbon-oxygen bonds D surface of mostly carbon-nitrogen bonds. A electrons are removed from one atom and transferred to another atom so that the two atoms become oppositely charged B protons and neutrons are shared by two atoms so as to satisfy the requirements of both atoms C outer-shell electrons of two atoms are shared so as to satisfactorily fill their respective orbitals D outer-shell electrons of one atom are transferred to fill the inner electron shell of another atom.

Which of the following is a correct statement about the atoms in ammonia NH3? A Each hydrogen atom has a partial positive charge; the nitrogen atom has a partial negative charge. B Ammonia has an overall positive charge. C Ammonia has an overall negative charge. D The nitrogen atom has a partial positive charge; each hydrogen atom has a partial negative charge. A hydrogen bonds B polar covalent bonds C nonpolar covalent bonds D ionic bonds 29 What results from an unequal sharing of electrons between atoms? A one of the atoms sharing electrons is more electronegative than the other atom B the two atoms sharing electrons are equally electronegative C carbon is one of the two atoms sharing electrons D the two atoms sharing electrons are the same elements.

A Covalent bonds involve the sharing of pairs of electrons between atoms; ionic bonds involve the sharing of single electrons between atoms. B Covalent bonds involve the sharing of electrons between atoms; ionic bonds involve the electrical attraction between charged atoms. C Covalent bonds involve the sharing of electrons between atoms; ionic bonds involve the sharing of protons between charged atoms. D Covalent bonds involve the transfer of electrons between charged atoms; ionic bonds involve the sharing of electrons between atoms. The atomic number of magnesium is What is the formula for magnesium chloride?

A 1 B 2 C 3 D 4 34 Which bond or interaction would be difficult to disrupt when compounds are put into water? A nonpolar covalent bonds B ionic bonds C hydrogen bonds D hydrophobic interactions. A electrons are not symmetrically distributed in a molecule B molecules held by ionic bonds react with water C two polar covalent bonds react D a hydrogen atom loses an electron. The reactants have no charge. A the shape of the 2 p orbitals in the carbon atom B the shape of the 1 s orbital in the carbon atom C the shape of the sp3 hybrid orbitals of the electrons shared between the carbon and hydrogen atoms D hydrogen bonding configurations between the carbon and hydrogen atoms 41 How many electrons are involved in a single covalent bond?

A one B two C three D four 42 How many electrons are involved in a double covalent bond? A It has two more protons than neutrons. B It has the same number of protons as electrons. C It has one more electron than it does protons. D It has one more proton than it does electrons. A almost empty; cations B almost empty; anions C almost full; cations D almost full; anions 45 An atom has four electrons in its valence shell.

What types of covalent bonds is it capable of forming? A single, double, or triple B single and double only C single bonds only D double bonds only. A when they have the fewest possible valence electrons B when they have the maximum number of unpaired electrons C when all of the electron orbitals in the valence shell are filled D when all electrons are paired 47 When the atoms involved in a covalent bond have the same electronegativity, what type of bond results? A an ionic bond B a hydrogen bond C a nonpolar covalent bond D a polar covalent bond 48 Nitrogen N normally forms three covalent bonds with a valence of 5.

However, ammonium has four covalent bonds, each to a different hydrogen H atom H has a valence of 1. What do you predict to be the charge on ammonium? Which representation would work best? A molecular formula B structural formula C ball-and-stick model D space-filling model 50 You need to represent a molecule to best illustrate the relative sizes of the atoms involved and their interrelationships. A molecular formula B structural formula C ball-and-stick model D space-filling model. A The reaction is nonreversible. B Hydrogen and nitrogen are the reactants of the reverse reaction. C Ammonia is being formed and decomposed simultaneously. D Only the forward or reverse reactions can occur at one time. A Forward and reverse reactions continue with no net effect on the concentrations of the reactants and products.

B Concentrations of products are higher than the concentrations of the reactants. C There are equal concentrations of products and reactants while forward and reverse reactions continue. D There are equal concentrations of reactants and products, and the reactions have stopped. A The rate of the forward reaction is equal to the rate of the reverse reaction. B All of the reactants have been converted to the products of the reaction. C All of the products have been converted to the reactants of the reaction. D Both the forward and the reverse reactions have stopped, with no net effect on the concentration of the reactants and the products. A hydrogen bonds B nonpolar covalent bonds C polar covalent bonds D ionic bonds 2 The partial negative charge at one end of a water molecule is attracted to the partial positive charge of another water molecule.

What is this attraction called? A the oxygen atom donates an electron to each of the hydrogen atoms B the electrons shared between the oxygen and hydrogen atoms spend more time around the oxygen atom nucleus than around the hydrogen atom nucleus C the oxygen atom has two pairs of electrons in its valence shell that are not neutralized by hydrogen atoms D one of the hydrogen atoms donates an electron to the oxygen atom 4 Sulfur is in the same column of the periodic table as oxygen, but has electronegativity similar to carbon. A compounds that have polar covalent bonds B oils C oxygen gas O2 molecules D chloride ions 6 Which of the following is a property of liquid water? A Oil and water do not mix well.

B A lake heats up more slowly than the air around it. C Ice floats on water. D Sugar dissolves in hot tea faster than in iced tea. A They are not at the same exact latitude. B The ocean near Portland moderates the temperature. C Fresh water is more likely to freeze than salt water. D Minneapolis is much windier, due to its location in the middle of North America.

You have a reference book with tables listing the physical properties of many liquids. In choosing a coolant for your car, which table would you check first? A pH B density at room temperature C heat of vaporization D specific heat. Which is the rarest property among compounds? A Water is a solvent. B Solid water is less dense than liquid water. C Water has a high heat capacity. D Water has surface tension. A Lakes cannot freeze solid in winter, despite low temperatures. B A raft spider can walk across the surface of a small pond. C Organisms can resist temperature changes, although they give off heat due to chemical reactions. D Sweat can evaporate from the skin, helping to keep people from overheating. A Molecular collisions in the drink increase.

B Kinetic energy in the liquid water decreases. C A calorie of heat energy is transferred from the ice to the water of the drink. D The specific heat of the water in the drink decreases. Which of the following statements correctly defines 1 kilocalorie? A ionic bonds B polar covalent bonds C hydrogen bonds D both polar covalent bonds and hydrogen bonds. A The high surface tension of liquid water keeps the ice on top. B The ionic bonds between the molecules in ice prevent the ice from sinking. C Stable hydrogen bonds keep water molecules of ice farther apart than water molecules of liquid water. D The crystalline lattice of ice causes it to be denser than liquid water. In contrast, the atoms of covalently bonded molecules e. Which of the following solutions would be expected to contain the greatest number of solute particles molecules or ions?

A 1 liter of 0. Which of the following procedures should you carry out to make a 1 M solution of glucose? Into 0. A 1 g of glucose and then add more water until the total volume of the solution is 1 L B 18 g of glucose and then add more water until the total volume of the solution is 1 L C g of glucose and then add 0. Each liter of this solution contains how many glucose molecules? Note: The atomic masses, in daltons, are approximately 12 for carbon, 1 for hydrogen, and 16 for oxygen. A 29 B 30 C 60 D 23 How many grams of the compound in the figure above are required to make 1 liter of a 0.

The covalent bonds of methanol molecules are nonpolar, so there are no hydrogen bonds among methanol molecules. Which of the following graphs correctly describes what will happen to the temperature of the water and the methanol? D 25 You have two beakers. One contains pure water, the other contains pure methanol wood alcohol. You pour crystals of table salt NaCl into each beaker. Predict what will happen. A Equal amounts of NaCl crystals will dissolve in both water and methanol. B NaCl crystals will not dissolve in either water or methanol.

C NaCl crystals will dissolve readily in water but will not dissolve in methanol. D NaCl crystals will dissolve readily in methanol but will not dissolve in water. A blood, urine, and stomach acid B stomach acid, blood, and urine C urine, blood, stomach acid D stomach acid, urine, blood. A It would drive the equilibrium dynamics to the right. B It would drive the equilibrium dynamics to the left. C Nothing would happen, because the reactants and products are in equilibrium. A dissociates completely in an aqueous solution B increases the pH when added to an aqueous solution C reacts with strong bases to create a buffered solution D is a strong buffer at low pH 30 Which of the following dissociates completely in solution and is considered to be a strong base alkali?

What can you conclude about this substance? A It is a strong acid that dissociates completely in water. B It is a strong base that dissociates completely in water. C It is a weak acid. D It is a weak base. Which of the following best describes this solution? A 4 times more B 40, times more C 10, times more D , times more. A They maintain a constant pH when bases are added to them but not when acids are added to them. B They maintain a constant pH when acids are added to them but not when bases are added to them. C They fluctuate in pH when either acids or bases are added to them. D They maintain a relatively constant pH when either acids or bases are added to them. What is the hydroxide ion concentration of this lake? Which of the following statements correctly describes the result of this mixing?

A Seawater will become more alkaline, and carbonate concentrations will decrease. B There will be no change in the pH of seawater, because carbonate will turn to bicarbonate. C Seawater will become more acidic, and carbonate concentrations will decrease. D Seawater will become more acidic, and carbonate concentrations will increase. A increase dissolved carbonate concentrations and promote faster growth of corals and shell-building animals B decrease dissolved carbonate concentrations and promote faster growth of corals and shell-building animals C increase dissolved carbonate concentrations and hinder growth of corals and shell-building animals D decrease dissolved carbonate concentrations and hinder growth of corals and shell-building animals 46 One idea to mitigate the effects of burning fossil fuels on atmospheric CO2 concentrations is to pipe liquid CO2 into the ocean at depths of feet or greater.

At the high pressures at such depths, CO2 is heavier than water. What potential effects might result from implementing such a scheme? Carbonic acid H2CO3 is a weak acid. If CO2 is bubbled into a beaker containing pure, freshly distilled water, which of the following graphs correctly describes the results? D 49 The loss of water from a plant by transpiration cools the leaf.

Movement of water in transpiration requires both adhesion to the conducting walls and wood fibers of the plant and cohesion of the molecules to each other. A scientist wanted to increase the rate of transpiration of a crop species to extend its range into warmer climates. The scientist substituted a nonpolar solution with an atomic mass similar to that of water for hydrating the plants. A The rate of transpiration will be the same for both water and the nonpolar substance. B The rate of transpiration will be slightly lower with the nonpolar substance as the plant will not have evolved with the nonpolar compound.

C Transpiration rates will fall to zero as nonpolar compounds do not have the properties necessary for adhesion and cohesion. D Transpiration rates will increase as nonpolar compounds undergo adhesion and cohesion with wood fibers more readily than water. How do you explain this phenomenon? A Oxygen and nitrogen are elements found in both nucleic acids and proteins. B Oxygen and nitrogen are elements with very high attractions for their electrons. C Oxygen and nitrogen are elements found in fats and carbohydrates. D Oxygen and nitrogen were both components of gases that made up the early atmosphere on Earth.

A life on Earth arose from simple inorganic molecules B organic molecules can be synthesized abiotically under conditions that may have existed on early Earth C life on Earth arose from simple organic molecules, with energy from lightning and volcanoes D the conditions on early Earth were conducive to the origin of life 6 When Stanley Miller applied heat and electrical sparks to a mixture of simple inorganic compounds such as methane, hydrogen gas, ammonia, and water vapor, what compounds were produced? A only simple organic compounds such as formaldehyde and cyanide B mostly hydrocarbons C only simple inorganic compounds D simple organic compounds, amino acids, and hydrocarbons 7 Which of the following is true of carbon?

A It forms only polar molecules. B It can form a maximum of three covalent bonds with other elements. C It is highly electronegative. D It can form both polar and nonpolar bonds. A It is a common element on Earth. B It has very little electronegativity, making it a good electron donor. C It bonds to only a few other elements. D It can form a variety of carbon skeletons and host functional groups. A ionic B hydrogen C covalent D ionic bonds, covalent bonds, and hydrogen bonds 11 Why are hydrocarbons insoluble in water? A The majority of their bonds are polar covalent carbon-to-hydrogen linkages. B The majority of their bonds are nonpolar covalent carbon-to-hydrogen linkages.

C They exhibit considerable molecular complexity and diversity. D They are less dense than water. A They have variations in arrangement around a double bond. B They have an asymmetric carbon that makes them mirror images. C They have the same chemical properties. D They have different molecular formulas. A enantiomers B structural isomers C cis-trans isomers D chain length isomers 18 The figure above shows the structures of glucose and fructose. A number of carbon, hydrogen, and oxygen atoms B types of carbon, hydrogen, and oxygen atoms C arrangement of carbon, hydrogen, and oxygen atoms D number of oxygen atoms joined to carbon atoms by double covalent bonds.

A enantiomers B radioactive isotopes C structural isomers D cis-trans isomers. For clarity, only the carbon skeletons are shown; hydrogen atoms that would be attached to the carbons have been omitted. D 22 Which of the pairs of molecular structures shown below depict enantiomers enantiomeric forms of the same molecule? A have identical three-dimensional shapes B are mirror images of one another C are mirror images of one another and have the same biological activity D are cis-trans isomers.

A amino B carbonyl C carboxyl D hydroxyl 27 A compound contains hydroxyl groups as its predominant functional group. A lacks an asymmetric carbon and is probably a fat or lipid B should dissolve in water C should dissolve in a nonpolar solvent D will not form hydrogen bonds with water. A carbonyl and amino groups B carboxyl and amino groups C amino and sulfhydryl groups D hydroxyl and carboxyl groups 29 Amino acids are acids because they always possess which functional group? A amino B carbonyl C carboxyl D phosphate. A only as an acid because of the carboxyl group B only as a base because of the amino group C as an acid and a base D as neither an acid nor a base 31 Which chemical group can act as an acid? A amino B carbonyl C carboxyl D methyl 32 Testosterone and estradiol are male and female sex hormones, respectively, in many vertebrates.

In what way s do these molecules differ from each other? A are structural isomers but have the same molecular formula B are cis-trans isomers but have the same molecular formula C have different functional groups attached to the same carbon skeleton D are enantiomers of the same organic molecule 33 What is the name of the functional group shown in the figure below? A are basic with respect to pH B are found in amino acids C contain nitrogen D are nonpolar. A glucose B starch C cellulose D DNA 3 How many molecules of water are used to completely hydrolyze a polymer that is 11 monomers long?

A 12 B 11 C 10 D 9 4 Which of the following best summarizes the relationship between dehydration reactions and hydrolysis? A Dehydration reactions assemble polymers; hydrolysis reactions break polymers apart. B Dehydration reactions eliminate water from membranes; hydrolysis reactions add water to membranes. C Dehydration reactions and hydrolysis reactions assemble polymers from monomers. D Hydrolysis reactions create polymers and dehydration reactions create monomers.

What would be the molecular formula for a molecule made by linking three glucose molecules together by dehydration reactions? A chitin B cellulose C amylopectin D amylose 9 What does the term insoluble fiber refer to on food packages? A fatty acid B polysaccharide C nucleic acid D monosaccharide. How is lactose classified? A are polymers of glucose B are cis-trans isomers of each other C are used for energy storage in plants D are structural components of the plant cell wall. A a hexose B a pentose C fructose D maltose 15 A glycosidic linkage is analogous to which of the following in proteins? A do not have a polar or charged region B do not have a nonpolar region C have hydrophobic and hydrophilic regions D are highly reduced molecules 17 How do phospholipids interact with water molecules?

A The polar heads avoid water; the nonpolar tails attract water because water is polar and opposites attract. B Phospholipids do not interact with water because water is polar and lipids are nonpolar. C The polar heads interact with water; the nonpolar tails do not. D Phospholipids dissolve in water. A contain serine or some other organic compound B have three fatty acids C have a glycerol backbone D have a phosphate 19 Which of the following is the best explanation for why vegetable oil is a liquid at room temperature while animal fats are solid? A Vegetable oil has more double bonds than animal fats.

B Vegetable oil has fewer double bonds than animal fats. C Animal fats have no amphipathic character. D Vegetable oil has longer fatty-acid tails than animal fats have. A are essential components of cell membranes B are not soluble in water C are made of fatty acids D contribute to atherosclerosis. A is a saturated fatty acid. B stores genetic information. C will be liquid at room temperature. D is a carbohydrate. A fatty acid B steroid C protein D phospholipid 27 Which one of the following is NOT a component of each monomer used to make proteins? A the long carbon-hydrogen tails of the molecule B the presence of a central C atom C the components of the R-group D the glycerol molecule that forms the backbone of the amino acid. What level of structure will be preserved?

A primary structure B secondary structure C tertiary structure D quaternary structure. A Proteins function best at certain temperatures. B Proteins have four distinct levels of structure and many functions. C Enzymes tend to be globular in shape. D Denatured unfolded proteins do not function normally. What is the significance of this finding? B It will be important to include cysteine in the diet of the mice. C Cysteine residues are involved in disulfide bridges that help form tertiary structure. D Cysteine causes bends, or angles, to occur in the tertiary structure of proteins. Use the following information when answering the corresponding question s.

Rhodopsins are light-sensitive molecules composed of a protein opsin and retinal derivative of vitamin A. There are two classes of rhodopsins. According to Oded Beje, one class has relatively slow dynamics a photocycle of approximately 0. The second class has faster dynamics a photocycle of approximately 0. Oded Beje was the first, in September , to report on a rhodopsin proteorhodopsin found in the domain Bacteria. Beje et al. What is the highest level of structure found in this protein? A primary B secondary C tertiary D quaternary.

Where would you expect to find these amino acids in a globular protein in aqueous solution? A Serine would be in the interior, and leucine would be on the exterior of the globular protein. B Leucine would be in the interior, and serine would be on the exterior of the globular protein. C Serine and leucine would both be in the interior of the globular protein. D Serine and leucine would both be on the exterior of the globular protein. Which of the following diseases are associated with an accumulation of misfolded polypeptides? A alter the primary structure of the protein but not its tertiary structure or function B cause the tertiary structure of the protein to unfold C always alter the biological activity or function of the protein D always alter the primary structure of the protein, sometimes alter the tertiary structure of the protein, and sometimes affect its biological activity.

In sickle-cell disease, as a result of a single amino acid change, the mutant hemoglobin tetramers associate with each other and assemble into large fibers. A only altered primary structure B only altered tertiary structure C only altered quaternary structure D altered primary structure and altered quaternary structure; the secondary and tertiary structures may or may not be altered 40 What is the term used for a protein molecule that assists in the proper folding of other proteins? A tertiary protein B chaperonin C renaturing protein D denaturing protein. A is a hydrolysis reaction B results in a peptide bond C joins two fatty acids together D links two polymers to form a monomer.

A The end has a hydroxyl group attached to the number 5 carbon of ribose. B The end has a phosphate group attached to the number 5 carbon of ribose. C The end has phosphate attached to the number 5 carbon of the nitrogenous base. D The end has a carboxyl group attached to the number 5 carbon of ribose. A transmit genetic information to offspring B function in the synthesis of proteins C make a copy of itself, thus ensuring genetic continuity D act as a pattern or blueprint to form DNA.

A 10 B 40 C 80 D It is impossible to tell from the information given. Each molecule may be used once, more than once, or not at all. A 1 B 5 C 12 D 14 53 Which of the following combinations of molecules illustrated could be linked to form a nucleotide? A 1, 2, and 11 B 3, 7, and 8 C 5, 9, and 10 D 11, 12, and 13 54 Which molecule is a saturated fatty acid? A 1 B 5 C 8 D 9 55 Which of the following molecules is a purine nitrogenous base? A 2 B 5 C 12 D 13 56 Which of the following molecules act as building blocks monomers of polypeptides? A 1, 4, and 6 B 2, 7, and 8 C 7, 8, and 13 D 11, 12, and 13 57 Which of the following pairs of molecules could be joined together by a peptide bond in a dehydration reaction?

A one molecule of 9 and three molecules of 10 B three molecules of 9 and one molecule of 10 C one molecule of 5 and three molecules of 9 D one molecule of 5 and three molecules of 10 59 Which of the following molecules is the pentose sugar found in RNA? Scientists there determine that the polypeptide sequence of hemoglobin from the new organism has 72 amino acid differences from humans, 65 differences from a gibbon, 49 differences from a rat, and 5 differences from a frog.

A humans than to frogs B frogs than to humans C rats than to frogs D gibbons than to rats. The accompanying table represents the results of an experiment where the effects of pH buffers on an enzyme found in saliva amylase were studied. A spectrophotometer set at nm was used to measure absorbance at the various pH levels every 20 sec for 2 min. The higher absorbance values would indicate greater enzyme activity. All experiments were conducted at the same temperature. Which statement correctly identifies the result that the optimum pH for amylase function is 7? A The pH with the lowest absorbance values would indicate the optimum pH for amylase since this pH does not affect the structure or function of the protein. B The pH with the highest absorbance values would indicate the optimum pH for amylase since this pH does not affect the structure or function of the protein.

C At pH 9, the enzyme is denatured and will lose its function, but not its structure. D At pH 4, the structure of the enzyme will be altered, and the enzyme would not be able to catalyze the reaction. A relative solubility of the component B size and weight of the component C percentage of carbohydrates in the component D presence or absence of lipids in the component 4 What is the reason that a modern transmission electron microscope TEM can resolve biological images to the subnanometer level, as opposed to tens of nanometers achievable for the best super-resolution light microscope?

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Students returning after an academic dismissal will be readmitted on probation and must meet their required term GPA requirements to avoid another dismissal. First Dismissal - Sit out one fall or spring semester; complete at least one 3 credit hour course that transfers to KU to meet KU Core Goals; earn a 2. Requests made after that will be for admission in the upcoming semester. This process is for active KU students. Students who have been dismissed from another KU School will need to submit a change of school request one week or earlier prior to classes starting. Non-dismissed students may request to change schools through the 20th day of the current semester; after that date requests will be considered for the next semester.

Deadlines are included on the form. Students applying for admission to the College from other schools in the university must meet the same minimum grade-point average requirements in KU attempted course work as continuing College students. A student may enroll in 1 course a semester under the option, if the course is not in their major or minor. To exercise the option, the student must fill out the online form via the Registrar's website during the fifth and sixth weeks of the semester or the third week of summer session and 8-week courses.

See the Academic Calendar for current dates for electing this option. After the close of the option period, the choice cannot be changed. Courses graded Credit or No Credit do not count in computing the grade-point average. Courses graded Credit are included in the total hours counted toward graduation. Courses graded No Credit do not count toward graduation. For more information, visit the KU Policy Library. Warning: Certain undesirable consequences may result from exercising the option. Some schools, scholarship committees, and honorary societies do not accept this grading system and convert grades of No Credit to F when computing grade-point averages.

See the Enrollment Guide for complete enrollment information. Immediately before the beginning of classes each term, an enrollment session is scheduled for new students. New students admitted for summer or fall term have an additional option of enrolling in fall courses during one of several summer orientation sessions. Invitations to orientation are sent automatically to newly admitted and readmitted students who applied for the spring, summer, or fall terms except non degree-seeking students. Readmitted students may attend a special abbreviated orientation session, may enroll during continuing enrollment, or may attend the enrollment sessions immediately before the start of the semester.

Readmitted students whose readmission applications are completed by a designated date also may enroll during continuing enrollment, after meeting with an advisor. All students must preregister for orientation and enrollment sessions. International students must complete the required check-in processes before enrollment and are encouraged to attend International Student Orientation, which includes advising and enrollment sessions. This enrollment allows students who are currently enrolled during one term to enroll for the next term. Spring-enrolled students enroll in April for the following summer session or fall semester or both.

Fall-enrolled students enroll in October or November for the following spring semester. Each semester, the Academic Calendar announces dates for late enrollment and the last day to submit a Petition to Late Enroll. Petitions are evaluated based on past academic performance. A student may enroll in a course or change class sections after the semester has been in session for 4 weeks only if the course has met fewer than 25 percent of the class sessions. For most classes, the faculty have established earlier dates for beginning class attendance and participation. A fee is assessed for late enrollment. The letters F and U unsatisfactory and No Credit indicate that the quality of work was such that, to obtain credit, the student must repeat regular course work.

See the KU Policy Library for more information. Undergraduates may earn honors upon graduation in 3 ways. The student may graduate with distinction or highest distinction, earn departmental honors in the major, or complete the University Honors Program. It is possible to earn honors in 1 of these areas, any combination of them, or all 3. Distinction and highest distinction are noted on the diploma. Of these, the top one-third is designated as graduating with highest distinction. Students must have completed at least 60 hours graded A through F in residence at KU including the hours in which they are enrolled during the semester of graduation.

Awards of distinction and highest distinction are based solely on the grade-point average determined by KU residence credit hours unless the overall grade-point average including transfer hours is lower than the residence grade-point average. In this case, the award is determined by the overall grade-point average. Students who rank in the upper 10 percent of their graduating class graduate with distinction. The upper third of those awarded distinction graduate with highest distinction. Potential candidates are determined in mid-April and invited to a recognition ceremony during Commencement weekend in May.

Final designation is determined in mid-July. Most departments and programs allow qualified majors to work toward graduation with departmental honors. Graduation with departmental honors is awarded in recognition of exceptional performance in the major, completion of a program of independent research or an alternative project, and a strong overall academic record. In addition to the requirements of individual departments and programs which must be approved by the College committee on undergraduate studies and advising , the College requires the following for graduation with departmental honors:. A department or program may petition to award graduation with departmental honors to deserving students who, for good reason, do not meet every College and departmental requirement.

Requirements for graduation with honors may be completed after the date on which certifications are requested from departments, and in some cases, requirements, if not needed for graduation, may be completed after a student has graduated. However, the Incomplete policy does apply and grades would lapse at the time of graduation. Undergraduates with grade-point averages of 3. An Honor Roll notation appears on the transcript.

The University Honors Program provides opportunities for outstanding and creative undergraduates in all schools at KU to develop their full potential during their undergraduate years. See Honors in this section of the online catalog for further information. The letter I indicates incomplete work, such as may be completed without re-enrollment in the course. The letter I should not be used when a definite grade can be assigned for the work done. At the time an I is reported on the electronic roster, the character and amount of work needed, as well as the date required for completion and lapse grade if further work is not completed by this date, should be indicated.

A student who has an I posted for a course must make up the work by the date determined by the instructor, in consultation with the student, which may not exceed 1 calendar year, or the last day of the term of graduation, whichever comes first. Summer enrollment is limited to 10 hours. Permission is not considered unless the student has demonstrated high levels of academic ability in previous semesters. Students are advised to enroll according to prerequisites and co-requisites noted in individual course descriptions. These prerequisites are enforced in a variety of ways including blocking enrollment, administrative drops without notice, etc.

The College of Liberal Arts and Sciences requires that 30 of these 45 credit hours be completed in residence. Departments are not allowed to require more than 40 hours in the major for the B. At least 15 hours in each major s must be taken in residence at KU. Students should complete a minimum of 30 credit hours each year. Students have a maximum of ten years to complete their undergraduate work in the College of Liberal Arts and Sciences under degree requirements in effect at the initial term of matriculation.

Students experiencing a break in enrollment during these ten years will follow their curricular requirements at the point of matriculation provided that the break in enrollment does not exceed two calendar years. Students readmitted after two years are held to the curricular requirements in place at the term of readmission. Students maintaining continuous enrollment but who do not complete their degree requirements within ten years, may petition the College to complete their degree requirements under the curricular requirements in effect during the term of admission.

CredTran is a transfer course equivalency system that lists more than 2, colleges and universities from which KU has accepted transfer courses in the past. If your school or course is not listed, your evaluation will be completed when you are admitted to KU. Only transfer grades of C or higher contribute to total hours earned for students entering KU in spring or after, and for courses taken in spring or after by all students. These include the university requirements for graduate study at KU outlined in the College and Graduate Studies sections of the KU Policy Library , the University Senate Rules and Regulations , the Graduate Studies sections of the online catalog, as well as the requirements of the College outlined in this catalog section.

In general, the student is subject to the regulations in place at the time of matriculation as a degree-seeking student. If degree requirements change, the student may opt to follow the new requirements or to continue under the regulations in place at the time of admission. Any student readmitted 10 years or more after his or her initial term as a degree-seeking student must fulfill the requirements in effect on the date of readmission to the graduate program. Information presented on this page is limited to the most frequently consulted policies and key milestones in the graduate career. The College then verifies that completed coursework meets all College and University requirements for master's students. Students earning a master's thesis degree must have completed at least 1 hour of thesis enrollment.

General rules for the preparation of a thesis are available on the Graduate Studies website. A final general examination or thesis defense in the major subject is required for MA and MS degrees. All master's exams must be preapproved by the College in advance of the scheduled exam date. Degrees in the Graduate Studies section of the online catalog. Coursework requirements for the doctoral degree are established and tracked by the department or program. The College then verifies that completed coursework meets all University and College requirements for doctoral students.

Graduate Studies requires that all doctoral students meet the Research Skills and Responsible Scholarship requirement before proceeding to the Comprehensive Exam. Specific requirements are determined by each department or program in consultation with Graduate Studies. Two semesters, which may include one summer session, must be spent in full-time resident study at KU. The College requires that residency be fulfilled before the comprehensive oral examination is scheduled. For more information on residency requirements, please see the Graduate Studies section of the online catalog.

The comprehensive oral examination covers the major field and any additional content for which the academic unit wishes to hold the student responsible. The examination is expected to be broader than a mere defense of the dissertation proposal. Exam dates must be approved by the College in advance of the scheduled exam date. The student must be enrolled the semester or summer session in which he or she completes the comprehensive oral examination. If more than 5 years elapses between the completion of the comprehensive exam and degree completion, the student may be required to retake the exam.

More information about comprehensive exam requirements may be found in the Graduate Studies section of the online catalog. Completion of the dissertation is the culminating phase of a doctoral program, marked by the final oral examination and defense of the dissertation. In all but the rarest cases, tentative approval of the dissertation is followed promptly by the final oral examination. The exam must be approved by the College in advance of the scheduled exam date. Refer to the Graduate Studies section of the online catalog for further information on the regulations governing the final oral examination, including committee composition and attendance regulations.

Guidelines for preparing and submitting the final copies of the dissertation are available on the KU Libraries' ETD website. Please see the Full-time Enrollment policy in the Graduate Studies section of the online catalog and the KU Policy Library for the definitions of full-time, half-time, and part-time enrollment. At a minimum, all graduate students must be continuously enrolled in the Fall and Spring semesters while completing the requirements for fulfillment of their degree.

Please consult the Graduate Studies section of the online catalog and the KU Policy Library for other enrollment regulations. No enrollment is required during the summer session unless it is the semester during which the student will graduate, in which case enrollment is required. Certain academic units have additional rules governing summer enrollment. After passing the Comprehensive Oral Exam, doctoral candidates must be continuously enrolled. During this time, until all requirements for the degree are completed including the filing of the dissertation or until 18 post-comprehensive hours have been completed whichever comes first , the candidate must enroll for a minimum of 6 hours a semester Fall and Spring.

At least one of these hours each semester must be in dissertation or approved dissertation-equivalent coursework. This may be as little as one dissertation or approved equivalent hour per semester. In addition, Graduate Studies requires a period of at least 1 month to elapse between the comprehensive oral exam and the final exam. Students that have completed all degree requirements before completing 18 hours are still required to continue enrollment until this 1-month requirement has been met. Generally, no student is allowed to enroll in full term courses with an established meeting time after the first 4 weeks of a semester or the first 2 weeks of a summer session.

Non-standard dated courses, or "short courses," as well as research or independent study courses with a "by appointment only" meeting time have different deadlines. Students should consult the academic calendar and the short courses listing for deadlines. If a student does not intend to enroll, he or she must determine the appropriate course of action in consultation with the department or program. The student may elect to Voluntarily Discontinue from the program, and must inform the department or program in writing of this decision.

The department will submit the necessary forms to the College. This option requires the student to seek re-admission to the program if they choose to return at a future date. They also remain eligible to seek admission to another department or program in the College. The student may also petition for a Leave of Absence of up to one calendar year. Students interested in this option should begin by consulting with their advisor. Similarly, if a student that has elected to Voluntarily Discontinue subsequently returns to the program, the time that has elapsed since his or her discontinuance does not count against the time to degree.

Time that accrues during these lapses of enrollment in which the student does not occupy any approved enrollment category i. International students seeking a Leave of Absence must consult with the International Support Services office prior to any change in enrollment status to determine how the change may affect their legal status. Students enrolled in two schools or working on two degrees at the same time must complete the work for both degrees. Courses may not be counted toward both degrees, except in the joint degree programs that have been established e. Please refer to the Combined Degrees information in the Graduate Studies section of the online catalog for a complete list of approved joint degree programs. Article II of the University Senate Rules and Regulations provides detailed information on regulations governing the grading of graduate coursework.

Only courses graded C or above are considered passing and may be counted for graduate credit. Courses graded C-, D or F may not be used to fulfill degree requirements. Incomplete I grades are used to note, temporarily, that a student's work has been satisfactory to date, but that they have been unable to complete a portion of the required course work during that semester due to circumstances beyond their control. Incomplete work must be completed within the time period prescribed by the course instructor, at which point a permanent grade will be assigned.

After one calendar year from the original grade due date, an Incomplete I grade will automatically convert to a grade of F or U, or the lapse-to grade assigned by the course instructor. The I grade is not appropriate for enrollments in thesis, dissertation, or research hours or the first semester of a two-semester sequence. Waiting Grades WG are placeholders and should only be used in rare instances when, for reasons beyond his or her control, an instructor is not able to assign a course grade by the deadline.

WG should not be used to delay evaluation of thesis or dissertation hour enrollments. This practice often leads to difficulties with timely graduation processing. WG is also not appropriate for students who are unable to submit their completed work by the grade deadline. In these cases an Incomplete may be more appropriate. Instructors should follow their unit's internal guidelines for use of Incomplete. In accordance with USRR 2. Degree requirements include those courses used to fulfill the Research Skills and Responsible Scholarship requirement. The plus or minus sign describes intermediate levels of performance between a maximum of A and a minimum of F. Intermediate grades are calculated as 0. Use of the Participation P grade is restricted in the College.

It is only approved for a limited number of courses for which special permission has been sought. When permission is granted, P is only used to indicate participation in thesis, dissertation, or research enrollments related to thesis or dissertation , or in the first semester enrollment of a two-semester sequence course. In any semester when evidence about performance is available, the instructor may elect to assign a letter grade of A, B, C, D, or F. A letter grade A, B, C, D, or F must be assigned in the last semester of enrollment to characterize the quality of the final product. It is the preferred scale for the grading of these courses in the College and is applied in the following manner:.

SP - Satisfactory Progress. Progress is consistent with the goals for the semester as agreed upon with the advisor; supports timely completion of the degree. LP - Limited Progress. Progress is less than what was agreed upon with the advisor; may cause delays in timely degree completion. Academic probation may be warranted. NP - No Progress. The student has provided no evidence of progress on the thesis or dissertation work, or work completed was insufficient to move the thesis or dissertation project forward. Probation is strongly encouraged and dismissal may be warranted. However, programs may elect to use any A-F scale. During calendar years when an established admission deadline falls during one of these times, CLAS graduate programs must either:.

For all GPA-related provisional admissions in the College, the program is required to provide an explanation as to what evidence they considered in determining that the student is prepared to undertake graduate level coursework. This may include a marked improvement in advanced undergraduate coursework, a gap in study during which time the prospective student gained significant professional experience, or other mediating factors relevant to the particular graduate program. Students in the College will remain on provisional status until they have completed their first nine hours of qualifying enrollment and achieved a cumulative GPA of at least.

Qualifying enrollment includes regularly scheduled courses e. It is up to the graduate program to alert the College Office of Graduate Affairs when the terms of the provisional admission have been met, at which time the department may request a removal of the provisional status. Students who fail to achieve at least a 3. However, departments may petition the College for the student to be placed on probation for one-semester in lieu of dismissal. Under no circumstances will probation beyond one semester be granted. To be in good standing, a student must maintain a 3. In any semester, a student whose cumulative GPA has fallen below a 3. Students are notified by the College of their probationary status.

The student has one semester not including the summer term in which to raise the cumulative GPA to a 3. Departments may petition the College for the student to be granted a one- semester extension of the probation. Students whose GPA falls below 2. In the absence of this recommendation, the College will dismiss the student. Upon recommendation of the department or program, a student may be placed on probation for failing to make satisfactory progress toward the degree. This may include, but is not limited to, failed exams or failure to make adequate and timely progress on the dissertation or thesis.

See the Good Academic Standing policy in the Graduate Studies section of the online catalog and the KU Policy Library for more information on what constitutes satisfactory progress. This typically occurs when a student fails to meet the terms of the probationary period. If dismissal occurs during the semester, the dismissal is effective immediately and the student is administratively withdrawn from coursework.

The department or program will notify the student in writing of the reasons for their dismissal. A student who has been dismissed from a graduate program at KU is not eligible for readmission to graduate study in any department or program at the University of Kansas. A student may petition for an exception. The petition must be approved by the department to which the student intends to apply, the graduate division of the College, and the Dean of Graduate Studies. Such petitions are rarely approved.

The University and the College have established time limits governing various stages of the graduate student career. Courses completed at the University of Kansas, or transfer credits from another university, are valid for a period of 10 years. Courses that were completed more than 10 years before the scheduling of the final defense may not be used to fulfill graduate degree requirements in the College of Liberal Arts and Sciences. With the endorsement of their graduate programs, students may petition the College to accept out-of-date course work to fulfill the requirements for their graduate degrees, provided they are able to justify why this course work meets the current standards of scholarship in the discipline.

Until the final manuscript of a thesis or dissertation is submitted, the student must be enrolled in accordance with enrollment policy. Graduate students in the College who do not file the final manuscript within the 6-month time limit must enroll in 3 hours a semester until the thesis or dissertation is completed and submitted. Doctoral degree students have a total of 8 calendar years, excluding any periods of absence due to an approved leave of absence or voluntary discontinuation from a program, to complete the Ph. A time limit extension may be granted by the College. All extension petitions require the student and department to prepare and submit a Graduate Degree Completion Agreement, which must then be approved by a designated subcommittee of the Committee on Graduate Studies.

Per Graduate Studies policy, extensions may be granted for up to 1 year. However, additional time may be requested in the Completion Agreement. If a Completion Agreement with a timeline greater than one year is approved, the department must submit a renewal petition annually after the first year until the Completion Agreement has ended. Renewal petitions must indicate the student's progress on the Completion Agreement and will receive expedited review. Academic units may set their own, more rigorous time limits. Academic integrity requires honest performance of academic and research responsibilities by students. These include, but are not limited to, ethical preparation of assignments, reports, and research papers; completion of examinations; ethical treatment of human and animal subjects; execution of administrative requirements; and a sincere and conscientious effort by students to abide by the policies set forth by instructors and research advisors.

Graduate Studies establishes an early deadline for degree completion for each semester and summer session, usually occurring at the end of the first 2 weeks of a semester or the end of the first week of summer session. If the student was enrolled the previous semester and meets all degree requirements including the submission of all required documentation by this early deadline, they are not required to enroll for that semester. Please consult the official Academic Calendar for specific dates. To be eligible for graduation, an application for degree must be submitted and all degree requirements met by this deadline. This includes the submission of all required documentation to the College Office of Graduate Affairs.

Undergraduates may earn honors upon graduation in 3 ways, in addition to making the honor roll each semester. Students may graduate with distinction or highest distinction, earn departmental honors in the major, or complete the University Honors Program. To be eligible, students must have completed at least 60 credit hours, graded A through F, in residence at KU. See Required Work in Residence below. Graduation with departmental honors is awarded in recognition of exceptional performance in the major and completion of a program of independent research or an alternative project.

In addition to the requirements of individual departments and programs which must be approved by the College committee on Undergraduate Studies and Advising - CUSA , the College requires the following for graduation with departmental honors:. When a candidate finishes all requirements, departments must notify College Advising and Student Services in writing. The College of Liberal Arts and Sciences offers several awards to recruit, support, and recognize outstanding graduate students, and to recognize faculty service, teaching excellence, and exemplary advising. Below, you will find a brief description of each award.

Fellows must submit an application for external funding to be eligible for a fifth year of support. The award is limited to those who completed an undergraduate degree at KU. The Committee on Graduate Studies in the College has established this award for students receiving a master's degree. Students are nominated for the award by their advisors. Graduate students may nominate any tenured or tenure-track faculty member in the College of Liberal Arts and Sciences who has served as an outstanding mentor. AAAS Arabic and Islamic Studies. An introduction to the study of Islam and the Arabic language in relation to Islamic cultures in Africa, the Mediterranean region, and beyond.

Topics covered include the historical origins of Islam in relation to the Arabic language and its cultures of origin. This course is interdisciplinary, including attention to the topic from the perspectives of historical unfolding of both the language and religion, geographic and cultural perspectives, political and economic concerns, and aesthetic perspectives, including literature and the arts.

Introduction to Africa. An introduction to the interdisciplinary study of African cultures and societies focusing on contemporary life on the continent. Topics to be covered include the geography, history, politics, and economics of the continent, as well as the religion, languages and literatures, music, and the arts. The interdisciplinary perspective will provide students with a sound basis for understanding contemporary African societies.

Introduction to African-American Studies. Interdisciplinary introduction to the basic concepts and literature in the disciplines covered in African American Studies. Includes the social sciences, and humanities including history, religion, and literature as well as conceptual framework for investigation and analysis of Black history and culture and society. Introduction to African History. An introduction to important historical developments in Africa. Topics include empires, kingdoms, the slave trade, European colonialism, liberation movements, national identities, and a return to independence. Same as HIST The Black Experience in the Americas. An interdisciplinary study of the history of the African peoples of the New World, relating their cultures and institutions to the African background and to their peculiar New World experiences up to and including the nineteenth century.

While the main emphasis is on the U. Approaches include demography, economics, social and political developments, literature, and music. Introduction to African History, Honors. An introduction to important historical developments in Africa, mainly south of the Sahara. Topics include early history, empires, kingdoms and city-states, the slave trade, southern Africa, partition and colonialism, the independence era, military and civilian governments, and liberation movements.

Approaches include literature, the visual arts, politics, economics, and geography. Open only to students in the University Honors Program or by consent of instructor. The Black Experience in the Americas, Honors. An intensive version of AAAS Introduction to West African History. This course treats West African history through the first part of the twentieth century. The student is provided with a perspective on the major historical patterns that gave rise to West Africa's development as an integral part of world history. Special attention is paid to anthropological, geographical, and technological developments that influenced West African political and socioeconomic changes. Course is designed to meet the critical thinking learning outcome of the KU Core.

Prerequisite: First-time freshman status. It prepares students for continued practice in cultural reading and writing and for the academic rigor that awaits them at the upper levels. Prerequisite: Consent of department. Culture and Health. This course offers a holistic, interdisciplinary approach to understandings of health, well-being, and disease within and across cultures. It draws upon the subfields of anthropology, as well as the humanities, natural sciences, and social sciences. This course should be of special interest to premedical students and majors in the allied health professions. Culture and Health, Honors. Brazil and Africa: Atlantic Encounters. This is a survey course on the history of the relationships between Brazil and Western Africa from the sixteenth century onward.

We examine the shape of the Atlantic world, the nature of the Portuguese empire in Brazil and Africa, the presence of Brazilian born agents in Western Africa, the cultural exchanges, the impact of colonial rule, and the responses of indigenous societies to these developments. Students develop familiarity with major historical concepts, themes, and subjects. The course also aims to explore history as process to make sense of the past and the present. African Traditional Religion and Thought. A study of African traditional religious beliefs, systems and practices and how these have conditioned spiritual, moral and social values, attitudes, social relationships and institutions, art, literature and music.

Topics covered include the African world-view, concepts of birth, life, marriage, death and reincarnation; the concurrent practice or monotheism, polytheism and the cult of the ancestors; and the extent of relevance to Black societies in the New World. Haiti: Culture and Identity. This course examines Haiti's identity and culture through historical, social, political, economic, linguistic and religious lenses. Through the study of texts, films and articles, it analyzes Haiti's place and influence in history as the first Black Republic and the second independent nation in the Western hemisphere. The slightly negative regions of one water molecule are attracted to the slightly positive regions of nearby water molecules, forming hydrogen bonds.

Each water molecule can form hydrogen bonds with up to four neighbors. They form, break, and reform with great frequency. Each hydrogen bond lasts only a few trillionths of a second. At any instant, a substantial percentage of all water molecules are bonded to their neighbors, creating a high level of structure. Collectively, hydrogen bonds hold water together, a phenomenon called cohesion. Cohesion among water molecules plays a key role in the transport of water and dissolved nutrients against gravity in plants. Water molecules move from the roots to the leaves of a plant through water-conducting vessels. As water molecules evaporate from a leaf, other water molecules from vessels in the leaf replace them. Hydrogen bonds cause water molecules leaving the vessels to tug on molecules farther down.

This upward pull is transmitted down to the roots. Adhesion, clinging of one substance to another, contributes too, as water adheres to the wall of the vessels. Surface tension, a measure of the force necessary to stretch or break the surface of a liquid, is related to cohesion. Water has a greater surface tension than most other liquids because hydrogen bonds among surface water molecules resist stretching or breaking the surface. Water behaves as if covered by an invisible film. Some animals can stand, walk, or run on water without breaking the surface. Water moderates temperatures on Earth. Water stabilizes air temperatures by absorbing heat from warmer air and releasing heat to cooler air. Water can absorb or release relatively large amounts of heat with only a slight change in its own temperature.

Atoms and molecules have kinetic energy, the energy of motion, because they are always moving. The faster a molecule moves, the more kinetic energy it has. Heat is a measure of the total quantity of kinetic energy due to molecular motion in a body of matter. Temperature measures the intensity of heat in a body of matter due to the average kinetic energy of molecules. As the average speed of molecules increases, a thermometer will record an increase in temperature. Heat and temperature are related, but not identical. When two objects of different temperatures come together, heat passes from the warmer object to the cooler object until the two are the same temperature. Molecules in the cooler object speed up at the expense of kinetic energy of the warmer object.

Ice cubes cool a glass of pop by absorbing heat from the pop as the ice melts. While there are several ways to measure heat energy, one convenient unit is the calorie cal. In many biological processes, the kilocalorie kcal is more convenient. Another common energy unit, the joule J , is equivalent to 0. Water stabilizes temperature because it has a high specific heat. Water has a high specific heat compared to other substances. For example, ethyl alcohol has a specific heat of 0. Water resists changes in temperature because of its high specific heat. In other words, water absorbs or releases a relatively large quantity of heat for each degree of temperature change. Heat must be absorbed to break hydrogen bonds, and heat is released when hydrogen bonds form.

Investment of one calorie of heat causes relatively little change to the temperature of water because much of the energy is used to disrupt hydrogen bonds, not speed up the movement of water molecules. A large body of water can absorb a large amount of heat from the sun in daytime during the summer and yet warm only a few degrees. At night and during the winter, the warm water will warm cooler air. Therefore, ocean temperatures and coastal land areas have more stable temperatures than inland areas. Living things are made primarily of water. Consequently, they resist changes in temperature better than they would if composed of a liquid with a lower specific heat. The transformation of a molecule from a liquid to a gas is called vaporization or evaporation.

This occurs when the molecule moves fast enough to overcome the attraction of other molecules in the liquid. Even in a low-temperature liquid with low average kinetic energy , some molecules are moving fast enough to evaporate. Heating a liquid increases the average kinetic energy and increases the rate of evaporation. Heat of vaporization is the quantity of heat that a liquid must absorb for 1 g of it to be converted from liquid to gas. Water has a relatively high heat of vaporization, requiring about cal of heat to evaporate 1 g of water at room temperature.

This is double the heat required to vaporize the same quantity of alcohol or ammonia. This is because hydrogen bonds must be broken before a water molecule can evaporate from the liquid. As moist tropical air moves to the poles, water vapor condenses to form rain, releasing heat. As a liquid evaporates, the surface of the liquid that remains behind cools, a phenomenon called evaporative cooling. This occurs because the most energetic molecules are the most likely to evaporate, leaving the lower—kinetic energy molecules behind.

Evaporative cooling moderates temperature in lakes and ponds. Evaporation of sweat in mammals or evaporation of water from the leaves of plants prevents terrestrial organisms from overheating. Evaporation of water from the leaves of plants or the skin of humans removes excess heat. Water is unusual because it is less dense as a solid than as a cold liquid. Most materials contract as they solidify, but water expands. Water begins to freeze when its molecules are no longer moving vigorously enough to break their hydrogen bonds.

As ice starts to melt, some of the hydrogen bonds break, and water molecules can slip closer together than they can while in the ice state. Therefore, ice floats on the cool water below. This oddity has important consequences for life. If ice sank, eventually all ponds, lakes, and even the ocean would freeze solid. During the summer, only the upper few centimeters of the ocean would thaw. Instead, the surface layer of ice insulates liquid water below, preventing it from freezing and allowing life to exist under the frozen surface. Water is the solvent of life. A liquid that is a completely homogeneous mixture of two or more substances is called a solution.

A sugar cube in a glass of water will eventually dissolve to form a uniform solution of sugar and water. The dissolving agent is the solvent, and the substance that is dissolved is the solute. In our example, water is the solvent and sugar is the solute. In an aqueous solution, water is the solvent. Water is not a universal solvent, but it is very versatile because of the polarity of water molecules. Water is an effective solvent because it readily forms hydrogen bonds with charged and polar covalent molecules.

The Cl? Each dissolved ion is surrounded by a sphere of water molecules, a hydration shell. Eventually, water dissolves all the ions, resulting in a solution with two solutes: sodium and chloride ions. Polar molecules are also soluble in water because they form hydrogen bonds with water. Even large molecules, like proteins, can dissolve in water if they have ionic and polar regions. Any substance that has an affinity for water is hydrophilic water-loving. These substances are dominated by ionic or polar bonds.

Some hydrophilic substances do not dissolve because their molecules are too large. For example, cotton is hydrophilic because cellulose, its major constituent, has numerous polar covalent bonds. However, its giant cellulose molecules are too large to dissolve in water. Water molecules form hydrogen bonds with the cellulose fibers of cotton, allowing you to dry yourself with your cotton towel as the water is pulled into the towel. Substances that have no affinity for water are hydrophobic water-fearing. These substances are nonionic and have nonpolar covalent bonds. Because there are no consistent regions with partial or full charges, water molecules cannot form hydrogen bonds with hydrophobic molecules.

Oils such as vegetable oil are hydrophobic because the dominant bonds, carbon-carbon and carbon-hydrogen, share electrons equally. Hydrophobic molecules are major ingredients of cell membranes. Chemical reactions depend on collisions of molecules and therefore on the concentrations of solutes in aqueous solution. We measure the number of molecules in units called moles. A mole is equal to the molecular weight of a substance but scaled up from daltons to grams. To illustrate, how could we measure out a mole of table sugar—sucrose C12H22O11?

A carbon atom weighs 12 daltons, hydrogen 1 dalton, and oxygen 16 daltons. One molecule of sucrose would weigh daltons, the sum of weights of all the atoms in sucrose, or the molecular weight of sucrose. To get one mole of sucrose, we would weigh out g. The advantage of using moles as a measurement is that a mole of one substance has the same number of molecules as a mole of any other substance. If substance A has a molecular weight of 10 daltons and substance B has a molecular weight of daltons, then we know that 10 g of substance A has the same number of molecules as g of substance B.

A mole of sucrose contains 6. Measuring in moles allows scientists to combine substances in fixed ratios of molecules. The concentration of a material in solution is called its molarity. A one molar solution has one mole of a substance dissolved in one liter of solvent, typically water. To make a 1 molar 1M solution of sucrose, we would slowly add water to g of sucrose until the total volume was 1 liter and all the sugar was dissolved.

The water molecule that lost the proton is now a hydroxide ion OH? This reaction is reversible. In pure water, only one water molecule in every million is dissociated. Although the dissociation of water is reversible and statistically rare, it is very important in the chemistry of life. Because hydrogen and hydroxide ions are very reactive, changes in their concentrations can drastically affect the chemistry of a cell. Adding certain solutes, called acids and bases, disrupts the equilibrium and modifies the concentrations of hydrogen and hydroxide ions. The pH scale is used to describe how acidic or basic a solution is. Organisms are sensitive to changes in pH. An acid is a substance that increases the hydrogen ion concentration in a solution.

Addition of an acid makes a solution more acidic. Any substance that reduces the hydrogen ion concentration in a solution is a base. Solutions in which concentrations of OH? These molecules dissociate completely in water. Other acids and bases NH3 are weak acids or bases. For these molecules, the binding and release of hydrogen ions are reversible. At equilibrium, there will be a fixed ratio of products to reactants. Adding a base does the opposite, increasing OH? The pH scale, ranging from 1 to 14, compresses the range of concentrations by employing logarithms. The pH of a neutral solution is 7. Acidic solutions have pH values less than 7, and basic solutions have pH values greater than 7. Most biological fluids have pH values in the range of 6 to 8.

However, the human stomach has strongly acidic digestive juice with a pH of about 2. To maintain cellular pH values at a constant level, biological fluids have buffers. Buffers accept hydrogen ions from the solution when they are in excess and donate hydrogen ions when they have been depleted. Buffers typically consist of a weak acid and its corresponding base.

One important buffer in human blood and other biological solutions is carbonic acid, which dissociates to yield a bicarbonate ion and a hydrogen ion. The chemical equilibrium between carbonic acid and bicarbonate acts as a pH regulator. Acid precipitation threatens the fitness of the environment. Acid precipitation is a serious assault on water quality in some industrialized areas. Uncontaminated rain has a slightly acidic pH of 5. The acid is a product of the formation of carbonic acid from carbon dioxide and water. Acid precipitation occurs when rain, snow, or fog has a pH that is more acidic than 5. Acid precipitation is caused primarily by sulfur oxides and nitrogen oxides in the atmosphere. These molecules react with water to form strong acids that fall to the surface with rain or snow.

The major source of these oxides is the burning of fossil fuels coal, oil, and gas in factories and automobiles. The presence of tall smokestacks allows this pollution to spread from its site of origin to contaminate relatively pristine areas thousands of kilometers away. The effects of acids in lakes and streams are more pronounced in the spring during snowmelt. As the surface snows melt and drain down through the snowfield, the meltwater accumulates acid and brings it into lakes and streams all at once. The pH of early meltwater may be as low as 3.

Acid precipitation has a great impact on the eggs and the early developmental stages of aquatic organisms that are abundant in the spring. Thus, strong acidity can alter the structure of molecules and impact ecological communities. Direct impacts of acid precipitation on forests and terrestrial life are more controversial. However, acid precipitation can impact soils by affecting the solubility of soil minerals. Acid precipitation can wash away key soil buffers and plant nutrients such as calcium and magnesium ions. It can also increase the concentrations of compounds such as aluminum to toxic levels.

This has done major damage to forests in Europe and substantial damage of forests in North America. Progress has been made in reducing acid precipitation. Chapter 04 - Carbon and the Molecular Diversity of Life. Carbon is unparalleled in its ability to form large, complex, and diverse molecules. Carbon accounts for the diversity of biological molecules and has made possible the great diversity of living things. Proteins, DNA, carbohydrates, and other molecules that distinguish living matter from inorganic material are all composed of carbon atoms bonded to each other and to atoms of other elements. These other elements commonly include hydrogen H , oxygen O , nitrogen N , sulfur S , and phosphorus P.

Organic compounds can range from simple molecules, such as CO2 or CH4, to complex molecules such as proteins, which may weigh more than , daltons. The overall percentages of the major elements of life C, H, O, N, S, and P are quite uniform from one organism to another. Variations in organic molecules can distinguish even between individuals of a single species. The science of organic chemistry began in attempts to purify and improve the yield of products obtained from other organisms. Initially, chemists learned to synthesize simple compounds in the laboratory, but had no success with more complex compounds.

The Swedish chemist Jons Jacob Berzelius was the first to make a distinction between organic compounds that seemed to arise only in living organisms and inorganic compounds that were found in the nonliving world. This led early organic chemists to propose vitalism, the belief that physical and chemical laws did not apply to living things. Support for vitalism began to wane as organic chemists learned to synthesize complex organic compounds in the laboratory. In , Stanley Miller at the University of Chicago set up a laboratory simulation of chemical conditions on the primitive Earth and demonstrated the spontaneous synthesis of organic compounds.

Such spontaneous synthesis of organic compounds may have been an early stage in the origin of life. Organic chemists finally rejected vitalism and embraced mechanism, accepting that the same physical and chemical laws govern all natural phenomena including the processes of life. Organic chemistry was redefined as the study of carbon compounds regardless of their origin. Organisms do produce the majority of organic compounds. The laws of chemistry apply to inorganic and organic compounds alike. Carbon has little tendency to form ionic bonds by losing or gaining 4 electrons to complete its valence shell.

Instead, carbon usually completes its valence shell by sharing electrons with other atoms in four covalent bonds. This tetravalence by carbon makes large, complex molecules possible. When carbon forms covalent bonds with four other atoms, they are arranged at the corners of an imaginary tetrahedron with bond angles of In molecules with multiple carbons, every carbon bonded to four other atoms has a tetrahedral shape.

However, when two carbon atoms are joined by a double bond, all bonds around those carbons are in the same plane and have a flat, three-dimensional structure. The three-dimensional shape of an organic molecule determines its function. The electron configuration of carbon makes it capable of forming covalent bonds with many different elements. The valences of carbon and its partners can be viewed as the building code that governs the architecture of organic molecules. In carbon dioxide, one carbon atom forms two double bonds with two different oxygen atoms. This arrangement completes the valence shells of all atoms in the molecule. While CO2 can be classified as either organic or inorganic, its importance to the living world is clear.

CO2 is the source of carbon for all organic molecules found in organisms. It is usually fixed into organic molecules by the process of photosynthesis. Urea, CO NH2 2, is another simple organic molecule in which each atom forms covalent bonds to complete its valence shell. Carbon chains form the skeletons of most organic molecules. The skeletons vary in length and may be straight, branched, or arranged in closed rings.

The carbon skeletons may include double bonds. Atoms of other elements can be bonded to the atoms of the carbon skeleton. Hydrocarbons are organic molecules that consist of only carbon and hydrogen atoms. Hydrocarbons are the major component of petroleum, a fossil fuel that consists of the partially decomposed remains of organisms that lived millions of years ago. Fats are biological molecules that have long hydrocarbon tails attached to a nonhydrocarbon component. Petroleum and fat are hydrophobic compounds that cannot dissolve in water because of their many nonpolar carbon-to-hydrogen bonds.

Isomers are compounds that have the same molecular formula but different structures and, therefore, different chemical properties. For example, butane and isobutane have the same molecular formula, C4H10, but butane has a straight skeleton and isobutane has a branched skeleton. The two butanes are structural isomers, molecules that have the same molecular formula but differ in the covalent arrangement of atoms. Geometric isomers are compounds with the same covalent partnerships that differ in the spatial arrangement of atoms around a carbon—carbon double bond. The double bond does not allow atoms to rotate freely around the bond axis. The biochemistry of vision involves a light-induced change in the structure of rhodopsin in the retina from one geometric isomer to another.

Enantiomers are molecules that are mirror images of each other. Enantiomers are possible when four different atoms or groups of atoms are bonded to a carbon. In this case, the four groups can be arranged in space in two different ways that are mirror images. They are like left-handed and right-handed versions of the molecule. Usually one is biologically active, while the other is inactive. Even subtle structural differences in two enantiomers have important functional significance because of emergent properties from specific arrangements of atoms. One enantiomer of the drug thalidomide reduced morning sickness, the desired effect, but the other isomer caused severe birth defects.

If we consider hydrocarbons to be the simplest organic molecules, we can view functional groups as attachments that replace one or more of the hydrogen atoms bonded to the carbon skeleton of the hydrocarbon. Each functional group behaves consistently from one organic molecule to another. The number and arrangement of functional groups help give each molecule its unique properties. As an example, the basic structure of testosterone a male sex hormone and estradiol a female sex hormone is the same. Both are steroids with four fused carbon rings, but they differ in the functional groups attached to the rings.

These functional groups interact with different targets in the body. There are six functional groups that are most important to the chemistry of life: hydroxyl, carbonyl, carboxyl, amino, sulfhydryl, and phosphate groups. All are hydrophilic and increase the solubility of organic compounds in water. In a hydroxyl group —OH , a hydrogen atom forms a polar covalent bond with an oxygen atom, which forms a polar covalent bond to the carbon skeleton.

Because of these polar covalent bonds, hydroxyl groups increase the solubility of organic molecules. Organic compounds with hydroxyl groups are alcohols, and their names typically end in -ol. If the carbonyl group is on the end of the skeleton, the compound is an aldehyde. If the carbonyl group is within the carbon skeleton, then the compound is a ketone. Isomers with aldehydes versus ketones have different properties. A carboxyl group —COOH consists of a carbon atom with a double bond to an oxygen atom and a single bond to the oxygen of a hydroxyl group. Compounds with carboxyl groups are carboxylic acids. An amino group —NH2 consists of a nitrogen atom bonded to two hydrogen atoms and the carbon skeleton. Organic compounds with amino groups are amines.

Amino acids, the building blocks of proteins, have amino and carboxyl groups. A sulfhydryl group —SH consists of a sulfur atom bonded to a hydrogen atom and to the backbone. This group resembles a hydroxyl group in shape. Organic molecules with sulfhydryl groups are thiols. Two sulfhydryl groups can interact to help stabilize the structure of proteins. A phosphate group —OPO32? A phosphate group connects to the carbon backbone via one of its oxygen atoms. Phosphate groups are anions with two negative charges, as two protons have dissociated from the oxygen atoms. One function of phosphate groups is to transfer energy between organic molecules. Adenosine triphosphate, or ATP, is the primary energy-transferring molecule in living cells.

These are the chemical elements of life. Living matter consists mainly of carbon, oxygen, hydrogen, and nitrogen, with smaller amounts of sulfur and phosphorus. These elements are linked by strong covalent bonds. Carbon, with its four covalent bonds, is the basic building block in molecular architecture. The great diversity of organic molecules with their special properties emerges from the unique arrangement of the carbon skeleton and the functional groups attached to the skeleton. Chapter 05 - The Structure and Function of Macromolecules. These large macromolecules may consist of thousands of covalently bonded atoms and weigh more than , daltons.

The four major classes of macromolecules are carbohydrates, lipids, proteins, and nucleic acids. A polymer is a long molecule consisting of many similar or identical building blocks linked by covalent bonds. The repeated units are small molecules called monomers. Some of the molecules that serve as monomers have other functions of their own. The chemical mechanisms that cells use to make and break polymers are similar for all classes of macromolecules. Monomers are connected by covalent bonds that form through the loss of a water molecule. This reaction is called a condensation reaction or dehydration reaction. When a bond forms between two monomers, each monomer contributes part of the water molecule that is lost.

One monomer provides a hydroxyl group —OH , while the other provides a hydrogen —H. Cells invest energy to carry out dehydration reactions. The process is aided by enzymes. The covalent bonds connecting monomers in a polymer are disassembled by hydrolysis, a reaction that is effectively the reverse of dehydration. In hydrolysis, bonds are broken by the addition of water molecules. A hydrogen atom attaches to one monomer, and a hydroxyl group attaches to the adjacent monomer. Our food is taken in as organic polymers that are too large for our cells to absorb. Within the digestive tract, various enzymes direct hydrolysis of specific polymers.

The resulting monomers are absorbed by the cells lining the gut and transported to the bloodstream for distribution to body cells. The body cells then use dehydration reaction to assemble the monomers into new polymers that carry out functions specific to the particular cell type. An immense variety of polymers can be built from a small set of monomers. Each cell has thousands of different kinds of macromolecules. These molecules vary among cells of the same individual. They vary more among unrelated individuals of a species, and even more between species.

This diversity comes from various combinations of the 40—50 common monomers and some others that occur rarely. These monomers can be connected in a great many combinations, just as the 26 letters in the alphabet can be used to create a great diversity of words. The simplest carbohydrates are monosaccharides, or simple sugars. Disaccharides, or double sugars, consist of two monosaccharides joined by a condensation reaction. Polysaccharides are polymers of many monosaccharides. Sugars, the smallest carbohydrates, serve as fuel and a source of carbon. Monosaccharides generally have molecular formulas that are some multiple of the unit CH2O. For example, glucose has the formula C6H12O6. Depending on the location of the carbonyl group, the sugar is an aldose or a ketose.

Most names for sugars end in -ose. Glucose, an aldose, and fructose, a ketose, are structural isomers. Monosaccharides are also classified by the number of carbons in the carbon skeleton. Glucose and other six-carbon sugars are hexoses. Five-carbon backbones are pentoses; three-carbon sugars are trioses. Monosaccharides may also exist as enantiomers. For example, glucose and galactose, both six-carbon aldoses, differ in the spatial arrangement of their parts around asymmetrical carbons.

Monosaccharides, particularly glucose, are a major fuel for cellular work. They also function as the raw material for the synthesis of other monomers, such as amino acids and fatty acids. While often drawn as a linear skeleton, monosaccharides in aqueous solutions form rings. Two monosaccharides can join with a glycosidic linkage to form a disaccharide via dehydration. Maltose, malt sugar, is formed by joining two glucose molecules. Sucrose, table sugar, is formed by joining glucose and fructose. Sucrose is the major transport form of sugars in plants. Lactose, milk sugar, is formed by joining glucose and galactose.

Polysaccharides, the polymers of sugars, have storage and structural roles. Polysaccharides are polymers of hundreds to thousands of monosaccharides joined by glycosidic linkages. Some polysaccharides serve for storage and are hydrolyzed as sugars are needed. Other polysaccharides serve as building materials for the cell or the whole organism. Starch is a storage polysaccharide composed entirely of glucose monomers. Most of these monomers are joined by 1—4 linkages number 1 carbon to number 4 carbon between the glucose molecules.

The simplest form of starch, amylose, is unbranched and forms a helix. Branched forms such as amylopectin are more complex. Plants store surplus glucose as starch granules within plastids, including chloroplasts, and withdraw it as needed for energy or carbon. Animals that feed on plants, especially parts rich in starch, have digestive enzymes that can hydrolyze starch to glucose. Animals store glucose in a polysaccharide called glycogen. Glycogen is highly branched like amylopectin. Cellulose is a major component of the tough wall of plant cells.

Plants produce almost one hundred billion tons of cellulose per year. It is the most abundant organic compound on Earth. Like starch, cellulose is a polymer of glucose. However, the glycosidic linkages in these two polymers differ. The difference is based on the fact that there are actually two slightly different ring structures for glucose. These two ring forms differ in whether the hydroxyl group attached to the number 1 carbon is fixed above beta glucose or below alpha glucose the plane of the ring. Starch is a polysaccharide of alpha glucose monomers. Cellulose is a polysaccharide of beta glucose monomers, making every other glucose monomer upside down with respect to its neighbors.

The differing glycosidic links in starch and cellulose give the two molecules distinct three-dimensional shapes. While polymers built with alpha glucose form helical structures, polymers built with beta glucose form straight structures. The straight structures built with beta glucose allow H atoms on one strand to form hydrogen bonds with OH groups on other strands. In plant cell walls, parallel cellulose molecules held together in this way are grouped into units called microfibrils, which form strong building materials for plants and for humans, as lumber. The enzymes that digest starch by hydrolyzing its alpha linkages cannot hydrolyze the beta linkages in cellulose. Some microbes can digest cellulose to its glucose monomers through the use of cellulase enzymes.

Many eukaryotic herbivores, from cows to termites, have symbiotic relationships with cellulolytic microbes, providing the microbe and the host animal access to a rich source of energy. Some fungi can also digest cellulose. Another important structural polysaccharide is chitin, used in the exoskeletons of arthropods including insects, spiders, and crustaceans. Chitin is similar to cellulose, except that it contains a nitrogen-containing appendage on each glucose monomer.

Pure chitin is leathery but can be hardened by the addition of calcium carbonate. Chitin also provides structural support for the cell walls of many fungi. The unifying feature of lipids is that they all have little or no affinity for water. This is because they consist mostly of hydrocarbons, which form nonpolar covalent bonds. Lipids are highly diverse in form and function. Fats store large amounts of energy. Although fats are not strictly polymers, they are large molecules assembled from smaller molecules by dehydration reactions. A fat is constructed from two kinds of smaller molecules: glycerol and fatty acids. Glycerol is a three-carbon alcohol with a hydroxyl group attached to each carbon.

A fatty acid consists of a carboxyl group attached to a long carbon skeleton, often 16 to 18 carbons long. The many nonpolar C—H bonds in the long hydrocarbon skeleton make fats hydrophobic. Fats separate from water because the water molecules hydrogen bond to one another and exclude the fats. In a fat, three fatty acids are joined to glycerol by an ester linkage, creating a triacylglycerol, or triglyceride.

The three fatty acids in a fat can be the same or different. Fatty acids may vary in length number of carbons and in the number and locations of double bonds.

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