1) Identify the following types of isomers, for ten points each.
They differ in the covalent arrangements of their atoms, such as butane and isobutane.
Answer: structural isomers
They have the same covalent partnerships, but they differ in their spatial arrangements, such as cis-but-2-ene and trans-but-2-ene.
Answer: geometric isomers
They are mirror images of each other, such as L-Dopa and D-Dopa.
Answer: enantiomers
2) Answer the following about organic functional groups and compounds important in biochemistry, for 2 and 4/13 points each.
Name the functional group consisting of a hydrogen atom bonded to an oxygen atom, which is bonded to a carbon skeleton, and give the name of compounds containing this functional group.
Answer: hydroxyl; alcohol
Name the functional group consisting of a carbon atom joined to an oxygen atom by a double bond, and give the name of compounds containing this group at the end of their carbon skeleton, and give the name of compounds containing this group elsewhere in the carbon skeleton.
Answer: carbonyl; aldehyde; ketone
Name the functional group consisting of an oxygen atom double-bonded to a carbon atome that is also bonded to a hydroxyl group, and give the name of compounds containing this group.
Answer: carboxyl; carboxylic acids
Name the functional group consisting of a nitrogen atom bonded to two hydrogen atoms and to the carbon skeleton, and give the name of compounds containing this group.
Answer: amino; amines
Name the functional group consisting of a sulfur atom bonded to an atom of hydrogen, and give the name of compounds containing this group.
Answer: sulfhydryl; thiols
Name the functional group consisting of a phosphate ion covalently attached by one of its oxygen atoms to the carbon skeleton, and give the name of compounds containing this group.
Answer: phosphate;
organic phosphates
3) Identify the following terms related to biochemical bonding from their definitions, for 4 and 2/7 points each.
A reaction in which two molecules are covalently bonded to each other through the loss of a small molecule.
Answer: condensation reaction
A specific type of condensation reaction in which the molecule lost is water.
Answer: dehydration reaction
A reaction in which bonds are broken by the addition of water molecules; it is the reverse of a dehydration reaction.
Answer: hydrolysis
A long molecule consisting of many identical or similar building blocks linked by covalent bonds.
Answer: polymers
The repeating molecular units which serve as the building blocks of a polymer.
Answer: monomers
The type of bonds between monosaccharides in sugars.
Answer: glycosidic linkages
The type of bonds between amino acids in proteins.
Answer: peptide bonds
4) Answer the following about monosaccharides, for 2.5 points each.
Monosaccharides can be divided into two major categories. In one, the carbonyl group is located on the end of the carbon skeleton, while in the other it is one away from the end. Name these two categories, respectively.
Answer: aldoses (aldehyde sugars); ketoses (ketone sugars)
Most monosaccharides can also be categorized based on how many carbon atoms they contain as triose sugars, pentose sugars, or hexose sugars. For each of the following monosaccharides, classify it based on both its carboyl location and its number of carbons. For example, if I said glucose, you would obviously answer "aldose, hexose".
Ribose
Answer: aldose, pentose
Fructose
Answer: ketose, hexose
Glyceraldehyde
Answer: aldose, triose
Galactose
Answer: aldose, hexose
Ribulose
Answer: ketose, pentose
5) Given a disaccharide, name its two component monosaccharides, for five points each.
Maltose
Answer: glucose, glucose
Lactose
Answer: glucose, galactose
Sucrose
Answer: glucose, fructose
6) Identify the following polysaccharides from their descriptions, for five points each.
A polymer of glucose monomers found in plants, and normally connected by 1-4 linkages, it stores energy.
Answer: starch
The simplest, unbranched form of starch.
Answer: amylose
A branched form of starch with 1-6 linkages at the branch points.
Answer: amylopectin
A highly branched polymer of glucose which stores energy in animals, usually in the liver and muscles.
Answer: glycogen
The most abundant organic compound on Earth, it is similar to starch except that the glucose monomers are in the Beta ring formation rather than the Alpha ring formation, and it is a major component of the cell walls in plants.
Answer: cellulose
A polysaccharide of glucose molecules with nitrogen-containing appendages, it is leathery but hardens when encrusted with calcium carbonate, and is used to build exoskeletons in arthropods.
Answer: chitin
7) Answer the following related to lipids, for three points each.
Fats consist of two major components. The first is an alcohol with three carbons, each bearing a hydroxyl group. The second is a chain of usually 16 to 18 carbons, with a carboxyl group at one end. Name these two components, respectively.
Answer: glycerol; fatty acid
Fats can be classified into these two categories based on whether there are any double bonds between carbon atoms in the fatty acid hydrocarbon tail.
Answer: saturated, unsaturated
Another term for a fat, this word reflects the fact that a fat consists of three fatty acids linked to one glycerol molecule.
Answer: triacylglycerol
These lipids are similar to fats, except that one of the fatty acids is replaced by a phosphate group.
Answer: phospholipids
This term describes a molecule which is both hyrdophobic and hydrophilic, such as phospholipids.
Answer: ambivalent
These are circular clusters of phospholipids which form in water, with the hydrophilic phosphate heads on the outside and the hydrophobic hydrocarbon tails on the inside.
Answer: micelle
This is a type of lipid characterized by a carbon skeleton consisting of four fused rings. Many function as hormones.
Answer: steroids
Many other steroids are synthesized from this steroid, which is a common component of animal cell membranes, but which may contribute to atherosclerosis.
Answer: cholesterol
8) Answer the following about amino acids, for five points each.
An amino acid consists of a carbon atom bound to a hydrogen atom, a side chain unique to each amino acid, and two functional groups. Name the two functional groups.
Answer: amino, carboxyl
There are twenty amino acids found in proteins, each distinguished by its side chain. Given a description of its side chain, identify the following amino acids.
The simplest amino acid, its side chain is just a hydrogen atom.
Answer: glycine
Its side chain is a methyl group.
Answer: alanine
Its side chain is an isopropyl group, and when it substitutes for glutamic acid in red blood cell proteins, it causes sickle-cell anemia.
Answer: valine
Its side chain is a sulfhydryl group.
Answer: cysteine
9) Answer the following concerning the four levels of protein structure, for six points each.
A protein's primary structure is its unique sequence of this type of molecule.
Answer: amino acids
A protein's secondary structure is the series of coils and folds which determine its conformation. One of the two most common types of secondary structures is a delicate coil held together by hydrogen bonding between every fourth amino acid, whereas in the other type, two regions of the polypeptide chain lie parallel to each other, with their backbones hydrogen bonded to each other. Name these two structures, respectively.
Answer: alpha-helix; pleated sheet
A protein's tertiary structure consists of irregular contortions from bonding between side chains of the various amino acids. When two cysteine monomers are brought close together, this type of covalent bond can form, riveting parts of the protein together.
Answer: disulfide bridge
A protein may consist of more than one polypeptide chain, and the combination of these chains is known as the protein's quaternary structure. When proteins fold, they are sometimes assisted by other proteins, known by this name, that serve as temporary braces.
Answer: chaperone
proteins
10) Answer the following about nucleotides, for 4 and 2/7 points each.
Nucleotides consist of three major components. Name them.
Answer: nitrogenous base, pentose (prompt on sugar), phosphate group
A nitrogenous base bound to a pentose sugar, without a phosphate group, is known by this term.
Answer: nucleoside
DNA differs from RNA in that its component pentose is lacking an oxygen on its number two carbon. Name the pentoses in DNA and in RNA, respectively.
Answer: deoxyribose, ribose
RNA molecules also differ from DNA molecules in that the nitrogenous base thymine is replaced by this other nitrogenous base.
Answer: uracil
11) Nitrogenous bases can be classified into two families. The first is characterized by six-membered rings of carbon and nitrogen atoms, while the second is characterized by a six-membered ring fused to a five-membered ring. Name these two families, respectively, for 4 and 2/7 points each.
Answer: pyrimidines; purines
Name the three members of the pyrimidine family, for 4 and 2/7 points each.
Answer: cytosine, thymine, uracil
Name the three members of the purine family, for 4 and 2/7 points each.
Answer: adenine, guanine
12) Answer the following concerning the chemical processes in an organism, for six points each.
The totality of an organism's chemical processes is known by this term, which comes from the Greek for "to change".
Answer: metabolism
Metabolism can be divided into processes which release energy by breaking down complex molecules to simpler compounds, and those processes which consume energy to build complicated molecules from simpler ones. Name these two processes, respectively.
Answer: catabolism; anabolism
There are two main types of catabolic pathways. In one, oxygen is consumed as a reactant along with the organic fuel. In the other, sugars are partially degraded without the help of oxygen. Name these two pathways, respectively.
Answer: cellular respiration; fermentation
13) Identify the following terms related to biological catalysts from their definitions, for three points each.
The general term for catalytic proteins.
Answer: enzymes
The reactant on which an enzyme acts.
Answer: substrate
The region of an enzyme molecule which actually binds to the substrate, typically a pocket or groove on its surface.
Answer: active site
Nonprotein molecules which assist enzymes, usually by binding permanently or reversibly to the active site.
Answer: cofactors
Organic molecules which act as cofactors.
Answer: coenzymes
Molecules which resemble the structure of a substrate and compete for admission to the active site, reducing the productivity of enzymes by blocking the substrates from entering the active sites.
Answer: competitive inhibitors
Molecules which bind to some part of an enzyme other than its active site, causing it to change conformation, making its active site unreceptive to its substrate.
Answer: noncompetitive inhibitors
A receptor site on an enzyme to which noncompetitive inhibitors can bind.
Answer: allosteric site
The process by which a metabolic pathway is turned off by its end-product, which acts as an inhibitor of an enzyme within the pathway.
Answer: feedback inhibition
An interaction of the constituent subunits of a protein causing a conformational change in one subunit to be transmitted to all the others.
Answer: cooperativity
14) Identify the following instruments used in the study of cells, for 7.5 points each.
In this type of microscope, visible light is passed through the specimen and then through glass lenses, which refract the light in such as way that the image is magnified as it is projected into the eye.
Answer: light microscope
In this type of microscope, a beam of electrons is focused using electromagnets through sections of preserved cells stained with atoms of heavy metals.
Answer: transmission electron microscope (prompt on just electron microscope)
In this type of microscope, the electron beam scans the surface of the sample, which is coated with a thin film of gold, producing a three-dimensional topography of the specimen.
Answer: scanning electron microscope (prompt on jus electron microscope)
These machines, which spin at up to 80,000 rpm, are used for cell fractionation, separating the major organelles so their individual functions may be studied.
Answer: ultracentrifuge
15) Answer the following about the basics of cells, for six points each.
Cells may be classified into two major categories. One, whose name comes from the Greek for "before kernel", has no nucleus. The other, whose name comes from the Greek for "true kernel", has a membrane-bound nucleus and membrane-bound organelles. Name these two categories, respectively.
Answer: prokaryotes; eukaryotes
The DNA in a prokaryote is concentrated in a region known by this name.
Answer: nucleoid
The entire region between the nucleus in a eukaryote and the cell membrane is known by this name.
Answer: cytoplasm
The cytoplasm consists of organelles suspended in this semifluid medium.
Answer: cytosol
16) In this bonus, and the eight which follow, we will examine the components of a eukaryotic cell. In this bonus, identify the following terms related to the nucleus, for six points each.
A double membrane, each a lipid bilayer with associated proteins, which is perforated by pores and surrounds the nucleus.
Answer: nuclear envelope
A netlike array of protein filaments which lines the nuclear side of the nuclear envelope and maintains the shape of the nucleus.
Answer: nuclear lamina
Material within the nucleus consisting of DNA organized along with proteins.
Answer: chromatin
Chromatin that is coiled into thick structures as the cell prepares to divide.
Answer: chromosomes
A structure within the nucleus where components of ribosomes are synthesized.
Answer: nucleolus
17) Identify the following terms related to the endomembrane system from their definitions, for 3.75 points each.
An extensive membranous network which is continuous with the outer nuclear membrane, composed of ribosome-studded and ribosome-free regions.
Answer: endoplasmic reticulum
The network of membranous tubules and sacs which compose endoplasmic reticulum.
Answer: cisternae
The internal compartment of endoplasmic reticulum.
Answer: cisternal space
This structure receives transport vesicles with materials produced by the endoplasmic reticulum at its cis-face, and releases its products from its trans-face.
Answer: Golgi apparatus
A membrane-bounded sac of hydrolytic enzymes which the cell uses to digest macromolecules.
Answer: lysosome
The two types of membrane-bound sacs in the cell, differentiated by their size.
Answer: vesicles, vacuoles
The membrane which encloses the large central vacuole in mature plant cells.
Answer: tonoplast
18) Identify the following terms related to the site of cellular respiration from their definitions, for ten points each.
The organelle in which cellular respiration takes place
Answer: mitochondrion
The infoldings of the mitochondrion's inner membrane, which give the membrane a large surface area, enhancing the productivity of cellular respiration.
Answer: cristae
The compartment in the mitochondrion within the inner membrane, in which some of the metabolic steps of cellular respiration take place.
Answer: mitochondrial matrix
19) Identify the following terms related to plastids in plant cells from their definitions, for five points each.
Colorless plastids which store starch, particularly in roots and tubers.
Answer: amyloplasts
Plastids which are rich in pigments which give fruits and flowers their orange and yellow hues.
Answer: chromoplasts
Plastids which contain the green pigment chlorophyll along with enzymes and other molecules that function in the photosynthetic production of food.
Answer: chloroplasts
The membranous system of flattened sacs inside the chloroplast.
Answer: thylakoids
Structures of thylakoids, stacked like poker chips.
Answer: grana
The fluid outside the thylakoids inside a chloroplast.
Answer: stroma
20) Identify the following terms related cell organelles not included in the previous bonuses, from their definitions, for 7.5 points each.
The sites where the cell makes proteins; they can be either free or bound.
Answer: ribosomes
Membrane-bound compartments which transfer hydrogen from substrates to oxygen, used to break down large molecules or detoxify harmful compounds.
Answer: peroxisomes
Peroxisomes produce this toxic chemical as a by-product, but contain enzymes to convert it to water.
Answer: hydrogen peroxide
Specialized peroxisomes in the fat-storing tissues of plant seeds which convert fatty acids to sugar.
Answer: glyoxysomes
21) Identify the following terms relating to the network of fibers in the cytoplasm of a cell from their definitions, for five points each.
The general term for the entire network of fibers in the cytoplasm which contributes to cell organization and activity.
Answer: cytoskeleton
There are three major components of the cytoskeleton. Identify them from their descriptions.
These fibers are hollow tubes made of alpha and beta tubulin, which form compression-resisting girders, contribute to cell motility, move chromosomes in cell division, and move organelles.
Answer: microtubules
These fibers are two intertwined strands of actin, which function in cytoplasmic streaming, cell motility, tension-bearing, and cell division.
Answer: microfilaments
These fibers are proteins of the keratin family supercoiled into thick cables, which anchor some organelles, form nuclear lamina, and bear tension.
Answer: intermediate filaments
Name the region near the nucleus which is also known as the microtubule-organizing center, from which microtubules grow.
Answer: cerntrosome
Name the pair of structures in animal cells which are composed of nine sets of triplet microtubules arranged in a ring, and replicate during cell division.
Answer: centrioles
22) Identify the following terms related to cell motility from their definitions, for 4 and 2/7 points each.
A locomotive appendage which undulates, driving a cell in the same direction as the axis of the appendage; there are usually no more than one or a few per cell.
Answer: flagellum
Locomotive appendages which work like oars, moving the cell in a direction perpendicular to its axis; there may be many per cell.
Answer: cilia
Cellular extensions by which a cell can crawl along a surface in ameboid movement.
Answer: pseudopodia
The two proteins which are interdigitated in muscle cells, and whose contractions and extensions can cause movement.
Answer: actin, myosin
A large contractile protein which forms the sidearms of microtubule doublets in cilia and flagella.
Answer: dynein
A structure similar to a centriole which anchors a cilium or flagellum.
Answer: basal body
23) There are three main types of interceullular junctions in animals. Identify them from their descriptions, for ten points each.
These connections form continuous belts around the cell, and the membranes of neighboring cells are actually fused, forming a seal that prevents leakage of extracellular fluid.
Answer: tight junctions
These junctions function like rivets, fastening cells together into strong epithelial sheets.
Answer: desmosomes
These connections provide cytoplasmic channels between adjacent cells, and special membrane proteins surround each pore, which is wide enough for small molecules to pass through.
Answer: gap junctions
24) Identify the following terms related to the substance in which animal tissue cells are embedded from their definitions, for five points each.
The general term for the substance of proteins and polysaccharides in which animal tissue cells are embedded.
Answer: extra-cellular matrix
The general term for proteins covalently bonded to carbohydrates, which are the major component of the extra-cellular matrix.
Answer: glycoproteins
The most abundant protein in animals, it forms strong fibers in the extra-cellular matrix and is found extensively in connective tissue and bone.
Answer: collagen
A type of glycoprotein containing up to 95% carbohydrate which forms complex networks in the extra-cellular matrix.
Answer: proteoglycans
Receptor proteins which are built into the plasma membrane, spanning the membrane and bound to microfilaments of the cytoskeleton, allowing them to transmit changes in the extra-cellular matrix to the cytoskeleton and vice versa.
Answer: integrins
A type of glycoprotein in the extra-cellular matrix which bind to integrins.
Answer: fibronectins
25) Answer the following related to cell membranes, for 7.5 points each.
The currently accepted model of cellular membranes holds that proteins are dispersed and individually inserted into a bilayer of phospholipids.
Answer: fluid mosaic model
There are two major types of membrane proteins. One type are generally trans-membrane proteins, with hydrophobic regions that completely span the hydrophobic interior of the membrane. The other type are not embedded in the lipid bilayer but rather are appendages loosely to the surface of the membrane. Name these two types, respectively.
Answer: integral proteins; peripheral proteins
Most membrane carbohydrates are branched with fewer than 15 sugar units, known by this name, from the Greek for "few".
Answer: oligosaccharides
26) Identify the following terms related to passive transport from their definitions, for 4 and 2/7 points each.
The tendency for molecules of any substance to spread out into the available space.
Answer: diffusion
The difference in molecules of a substance per volume in two different regions, down which the substance will diffuse.
Answer: concentration gradient
The diffusion of water across a selectively permeable membrane.
Answer: osmosis
The control of water balance in a cell
Answer: osmoregulation
Give, respectively, the relative terms for a solution with higher concentration, lower concentration, and the same concentration as a given solution.
Answer: hypertonic; hypotonic; isotonic
27) A cell may gain or lose water depending on the concentration of its environment relative to itself. Give, respectively, the terms for an animal cell in hypertonic, isotonic, and hypotonic solutions, for five points each.
Answer: shriveled; normal; lysed
Give, respectively, the terms for a plant cell in hypertonic, isotonic, and hypotonic solutions, for five points each.
Answer: plasmolyzed; flaccid; turgid
28) Answer the following related to active transport, for 7.5 points each.
One of the most important transport systems in cells is a pump which creates steep concentration gradients by transporting three molecules of one cation out of the cell for every two molecules of another cation pumped into the cell. Name the two cations, respectively.
Answer: sodium; potassium
This type of pump actively transports hydrogen ions out of the cell.
Answer: proton pump
Transports, such as the sodium-potassium pump and the proton pump, which generate a voltage across a membrane by transferring charge across the membrane, are known by this name.
Answer: electrogenic pump
29) Identify the following terms related to the transport of large molecules across a membrane from their definitions, for six points each.
The secretion of macromolecules out of the cell by the fusion of vesicles with the plasma membrane.
Answer: exocytosis
The reception of macromolecules and particulate matter into the cell by forming new vesicles from the plasma membrane.
Answer: endocytosis
A type of endocytosis in which a cell engulfs a particle by wrapping pseudopodia around it and packaging it within a vacuole; it is also known as "cellular eating".
Answer: phagocytosis
A type of endocytosis in which the cell gulps droplets of extracellular fluid in tiny vesicles; it is also known as "cellular drinking".
Answer: pinocytosis
A type of endocytosis in which proteins in the membrane with specific receptor sites are exposed to the extracellular fluid, making the transport specific to certain substances.
Answer: receptor-mediated endocytosis
30) Answer the following about the splitting of sugar, for three points each.
Give the general term for the catabolic pathway which breaks down glucose molecules, the first process in cellular respiration and fermentation.
Answer: glycolysis
In glycolysis, one molecule of glucose is converted into two molecules of this compound.
Answer: pyruvate
Through the glycolysis pathway, for each molecule of glucose, two molecules of one compound are phosphorylated from ADP, and two molecules of another compound are reduced from NAD+. Give the full names of these two compounds, respectively.
Answer: adenosine triphosphate; nicotinamide adenine dinucleotide hydride
Glycolysis is a ten-step pathway, involving ten enzymes. Name the two enzymes which phosphorylate ADP to make ATP, and the two enzymes which phosphorylate glucose from ATP, forming ADP.
Answer: phosphoglycerokinase, pyruvate kinase; hexokinase, phosphofructokinase
Name the two intermediates in the glycolysis pathway which have two phosphate groups attached.
Answer: fructose 1,6-biphosphate, 1,3-bisphosphoglycerate
31) Answer the following concerning cellular respiration after glycolysis, for five points each.
Upon entering the mitochondrion, a molecule of pyruvate is converted into two compounds, as it reacts with Coenzyme A, and one molecule of NAD+ is reduced to NADH. Name these two compounds.
Answer: acetyl CoA, carbon dioxide
Name the cycle of reactions which takes place in the mitochondrion, reducing three molecules of NAD+, reducing one molecule of FAD, phosphorylating one molecule of ADP, and releasing two molecules of carbon dioxide, for each molecule of acetyl CoA.
Answer: Krebs cycle
Identify the following intermediates in the Krebs cycle from their descriptions.
This six-carbon molecule is formed immediately after the addition of an acetyl CoA molecule.
Answer: citrate
This four-carbon molecule is formed immediately following the release of Coenzyme A and the phosphorylation of ADP into ATP.
Answer: succinate
This four-carbon molecule is formed from malate and is the immediate precursor of citrate.
Answer: oxaloacetate
32) Identify the following terms related to the completion of cellular respiration from their definitions, for six points each.
A series of reactions in the mitochondrion membrane that uses FADH2 and NADH molecules produced in glycolysis and the Krebs cycle and breaks the fall of electrons to oxygen into several energy-releasing steps instead of one explosive reaction.
Answer: electron transport chain
The production of ATP using energy derived from the redox reactions of an electron transport chain.
Answer: oxidative
phosphorylation
The production of ATP using the energy of hydrogen-ion gradients created by the electron transport chain to phosphoylate ADP into ATP.
Answer: chemiosmosis
The potential energy stored in the form of an electrochemical gradient, generated by the pumping of hydrogen ions across biological membranes during chemiosmosis.
Answer: proton-motive
force
A cluster of several membrane proteins found in the mitochondrial cristae that use the energy of a hydrogen-ion concentration gradient to make ATP.
Answer: ATP synthase
33) Identify the following terms related to catabolic pathways other than cellular respiration from their definitions, for ten points each.
A catabolic process which makes a limited amount of ATP from glucose without an electron transport chain, oxidizing NADH back to NAD+ by some alternate mechanism.
Answer: fermentation
In this type of fermentation, common in yeast, pyruvate molecules are converted into acetaldehyde, which is then reduced to ethanol as NADH is oxidized to NAD+.
Answer: alcohol fermentation
In this type of fermentation, common in human muscles, pyruvate molecules are reduced to lactate as NADH is oxidized to NAD+.
Answer: lactic acid fermentation
34) Identify the following terms related to the first of the two processes involved in photosynthesis from their definitions, for three points each.
The collective name for this process, which uses solar energy to split water, transferring the electrons and hydrogen atoms to nicotinamide adenine dinucleotide phosphate and phosphorylating ADP to ATP.
Answer: light reactions
In the thylakoid membrane, chlorophyll is organized along with proteins and other small organic molecules into these systems, which can absorb light.
Answer: photosystems
There are two photosystems, each with a reaction-center chlorophyll molecule named for the wavelengths at which it absorbs light. Give the names of the reaction-centers for Photosystem I and Photosystem II, respectively.
Answer: P700; P680
When P680 absorbs light, two electrons are excited and jump to a specialized chlorophyll a molecule. The electron "hole" in P680 is filled by splitting water into oxygen, hydrogen atoms, and electrons. The excited electrons then cascade down an electron transport chain consisting of three types of electron carriers. The electrons end up filling the electron "hole" in P700, which is created when it absorbs light, exciting some of its electrons into another of the specialized chlorophyll a molecules. These electrons then fall down another electron transport chain consisting of an iron-containing protein. At the end, an enzyme transfers the electrons from this protein to NADP+, creating NADPH. Give the name for the specialized chlorophyll a molecule, the three types of electron carriers in the first electron transport chain, the iron-containing protein, and the enzyme which transfers electrons to NADP+, respectively.
Answer: primary acceptor; plastoquinione, cytochromes, plastocyanin; ferredoxin; NADP+ reductase
35) Answer the following about photosynthetic pigments, for five points each.
This blue-green pigment is the only one which can participate directly in the light reactions.
Answer: chlorophyll a (prompt on just chlorophyll)
This yellow-green accessory pigment is almost identical to chlorophyll a, but has a slightly different absorption spectrum.
Answer: chlorophyll b
Other accessory pigments are hydrocarbons of various shades of yellow and orange, and function in photoprotection, dissipating excessive light energy which might damage chlorophyll.
Answer: caretenoids
Name the two colors of light most effective for photosynthesis, and the least effective color.
Answer: red, blue; green
36) Identify the following terms related to the second step in photosynthesis from their definitions, for ten points each.
The cycle of reactions in the chloroplast which uses nine molecules of ATP and six molecules of NADPH produced by the light reactions to convert three molecules of carbon dioxide to one molecule of a sugar.
Answer: Calvin cycle
The three-carbon phosphorylated sugar which is directly produced by the Calvin cycle.
Answer: glyceraldehyde-3-phosphate (prompt on G3P)
The most abundant protein on Earth, which serves as an enzyme to attach a carbon dioxide molecule to ribulose bisphosphate in the Calvin cycle.
Answer: rubisco (or ribulose bisphosphate carboxylase)
37) Identify the following terms related to carbon fixation from their definitions, for 3 and 1/3 points each.
A plant which uses the Calvin cycle for the initial steps that incorporate carbon dioxide into organic material, forming a three-carbon compound as the first stable intermediate.
Answer: C3 plant
A metabolic pathway that consumes oxygen, releases carbon dioxide, generates no ATP, and decreases photosynthetic output; it usually occurs on hot, dry, bright days when stomata close and the oxygen content in a leaf exceeds that of carbon dioxide.
Answer: photorespiration
A plant which combats photorespiration by prefacing the Calving cycle with reactions that incorporate carbon dioxide into four-carbon compounds, the end-product of which supplies carbon dioxide for the Calvin cycle.
Answer: C4 plant
In C4 plants, there are two types of photosynthetic cells. One type are tightly arranged around the veins of the leaf, and are the only type in which the Calvin cycle occurs. The other type are loosely arranged on the leaf surface, and incorporate carbon dioxide into four-carbon sugars. Name these two types of cells, respectively.
Answer: bundle-sheath cells; mesophyll cells
In C4 plants, carbon dioxide is added to a three-carbon molecule by an enzyme to form a four-carbon sugar. Name the three-carbon sugar, the enzyme, and the four-carbon sugar, respectively.
Answer: phosphoenolpyruvate (PEP); PEP carboxylase; oxaloacetate
This type of metabolism is used by some plants to combat photorespiration by converting carbon dioxide that enters open stomata at night into organic acids which release carbon dioxide for the Calvin cycle during the day, when the stomata are closed to conserve water.
Answer: crassulacean acid metabolism (prompt on CAM)
38) Identify the following terms related to cell communication from their definitions, for 3 and 1/3 points each.
This is a series of steps involving reception, transduction, and response by which a cell takes action based on external signals.
Answer: signal-transduction pathway
This type of protein is activated when a receptor protein in the membrane is activated by a signal molecule and displaces a GDP molecule on this protein with a GTP molecule, activating this protein, which in turn activates enzymes which lead to a cellular response.
Answer: G-protein
When activated, the cytoplasmic side of this type of receptor protein catalyzes the transfer of phosphate groups from ATP to an amino acid on a substrate protein.
Answer: tyrosine-kinase receptor
These channels are protein pores in the plasma membrane that open or close in response to a chemical signal, allowing or blocking the flow of specific ions, such as Na+ or Ca2+.
Answer: ligand-gated ion channels
This term refers to small, nonprotein, water-soluble molecules or ions which relay signals within a cell.
Answer: second
messangers
This ring-shaped molecule made from ATP is a second messenger.
Answer: cyclic adenosine monophosphate (or cyclic AMP)
This enzyme converts ATP to cyclic AMP in response to an external signal, such as epinephrine.
Answer: adenylyl cyclase
These two second messengers are produced by cleavage of the phospholipids in the plasma membrane, and lead to the release of calcium from the endoplasmic reticulum.
Answer: diacylglycerol (DAG), inositol trisphosphate (IP3)
39) Answer the following terms related to the cell cycle, for three points each.
This term refers to the cell's total hereditary endowment of DNA.
Answer: genome
All eukaryotic cells can be classified into two categories, reproductive cells and non-reproductive cells. Give the names and the number of chromosomes present in the human versions of each category, respectively.
Answer: gametes : 23; somatic cells : 46
Each chromosome duplicated in preparation for cell division consists of two of these, which are identical copies of the chromosome's DNA molecule. They are separated during cell division.
Answer: sister chromatids
This is the centralized region joining two sister chromatids.
Answer: centromere
Each chromatid has this structure of proteins and specific sections of chromosomal DNA at the centromere. They are pulled apart during cell division.
Answer: kinetochores
This assemblage of microtubules orchestrates chromosome movement during cell division, pulling the kinetochores apart.
Answer: mitotic spindle
This structure is a double membrane across the midline of a dividing plant cell, between which the new cell wall forms.
Answer: cell plate
40) Answer the following about the phases of the cell cycle, for 2.5 points each.
There are two major phases in the cell cycle. During the first, which often accounts for ninety percent of the cycle, the cell grows and copies its chromosomes. During the second, the cell divides. Name these two phases, respectively.
Answer: interphase; mitotic phase
There are three phases within interphase. During the first, the cell begins to grow. During the second, the cell continues to grow while replicating its DNA. During the third, the cell completes its growth. Name these three phases, respectively.
Answer: G1 (gap 1); S; G2 (gap 2)
There are six phases within the mitotic phase. Identify them from their descriptions, which are given in chronological order.
In this phase, chromatin fibers condense into chromosomes. The nucleoli disappear. Each duplicated chromosome appears as two identical sister chromatids joined together. The mitotic spindle begins to form. The centrosomes move away from each other.
Answer: prophase
In this phase, the nuclear envelope fragments. Each of the two chromatids of a chromosome now have developed a kinetochore, and some microtubules attach to the kinetochores.
Answer: prometaphase
In this phase, the centrosomes have reached opposite poles. The chromosomes convene on an imaginary plane equidistant between the two poles. The sister chromatids of each chromosome straddle this metaphase plate.
Answer: metaphase
In this phase, the paired centromeres of each chromosome separate, liberating the sister chromatids from each other. The kinetochore microtubules shorten, moving the chromatids to opposite poles.
Answer: anaphase
In this phase, nuclei form at the two poles of the cell. Nuclear envelopes arise, and the chromosomes become less tightly coiled. Mitosis is completed.
Answer: telophase
In this phase, separate from mitosis, which is the replication of the nucleus, but still in the mitotic phase, the cytoplasm is divided, forming two new daughter cells.
Answer: cytokinesis
In animal cells, cytokinesis initially forms this structure, which pinches the cell in two.
Answer: cleavage furrow
41) Identify the following terms related to phosphorylating enzymes from their definitions, for six points each.
An enzyme that transfers phosphate groups from ATP to a protein.
Answer: protein kinase
An enzyme that remove phosphate groups from proteins.
Answer: protein phosphatase
A protein with a cyclically fluctuating concentration in the cell.
Answer: cyclin
A phosphate-transferring enzyme which must be attached to a cyclin protein to be activated.
Answer: cyclin-dependent kinase (Cdks)
The first cyclin-dependent kinase to be discovered, it triggers the cell's passage past the G2 checkpoint into M phase.
Answer: maturation promoting factor (MPF)
42) Identify the following terms related to cancer from their definitions, for six points each.
A mass of abnormal cells within an otherwise normal tissue.
Answer: tumor
The process that converts a normal cell to a cancer cell.
Answer: transformation
A type of tumor in which the abnormal cells remain at the original site, and can usually be completely removed by surgery.
Answer: benign tumor
A type of tumor which is invasive and can impair the function of organs.
Answer: malignant tumor
The spread of cancer cells beyond their original site.
Answer: metastasis
43) Answer the following terms related to cell divisions which create gametes, for 2.5 points each.
This type of cell division produces gametes with half the chromosome number of the original cell. In Phase I, homologous chromosomes are separated, while in Phase II, which is similar to mitosis, sister chromatids are separated.
Answer: meiosis
Another term for fertilization, this refers to the union of gametes.
Answer: syngamy
This term refers to a fertilized egg.
Answer: zygote
All eukaryotic cells can be classified into two categories, depending on whether they have one or two sets of chromosomes. Name these two categories, respectively.
Answer: haploid; diploid
In this process during prophase I of meiosis, the duplicated chromosomes pair with their homologues.
Answer: synapsis
This term refers to the four closely associated chromatids of a homologous pair.
Answer: tetrad
This process is the reciprocal exchange of genetic material between nonsister chromatids during synapsis of meiosis I.
Answer: crossing over
This X-shaped region represents homologous chromatids that have exchanged genetic material through crossing over.
Answer: chiasma
The typical plant life cycle consists of both a multicellular diploid form and a multicellular haploid form. Give the name for this life cycle, as well as the names for both the diploid and haploid stages, respectively.
Answer: alternation of generations; sporophyte; gametophyte
44) Identify the following terms related to genetics from their definitions, for 1 and 7/8 points each.
A heritable feature, such as flower color, that varies among individuals.
Answer: character
Each variant of a character, such as a purple flower.
Answer: trait
The mating, or crossing, of two varieties.
Answer: hybridization
Plants which, when they self-pollinate, have offspring of all the same variety.
Answer: true-breeding
Alternative versions of a gene.
Answer: alleles
Having a pair of identical alleles for a character.
Answer: homozygous
Having two different alleles for a gene.
Answer: heterozygous
The allele which is expressed when an organism is heterozygous for a character.
Answer: dominant allele
The allele which is not expressed when an organism is heterozygous for a character.
Answer: recessive allele
The genetic makeup of an organism, noting all its dominant and recessive alleles
Answer: genotype
The appearance of an organism, determined by the expression of its genotype
Answer: phenotype
Mendel's first law, which states that allele pairs separate during gamete formation, and then randomly re-form pairs during the fusion of gametes at fertilization.
Answer: law of segregation
Breeding of an organism of unknown genotype with a homozygous recessive individual to determine the unknown genotype.
Answer: testcross
Give the names of the first three generations in a monohybrid cross.
Answer: P (parental), F1 (first filial), F2 (second filial)
45) Answer the following related to Mendel's second law, for ten points each.
Name Mendel's second law, which states that each allele pair segregates independently during gamete formation, and applies when genes for two traits are located on different pairs of homologous chromosomes.
Answer: law of independent assortment
Use the law of independent assortment to answer the following question. Assume yellow seeds are dominant to green seeds and that round seeds are dominant to wrinkled seeds. Cross a homozygous yellow-round seed with a homozygous green-wrinkled seed, and then self-pollinate the F1 generation. What will be the ratio of yellow-round to green-round to yellow-wrinkled to green-wrinkled seeds in the F2 generation?
Answer: 9:3:3:1 (YYRR*yyrr = YyRr for F1)
Use the law of multiplication to answer the following question. Assume purple flowers are dominant to white flowers, yellow seeds are dominant to green seeds, and round seeds are dominant to wrinkled seeds. A gardener crosses pure-breeding purple-flowered, yellow-round seeded peas with white-flowered, green-wrinkled peas. What fraction of the F2 generation are expected to be pure-breeding with white flowers and round seeds and heterozygous with regard to seed color?
Answer: 1/32 (PPYYRR*ppyyrr = PpYyRr for F1 , 1/4 pp, 1/2 Yy, 1/4 RR in F2)
46) Identify the following terms related to problems with simple Mendelian genetics from their definitions, for five points each.
A type of inheritance in which F1 hybrids have an appearance that is intermediate between the phenotypes of the parental varieties.
Answer: incomplete dominance
A type of inheritance in which both alleles are separately manifest in the phenotype.
Answer: codominance
The ability of a gene to affect an organism in many ways.
Answer: pleiotropy
The ability of a gene at one locus to alter the phenotypic expression of a gene at a second locus.
Answer: epistasis
An additive effect of two or more genes on a single phenotypic quantitative character.
Answer: polygenic inheritance
The range of phenotypic possibilities over which a genotype may be expressed due to environmental variations.
Answer: norm of reaction
47) Identify the following genetic diseases from their descriptions, for 7.5 points each.
It is the most common lethal genetic disease in the US, and is caused by the lack of a membrane protein that transports chloride ion between cells and the extracellular fluid, causing a buildup of mucus.
Answer: cystic fibrosis
Most common among Ashkenazic Jews, it is caused by a dysfunctional enzyme that fails to break down brain lipids of a certain class, and causes death within a few years.
Answer: Tay-Sachs disease
The most common inherited disease among blacks, it is caused by the substitution of one amino acid in hemoglobin, deforming red blood cells. Those who are carriers of this disease may be more resistant to malaria.
Answer: sickle-cell anemia
One of the few lethal diseases caused by a dominant allele, it has no obvious effect until the individual is at least 35 years old, but then begins an irreversible and fatal deterioration of the nervous system.
Answer: Huntington's disease
48) Identify the following terms related to the chromosomal basis of inheritance from their definitions, for 4 and 2/7 points each.
The most common phenotype in the natural population.
Answer: wild type
Traits that are alternatives to the wild type.
Answer: mutant phenotypes
Offspring whose phenotype matches exactly matches that of one of its parent's phenotypes.
Answer: parental type
Offspring whose phenotype is different from both of its parents' phenotypes.
Answer: recombinant
Genes which are located on the same