BIOL - 1260 - final exam

which of the following statements is true about enzyme catalyzed reactions?

a. they release more free energy than noncatalyzed reactions

b. they require energy to activate the enzyme

c. the free-energy change of the reaction is opposite from the reaction that occurs in the absence of the enzyme

d. the reaction is faster than the same reaction in the absence of the enzyme

e. an enzymes catalyzes a reaction by raising the activation energy

which of the following statements is true about enzyme catalyzed reactions?

a. they release more free energy than noncatalyzed reactions

b. they require energy to activate the enzyme

c. the free-energy change of the reaction is opposite from the reaction that occurs in the absence of the enzyme

d. the reaction is faster than the same reaction in the absence of the enzyme

e. an enzymes catalyzes a reaction by raising the activation energy

d

during a laboratory experiment, you discover that an enzyme-catalyzed reaction has a delta G of -20 kcal/mol. if you double the amount of enzyme in the reaction, what will be the new delta G for the reaction?

-20 kcal/mol

enzymes -

increase the rate of a reaction by lowering the activation energy

enzymes would be needed for starch to decompose rapidly because -

the activation energy barrier for this reaction cannot easily be surmounted at ambient temperature

human enzymes function less efficiently in temperatures above body temp. which of the FBIS most directly corresponds to this phenomenon, given the effect of temperature on enzyme integrity?

structure and function

_ is a product of glycolysis, pyruvate processing and the Krebs cycle

NADH

the glucose molecule has a large quantity of energy in its -

C-H bonds

in glycolysis, for each molecule of glucose oxidized to pyruvate -

two molecules of ATP are used and four molecules of ATP are produced

which of the following statements about NAD+ is true?

a. NAD+ has more chemical energy than NADH

b. NAD+ can donate electrons for use in oxidative phosphorylation

c. NAD+ is oxidized by the action of hydrogenases

d. in the absence of NAD+, glycolysis can still function

e. NAD+ is reduced to NADH during glycolysis, pyruvate oxidation, and the citric acid cycle

e

how many times must pyruvate be processed into acetyl coA for each glucose molecule that undergoes glycolysis?

2

starting with citrate, which of the following combinations of products would result from three acetyl-coA molecules entering the citric acid cycle?

a. 1 ATP, 2 CO2, 3 NADH, and 1 FADH2

b. 2 ATP, 2 CO2, 3 NADH, and 3 FADH2

c. 3 ATP, 3 CO2, 3 NADH, and 3 FADH2

d. 3 ATP, 6 CO2, 9 NADH, and 3 FADH2

d

at what point in cellular respiration is a molecule of glucose fully oxidized?

after two rounds of the krebs cycle

the energy of electron transport serves to move protons to the outer mitochondrial compartment. how does this help the mitochondrion produce ATP?

the translocation of protons sets up the electrochemical gradient that drives ATP synthesis in the mitochondria

in what ways does the electron transport chain and oxidative phosphorylation demonstrate the coupling of an endergonic and exergonic reaction?

the movement of electrons across the protein complexes of the ETC power the pumping of protons from the matrix to the intermembrane space of the mitochondrion

substrate-level phosphorylation accounts for what percentage of total ATP produced by the ETC and chemiosmosis?

0%

which of the following describes ATP synthase?

a. a transmembrane protein

b. drives the formation of ATP from ADP and P

c. a substrate level enzyme phosphorylating agent

d. functions only in fermentation

e. a pump

a,b,e

which of the following FBIs is best illustrated by oxidative phosphorylation?

a. systems

b. transformations of energy

c. evolution

d. structure and function

e. information flow

b

why are fermentation reactions important for cells?

they regenerate NAD+ so that glycolysis can continue to operate

in the absence of oxygen, yeast cells can obtain energy by fermentation, resulting in the production of -

ATP, CO2, and ethanol

covalent bond formation depends on the ability of atoms to -

share electrons with other atoms

how do ionic bonds differ from covalent bonds?

electrons are not shared between two atomic nuclei in ionic bonds as they are in covalent bonds

which of the following contains a polar covalent bond?

a. CH4

b. NaCl

c. H2

d. H2O

d

nitrogen is more electronegative than hydrogen. which of the following is a correct statement about the atoms in ammonia (NH3)?

a. ammonia has an overall positive charge

b. the nitrogen atom has a partial positive charge; each hydrogen atom has a partial negative charge

c. ammonia has an overall negative charge

d. each hydrogen atom has a partial positive charge; the nitrogen atom has a partial negative charge

e. there are covalent bonds between the hydrogen atoms and polar bonds between each hydrogen atom and the nitrogen atom

d

lipids that form membranes have what kind of structure?

polar heads and nonpolar tails; the polar heads interact with water

what type of bond forms between two water molecules?

hydrogen bond

when a transmembrane protein folds into its shape and plants itself in the phospholipid bilayer, where would we expect to find alanine (a nonpolar amino acid) within the structure of said protein?

toward the interior of the protein, away from water

simple diffusion would suggest that NaCl -

will move from an area of high concentration to an area of low concentration

what does glucose need to move from an area of higher concentration to an area of lower concentration?

a transport protein (facilitated diffusion)

whenever energy is transformed, there is always an increase in the -

entropy of the universe

a chemical reaction that has a positive delta G is best described as -

endergonic

living organisms can harvest the energy produced by exergonic reactions to -

drive endergonic reactions

which statement is true of the following reaction? C6H12O6 + 6O2 → 6CO2 + 6H2O

a. glucose oxygens are oxidized to water

b. glucose carbons are oxidized to carbon dioxide

c. glucose carbons are reduced to carbon dioxide

d. glucose oxygens are oxidized to carbon dioxide

b

according to the pressure-flow hypothesis of phloem transport, -

high turgor pressure in source sieve-tube elements pushes phloem sap to sink sieve-tube elements with low turgor pressure

which of the following is completed by prokaryotes?

a. providing nitrogen via arbuscular mycorrhizal fungi

b. nitrogen fixation

c. the growth of ectomycorrhizal fungi

d. carbon fixation

e. none of the above

nitrogen fixation

which of the following is characteristic of ectomycorrhizal fungi?

a. EMF form a sheath around root cells

b. EMF penetrate cell walls

c. EMF release peptidases to help break down decaying material in the soil

d. EMF hyphae resemble “small trees”

e. EMF fixes nitrogen, unlike arbuscular mycorrhizal fungi

a,c

a small plant lives on a tree branch and penetrates its vascular system with haustoria; the small plant draws water and nutrients from the tree. this is an example of -

a parasitic plant

the large surface area in the small intestine directly facilitates -

absorption

choose the correct statement from the list below.

a. carb digestion begins in the mouth with salivary amylase

b. carb absorption occurs primarily in the large intestine

c. carbs are fully digested after passage through the stomach

d. bile salts from the gall bladder are essential to the digestion of carbs

a

why is breathing more difficult at high altitudes, such as at the top of Mount Everest?

the lower partial pressure of oxygen in the atmosphere reduces the rate of diffusion of oxygen into your body

in mammals, gas exchange between the atmosphere and the pulmonary blood occurs in the -

alveoli

most of the carbon dioxide produced by humans is -

converted to bicarbonate ions and protons by carbonic anhydrase, an enzyme in red blood cells

which of the following promotes oxygen release from hemoglobin?

a. a decrease in carbonic anhydrase activity

b. an increase in oxygen level

c. a decrease in temperature

d. a decrease in pH

e. an increase in the partial pressure of oxygen in tissue blood

d

blood returning to the mammalian heart in a pulmonary vein drains first into the -

left atrium

a molecule of air must first pass through the bronchi → bronchiole → alveolus → pulmonary capillaries and veins → left atrium and ventricle of the heart before reaching the vessels that will lead it to muscle cells.

true or false

true

why are there several structurally different pigments in the reaction centers of photosystems?

this arrangement enables the plant to absorb light energy of a variety of wavelengths

what event accompanies energy absorption by chlorophyll?

an electron is excited

the electrons of photosystem 2 are excited and transferred to electron carriers. from which molecule or structure do the photosystem 2 replacement electrons come?

water

what is the main purpose of light dependent reactions of photosynthesis?

to produce NADPH and ATP

which of the following occurs during the light reactions?

a. ADP is produced

b. NADPH is oxidized

c. NAD is reduced

d. an electrochemical gradient is established

e. carbon dioxide is produced

d

what is the primary function of the Calvin cycle?

synthesizing simple sugars from carbon dioxide

what is a disadvantage of having small, needlelike leaves?

decreased efficiency of light capture

which of the following would be considered part of the shoot system of a plant?

a. the leaves

b. the branches on a tree

c. the stem of a plant of the trunk of the tree

d. the roots

e. A-C

e

what is meant by phenotypic plasticity in roots and shoots?

the ability to modify form depending on environmental conditions

bryophyllum daigremontianum produces hundreds of asexual baby plantlets that are genetically identical to the parent plant and can grow into mature plants. predict whether plantlets obtained from a single parent plant but grown under different environmental conditions would likely show the same phenotypes

even though the plantlets are genetically identical, they would likely show different phenotypes because of phenotypic plasticity

we would expect the root system of a plant grown in a dry environment to -

be long and extensive to maximize water absorption

the sieve tube and companion cells together form the -

phloem

match the following description/route with its appropriate term.

a. symplastic - water travels in between the cell wall and cell membrane

b. transmembrane - water travels in between the cell wall and cell membrane

c. aposymplastic - water drifts from cell wall to cell cytosol

d. apoplastic - water travels in the cell walls

e. casparian route - water travels along the waxy casparian strip and permeates the cell

b

the transport of a water column up a very tall tree can be explained by -

cohesive and adhesive forces of the water column under evaporative tension

which of the following would tend to increase transpiration?

a. dry soil

b. an increase number of stomata

c. spiny (thin) leaves

d. a lower potential in the air surrounding the stomata

e. a higher potential in the air surrounding the stomata

b,d

which of the following could be a source when it comes to sugar production in a plant?

a. a brand new leaf

b. a fully mature leaf doing photosynthesis

c. a root

d. a dying leaf late in autumn

e. none of the above

b

what is the only type of chemical signal that diffuses locally and affects nearby cells?

paracrine signal

which of the following best describes the neuroendocrine-to-endocrine pathway of hormone action?

a. a gland releases directly into a neural structure, thus regulating neural functions

b. a structure within the nervous system produces a hormone and releases it directly onto an endocrine gland

c. a gland exhibits negative feedback on the nervous system by releasing hormones into a neural tissue both directly and indirectly through the circulation

d. a structure within the nervous system produces and releases a hormone that regulates the activity of an endocrine gland

d

analysis of a blood sample from a fasting individual who had not eaten for 24 hours would be expected to reveal high levels of -

glucagon

suppose a small furry rabbit is hopping along, but suddenly detects a nearby predator. which hormone may be released immediately and act via a G-protein coupled receptor?

epinephrine

vasopressin and desmopressin both aid in the reabsorption of water in the kidneys

true or false

true

which of the following is an effect of ABA release in plants?

a. closing of stomata

b. relaxing of guard cells surrounding stomata

c. cessation of lateral root growth

d. cessation of vertical root growth

e. death of leaves

a,b,c

gibberellins promote upward growth of the plant by triggering a large supply of - to be released

glucose

which is an example of positive feedback in humans?

a. hormones released during childbirth trigger contractions, which in turn trigger contractions that get closer and closer together

b. blood clotting releases more blood clotting factors so that the bleeding can stop quickly

c. shivering to raise body temperature can lead to more shivering

d. a and b but not c

e. a, b, and c

d

the operation of the sodium potassium pump in neurons moves -

sodium ions into the cell and potassium ions out of the cell

the depolarization phase of an action potential requires -

opening of Na+ channels in the membrane

why are action potentials usually conducted in one direction?

the refractory period prevents reopening of voltage gated Na+ channels

in multiple sclerosis, the myelin sheaths around the axons of the brain and spinal cored are damaged and demyelination results. how does this disease manifest at the level of action potential?

1. action potentials move in the opposite direction on the axon

2. action potentials move more slowly along the axon

3. no action potentials are transmitted

only 2

in a synapse, neurotransmitter chemicals are received by -

receptors on the postsynaptic neuron

neurotransmitters categorized as inhibitory are expected to -

hyperpolarize the membrane (make it more negative than the resting potential)

what happens if twice as many inhibitory postsynaptic potentials (IPSPs) as excitatory postsynaptic potentials (EPSPs) arrive at a postsynaptic neuron in close proximity?

no action potential results

when the mammalian brain compares the actual temperature of the body to the preferred temperature of the body, which component of a homeostatic control system is being used?

integrator

which of the following would not be under homeostatic control?

a. body temp

b. blood osmolarity

c. height

d. blood sugar

e. pH

d

a woman standing and watching the stars on a cool, calm night will lose most of her body heat by -

radiation

compared to ectotherms, endothermic animals are likely to be at the greatest disadvantage in -

environments with variable and limited food sources

which term best describes an animal that, although generating a significant amount of heat through metabolism, does not maintain a constant body temperature?

heterothermic endotherm

osmolarity refers to the number of solutes in a solution surrounding an animal cell

true or false

false

freshwater fish reside in hypotonic environments. they do not drink water, and they excrete large volumes of hypotonic urine in an effort to osmoregulate. how do they obtain an adequate supply of electrolytes?

cells on the gill filaments take up additional electrolytes from freshwater

which of these is not a characteristic of being an osmoregulating fish in a marine environment?

a. osmoregulating marine fish excrete large volumes of dilute urine

b. osmoregulating marine fish do not need to make special proteins to protect their cells from high urea concentrations in their tissues

c. osmoregulating marine fish need to expend energy to excrete NaCl

d. osmoregulating marine fish need to drink large amounts of seawater

a

what is a function of ADH?

ADH triggers the insertion of water channels called aquaporins, thereby increasing the amount of water reabsorbed by the collecting duct

what is the function of the Loop of Henle in mammalian kidneys?

to create an osmotic gradient that permits the reabsorption of water and various solutes

not all intercellular signals require transduction. which of the following signals would be processed without transduction?

a. a signal that binds to a receptor in the cell membrane

b. a signal that is weakly bound to a nucleotide

c. a lipid soluble molecule

d. a signal that binds to the extracellular matrix

c

protein kinase is an enzyme that -

activates or inactivates other proteins by adding a phosphate group to them

what are the two main outcomes of interactions among species?

influence the distribution and abundance of the interacting species and are agents of natural selection

commensalism is a - interaction

+/0

competition is a - interaction

-/-

the range of resources that a species can use and the range of conditions it can tolerate

ecological niche

niche overlap leads to -

competition

consumption is a - interaction

+/ -

mutual ism is a - interaction

+/ +

_ describes the number of species living in a habitat, community, biome, or biosphere

species richness

the relative abundance of different species

species diversity

_ and _ describe consumption interactions in a community

food chains and food webs

the amount of nutrients, sunlight, or water determines the abundance of primary producers available at the bottom of the food web are ecosystem engineers

bottom up

presence or absence of consumers from the top of the food web changes the species composition in the community

top down

have a greater impact on community structure than their abundance would suggest

keystone species