exam 3 questions

Question 1

An autotroph is an organism that

Answer 1

does both a and b

a. extracts energy from organic sources.
b. converts energy from sunlight into chemical energy

Question 2

Which of the following processes is (are) required for the complete oxidation of glucose?

Answer 2

all of the choices are correct

a. The Krebs cycle
b. Glycolysis
c. Pyruvate oxidation

Question 3

Which of the following is NOT a product of glycolysis?

Answer 3

CO2

Question 4

Glycolysis produces ATP by

Answer 4

substrate-level phosphorylation

Question 5

What is the role of NAD+ in the process of cellular respiration?

Answer 5

It functions as an electron carrier

Question 6

The reactions of the Krebs cycle occur in the

Answer 6

matrix of the mitochondria

Question 7

the electrons carried by NADH and FADH2 can be

Answer 7

moved between proteins in the inner membrane of

the mitochondrion

Question 8

which of the following is NOT a true statement regarding cellular respiration?

Answer 8

Electrons have a higher potential energy at the end

of the process.

Question 9

The direct source of energy for the ATP produced by ATP synthase comes from

Answer 9

a proton gradient

Question 10

Anaerobic respiration

Answer 10

yields less energy than aerobic respiration because other final electron acceptors have lower affinity for electrons than O2

Question 11

what is the importance of fermentation to cellular metabolism?

Answer 11

It oxidizes NADH to NAD+ in the absence of O2

Question 12

The link between electron transport and ATP synthesis

Answer 12

is a proton gradient.

Question 13

a chemical agent that makes holes in the inner membrane of the mitochondria would

Answer 13

stop ATP synthesis.

Question 14

Yeast cells that have mutations in genes that encode enzymes in glycosides can still grow on glycerol. They are able to utilize glycerol because it

Answer 14

can feed into the Krebs cycle and generate ATP via e- transport and chemiosmosis.

Question 15

the light-dependent rxns of psyn are responsible for the production of

Answer 15

ATP and NADPH

Question 16

Which region of a chloroplast is associated with the capture of light energy?

Answer 16

Thylakoid membrane

Question 17

The colors of light that are most effective for photosynthesis are

Answer 17

red, blue, and violet

Question 18

During noncyclic photosynthesis, photosystem I functions to ___________, and photosystem II functions to ______________.

Answer 18

reduce NADP+; oxidize H2O

Question 19

How is a reaction center pigment in a photosystem different from a pigment in the antenna complex?

Answer 19

The reaction center pigment loses an electron when it absorbs light energy.

Question 20

The ATP and NADPH from the light reactions are used

Answer 20

during the reactions of the Calvin cycle to produce glucose.

Question 21

The carbon fixation reaction converts

Answer 21

inorganic carbon into an organic acid.

Question 22

C4 plants initially fix carbon by

Answer 22

incorporating CO2 into oxaloacetate, which is converted to malate.

Question 23

The overall flow of electrons in the light reactions is from

Answer 23

H2O to NADPH.

Question 24

If you could measure pH within a chloroplast, where would it be lowest?

Answer 24

In the lumen of the thylakoid

Question 25

The excited electron from photosystem I

Answer 25

Both a and c are correct. a. can be returned to the reaction center to generate ATP by cyclic photophosphorylation. c. is replaced by an electron from photosystem II.

Question 26

If the Calvin cycle runs through six turns

Answer 26

enough carbon will be fixed to make one glucose, but they will not all be in the same molecule.

Question 27

Which of the following are similarities between the structure and function of mitochondria and chloroplasts?

Answer 27

Both a and c are correct. a. They both create internal proton gradients by electron transport. reactions. c. They both have a double membrane system.

Question 28

Given that the C4 pathway gets around the problems of photorespiration, why don’t all plants use it?

Answer 28

It also has an energetic cost.

Question 29

if the thylakoid membrane became leaky to ions, what would you predict to be the result on the light reactions?

Answer 29

It would stop ATP production.

Question 30

the overall process of photosynthesis

Answer 30

results in the reduction of CO2 and the oxidation of H2O.

Question 31

the function of a __ is to add phosphates to proteins, whereas a __ functions to remove the phosphates

Answer 31

protein kinase, protein phosphatase

Question 32

which of the following receptor types is NOT a membrane receptor a. channel-like receptor b. enzymatic receptor c. G protein-coupled receptor d. steroid hormone receptors

Answer 32

steroid hormone receptors

Question 33

how does the function of an intracellular receptor differ from that of a membrane receptor?

Answer 33

the intracellular receptor binds DNA

Question 34

signaling through receptor tyrosine kinases often

Answer 34

leads to the activation of a cascade of kinase enzymes

Question 35

what is the function of Ras during tyrosine kinase cell signaling?

Answer 35

it links the receptor protein to the MAP kinase pathway

Question 36

which of the following best describes the immediate effect of ligand binding to a G protein-coupled receptor?

Answer 36

the G protein trimer releases a GDP and binds a GTP

Question 37

the action of steroid hormones is often longer-lived than that of peptide hormones. this is because they

Answer 37

they turn on gene expression to produce proteins that persist in the cell

Question 38

the ion Ca2+ can act as a second messenger because it is

Answer 38

normally at a low level in the cytoplasm

Question 39

different receptors can have the same effect on a cell. one reason for this is that

Answer 39

signal transduction pathways intersect- the same pathway can be stimulated by different receptors

Question 40

in comparing small G proteins like Ras and GPCR proteins, we can say that

Answer 40

both proteins have intrinsic GTPase activity that stops signaling & both proteins are active bound to GTP

Question 41

the same signal can have different effects in different cells because there

Answer 41

a. are different receptor subtypes that initiate different signal transduction pathways. b. may be different coactivators in different cells. c. may be different target proteins in different cells’ signal transduction pathways.

Question 42

The receptors for steroid hormones and peptide hormones are fundamentally different because

Answer 42

peptides are hydrophilic and steroids are hydrophobic

Question 43

paracrine signaling is characterized by

Answer 43

secreted by neighboring cells

Question 44

signal transduction pathways

Answer 44

include the intracellular events stimulated by an extracellular signal

Question 45

a covalent bond between 2 atoms represents what kind of energy?

Answer 45

potential energy

Question 46

during a redox rxn the molecule that gains an electron has been

Answer 46

reduced and now has a higher energy level

Question 47

an endergonic rxn has the following properties

Answer 47

+∆G and the rxn is not spontaneous

Question 48

a spontaneous rxn is one in which

Answer 48

the reactants have a higher free energy than the products

Question 49

what is activation energy?

Answer 49

the energy required to initiate a chemical rxn

Question 50

which of the following is not a property of a catalyst?

Answer 50

a catalyst lowers the free energy of the reactants

Question 51

where is the energy stored in a molecule of ATP?

Answer 51

in the bonds connecting the two terminal phosphate groups

Question 52

cells use ATP to drive endergonic rxns because

Answer 52

energy released by ATP hydrolysis makes ∆G for coupled rxns more negative

Question 53

which of the following statements is not true about enzymes?

Answer 53

enzymes make ∆G for a rxn more negative

Question 54

ATP hydrolysis has a ∆G of -7.4 kcal/mol. Can an endergonic rxn with a ∆G of 12 kcal/mol be "driven" by ATP hydrolysis?

Answer 54

no, the overall ∆G is still positive

Question 55

an online auction site offers a perpetual-motion machine. You decide not to bid on this because

Answer 55

the second law says that energy loss due to entropy will not allow for perpetual motion

Question 56

enzymes have similar responses to both changes in temperature and pH. The effect of both is on the

Answer 56

three-dimensional shape of the enzyme

Question 57

feedback inhibition is an efficient way to control a metabolic pathway because the

Answer 57

first enzyme is the pathway inhibited by the end-product of the pathway