exam 3 functional biology

Cells commonly use the hydrolysis of ______ to drive chemical reactions.

ATP

During chemiosmosis, the energy in the form of a proton gradient is converted to chemical potential energy in ________ molecules.

ATP

energy liberation phase

ATP and NADH are synthesized

energy investment phase

ATP is hydrolyzed, and its phosphate groups are attached to glucose

The light reactions of photosynthesis produce three chemical products: ______ , _______ , and ______.

ATP, O2, NADPH

The interaction between enzyme and substrate resembles a lock and key. Which of the following accurately describes this analogy?

An enzyme is like a lock, into which the substrate must fit like a key.

Cellular respiration regenerates the ______ that is used during photosynthesis.

CO2

What is an induced fit between enzyme and substrate?

Conformational changes that cause enzyme and substrate to bind more tightly to one another

What is produced by the binding of reactants to an enzyme?

Enzyme-substrate complex

Why do changes in the pH of the fluid in which an enzyme is dissolved affect the enzyme's ability to function?

Enzymes have particular pH values at which they function best.

What is produced at the end of the second phase of the Calvin cycle?

Glyceraldehyde 3-phosphate

What happens when the transition state is reached?

The chemical reaction can readily proceed. Bonds are stretched to their limit in the reactant molecules.

How do enzymes lower the activation energy of a chemical reaction?

When reactants are bound to enzymes, they can be strained, making it easier to achieve the transition state. Enzymes can bring reactants closer together.

What is a metabolic cycle?

a series of reactions that regenerates organic molecules

cleavage phase

a six carbon molecule is converted to two three-carbon molecules

The initial input of energy needed to overcome repulsion between molecules in a chemical reaction is called

activation energy

where does a substrate bind on an enzyme in order for a chemical reaction to take place?

active site

The principal energy-yielding pathway that involves the breakdown of glucose in the presence of oxygen is called ________ ________.

aerobic respiration

Some organisms can metabolize organic molecules in the absence of oxygen by using a substance other than O2 as the final electron acceptor of an electron transport chain. This process is called ______.

anaerobic respiration

Cofactors

are usually inorganic ions, such as Fe or Zn, that temporarily bind to the surface of an enzyme and promote a chemical reaction.

A(n) ______ is a substance that speeds up the rate of a chemical reaction without being consumed or altered in the process.

catalyst

The reaction center of PSII contains a pigment called P680. This P680 pigment is most commonly excited by resonance energy transfer from a(n) _________ pigment molecule in the light-harvesting complex.

chlorophyll

Some small organic molecules temporarily attach to an enzyme and promote a chemical reaction without being changed during the reaction. Such molecules are called

coenzymes

During chemiosmosis, energy stored in a proton gradient is ___

converted to chemical bond energy in ATP

During chemiosmosis, energy stored in a proton gradient is ______.

converted to chemical bond energy in ATP

In the visible spectrum, light energy may be absorbed by boosting ______ to higher atomic energy levels, sometimes called energy shells.

electrons

NADP+ reductase accepts two electrons from ______ and catalyzes the production of ______.

ferredoxin; NADPH

In photosystem II, ______-energy electrons are transferred from P680* to pheophytin, and ______-energy electrons are transferred to P680+ to produce P680.

high;low

what molecule is produced during fermentation in muscle cells?

lactate

Coenzymes

organic molecules that temporarily bind to an enzyme and participate in the chemical reaction but are left unchanged after the reaction is completed

What molecule is produced by photosystem II?

oxygen

For an electron to absorb light energy, it must absorb a(n) _________ that contains enough energy to overcome the energy difference between the orbital the electron is in, and the one to which it will be boosted.

photon

Muscle cells overcome the buildup of NADH and decrease of NAD+ under anaerobic conditions by

reducing pyruvate to lactate

Muscle cells overcome the buildup of NADH and decrease of NAD+ under anaerobic conditions by _______.

reducing pyruvate to lactate

During cellular respiration, acetyl-CoA is formed during a reaction that also does what?

removes CO2 from pyruvate

In the light-harvesting complex of PSII, when a pigment molecule absorbs a photon, an electron gets boosted to a higher energy level. This energy is then transferred to adjacent pigment molecules via _______ _________ transfer.

resonance energy

When a reactant binds to the active site of an enzyme, this produces the enzyme _____ complex

substrate

Anabolic pathways are regulated to ensure

that a cell synthesizes molecules only when they are needed

The wavelength of light that a pigment absorbs depends on ______.

the amount of energy needed to boost an electron to a higher orbital

Many of the chemical reactions that occur in cells are endergonic. These reactions are possible because they are coupled to

the hydrolysis of ATP

Many of the chemical reactions that occur in cells are endergonic. These reactions are possible because they are coupled to ______.

the hydrolysis of ATP

The electrons that exit PSII are replenished by electrons from oxidized ______ , which yields oxygen gas that can be used by plant cells or released to the environment.

water

The amount of energy needed to boost an electron to a higher orbital determines the _________ of light that a pigment will absorb.

wavelength

Which of the following statements is true about all forms of anaerobic respiration?

A molecule other than O2 is used as the final electron acceptor.

What must happen immediately before a reaction occurs with or without a catalyst?

A transition state must be reached.

How does temperature affect the functioning of an enzyme?

Increasing the temperature outside the optimal range for an enzyme can alter the enzyme's structure and impair its function.

In PSII, water is "split" and the electrons are used to replenish excited electrons that are lost from the photosystem. The loss of electrons during the oxidation, or "splitting" of water, results in the formation of gas.

OXYGEN

Each turn of the citric acid cycle produces ___molecule(s) of CO2.

2

For every glucose molecule that enters glycolysis, the energy liberation phase (steps 6-10) generates a total of _______.

2 NADH and 4 ATP molecules

acetyl-CoA

2 carbons

The third stage of glycolysis (steps 6-10) is called the energy liberation phase. It produces a total of ________ molecule(s) of NADH and _______ molecule(s) of ATP for every molecule of glucose that enters the pathway. Note: This question is NOT asking about the net yield but the total.

2,4

oxaloacetate

4 carbons

citrate

6 carbons

The general equation for photosynthesis in green plants is: CO2+ 2H2O + light energy ----> CH2O + O2 + H2O. Which of the following represents the reactants (types and amount of each) that are required for the production of glucose (C6H12O6)?

6CO2 + 12H2O + light energy

Prosthetic groups..

...are small molecules that are permanently attached to the surface of an enzyme and aid in enzyme function

carbon dioxide

1 carbon

Each turn of the citric acid cycle produces ___ molecules of CO2.

2

How does an electron located in the pigment of the light-harvesting complexes become excited?

Light excites an electron in a pigment found in the light-harvesting complexes of the photosystems.

During linear electron flow, high-energy electrons are ultimately transferred to

NADP

The synthesis of NADPH is catalyzed by which of the following?

NADP+ reductase