BIOL 410 Ch. 6, 7, 8

Which one of the following statements about the formation of a peptide bond is incorrect?

The reaction is spontaneous.

When carbohydrates are oxidized, the C-H bonds of the carbohydrate become C-O bonds of carbon dioxide. Oxidation is defined as a loss of electrons, but carbon does not become positively charged in the process. Why then is this considered carbon oxidation?

The shared electrons in C-O bonds spend less time close to the carbon nucleus than shared electrons in C-H bonds.

The electrical component of an electrochemical gradient is due to:

a greater concentration of positive charges on the side of the membrane with the highest concentration of protons.

How many ATP are directly produced from the Kreb cycle per Acetyl CoAs that enter?

1

The chemiosmotic theory explains that ______ on the inside of the sac is separated from _______ on the outside of the sac by a membrane.

A very strong positive charge ; the negatively charged environment

Order the forms of ATP from most number of phosphates to least number of phosphates.

ATP ; ADP ; AMP

Photorespiration in chloroplasts differs from cellular respiration in mitochondria in that _______.

ATP is required for photorespiration but is a product of mitochondrial respiration

Complete oxidation of glucose to CO2 involves two different mechanisms for synthesizing ATP, oxidative phosphorylation and substrate-level phosphorylation. Which is true of substrate-level phosphorylation?

An enzyme catalyzes the transfer of a phosphate group to ADP from an organic molecule to form ATP.

Glycolysis is an _____ process. Meaning that oxygen ________ requires.

Anaerobic : is not

_______ organisms dependent upon the sun for energy.

Both A and B

In the Kreb's cycle, what is true about the two carbons that bind to CoA?

Both carbons are lost as CO2

Which of these summarizes the overall reactions of cellular respiration?

C6H12O6 + 6 O2 → 6 CO2 + 6 H2O + energy

The coenzyme electron carriers produced in the Krebs cycle are _____.

FADH2 and NADH2

An uncatalyzed reaction has a higher ΔG than the same reaction when catalyzed by an enzyme.

False

For every NADH, the electron transport chain can make 4 ATP.

False

Heterotrophs do not require preassembled organic molecules to make other organic molecules.

False

No energy input is required to generate energy from glucose in metabolism.

False

The statement "matter can neither be created nor destroyed" is part of the _____.

First Law of Thermodynamics

In the electromagnetic radiation spectrum, order the following from shorter waves to longer waves.

Gamma radiation, visible light, infrared

In the electromagnetic radiation spectrum, order the following from lower energy to higher energy.

Infrared, visible light, gamma radiation

Which area in the mitochondria is proton rich?

Intermembrane space

During rapid physical activity, lactic acid is made from _____.

Pyruvate

For a pigment to absorb light, there must be alternating double and single bonds.

True

In general, enzymes change the speed of reactions by lowering the energy of activation of a chemical reaction.

True

One of the unique things about ATP synthase is that one of the protein domains spin.

True

The electrochemical gradient in a chloroplast can have a concentration of protons 1,000 times greater on one side of a thylakoid membrane than the other.

True

Glycolysis is a series of chemical reactions (endergonic and exergonic) by which the cell can obtain ATP. NAD+ plays a crucial role in the reactions of glycolysis by:

accepting electrons from glucose so that glucose gets partially oxidized to pyruvate.

Each round of the citric acid cycle begins when the 4-carbon molecule oxaloacetate is converted to the 6-carbon molecule citrate. As the cycle progresses, two carbons are eliminated to regenerate the oxaloacetate. The added carbon is supplied by ____ and the two eliminated carbons are released as ____.

acetyl-CoA; CO2

Enzymes catalyze chemical reactions by lowering the ______

activation energy.

The assembly of glucose into polysaccharides is:

an anabolic process.

In a metabolic pathway, a series of enzymatic reactions catalyzes the conversion of molecule A to molecule E. Several intermediate steps are involved in which the product of one reaction becomes the substrate for the next. The graph illustrates the changes of free energy that occur at each step in the pathway.

an exergonic reaction

A new experimental pesticide is being tested by a large agricultural chemical company. An unfortunate side effect in plants treated with this new product is a decrease in NADPH production in the chloroplasts. (Interestingly, reduction of NAD+ to NADH in the mitochondria is unaffected.) Given this observation, which of the following would you expect to observe in the chloroplasts of these plants?

an increase in 3-phosphoglycerate levels and a decrease in RuBP production

Which of the following types of inhibitors is(are) likely to bind to the active site of an enzyme? Select all correct choices.

an irreversible inhibitor a competitive inhibitor

How many net (total minus expended) ATP are returned from glycolysis?

b. 2

Anabolic pathways of metabolism are pathways that:

build complex molecules from simple ones.

Carbon atoms of CO2 are incorporated into organic molecules in a series of dark reactions called ______

carbon fixation.

Arrange the steps in the Calvin cycle in order from earliest to latest.

carboxylation, reduction, regeneration

Animals such as humans would be classified as:

chemoheterotrophs.

A molecule that closely resembles the shape and/or type of a substrate for an enzyme might serve as a(n)

competitive inhibitor

Which reaction in photosynthesis reduces CO2?

dark reaction

The Second Law of Thermodynamics simply states that _______

disorder (or entropy) in the universe is continually increasing.

The First Law of Thermodynamics simply states that _______

energy can neither be created nor destroyed, just changed from one form to another.

During fermentation in yeast cells, acetyl aldehyde is further reduced by NADH protons to make ____.

ethanol

The molecule lactic acid is associated with________.

fermentation

When fats are used as an energy source, the fatty acids are broken down to acetyl-CoA. That means that fats bypass the reactions of ______ and enter the respiratory pathway at ________.

glycolysis ; the citric acid cycle

Leaves absorb the least amount of light in the range of the visible spectrum.

green

The acquisition of a relatively small amount of genetic material from an organism that is not a parent of the receiving organism is referred to as:

horizontal gene transfer.

In the chloroplast, cytochrome b6f is an important complex in the photosynthetic electron transport chain because it accepts electrons from photosystem II and donates them to photosystem I. Another vital function of cytochrome b6f is that during its reduction-oxidation cycle it pumps ______ from the _____.

hydrogen ions; stroma into the thylakoid

The wavelengths of light that chlorophyll most readily absorbs are:

in the ultraviolet wavelengths of the spectrum

ATP is a good energy currency for cells because it has a(n) ____________ amount of Gibbs free energy

intermediate

ATP is a good energy currency for cells because it has a(n) ____________ amount of Gibbs free energy.

intermediate

In a thylakoid membrane, absorbed light energy is passed from one chlorophyll molecule to another until:

it is passed to a reaction center.

The primary reason surplus carbohydrates in plants are stored as starch is because:

leaving them as individual monosaccharides would upset the osmotic balance of the cell.

Which reaction in photosynthesis captures energy from light?

light reaction

Which of the following describes ATP hydrolysis? Select all correct choices.

often coupled to a reaction that has a positive ΔG spontaneous exergonic

The Krebs cycle begins with a 4 carbons sugar called ________ to which a 2 carbon acetyl group is added.

oxalacetic acid

In glycolysis, a major portion of the energy remains in the final product, which is called _______.

pyruvate

Which of the following is moved into the mitochondria after glycolysis if oxygen is present?

pyruvate

The chlorophyll at the center of the photosytems that loses an excited electron is called the_______ chlorophyll.

reaction center

The potential energy in a molecule of ATP is held in the:

repulsion of the phosphate groups from each other.

The most abundant protein on Earth is:

rubisco.

Metabolism is a key component for keeping the cell from falling apart by utilizing energy to repair the cell. Metabolism is an example of which law of thermodynamics?

second

Which of the following is common to both cellular respiration and the light reactions of photosynthesis?

the chemiosmotic formation of ATP

Photorespiration results in:

the consumption of ATP and the loss of CO2

What is the purpose of an enzyme?

to both increase the rate of a specific reaction and decrease the transition state

The highest free energy of a reaction is found in the ____________(s) of that reaction.

transition state

Which is the shortest wavelength and highest-energy photons within the visible spectrum and one of the regions where chlorophylls absorb.

violet-blue

What molecule is oxygen derived from during photosynthesis?

water

In green plant photosynthesis, the electron donor for the light dependent reaction is ______

water.

How many protons are pumped into the outer compartment for every NADH?

9

One of the most important coenzymes that accepts electrons/hydrogens in cellular respiration is _______

NAD+.

Following the citric acid cycle but before the electron transport chain and oxidative phosphorylation, most of the energy from the original glucose molecule is found in ________.

NADH

Which one of the following would least likely be found in the outer regions of the granal stacks?

Photosystem II

Which of the following statements reflects the second law of thermodynamics?

The amount of useable energy resulting from a reaction will always be less than the total energy available in the starting materials.

An example of high potential energy is:

a ball sitting at the top of the stairs.

Clusters of chlorophyll and accessory pigments are called ________.

photosystems

What are the waste products of respiration? (select all that apply)

CO2 H2O

Autotrophs typically obtain their carbon from:

CO2.

What process(es) happen(s) when pyruvic acid goes into the matrix of the mitochondria?

All of the above

The reducing agent during the Calvin cycle is:

NADPH.

Low concentrations of detergent make membranes leaky to small molecules and ions without damaging proteins. In isolated mitochondria exposed to detergent, the molecules of the electron transport chain and of ATP synthase remain intact. Do you expect ATP synthesis to continue in the presence of low concentrations of detergent?

No, because with a leaky membrane, H+ gradient cannot be maintained.

Which of the following could be true if a plant cell is exposed to a toxin that makes the thylakoid membrane freely permeable to hydrogen ions?

There would be no ATP available to drive carbohydrate synthesis in the Calvin cycle.