Biology Chapter 4

The number of ATPs produced directly as a result of one turn of the citric acid cycle is

1

An acetyl group contains how many carbons

2

How many molecules are formed from the cleavage of glucose during the first step of glycolysis? How many carbons are found in the resulting molecules?

2 molecules, each with 3 carbons

Overall, the final products of glycolysis are

2 pyruvate, 2 ATP, and 2 NADH.

For the complete respiration of one molecule of glucose, the citric acid cycle must turn a total of

2x

How many NADH are produced by the citric acid cycle per turn?

3

What are the correct outputs, during the citric acid cycle, from one molecule of glucose?

6 NADH, 4 CO2, 2 ATP, 2 FADH2

Which of the following is consistent with the laws of physics governing energy?

Eventually, sunlight that is absorbed on the earth returns to the atmosphere as dispersed heat

Which of the following statements about glycolysis is true?

Glycolysis breaks glucose down to two pyruvate molecules.

During an enzymatic reaction, what happens to the enzyme?

The enzyme and the substrate form a temporary complex.

While eating some yogurt, you have to leave and accidentally leave it sitting on the table. A day later you return and find the surface of the yogurt is no longer smooth but has broken into several liquefied products. You correctly guess that enzymes from your saliva, via the spoon, has continued digesting the yogurt in your absence (since enzymes are not used up during the digesting process). What will happen over time?

The reaction will continue until all the substrate is used and the enzyme will still remain.

If there are 12 different intermediate products produced during production of a molecule in a cell, we can expect that there

are about 12 enzymes, at least one responsible for each step in the metabolic pathway

Which stage(s) will produce carbon dioxide in cellular respiration?

both the formation of acetyl CoA and the citric acid cycle

Cellular respiration involves all of the following except

breathing in and out

Which molecules are the products of aerobic respiration?

carbon dioxide and water

The production of ATP as a result of an electrochemical gradient is called

chemiosmosis

Which pathway in cellular respiration will produce ATP, NADH2, and carbon dioxide?

citric acid cycle

The main reason that ATP is considered the energy currency in cells is because it

contains accessible energy in phosphate bonds.

The ATP synthase complex is located in the

cristae of mitochondria

The largest number of ATP molecules is produced in which phase of cellular respiration?

electron transport chain

Chemical reactions that require the input of energy are

endergonic reactions

A reactant will always produce the same type of product, regardless of the enzymes present

false

All of the ATP molecules formed by the complete oxidation of glucose result from the electron transfer chain.

false

All of the energy that a plant stores in the bonds of glucose are available to an animal to power its muscles.

false

Because the inside of a cell is more organized than the outside, the inside of the cell has increased entropy.

false

Enzymes maintain their same shape when they bind to a substrate.

false

Heat is not a form of energy.

false

Since enzymes are not used up during a reaction, they do not play any role in the reaction.

false

The addition of an enzyme will change the end result of a reaction. In other words, a particular reaction will result in a different product if an enzyme is used.

false

The most efficient method to produce ATP in animal cells is by glycolysis.

false

There is a net gain of four ATPs as a result of glycolysis.

false

The only end product of alcoholic fermentation is the alcohol.

false(it aslo produces carbon dioxide)

The citric acid cycle turns once for each original glucose molecule.

false(it turns 2x)

Which of the following statements about fermentation is not true?

fermentation includes the citric acid cycle

The amount of energy available to do work after a chemical reaction has occurred is called

free energy

Which of the following is a substrate of cellular respiration?

gluecose

What is the correct order of phases in the release of energy from glucose?

glycolysis, formation of acetyl CoA, citric acid cycle, electron transport chain

Each enzyme has a particular substrate because enzymes

have active sites complementary in shape to their substrates.

Which of the following is not an example of fermentation used by organisms to produce ATP?

humans producing alcohol

Chemiosmosis involves the movement of ___.

hydrogen ions across a mitochondrial membrane

Why do organisms without oxygen need to convert pyruvate to lactate?

in order to regenerate NAD+

The function of an enzyme is to

increase the rate of a metabolic reaction.

Glycolysis is likely to have evolved before the citric acid cycle and electron transport chain because

it is found in all living organisms

Which energy association is correct?

kenetic energy is energy of motion

Muscles undergo fermentation when

no oxygen is available.

The final acceptor for hydrogen ions in aerobic cellular respiration is

oxygen

Which of the following is a by-product of photosynthesis?

oxygen

Which molecules are the reactants or substrates for aerobic respiration?

oxygen and glucose

Most enzymes are

protein molecules

Occasionally someone claims to have built a machine that can run forever, producing as much energy as it consumes. This has always been disproved because it violates

the second law of thermodynamics

Lactose is milk sugar that is broken down by the enzyme lactase. The reason that some people are "lactose intolerant" could be because

they are missing the enzyme lactase in their digestive system.

The energy difference between the reactant glucose and oxygen molecules and the product water and carbon dioxide is 686 kilocalories, yet the 36 ATP molecules produced are only storing 263 kilocalories in their outermost phosphate bond. The rest of the energy went

to provide heat that is soon lost from the organism.

Why does chemiosmosis require a membrane?

to separate two compartments of the cell to allow for gradient formation

In feedback inhibition of a metabolic pathway, where does the inhibitor bind?

to the enzyme of the first reaction

Enzymes, coenzymes, and cofactors provide a mechanism for a cell to regulate the metabolism of a large amount of cell products using small quantities of chemicals.

true

Fermentation follows glycolysis in some cells if oxygen is not available.

true

Less energy is needed to bring about a reaction when an enzyme is present.

true

NADH and FADH2 bring electrons to the electron transport chain during cellular respiration.

true

Pyruvate contains less chemical energy than glucose.

true

Ultimately, humans get their energy from the sun.

true

An acetyl group contains how many carbons?

two

ATP can be broken down into

ADP plus phosphate plus energy.

The "energy currency" of the cell is ___.

ATP

Which is true about energy of activation?

Adding the correct enzyme can lower the energy of activation.

Which of the following is NOT an example of an energy transformation?

All of these are examples of energy transformations.

While eating a container of yogurt, you have to leave, so you store the yogurt in the refrigerator. A day later you return and find the surface of the yogurt is no longer smooth but has broken into several liquified products. You correctly guess that enzymes from your saliva, via the spoon, have continued digesting the yogurt in your absence. What will happen over time?

As long as the enzyme is not denatured by environmental conditions, the reaction will continue until all of the substrate is used up.

If A has a free energy of 38 units, and C has a free energy of 45 units, and the reaction is exergonic, based on the calculation of free energy, which is the substrate and which is the product?

C is the substrate and A is the product.

Which of the following statements most accurately describes the first law of thermodynamics?

Energy can be neither created nor destroyed but it can be changed from one form to another.

Which statement most accurately describes the second law of thermodynamics?

Energy cannot be changed from one form to another without a loss of usable energy

Pyruvate can be converted to lactate instead of going to the formation of acetyl CoA. Why does this occur?

Oxygen is not available.

Why is cellular respiration organized into four phases?

So that the energy within the glucose molecule can be released in a stepwise fashion

In cellular respiration, what is the relationship between the energy content of the reactants (glucose and O2) and products (CO2 and H2O)?

The energy content of the reactants (glucose and O2) must be greater than the energy content of the products (CO2 and H2O).

Which of the following is not true about enzymes?

They are consumed by the reactions they catalyze.

Which of the following statements is true about enzymes?

They catalyze only one specific type of reaction.

What do the electrons added to NAD+ do?

They go into the electron transport chain for ATP production.

We often say that we need food for energy. In a biological sense, is this correct?

Yes, because the food we eat has potential energy in its structure and this chemical energy can be converted into mechanical energy.

The cholesterol synthesized by cells uses which component of the glycolytic pathway as a starting point?

acetyl CoA

The location in which the enzyme and substrate complexes is called the

active site

ATP contains

an adenine base, a ribose sugar, and three phosphate groups.

The specificity of an enzyme to a substrate is currently best explained by

the introduced fit model