Question 1

As an energy carrier, ATP differs from NADPH in that

Accepted Answer

ATP transfers energy through phosphorylation, which involves adding or removing a phosphate group to or from a molecule, whereas NADPH donates electrons and hydrogen ions in redox reactions for use in biosynthesis.

Question 2

Which of the following statements describe the function of the light reaction in photosynthesis?

Accepted Answer

The answer of Which of the following statements describe the...

Question 3

The enzyme rubisco is important to the process of

Accepted Answer

Rubisco is an enzyme that plays a key role in the process of carbon fixation, which is part of the process of photosynthesis. Rubisco helps to convert atmospheric carbon dioxide (CO2) into a usable form of carbon that can be incorporated into organic compounds, such as glucose.

Question 4

What best summarizes the events of the Calvin cycle?

Accepted Answer

The Calvin cycle uses ATP and NADPH produced by the light reactions to convert carbon dioxide into sugars.

Question 5

Glycolysis is an anaerobic process, indicating that the glycolytic reactions

Accepted Answer

The question asks for an anaerobic process, which means it does not require oxygen. The only option that fits this criteria is choice A, which states that glycolysis requires no oxygen.

Question 6

Which of the following is either consumed or synthesized in virtually every cellular reaction?

Accepted Answer

ATP (adenosine triphosphate) is the molecule used by cells as a source of energy for most cellular processes. It is synthesized through cellular respiration and is also utilized in virtually every cellular reaction as a source of energy.

Question 7

Which of the following statements comparing photosynthesis and cellular respiration is accurate?

Accepted Answer

Both photosynthesis and cellular respiration require electron transport chains. This is because both processes involve the transfer of electrons to generate ATP. In photosynthesis, electrons are transferred from water to NADP+ via an electron transport chain, while in cellular respiration, electrons are transferred from glucose to oxygen via an electron transport chain. Options A and B are incorrect as photosynthesis is an anabolic pathway and water is formed during photosynthesis, not broken apart. Option D is incorrect as photosynthesis produces oxygen as a metabolic end product, not CO2.

Question 8

When ATP breaks down into ADP and a phosphate group,

Accepted Answer

When ATP breaks down into ADP and a phosphate group, energy is released and can power cellular activities. This energy can be used to drive chemical reactions or for other cellular processes that require energy.

Question 9

Which of these carries the most energy?

Accepted Answer

ATP (adenosine triphosphate) carries the most energy among the given choices because it is the main energy currency of cells and is used to power many cellular processes. ADP (adenosine diphosphate) is a precursor to ATP and has less energy stored in its molecular bonds. NADH (nicotinamide adenine dinucleotide, reduced form) and NAD+ (nicotinamide adenine dinucleotide, oxidized form) are involved in redox reactions and electron transport, but do not carry as much energy as ATP.

Question 10

Some kinds of drain cleaners use enzymes rather than strong, more dangerous chemicals. These enzymes must be able to

Accepted Answer

Enzymes are biological catalysts that catalyze reactions in living organisms. In this case, the enzymes in drain cleaners catalyze catabolic reactions, which break down the organic material causing the clog.

Question 11

Examine the illustration below. Which statement best summarizes the contribution of Photosystem I (PSI) during photosynthesis?

Accepted Answer

Photosystem I (PSI) generates NADPH by exciting electrons that are transported to the Calvin cycle where they reduce the carbon in CO₂. This is important for the synthesis of carbohydrates during photosynthesis.

Question 12

A plant cell is mutated so ATP synthase no longer functions. Which process will be affected?

Accepted Answer

ATP synthase is involved in both photosynthesis and respiration, as it synthesizes ATP from ADP and inorganic phosphate during the light-dependent reactions of photosynthesis and the electron transport chain of cellular respiration.

Question 13

In photosynthesis, the carbon used to make sugars is

Accepted Answer

Carbon used to make sugars in photosynthesis is provided by carbon dioxide, which is taken in from the air and converted into organic molecules through the process of photosynthesis. Enzymes are important in facilitating the chemical reactions involved in photosynthesis, but they do not provide the carbon used to make sugars. DNA does not directly contribute to the carbon used in photosynthesis, and while some oxidation reactions may occur during photosynthesis, this is not the primary source of carbon used to make sugars.

Question 14

Plants and animals use different energy storage molecules, yet they both use the same mechanism to "burn" their stored energy. How can plants and animals both be successful, even though they "burn" different energy storage molecules?

Accepted Answer

The breaking of chemical bonds in energy storage molecules releases energy regardless of the specific molecule. Therefore, even though plants and animals use different energy storage molecules (plants use starch and animals use glycogen), they can both use the same mechanism of breaking down these molecules to release energy.

Question 15

The three stages of cellular respiration (in order) are

Accepted Answer

The three stages of cellular respiration, in order, are glycolysis, the Krebs cycle (also known as the citric acid cycle or TCA cycle), and oxidative phosphorylation (which includes the electron transport chain and chemiosmosis). Photosynthesis and fermentation are not stages of cellular respiration.

Question 16

The energy carriers NADPH and NADH differ structurally. Functionally they

Accepted Answer

The answer of The energy carriers NADPH and NADH differ...

Question 17

The chemical 3-(3,4-dichloro-phenyl)-1,1-dimethylurea (DCMU) blocks the movement of electrons at the point indicated by the black, downward-pointing arrow in the figure below. Which of the following would be an immediate effect of treating a chloroplast with this drug?

Accepted Answer

DCMU is an inhibitor of photosystem II, and it blocks electron flow from the primary electron acceptor to plastoquinone. This causes a decrease in the amount of ATP and NADPH produced in the light reactions, as well as a decrease in the rate of water splitting. Without electron flow, a proton gradient cannot be created, so ATP cannot be made. Therefore, choice C is the correct answer.

Question 18

Cells contain the molecule GTP (guanosine triphosphate). Would this molecule be useful as an energy carrier (similar to ATP)?

Accepted Answer

GTP is structurally similar to ATP as both contain three phosphate groups. As a result, GTP can also provide energy like ATP by transferring a phosphate group via hydrolysis reactions. Therefore, GTP can be considered as an energy carrier similar to ATP. Option A is incorrect because the absence of adenosine does not necessarily mean that a molecule cannot carry energy. Option B is incorrect because the number of phosphates in a molecule does not definitively determine its ability to carry energy. Option C is partially correct, as both GTP and ATP contain nitrogenous bases; however, this alone is not sufficient to justify GTP's ability to function as an energy carrier.

Question 19

What is the role of water in photosynthesis?

Accepted Answer

Water is split during the light-dependent reactions of photosynthesis, providing electrons to chlorophyll for the process of photosynthesis to occur. The splitting of water also produces oxygen gas as a byproduct.

Question 20

Each time you take a breath you are bringing in the oxygen you need to stay alive. The ultimate source of the oxygen used by all aerobic organisms comes from a reaction that breaks down

Accepted Answer

The ultimate source of the oxygen used by all aerobic organisms comes from the process of photosynthesis, specifically, the light-dependent reactions that occur in the thylakoid membranes of chloroplasts. In these reactions, water is split, releasing oxygen as a byproduct, and the energy from this process is used to produce ATP and NADPH that are used in the subsequent light-independent reactions to produce glucose. Carbon dioxide is also involved in the light-independent reactions, but it is not the ultimate source of oxygen.

Quiz 4: How Cells Work