Question 1

How and where is ATP made in a eukaryotic cell?

Accepted Answer

ATP can be made in the cytoplasm by direct phosphorylation of ADP, but it can also be made in the mitochondria by the enzyme complex ATP synthase, which uses the energy from a proton gradient to synthesize ATP. Additionally, certain cell types such as chloroplasts and some bacteria can also make ATP through photosynthesis or other metabolic pathways. Therefore, choice C is the best answer.

Question 2

Organisms that can manufacture their own chemical energy are called ________.

Accepted Answer

Autotrophs are organisms that can manufacture their own chemical energy through photosynthesis or chemosynthesis. This means they do not have to rely on other organisms for their energy source, unlike heterotrophs which obtain their energy by consuming other organisms. Oligotrophs are organisms that grow in conditions with very low nutrient levels, and chemotrophs are organisms that obtain their energy through chemical reactions.

Question 3

What oxidizing agent is used to temporarily store high energy electrons harvested from glucose molecules in a series of gradual steps in the cytoplasm?

Accepted Answer

NAD+ (nicotinamide adenine dinucleotide) is the oxidizing agent used to temporarily store high energy electrons harvested from glucose molecules. It is reduced to NADH during the oxidation of glucose in the cytoplasm.

Question 4

One way to generate acetyl-CoA is to convert pyruvate into acetyl-CoA by stripping off a CO₂ molecule.The removal of CO₂ is referred to as what type of reaction?

Accepted Answer

The removal of CO₂ from pyruvate is referred to as decarboxylation.

Question 5

All of the reactions of cellular respiration that occur after glycolysis take place in what part of the eukaryotic cell?

Accepted Answer

The reactions of cellular respiration after glycolysis occur in the mitochondria of eukaryotic cells. The Krebs cycle and oxidative phosphorylation all take place within the mitochondrial matrix or inner membrane. Therefore, choice C, the mitochondria, is the correct answer.

Question 6

This process is common to all living cells:

Accepted Answer

Glycolysis is a universal process that occurs in the cytoplasm of all living cells, regardless of whether they are prokaryotic or eukaryotic.

Question 7

When oxygen is unavailable during heavy exercise what process do muscle cells use for energy generation?

Accepted Answer

Muscle cells switch to glycolysis coupled with lactate fermentation to generate energy when oxygen is unavailable during heavy exercise. This process allows for the temporary production of ATP without the need for oxygen, producing lactate as a byproduct.

Question 8

If you take into account the amount of ATP generated by ATP synthase per molecule of NADH produced in aerobic respiration,the net number of ATP molecules produced by substrate-level phosphorylation,and the fact that NADH molecules produced in the cytoplasm have to be transported into the mitochondria,what is the predicted energy yield of glycolysis in eukaryotic cells?

Accepted Answer

The answer of If you take into account the amount...

Question 9

In animals that take in oxygen from their environment,glucose is broken down into carbon dioxide and water in a process called

Accepted Answer

Animals that take in oxygen from their environment undergo aerobic respiration to break down glucose into carbon dioxide and water. Anaerobic respiration occurs in the absence of oxygen and produces lactic acid or ethanol and carbon dioxide. Organic compound respiration is not a recognized term. Glucose respiration is also not a recognized term and is too broad as there are different types of respiration that involve glucose as a substrate.

Question 10

It is thought that the oldest stage of cellular respiration from an evolutionary perspective is

Accepted Answer

Glycolysis is a very ancient metabolic pathway, and it is thought to have evolved even before the presence of oxygen on Earth. Glycolysis occurs in the cytoplasm of almost all living organisms, both aerobic and anaerobic. Therefore, it is the oldest stage of cellular respiration from an evolutionary perspective.

Question 11

What must happen to amino acids before they can be used in catabolic reactions?

Accepted Answer

Amino acids must be deaminated, which is the removal of their amino group, before they can be used in catabolic reactions. This process results in the production of ammonia, which is toxic to the body and must be converted to urea for excretion.

Question 12

During what step of glycolysis are two ATP molecules required?

Accepted Answer

Two ATP molecules are required during the glucose priming step of glycolysis. This is when the glucose molecule is phosphorylated twice by ATP to form fructose-1,6-bisphosphate.

Question 13

Organisms that depend on the energy stored in chemical bonds by other organisms for their food energy are called ________.

Accepted Answer

Heterotrophs cannot produce their own food and rely on consuming other organisms for energy. Autotrophs are able to produce their own food through processes such as photosynthesis. Oligotrophs are organisms that require a low level of nutrients to survive. Chemotrophs are organisms that obtain energy from chemicals rather than sunlight.

Question 14

Many types of cancer cells have been detected to secrete significant levels of lactate.Do you think these cells are likely undergoing beta-oxidation?

Accepted Answer

If the cancer cells are producing lactate, it is unlikely that they are undergoing beta-oxidation. Beta-oxidation produces acetyl-CoA, which enters the citric acid cycle to generate ATP. However, lactate is produced when pyruvate is converted to lactate in the absence of oxygen. This is known as anaerobic glycolysis, which occurs as a result of the Warburg effect in cancer cells. Therefore, it is unlikely that lactate-producing cancer cells are undergoing beta-oxidation.

Question 15

What stage of cellular respiration can occur in human cells with or without oxygen present?

Accepted Answer

Glycolysis can occur with or without oxygen. It is the initial step of cellular respiration, where glucose is broken down into pyruvate, producing ATP and NADH without the need for oxygen.

Question 16

A human cell has a mutation in the gene that encodes the enzyme that generates lactate from pyruvate,rendering that enzyme completely non-functional.Assuming that there is ample glucose present,how would this cell generate energy in the presence of oxygen?

Accepted Answer

If the enzyme that generates lactate from pyruvate is non-functional, the cell would still be able to generate energy through aerobic respiration. In aerobic respiration, pyruvate is converted into acetyl-CoA, which is then used in the citric acid cycle to generate ATP through oxidative phosphorylation.

Question 17

What molecule can oxidize NADH?

Accepted Answer

The answer of What molecule can oxidize NADH?
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Question 18

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

Accepted Answer

The final product of glycolysis is pyruvate, which contains a high amount of energy. However, not all of the energy is kept in pyruvate; some of it is lost as heat during the reactions.

Question 19

In the reaction: C₄H₆O₄ + FAD →C₄H₄O₄ + FADH₂,what type of reaction took place to remove the protons from C₄H₆O₄?

Accepted Answer

Dehydrogenation is the process of removing hydrogen atoms from a molecule. In this reaction, protons (H+) are removed from C₄H₆O₄, indicating a dehydrogenation reaction.

Question 20

In aerobic respiration,chemiosmotic generation of ATP is driven by:

Accepted Answer

Chemiosmotic generation of ATP in aerobic respiration is driven by a difference in H+ concentration on the two sides of the inner mitochondrial membrane. This gradient is created by the electron transport chain and is used by ATP synthase to produce ATP. Option A is incorrect because it refers to photosynthesis and not aerobic respiration. Option B is incorrect because although a Na+/K+ pump is involved in maintaining the electrochemical gradient, it is not directly responsible for ATP generation. Option D is incorrect as osmosis of macromolecules is not involved in chemiosmotic generation of ATP. Option E is incorrect because large quantities of ADP do not directly contribute to the chemiosmotic generation of ATP, although it is required as a substrate along with Pi.

Quiz 7: How Cells Harvest Energy