Question 1

A new organism is discovered which contains a super enzyme that requires no ATP to split glucose into pyruvate but cannot function if oxygen is present. What is this organism's net production of ATP from one molecule of glucose?

Accepted Answer

Oxygen is not present, therefore, the organisms would go through fermentation. The 2 molecules of ATP that are normally needed in the energy investment phase of fermentation are no longer utilized, therefore, there is a net gain of 4 ATP during fermentation instead of the normal net gain of 2 ATP.

Question 2

How many ATP are produced from the 10 NADH that are formed during the citric acid cycle?

Accepted Answer

Each NADH will yield 3 ATP when it moves to the electron transport chain. There are a total of 10 NADH, which will yield 30 ATP.

Question 3

By-products of cellular respiration include

Accepted Answer

Carbon dioxide and water are both released as glucose is broken down. ATP is the desired product.

Question 4

Where do the protons and electrons come from that are used in the electron transport chain?

Accepted Answer

The electron transport chain located in the cristae of mitochondria is a series of carriers that pass electrons from one to the other. NADH and FADH₂ deliver electrons to the chain; the H atoms attached to the NADH and FADH₂ consist of an e- and a hydrogen ion.

Question 5

What would happen if NAD+ were not available for cellular respiration?

Accepted Answer

Ten molecules of NADH are converted to ATP through the electron transport chain producing 30 ATP. Without the NADH, cellular respiration would yield 6-8 ATP molecules as opposed to 36-38 ATP with NADH.

Question 6

If you were able to stop the process of cellular respiration after the completion of the electron transport chain but prior to chemiosmosis, what would you find is true about the pH in the mitochondria?

Accepted Answer

The pumping of H⁺ into the intermembrane space establishes an unequal distribution of H⁺; in other words, there are many H+ in the intermembrane space and few in the matrix of a mitochondrion. Acids are associated with an increase in H+ ions.

Question 7

You have decided to try to make your own wine by adding yeast to a sweet grape juice. After allowing plenty of time for the yeast to grow, you find that although the sugar levels in the juice are decreased, there is no alcohol in the mixture. What could have been the reason fermentation did not occur?

Accepted Answer

Yeasts are good examples of microorganisms that generate ethyl alcohol and CO₂ when they go through fermentation, which occurs in anaerobic environments. If they are in an aerobic environment, they will completely oxidize glucose to carbon dioxide and water.

Question 8

Which of the following reactions is not part of the cellular respiration pathway?

Accepted Answer

Cellular respiration includes glycolysis, the preparatory reaction, the citric acid cycle, and the electron transport chain. The Calvin cycle is part of photosynthesis.

Question 9

The enzyme that converts pyruvic acid into acetyl-CoA requires vitamin B₁, also called thiamine. Vitamin B₁ has to be taken in through the diet of an individual. At what phase would cellular respiration come to a halt without B₁?

Accepted Answer

To enter the citric acid cycle, pyruvate must be converted into acetyl-CoA.

Question 10

Yeast is used to make bread rise by producing ________ during fermentation.

Accepted Answer

Yeasts are good examples of microorganisms that generate ethyl alcohol and CO₂ when they carry out fermentation. When yeast is used to leaven bread, the CO₂ makes the bread rise.

Question 11

How many total ATP are produced during glycolysis?

Accepted Answer

During glycolysis, there is a total of 4 ATP produced. Glycolysis requires 2 ATP to get started and then produces 4, so there will be a net gain of 2 ATP from glycolysis.

Question 12

What will occur if oxygen is not available in great enough quantity during cellular respiration?

Accepted Answer

Overall, the role of oxygen in cellular respiration is to act as the final acceptor of electrons in the electron transport chain. In the absence of oxygen the cell will shift towards anaerobic respiration.

Question 13

Fermentation occurs if

Accepted Answer

Fermentation is an anaerobic doesn't use oxygen) breakdown of glucose resulting in the production of 2 ATP per glucose.

Question 14

A family took their newborn to the doctor. They were worried something was wrong because the baby seemed to be in constant pain. He had large amounts of lactic acid accumulating in his muscle cells. Doctors figured out that the child had a rare disease in which mitochondria are missing from skeletal muscle cells. Which of the following statements explains what they found?

Accepted Answer

Lactic acid fermentation occurs in normal animal muscle cells when there is a lack of oxygen. In this case, lactic acid fermentation would occur because even if there wasn't a lack of oxygen, mitochondria, the organelle in which cellular respiration takes place, are absent.

Question 15

In animals, lactate forms from fermentation. Lactate

Accepted Answer

Lactate is transported to the liver where it is reconverted to pyruvate.

Question 16

In cellular respiration, most ATP are produced directly as a result of

Accepted Answer

Most of the ATP produced comes from the electron transport chain and the ATP synthase complex. Per glucose, 10 NADH and 2 FADH₂ take electrons from glycolysis and the citric acid cycle to the electron transport chain. The maximum number of ATP produced by the chain is therefore 34 ATP, and the maximum number produced by both the chain and substrate-level ATP synthesis is 38.

Question 17

The functioning of an electron transport chain is analogous to

Accepted Answer

The electron transport chain functions by transferring electrons through a series of carriers, releasing energy in small, manageable amounts, similar to descending a flight of stairs one step at a time.

Question 18

Which process is used to make bread rise?

Accepted Answer