Q: A cell with depleted NAD+ cannot continue glycolysis. Which equation represents the reaction that fermentation uses to regenerate NAD+?

$$\text{Pyruvate} + \text{NADH} \rightarrow \text{Lactate} + \text{NAD}^+$$

Question 1

Which of the following best describes the relationship between a gene and an allele?

Accepted Answer

A gene is a sequence of DNA encoding for a trait, and an allele is a different variant of that gene.

Question 2

An individual with genotype $$Aa$$ for a recessive disease is considered a carrier. Why?

Accepted Answer

Because the individual possesses one normal and one mutated allele, allowing them to pass the mutated allele to offspring without expressing the disease.

Question 3

If two carrier parents ($$Aa 	imes Aa) $$for an autosomal recessive disorder have a child, what is the probability that the child will be affected?

Accepted Answer

1/4

Question 4

Why do X-linked recessive disorders affect males more frequently than females?

Accepted Answer

Because males inherit only one X chromosome, so a single mutated allele will cause the disorder.

Question 5

A carrier mother for an X-linked recessive disorder ($$X^R X^r) $$has a son. What is the probability that her son will inherit the disorder?

Accepted Answer

1/2

Question 6

Where does glycolysis occur within a eukaryotic cell, and does it require molecular oxygen?

Accepted Answer

Glycolysis occurs in the cytoplasm and does not require oxygen.

Question 7

How many ATP molecules must be invested during the first phase of glycolysis for every molecule of glucose broken down?

Accepted Answer

$$2$$

Question 8

What are the net yields of ATP, NADH, and pyruvate from the complete glycolytic processing of one glucose molecule?

Accepted Answer

$$2$$ ATP, $$2$$ NADH, $$2$$ pyruvate

Question 9

Why does glycolysis halt if a cell runs out of NAD+, and how does fermentation solve this problem under anaerobic conditions?

Accepted Answer

Glycolysis halts because NAD+ is required to accept electrons; fermentation regenerates NAD+ by reducing pyruvate.

Question 10

Phosphofructokinase-1 (PFK-1) is a key regulatory enzyme in glycolysis. How do cellular energy signals affect its activity?

Accepted Answer

High ATP levels inhibit PFK-1, while high AMP levels activate it.

Question 11

A patient with a mutation in the gene encoding PFK-1 has impaired glycolysis. Which of the following best explains the effect on cellular metabolism?

Accepted Answer

The cell will accumulate fructose-6-phosphate and have reduced ATP production.

Question 12

If a cell is exposed to an environment lacking oxygen, which pathway will it use to regenerate NAD+ and continue glycolysis?

Accepted Answer

Fermentation

Question 13

Which of the following best describes the difference between genotype and phenotype?

Accepted Answer

Genotype is the genetic makeup, while phenotype is the observable trait.

Question 14

A cell with depleted NAD+ cannot continue glycolysis. Which equation represents the reaction that fermentation uses to regenerate NAD+?

Accepted Answer

$$	ext{Pyruvate} + 	ext{NADH} ightarrow 	ext{Lactate} + 	ext{NAD}^+$$

Question 15

In a population, a rare autosomal recessive disease is present. If both parents are carriers ($$Aa$$), what is the probability that their child will be a carrier but not affected?

Accepted Answer

1/2

Question 16

Which scenario would result in a female expressing an X-linked recessive disorder?

Accepted Answer

She inherits mutated alleles from both parents.

Question 17

Which of the following is a multi-step regulatory mechanism that ensures glycolysis is responsive to cellular energy needs?

Accepted Answer

PFK-1 is inhibited by high ATP and activated by high AMP, allowing glycolysis to increase when energy is low.

Question 18

A scientist observes that glycolysis is proceeding rapidly in a cell despite high ATP levels. Which mutation could explain this phenomenon?

Accepted Answer

A mutation that makes PFK-1 insensitive to ATP inhibition.

Cell Biology Study Guide: Genes, Alleles, Genotype/Phenotype, Inheritance, and Glycolysis

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