Pearls from AAMC Materials

Question 1

Since glycolysis produces _ ATP molecules per glucose molecule, and 3 Na+ molecules are extruded for each ATP molecule utilized by the sodium pump, a total of _ molecules of Na+ are extruded per molecule of glucose.

Answer 1

2

6

(From AAMC Biology practice questions)

Question 2

What would happen if oligonucleotides, such as mRNA, were not degraded rapidly by intracellular agents?

Answer 2

The coordination of cell differentiation would be negatively affected.

The destruction of mRNA prevents continuous protein production, allowing the cell to change its protein expression over time. The coordination of cell differentiation during development is extremely sensitive to the timing of mRNA turnover.

(Biology question pack vol. 1)

Question 3

Detection of myoglobin in the urine could indicate damaged muscle OR damaged kidney. Myoglobin IS/ IS NOT found in bone as well.

Answer 3

IS NOT

(AAMC Biology question pack, vol. 1)

Question 4

One of the key differences between mitosis and meiosis occurs during their respective anaphases. During anaphase of mitosis, sister chromatids are pulled apart at the centromeres, each becoming an independent chromosome in the two diploid daughter cells. During anaphase I of meiosis I, homologous pairs of chromosomes are separated into the two daughter cells. However, each chromosome still consists of two sister chromatids joined to each other at the _________. It is not until anaphase II of meiosis II that the centromere is split and the sister chromatids separate.

Answer 4

centromere

(AAMC Biology question pack, vol. 1)

Question 5

Things to know about inbreeding:

1. The chances of getting a pair of deleterious recessive genes increase enormously when the mate is a relative, because relatives are likely to have a similar genotype.
2. Inbreeding ________ genetic diversity
3. it has no effect on spontaneous mutations

Answer 5

decreases

(AAMC Biology question pack, vol. 1)

Question 6

The sperm ________ contains the mitochondria which supplies the energy the tail needs to move. The tail moves with a whip-like movement to propel the sperm. The fact that there are so many mitochondria here suggests that sperm motility requires a large amount of ___.

Answer 6

midpiece

ATP

(From AAMC Biology Question pack vol. 1)

Question 7

What is the most likely reason that an enzyme like pepsin, which has a pH optimum of 1.5, would catalyze protein only very slowly at a pH of 1.0?

Answer 7

Under conditions of excess stomach acidity, the 3-D structure of pepsin is likely changed.

(From AAMC Biology Question pack vol. 1)

Question 8

Aldosterone, which is produced by the adrenal _______, causes Na⁺ __________ by kidney tubules. Such a mechanism decreases Na⁺ levels in the urine.

Answer 8

cortex

reabsorption

(From AAMC Biology Question pack vol. 1)

Question 9

Fast-twitch muscle fiber metabolism is largely limited to glycolytic pathways, implying, they need less oxygen. Slow-twitch fibers do not undergo hypertrophy in response to anaerobic exercise. These endurance fibers are adapted for aerobic exercises such as long distance running.

According to the passage, relative to slow-twitch fibers, fast-twitch fibers are likely to exhibit which property?

A. Greater Ca²⁺-pumping capacity

B. Increased capillary density

C. More mitochondria

D. Higher levels of oxygen-binding proteins

Answer 9

A. Greater Ca -pumping capacity

Arrive at this conclusion by process of elimination. If endurance fibers are adapted for aerobic exercise, they will have the features described in B, C, and D.

[Practice Exam 3, q 5 of Bio/Biochem]