AAMC MCAT Biological and Biochemical Foundations 2

Question 1

During which phase of mitosis do chromosomes align at the equatorial plate?

Accepted Answer

Metaphase

Answer

During metaphase, chromosomes align along the metaphase plate so spindle fibers can attach to kinetochores for proper segregation.

Question 2

What does the lac operon repressor do when lactose is absent?

Accepted Answer

Binds the operator and blocks transcription

Answer

Without lactose, the repressor binds the operator region, physically preventing RNA polymerase from transcribing the structural genes.

Question 3

Which chemical bond connects nucleotides in a DNA strand?

Accepted Answer

Phosphodiester bond

Answer

Phosphodiester bonds link the 3' carbon of one nucleotide's sugar to the 5' phosphate of the next, forming the DNA backbone.

Question 4

Where does the TCA (Krebs) cycle take place in eukaryotic cells?

Accepted Answer

Mitochondrial matrix

Answer

TCA cycle enzymes reside in the mitochondrial matrix, where acetyl-CoA is oxidized to CO2 with production of NADH and FADH2.

Question 5

What is the function of telomerase?

Accepted Answer

Extends telomeres to prevent chromosome shortening during replication

Answer

Telomerase adds repetitive sequences to chromosome ends, preventing the progressive shortening that would otherwise occur with each replication cycle.

AAMC - Association of American Medical Colleges Practice Test

AAMC - Association of American Medical Colleges Practice Test

AAMC MCAT Biological and Biochemical Foundations 2