SAT - Biology Subject Mendelian and Molecular Genetics Questions and Answers

Question 1

In a dihybrid cross between two pea plants heterozygous for both tallness (T) and purple flowers (P), what is the expected phenotypic ratio of the offspring? (Tall is dominant to short, and purple is dominant to white).

Accepted Answer

9 tall, purple : 3 tall, white : 3 short, purple : 1 short, white

Answer

3 tall, purple : 1 short, white

Answer

1 tall, purple : 1 tall, white : 1 short, purple : 1 short, white

Answer

All offspring will be tall with purple flowers.

Question 2

Which of the following enzymes is responsible for unwinding the DNA double helix during replication?

Accepted Answer

Helicase

Answer

DNA Polymerase

Answer

DNA Ligase

Answer

Primase

Question 3

A red-flowered snapdragon is crossed with a white-flowered snapdragon, and all the offspring have pink flowers. This pattern of inheritance is known as:

Accepted Answer

Incomplete dominance

Answer

Codominance

Answer

Complete dominance

Answer

Polygenic inheritance

Question 4

The lac operon in E. coli is a classic example of gene regulation. The operon is transcribed at a high level under which of the following conditions?

Accepted Answer

Low glucose, high lactose

Answer

High glucose, low lactose

Answer

High glucose, high lactose

Answer

Low glucose, low lactose

Question 5

A man with type AB blood and a woman with type O blood have a child. What is the probability that their child will have type A blood?

Accepted Answer

50%

Answer

0%

Answer

25%

Answer

100%

Question 6

During protein synthesis, the process of converting the genetic information from messenger RNA (mRNA) into a sequence of amino acids is called:

Accepted Answer

Translation

Answer

Replication

Answer

Transcription

Answer

Transformation