protein synthesis begins with a process known as transcription where does this process occur

HESI RN

Biology Practice Test

1. Protein synthesis begins with a process known as transcription. Where does this process occur?

A. In the cytoplasm
B. In the nuclear envelope
C. In the ribosome unit
D. In the nucleus

Correct answer: D

Rationale: The correct answer is D: In the nucleus. Transcription, the initial step of protein synthesis, takes place in the nucleus where DNA is transcribed into mRNA. This mRNA then leaves the nucleus and enters the cytoplasm where translation occurs on the ribosomes. Choices A, B, and C are incorrect because transcription specifically occurs in the nucleus, not in the cytoplasm, nuclear envelope, or ribosome unit.

2. What percentage of the parents' offspring is predicted to have a cleft chin if one parent carries the recessive gene for a cleft chin (c) while the other parent does not?

A. 25%
B. 50%
C. 0%
D. 75%

Correct answer: C

Rationale: The correct answer is C (0%). If one parent carries the recessive gene for a cleft chin while the other parent does not carry it, none of their offspring is predicted to have a cleft chin. This is because the cleft chin trait is recessive, so for an offspring to express this trait, they would need to inherit the gene from both parents. In this scenario, none of the offspring will inherit the recessive gene from both parents, so the percentage of offspring predicted to have a cleft chin is 0%. Choices A, B, and D are incorrect because in this situation, the offspring will not express the cleft chin phenotype, although they could be carriers of the recessive gene.

3. What is the composition of the cellular membrane?

A. A bilayer of phospholipid molecules
B. A single layer of phospholipid molecules
C. Proteins that act as transport highways
D. Carbohydrates

Correct answer: A

Rationale: The cellular membrane is primarily composed of a phospholipid bilayer, which consists of two layers of phospholipid molecules. These molecules have a hydrophilic (water-attracting) head and hydrophobic (water-repelling) tail, creating a barrier that separates the internal cellular environment from the external surroundings. While proteins are embedded within this bilayer and act as transport channels, receptors, and structural support, carbohydrates are found on the outer surface of the membrane for cell recognition and signaling purposes. Therefore, the correct answer is a bilayer of phospholipid molecules.

4. Which of the following is a group of three RNA nucleotides?

A. A stop codon
B. A codon
C. An anticodon
D. tRNA

Correct answer: B

Rationale: The correct answer is B - A codon. A codon is a sequence of three RNA nucleotides that specifies a particular amino acid or a stop signal during protein synthesis. Choice A, a stop codon, is a sequence of three nucleotides that signals the termination of protein synthesis. Choice C, an anticodon, is a group of three nucleotides found in tRNA that pairs with the complementary codon in mRNA. Choice D, tRNA, stands for transfer RNA, which is a type of RNA that carries amino acids to the ribosome during protein synthesis.

5. What is the most important function of carbohydrates?

A. Store and provide energy for the body
B. Create amino acids
C. Maintain body temperature
D. Insulate body organs against shock

Correct answer: A

Rationale: The most important function of carbohydrates is to store and provide energy for the body through metabolic processes. Carbohydrates are broken down into glucose, which is used as the primary source of energy for various cellular functions. Choice B is incorrect because amino acids are the building blocks of proteins, not directly created by carbohydrates. Choice C is incorrect as the regulation of body temperature is primarily controlled by mechanisms such as sweating and shivering, not carbohydrates. Choice D is incorrect as insulation of body organs against shock is mainly provided by adipose tissue, not carbohydrates.