which structure in the skin is responsible for producing melanin

ATI TEAS 7

Practice Science TEAS Test

1. Which structure in the skin is responsible for producing melanin?

A. Sudoriferous gland
B. Melanocyte
C. Sebaceous gland
D. Hair follicle

Correct answer: B

Rationale: The correct answer is B: Melanocyte. Melanocytes in the skin are responsible for producing melanin, the pigment that gives skin its color and provides protection against harmful UV radiation. Sudoriferous glands produce sweat, sebaceous glands produce sebum (oil), and hair follicles are associated with hair growth. However, the specific function of producing melanin is attributed to melanocytes, making them the correct answer in this context.

2. What is the name of the muscular ring that controls the passage of food from the esophagus to the stomach?

A. Pyloric sphincter
B. Cardiac sphincter
C. Ileocecal valve
D. Sphincter of Oddi

Correct answer: B

Rationale: The correct answer is the Cardiac sphincter (lower esophageal sphincter). It is situated at the junction of the esophagus and the stomach, controlling the passage of food into the stomach. The cardiac sphincter opens and closes to regulate the flow of food and prevent reflux. The pyloric sphincter, on the other hand, is located between the stomach and the small intestine, not the esophagus and stomach. The ileocecal valve is positioned between the small and large intestines, while the Sphincter of Oddi is found in the duodenum, not between the esophagus and stomach.

3. Which type of cells are found in the hair bulb and are responsible for hair growth?

A. Basal
B. Epidermal
C. Epithelial
D. Merkel

Correct answer: C

Rationale: The correct answer is C: Epithelial. The hair bulb contains actively growing epithelial cells responsible for hair growth. Basal cells are located in the basal layer of the epidermis, not specifically in the hair bulb, making choice A incorrect. Epidermal cells are part of the outer layer of the skin, so choice B is incorrect. Merkel cells are related to touch sensations in the skin, not hair growth, making choice D incorrect.

4. Which organelle in the cell is responsible for protein synthesis?

A. Ribosome
B. Nucleus
C. Mitochondrion
D. Golgi apparatus

Correct answer: A

Rationale: The correct answer is A: Ribosome. Ribosomes are the organelles responsible for protein synthesis in the cell. They are the cellular machinery where translation, the process of assembling proteins from amino acids based on mRNA sequences, occurs. Ribosomes can be found floating freely in the cytoplasm or attached to the endoplasmic reticulum. The nucleus (choice B) houses DNA but is not directly involved in protein synthesis. Mitochondria (choice C) are responsible for energy production through cellular respiration, not protein synthesis. The Golgi apparatus (choice D) is involved in modifying, sorting, and packaging proteins for secretion, not in the synthesis of proteins.

5. Which of the following enzymes is responsible for adding a nucleotide to a growing DNA chain?

A. Helicase
B. Ligase
C. Nuclease
D. Polymerase

Correct answer: D

Rationale: The correct answer is Polymerase. Polymerase is the enzyme responsible for adding nucleotides to a growing DNA chain during DNA replication. Helicase unwinds the DNA double helix to separate the DNA strands for replication, Ligase joins DNA fragments together by catalyzing the formation of phosphodiester bonds between them, and Nuclease cuts or degrades DNA strands. Therefore, choices A, B, and C are incorrect in the context of adding nucleotides to a growing DNA chain.