Which structure in the skin is responsible for producing hair?
- A. Sudoriferous gland
- B. Sebaceous gland
- C. Melanocyte
- D. Hair follicle
Correct Answer: D
Rationale: The correct answer is D: Hair follicle. Hair follicles are structures in the skin responsible for producing hair. They are specialized structures that contain the hair root and the bulb, where hair growth originates. Sudoriferous glands produce sweat, sebaceous glands produce sebum, and melanocytes are responsible for producing melanin, the pigment that gives hair and skin their color. Choices A, B, and C are incorrect because sudoriferous glands produce sweat, sebaceous glands produce sebum, and melanocytes produce melanin, respectively, but they are not responsible for producing hair.
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Which of the following correctly orders the layers of the epidermis from most superficial to deepest?
- A. S. spinosum, S. basale, S. corneum, S. granulosum, S. lucidum
- B. S. corneum, S. lucidum, S. granulosum, S. spinosum, S. basale
- C. S. corneum, S. spinosum, S. basale, S. granulosum, S. lucidum
- D. S. basale, S. spinosum, S. granulosum, S. lucidum, S. corneum
Correct Answer: B
Rationale: The correct order of the layers of the epidermis from most superficial to deepest is: Stratum corneum, Stratum lucidum, Stratum granulosum, Stratum spinosum, Stratum basale. Choice B, 'S. corneum, S. lucidum, S. granulosum, S. spinosum, S. basale,' provides the accurate layering from the outermost to the innermost layer of the epidermis. Choice A is incorrect as it starts with Stratum spinosum, which is not the most superficial layer. Choice C is incorrect as it places Stratum spinosum before Stratum basale. Choice D is incorrect as it starts with Stratum basale, which is the deepest layer of the epidermis.
Mesosomes are the internal extensions of which of the following?
- A. Capsule
- B. Cell membranes
- C. Cell wall
- D. Chromatin body
Correct Answer: B
Rationale: Mesosomes are the internal extensions of the cell membrane, not the capsule, cell wall, or chromatin body. They play a crucial role in cell division and are essential for various cellular processes such as respiration and cell wall formation. Mesosomes are not associated with the capsule (choice A), cell wall (choice C), or chromatin body (choice D), making these options incorrect.
Which of the following has a smaller genetic scale than a chromosome?
- A. Genome
- B. Gene
- C. DNA
- D. All of the above
Correct Answer: B
Rationale: The correct answer is 'B: Gene.' A gene is a segment of DNA and is smaller in scale than a chromosome. Genes are the fundamental units of heredity, containing the instructions for building and maintaining an organism. While a chromosome is a larger structure that carries many genes, each gene is a specific segment of DNA responsible for encoding a particular protein or RNA molecule. Choices A, C, and D are incorrect. The 'Genome' (Choice A) refers to the complete set of an organism's genetic material, including all of its genes, while 'DNA' (Choice C) is the molecule that carries the genetic instructions. 'All of the above' (Choice D) is incorrect because not all options have a smaller genetic scale than a chromosome.
Which of the following neurotransmitters is associated with the feeling of happiness and well-being?
- A. Dopamine
- B. Serotonin
- C. GABA
- D. Acetylcholine
Correct Answer: B
Rationale: The correct answer is B: Serotonin. Serotonin is a neurotransmitter known for its role in mood regulation, promoting feelings of happiness and well-being. It helps regulate emotions, sleep, and appetite. Low levels of serotonin have been linked to conditions like depression and anxiety. Choice A, Dopamine, is more associated with pleasure and reward pathways in the brain. GABA (Choice C) is an inhibitory neurotransmitter involved in reducing neuronal excitability, not primarily linked to happiness. Acetylcholine (Choice D) is involved in muscle contraction and has functions related to memory and attention, but it is not primarily associated with feelings of happiness and well-being.
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.