Nokea
Where does the maturation of T-cells and the production of T-cell receptors occur?
- A. Thymus
- B. Spleen
- C. Lymph nodes
- D. Bone marrow
Correct Answer: A
Rationale: The correct answer is the Thymus. T-cells mature and develop their receptors in the thymus gland, making it a vital organ for the immune system. The thymus provides the necessary environment for T-cells to differentiate and acquire their specific receptors and functions, which are essential for their role in the adaptive immune response. The spleen, lymph nodes, and bone marrow are all important components of the immune system, but they do not primarily serve as sites for T-cell maturation and T-cell receptor production.
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What is hydroxyapatite?
- A. A mixture of minerals such as calcium and phosphorus that strengthen the collagen matrix of bone.
- B. The structural unit of a bone that runs the length of the bone.
- C. The covering of bones at the point of articulation to prevent grinding.
- D. The lightest portion of a long bone and concentrated at the ends.
Correct Answer: A
Rationale: Hydroxyapatite is a mineral compound composed of calcium and phosphorus that plays a crucial role in strengthening the collagen matrix of bones, contributing to their structural integrity and hardness. It is a key component of bone tissue and provides the mineralization necessary for bone strength and density. Choice B is incorrect because the structural unit of a bone is the osteon or Haversian system, not hydroxyapatite. Choice C is incorrect as it describes cartilage, not hydroxyapatite. Choice D is incorrect as it refers to the epiphysis, which is not synonymous with hydroxyapatite.
Which of the following is an effect of high blood pressure?
- A. Smoking
- B. Excessive dietary salt
- C. Renal vessel damage
- D. Older age
Correct Answer: C
Rationale: The correct answer is C: Renal vessel damage. High blood pressure can lead to damage in blood vessels throughout the body, including the kidneys. When blood vessels in the kidneys are affected, it can impair kidney function and potentially lead to kidney disease. Smoking (Choice A) and excessive dietary salt (Choice B) can contribute to high blood pressure but are not direct effects of high blood pressure itself. Older age (Choice D) is a risk factor for developing high blood pressure but is not a direct effect of high blood pressure.
What is the function of the alveoli in the lungs?
- A. To exchange carbon dioxide for oxygen
- B. To transport air to the lungs
- C. To filter blood
- D. To produce mucus
Correct Answer: A
Rationale: The corrected answer is A: 'To exchange carbon dioxide for oxygen.' The alveoli in the lungs are responsible for facilitating gas exchange, where oxygen from inhaled air diffuses into the bloodstream, and carbon dioxide from the bloodstream diffuses into the alveoli to be exhaled. This process is vital for respiration and maintaining proper oxygen levels in the body. Choices B, C, and D are incorrect. Choice B is incorrect because the alveoli are not involved in transporting air to the lungs; they are primarily responsible for gas exchange. Choice C is incorrect because the alveoli do not filter blood; their main function is gas exchange. Choice D is incorrect because alveoli do not produce mucus; mucus is produced by other specialized cells in the respiratory system.
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.
What is the primary function of the nervous system?
- A. To produce hormones
- B. To transmit electrical impulses
- C. To carry oxygen
- D. To transport nutrients
Correct Answer: B
Rationale: The correct answer is B: To transmit electrical impulses. The primary function of the nervous system is to transmit electrical impulses and coordinate body activities. While hormones are produced by the endocrine system, not the nervous system, oxygen transportation is mainly carried out by the respiratory system, and nutrient transport is primarily the role of the circulatory system. Therefore, choices A, C, and D are incorrect as they do not align with the primary function of the nervous system.