Nokea
Regarding the flavoprotein – cytochrome system:
- A. cytochrome oxidase is the first step in the chain
- B. occurs within the endoplasmic reticulum
- C. substrates are pyruvate, water and oxygen and ATP
Correct Answer: C
Rationale: The correct answer is C because the substrates of the flavoprotein-cytochrome system are pyruvate, water, oxygen, and ATP. Pyruvate is oxidized to produce energy in the form of ATP, water is a byproduct of the electron transport chain, and oxygen is the final electron acceptor. Choices A and B are incorrect because cytochrome oxidase is not the first step in the chain, and the system does not occur within the endoplasmic reticulum. Choice D is incomplete.
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Mineralocorticoid is to aldosterone as glucocorticoid is to ________.
- A. testosterone
- B. estrogen
- C. cortisol
- D. epinephrine
Correct Answer: C
Rationale: Mineralocorticoids regulate electrolyte and fluid balance, with aldosterone being the primary mineralocorticoid. Glucocorticoids regulate metabolism and immune response, with cortisol being the primary glucocorticoid. Therefore, the correct answer is C: cortisol. Testosterone (A) and estrogen (B) are sex hormones, not corticosteroids. Epinephrine (D) is a hormone produced by the adrenal medulla, not a corticosteroid.
Failure of the pituitary to stop producing growth hormone after body growth is completed results in _______.
- A. Gigantism
- B. Tetany
- C. Kidney failure
- D. Acromegaly
Correct Answer: D
Rationale: The correct answer is D: Acromegaly. After body growth is completed, excess growth hormone causes the bones and soft tissues to continue growing abnormally, leading to enlarged hands, feet, and facial features. Gigantism occurs before growth plates close, resulting in overall increased body size. Tetany is caused by low calcium levels, not excess growth hormone. Kidney failure is unrelated to pituitary hormone regulation.
A newly developed pesticide has been observed to bind to an intracellular hormone receptor. If ingested, residue from this pesticide could disrupt levels of .
- A. melatonin
- B. thyroid hormone
- C. growth hormone
- D. insulin
Correct Answer: B
Rationale: Step-by-step rationale for why choice B (thyroid hormone) is correct:
1. Thyroid hormone is a key hormone that regulates metabolism and growth.
2. Intracellular hormone receptors are specific to certain hormones.
3. Disruption of thyroid hormone levels can lead to metabolic disorders.
4. Pesticide binding to the thyroid hormone receptor can interfere with its normal function.
Summary of why other choices are incorrect:
A: Melatonin regulates sleep-wake cycles, not metabolism.
C: Growth hormone regulates growth and development, not metabolism.
D: Insulin regulates blood sugar levels, not metabolism.
The release of oxytocin is controlled by _____ feedback.
- A. negative
- B. neutral
- C. positive
Correct Answer: C
Rationale: The correct answer is C: positive feedback. Oxytocin release is triggered by the positive feedback mechanism. When oxytocin is released in response to a stimulus, it further stimulates the release of more oxytocin, intensifying the effect. This continuous loop enhances the initial response, leading to a cascade effect. Negative feedback (choice A) works to maintain homeostasis by counteracting the initial stimulus, which is not the case for oxytocin release. Neutral feedback (choice B) does not play a significant role in regulating hormone release. Choice D is incomplete and irrelevant.
What characteristic is related to Hashimoto's thyroiditis?
- A. Enlarged thyroid gland
- B. Viral-induced hyperthyroidism
- C. Bacterial or fungal infection of thyroid gland
- D. Chronic autoimmune thyroiditis with antibody destruction of thyroid tissue
Correct Answer: D
Rationale: Hashimoto's thyroiditis is an autoimmune disorder in which antibodies attack and destroy thyroid tissue, leading to hypothyroidism.