Nokea
Which statement about catalysts is correct?
- A. They decrease the time taken for a reaction to finish and they are unchanged at the end of the reaction.
- B. They decrease the time taken for a reaction to finish and they are used up in the reaction.
- C. They increase the time taken for a reaction to finish and they are unchanged at the end of the reaction.
- D. They increase the time taken for a reaction to finish and they are used up in the reaction.
Correct Answer: A
Rationale: The correct answer is A. Catalysts decrease the activation energy required for a reaction, speeding up the reaction without being consumed in the process. They provide an alternative pathway for the reaction to proceed, facilitating the reaction without being altered themselves. This is why they are unchanged at the end of the reaction. Choice B is incorrect because catalysts are not used up in the reaction. Choices C and D are also incorrect as catalysts do not increase the time taken for a reaction to finish nor are they consumed in the reaction.
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Which of the following hormones does NOT aid in regulating fuel metabolism?
- A. insulin
- B. aldosterone
- C. glucagon
- D. cortisol
Correct Answer: B
Rationale: Correct Answer: B - aldosterone
Rationale:
1. Aldosterone is a hormone produced by the adrenal glands that primarily regulates salt and water balance, not fuel metabolism.
2. Insulin helps in lowering blood sugar levels by facilitating glucose uptake by cells.
3. Glucagon stimulates the release of glucose from the liver to raise blood sugar levels.
4. Cortisol plays a role in mobilizing energy stores during stress.
Summary:
Aldosterone does not directly impact fuel metabolism like insulin, glucagon, and cortisol do. Insulin lowers blood sugar levels, glucagon raises blood sugar levels, and cortisol mobilizes energy stores during stress.
Pituitary disorder caused by excess growth of the body:
- A. Dwarfism
- B. Gigantism
- C. Goiter
- D. Cretinism
Correct Answer: B
Rationale: The correct answer is B: Gigantism. Gigantism is caused by excess growth hormone production from the pituitary gland before puberty, leading to abnormal growth and height. Dwarfism (choice A) is the opposite condition, characterized by stunted growth. Goiter (choice C) is a thyroid disorder, not related to pituitary gland. Cretinism (choice D) is a condition caused by thyroid hormone deficiency, not pituitary gland disorder.
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.
Which of the following is a characteristic of steroid hormones?
- A. catalyze cyclic AMP
- B. diffuse through the plasma membranes of target cells
- C. enter the nucleus
- D. activate genes to transcribe mRNA for protein synthesis
Correct Answer: B
Rationale: The correct answer is B because steroid hormones are lipid-soluble, allowing them to easily diffuse through the plasma membranes of target cells. Once inside the cell, they bind to intracellular receptors to regulate gene expression. Choice A is incorrect because steroid hormones do not catalyze cyclic AMP; that is a function of peptide hormones. Choice C is incorrect because steroid hormones do not enter the nucleus directly but bind to intracellular receptors in the cytoplasm. Choice D is incorrect because while steroid hormones do activate genes to transcribe mRNA for protein synthesis, the initial step involves binding to receptors in the cytoplasm, not directly activating gene transcription.
Receptors for steroid hormones are found .
- A. on nutrient molecules, such as glucose
- B. in the interstitial fluid
- C. in the cytoplasm of the cells of target tissues
- D. in the cell membranes of target tissues
Correct Answer: C
Rationale: The correct answer is C because steroid hormones are lipid-soluble and can diffuse through cell membranes. Once inside the cell, they bind to specific receptors in the cytoplasm. This hormone-receptor complex then enters the nucleus to regulate gene expression. Option A is incorrect because steroid hormone receptors are not found on nutrient molecules like glucose. Option B is incorrect as these receptors are not typically located in the interstitial fluid. Option D is also incorrect because steroid hormone receptors are not located on the cell membranes of target tissues.