ati teas 7 science

Correct Answer: C

Rationale: The myelin sheath is derived from nervous tissue, specifically glial cells. Glial cells, also known as neuroglia, support and protect nerve cells. They produce the myelin sheath, which insulates nerve fibers and allows for faster transmission of nerve impulses. Epithelial tissue (choice A) primarily covers and lines body surfaces, muscle tissue (choice B) is responsible for movement, and connective tissue (choice D) provides support and structure to the body. None of these tissues are involved in the production of the myelin sheath, making them incorrect choices.

Correct Answer: B

Rationale: The correct answer is B: Skeletal. Skeletal muscles are responsible for voluntary movements because they are attached to bones and are under conscious control. They enable us to move our body parts intentionally. Smooth muscles (A) are involuntary and found in internal organs. Cardiac muscles (C) are also involuntary and specific to the heart. Option D simply defines a term and is not a type of muscle.

Correct Answer: B

Rationale: The correct answer is B: Glomerulus. The glomerulus is a tuft of capillaries located within the nephron, specifically in the renal cortex. It is responsible for filtering blood and forming the initial filtrate in the process of urine formation. The other choices are incorrect because: A: Ureter - a tube that carries urine from the kidneys to the bladder. C: Nephron - the functional unit of the kidney that includes the glomerulus but is not solely responsible for filtering blood. D: Renal artery - carries oxygenated blood to the kidneys but is not directly involved in the filtration process.

Correct Answer: B

Rationale: The correct answer is B: Thyroxine. Thyroxine is a hormone produced by the thyroid gland that plays a key role in regulating metabolism. It controls the body's metabolic rate, impacting energy levels and weight. Adrenaline (A) is produced by the adrenal glands and is involved in the fight-or-flight response. Cortisol (C) is produced by the adrenal glands and is known as the stress hormone. Insulin (D) is produced by the pancreas and regulates blood sugar levels, not metabolism. Thyroxine directly influences metabolism, making it the correct choice.

Correct Answer: B

Rationale: The correct answer is B: 23. In humans, each normal cell contains 23 pairs of chromosomes, making a total of 46 chromosomes. The pairs consist of one chromosome from each parent, ensuring genetic diversity. Choices A, C, and D are incorrect because they do not reflect the accurate number of chromosome pairs in a human cell. Option A (46) is the total number of chromosomes, not pairs. Option C (64) and D (32) are not the correct numbers of chromosome pairs in a human cell.