ati teas 7 science

Correct Answer: B

Rationale: The correct answer is B: Myosin. Myosin is the protein complex responsible for the thick filament in the sarcomere. It forms cross-bridges with actin during muscle contraction. Actin (choice A) is the thin filament in the sarcomere. Tropomyosin (choice C) is a regulatory protein that covers the myosin-binding sites on actin when the muscle is at rest. Troponin (choice D) is another regulatory protein that helps regulate muscle contraction by binding calcium ions.

Correct Answer: B

Rationale: The correct answer is B: It runs 3' to 5'. The antisense strand of DNA runs in the opposite direction to the sense strand. This is essential for complementary base pairing during transcription. The 3' to 5' direction allows RNA polymerase to synthesize RNA in the 5' to 3' direction, following the template of the antisense strand. Therefore, choice B is correct. Choices A and C are incorrect because the directionality of the antisense strand is opposite to 5' to 3' and it is used in transcription, not replication. Choice D is incorrect as DNA is stored in the cell nucleus in a double helix structure, not in a specific direction.

Correct Answer: B

Rationale: The correct answer is B: Mitosis. Mitosis is the type of cell division responsible for growth and repair in multicellular organisms. During mitosis, a cell divides into two identical daughter cells, ensuring the growth and repair of tissues. Meiosis (A) is involved in sexual reproduction, not growth or repair. Binary fission (C) is a form of asexual reproduction in prokaryotic cells, not growth or repair. Osmosis (D) is the passive movement of water across a semi-permeable membrane, not a form of cell division.

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: A

Rationale: The correct answer is A because polygenic inheritance refers to a trait that is influenced by multiple genes working together to produce a single phenotype. In contrast, pleiotropy occurs when a single gene has multiple effects on different traits. This distinction is crucial as it highlights the difference in the genetic basis of these phenomena. The other choices are incorrect because they either misinterpret the definitions of polygenic inheritance and pleiotropy (B and C) or provide vague statements without accurately distinguishing between the two concepts (D). The key to selecting the correct answer lies in understanding the fundamental genetic mechanisms underlying polygenic inheritance and pleiotropy.