ati teas 7 science

Correct Answer: C

Rationale: The correct answer is C, the Combined oral contraceptive pill. This method uses hormones like estrogen and progestin to prevent ovulation. Firstly, estrogen suppresses follicle-stimulating hormone (FSH) production, inhibiting follicular development. Secondly, progestin thickens cervical mucus, preventing sperm penetration. Lastly, progestin also inhibits luteinizing hormone (LH) surge, preventing ovulation. Spermicide (A) works by killing sperm but does not prevent ovulation. Barrier methods (B) like condoms and diaphragms physically block sperm from reaching the egg but do not affect ovulation. Intrauterine devices (IUDs) (D) work by preventing sperm from fertilizing the egg or by altering the uterine lining, but they do not directly prevent ovulation.

Correct Answer: A

Rationale: The correct answer is A: Epimysium. The epimysium is the outermost layer of connective tissue that surrounds the entire skeletal muscle. It provides protection and support to the muscle fibers within it. Perimysium (B) surrounds bundles of muscle fibers, while endomysium (C) surrounds individual muscle fibers. Myofibril (D) is not a connective tissue sheath but rather a structure within muscle fibers that contain contractile proteins. Therefore, A is the correct answer as it pertains to the sheath that surrounds the entire skeletal muscle.

Correct Answer: C

Rationale: The correct answer is C: Testes. The testes are responsible for producing testosterone, a male sex hormone. They contain specialized cells called Leydig cells that produce testosterone. The adrenal glands (A) produce hormones like cortisol and adrenaline, not testosterone. The pituitary gland (B) regulates hormone production but does not directly produce testosterone. The pancreas (D) produces insulin and other digestive enzymes, not testosterone. Therefore, the testes are the correct answer for testosterone production.

Correct Answer: B

Rationale: The correct answer is B: Cerebrospinal fluid. This is the protective fluid that surrounds the brain and spinal cord. It acts as a cushion, providing mechanical protection, and helps to maintain a stable environment for the central nervous system. Blood (A) does not directly surround the brain and spinal cord. Myelin sheath (C) is a protective covering of nerve fibers, not the fluid surrounding the brain and spinal cord. Insulin (D) is a hormone involved in regulating blood sugar levels and is not the fluid that protects the brain and spinal cord.

Correct Answer: C

Rationale: The correct answer is C: RBC (Red Blood Cell). RBCs are biconcave discs that are round and flat without a nucleus. This unique shape allows for efficient gas exchange and flexibility to pass through narrow capillaries. Rationale: 1. Plasma (Choice A) is the liquid component of blood that carries various substances but does not have a specific shape or structure like RBCs. 2. Platelets (Choice B) are cell fragments involved in blood clotting and do not have the described characteristics of a biconcave disc without a nucleus. 3. WBCs (Choice D) are white blood cells responsible for immune responses and have a nucleus, unlike RBCs. In summary, RBCs are the only blood constituent among the choices that fits the description provided in the question.