TEAS Practice Test Science

Correct Answer: C

Rationale: The correct answer is C: Thymus. The thymus is responsible for maturing T cells, a type of white blood cell crucial for immune responses. The thymus is where immature T cells develop into functional T cells through a process called thymic education. The other choices are incorrect because the hypothalamus (A) is involved in regulating hormones, the pineal gland (B) regulates sleep-wake cycles, and the thyroid (D) produces hormones that regulate metabolism. These structures do not have a direct role in maturing T cells.

Correct Answer: B

Rationale: The correct answer is B: Meiosis Prophase I. Crossing over occurs during Prophase I of meiosis, specifically during the substage called pachytene. This is when homologous chromosomes pair up and exchange genetic material. This process creates genetic diversity among offspring. Choice A, Mitosis Prophase, is incorrect because crossing over does not occur during mitosis, as homologous chromosomes do not pair up in mitosis. Choice C, Meiosis Prophase II, is incorrect because crossing over only occurs during Prophase I, not Prophase II. Choice D, Interphase, is incorrect because crossing over does not occur during interphase, as it is a phase where the cell prepares for division and DNA replication occurs.

Correct Answer: B

Rationale: The correct answer is B: Liver. The liver produces bile, a greenish-yellow fluid that aids in digestion by breaking down fats. The pancreas (choice A) produces digestive enzymes, not bile. The gallbladder (choice C) stores and concentrates bile produced by the liver, but it does not produce bile itself. The stomach (choice D) produces gastric juices to break down food, but it does not produce bile. Therefore, the liver is the organ responsible for producing bile to aid in digestion.

Correct Answer: B

Rationale: The correct answer is B: Dendrite. Dendrites are the part of the neuron that receives signals from other neurons, allowing for communication between neurons. They contain receptors that bind to neurotransmitters released by neighboring neurons. The axon (A) is responsible for transmitting signals away from the cell body. The synapse (C) is the junction between two neurons where neurotransmitters are released. The myelin sheath (D) is a protective covering that insulates the axon and speeds up signal transmission but does not receive signals from other neurons.

Correct Answer: B

Rationale: The correct answer is B: Larynx. The larynx houses the vocal cords, which vibrate to produce sound for voice production. The pharynx is involved in swallowing, the trachea is responsible for air passage to the lungs, and the bronchi are the airways that branch off from the trachea into the lungs. The larynx specifically contains the vocal cords, making it the structure responsible for voice production.