TEAS 7 Science Practice Test

Correct Answer: A

Rationale: The correct answer is A. In a hypertonic solution, the concentration of solutes outside the cell is higher than inside. Water moves out of the cell via osmosis to equalize concentrations, causing the cell to shrink. This is due to the higher osmotic pressure outside the cell. Choices B and C are incorrect because in a hypertonic solution, water moves out of the cell, causing it to shrink, not swell or remain the same size. Choice D is incorrect as pH is not directly affected by osmosis.

Correct Answer: A

Rationale: Correct Answer: A - A strong acid completely ionizes in water. Rationale: 1. Strong acids fully dissociate into ions in water, leading to a high concentration of H+ ions. 2. This complete ionization results in a low pH. 3. Strong acids do not reversibly donate more than one proton or contain metal atoms. 4. Strong acids can decompose under certain conditions, so choice D is incorrect.

Correct Answer: D

Rationale: The correct answer is D: mitochondria. Mitochondria are known as the powerhouse of the cell and are responsible for producing energy in the form of ATP through aerobic respiration. Muscle cells require a significant amount of energy for contraction, making mitochondria crucial in supplying this energy. Ribosomes (choice A) are involved in protein synthesis and are not directly related to energy production in cells. Chloroplasts (choice B) are only found in plant cells and are responsible for photosynthesis, not energy production in muscle cells. Vacuoles (choice C) are primarily involved in storage and maintaining cell structure, not energy production. Therefore, D is the correct answer as it directly relates to the energy needs of muscle cells.

Correct Answer: B

Rationale: The correct answer is B: sinoatrial node. The sinoatrial node is a cluster of specialized cells in the right atrium responsible for initiating the electrical impulses that regulate the heartbeat. It acts as the heart's natural pacemaker by setting the pace for the heart's contractions. The other choices are incorrect because: A: Sinus venosus is an embryonic structure in the heart, not the natural pacemaker. C: Atrioventricular node is responsible for conducting the electrical signal from the atria to the ventricles, not for generating the initial signal. D: Tricuspid valve is a heart valve that prevents backflow of blood from the right ventricle to the right atrium, not involved in generating electrical signals.

Correct Answer: C

Rationale: The correct answer is C: synapse. Neurotransmitters are chemicals that transmit signals between neurons. The synapse is the gap between neurons where these chemical messages are transmitted. Schwann cells are responsible for myelinating axons, ganglion is a cluster of nerve cell bodies, and the axon is the part of a neuron that carries the signal away from the cell body. Therefore, the synapse is the structure specifically involved in transmitting neurotransmitters between neurons.