ATI TEAS 7 Science

Correct Answer: A

Rationale: The correct answer is A: Hypothesis. In the scientific method, a scientist creates a hypothesis based on observations or research. A model can be a representation or simulation of a process or system that helps in understanding or predicting outcomes. By creating a model during the hypothesis step, the scientist can visually or conceptually test their proposed explanation or prediction. This aids in designing experiments or gathering data to test the hypothesis further. Data analysis (B) occurs after experimentation, where collected data is analyzed. Experimentation (C) involves testing the hypothesis through controlled experiments. Conclusion (D) is the final step where the scientist interprets the results.

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: 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: C

Rationale: The correct answer is C: Buffering system. The body maintains a relatively constant blood pH level through the buffering system, which involves the action of bicarbonate ions, carbonic acid, and other buffering molecules that help regulate pH by neutralizing excess acids or bases. This system acts quickly to prevent drastic changes in blood pH when there are fluctuations in blood carbon dioxide concentration. Cellular respiration (A) generates carbon dioxide, gas exchange (B) involves the exchange of gases in the lungs, and deoxygenation (D) refers to the loss of oxygen by the blood, but these processes are not primarily responsible for maintaining blood pH stability.

Correct Answer: A

Rationale: Diastole is the correct answer because it specifically refers to the relaxation phase of the heart muscle. During diastole, the heart fills with blood before contracting in systole. Systole is the contraction phase, not relaxation. Asystole is the absence of heart contractions, not relaxation. Cardiastole is not a recognized term in relation to the heart's relaxation. Therefore, diastole is the most appropriate term for describing the relaxation of the heart muscle.