ati teas 7 science

Correct Answer: B

Rationale: The correct answer is B: Lactic acid. When creatine phosphate is used as an energy source for short bursts of muscle activity, it is rapidly broken down into creatine and phosphate. The breakdown of creatine phosphate leads to the production of lactic acid through anaerobic glycolysis. Lactic acid accumulation causes muscle fatigue during intense exercise. A: Glucose is not the breakdown product of creatine phosphate. Glucose is a common fuel for cellular respiration but is not directly produced from creatine phosphate breakdown. C: Carbon dioxide is not the breakdown product of creatine phosphate. Carbon dioxide is produced during the Krebs cycle in aerobic respiration, not from the breakdown of creatine phosphate. D: Creatine is not the breakdown product of creatine phosphate. Creatine is one of the compounds formed when creatine phosphate is broken down, but it is not the final breakdown product.

Correct Answer: C

Rationale: The correct answer is C: GABA. GABA is an inhibitory neurotransmitter that slows down neuron activity by binding to GABA receptors, leading to hyperpolarization of the neuron and reducing the likelihood of firing an action potential. This process helps to prevent overexcitation in the nervous system. A: Acetylcholine is primarily an excitatory neurotransmitter involved in muscle control and cognitive function. B: Dopamine plays a role in reward-motivated behavior and movement, but it is not primarily responsible for slowing down neuron activity. D: Serotonin is involved in regulating mood, appetite, and sleep, but it does not directly slow down neuron activity to prevent overexcitation.

Correct Answer: A

Rationale: The correct answer is A: Desertification. Desertification refers to the gradual loss of topsoil due to wind or water erosion, leading to the conversion of fertile land into desert-like conditions. This process is a result of unsustainable land use practices, such as overgrazing and deforestation. Leaching (B) is the process of nutrients being washed out of the soil by excess water, not specifically related to topsoil loss. Salinization (C) is the accumulation of salt in the soil, not directly related to topsoil erosion. Acidification (D) refers to the decrease in soil pH levels, not the loss of topsoil.

Correct Answer: D

Rationale: The correct answer is D: Aorta. The aorta is responsible for pumping oxygenated blood to the body. This happens after the oxygenated blood leaves the left ventricle of the heart through the aortic valve. The aorta is the largest artery in the body and carries blood to all parts of the body, supplying oxygen and nutrients. The other choices are incorrect because: A: Right ventricle pumps deoxygenated blood to the lungs. B: Left ventricle pumps oxygenated blood to the body. C: Pulmonary artery carries deoxygenated blood from the heart to the lungs for oxygenation.

Correct Answer: A

Rationale: The correct answer is A: Calcitonin. Calcitonin is produced by the thyroid gland and functions to lower blood calcium levels by promoting calcium deposition in bones and inhibiting calcium reabsorption in the kidneys. This hormone opposes the action of parathyroid hormone (PTH), which increases blood calcium levels by promoting calcium release from bones and increasing calcium reabsorption in the kidneys. Thyroxine is a thyroid hormone that regulates metabolism and growth, not calcium levels. Insulin is a hormone produced by the pancreas that regulates blood sugar levels, not calcium levels. Thus, A is the correct answer as it directly regulates calcium levels in the blood through its actions on bones and kidneys.