Practice TEAS Science Test

Correct Answer: B

Rationale: The correct answer is B: Medulla oblongata. The medulla oblongata, located in the brainstem, controls essential functions like breathing and heart rate. It contains centers that regulate these automatic processes. The cerebrum (A) is responsible for higher brain functions, not controlling basic physiological functions. The thalamus (C) serves as a relay station for sensory information, not for regulating breathing and heart rate. The cerebellum (D) plays a role in coordination and movement, not in controlling vital functions like breathing and heart rate.

Correct Answer: D

Rationale: The correct answer is D: Cardiovascular. The cardiovascular system is responsible for transporting dissolved oxygen from the lungs to the spleen. Step 1: Oxygen is inhaled into the lungs during respiration. Step 2: Oxygen diffuses into the bloodstream through the alveoli in the lungs. Step 3: The oxygen-rich blood is pumped by the heart to the spleen and other body tissues. The immune system (A) is responsible for fighting off infections, not oxygen transport. The endocrine system (B) regulates hormones, not oxygen transport. The respiratory system (C) is involved in the exchange of gases in the lungs but does not transport oxygen to the spleen.

Correct Answer: D

Rationale: Platelets play a crucial role in clotting blood. When a blood vessel is damaged, platelets rush to the site to form a plug, preventing excessive bleeding. This process, known as hemostasis, involves platelets adhering to the damaged vessel wall, releasing chemicals to attract more platelets, and forming a clot to stop bleeding. Platelets do not transport oxygen (choice A), fight infection (choice B), or produce antibodies (choice C). Thus, the correct answer is D - Clot blood.

Correct Answer: B

Rationale: The correct answer is B: Depolarization of the SA node. The P-wave in an ECG represents atrial depolarization, which is initiated by the SA node. This electrical signal spreads through the atria causing them to contract. Choice A is incorrect because the P-wave corresponds to atrial depolarization, not repolarization. Choice C is incorrect as the QRS complex represents ventricular depolarization. Choice D is incorrect as the T-wave represents ventricular repolarization. Therefore, the SA node depolarization is accurately represented by the P-wave in an ECG.

Correct Answer: B

Rationale: The correct answer is B: 12 NADPH and 18 ATP. In the Calvin cycle of photosynthesis, each molecule of CO2 requires 2 NADPH and 3 ATP for reduction to glucose. Therefore, to reduce 6 molecules of CO2, you would need 6 x 2 = 12 NADPH and 6 x 3 = 18 ATP. This is why choice B is the correct answer. Choices A, C, and D have incorrect combinations of NADPH and ATP that do not match the stoichiometry of the Calvin cycle for the reduction of CO2 to glucose.