Practice TEAS Science Test

Correct Answer: B

Rationale: The correct answer is B: Medulla oblongata. This part of the brain is located in the brainstem and is responsible for controlling vital involuntary functions like breathing, heart rate, and blood pressure. It contains nuclei that regulate these activities and plays a crucial role in maintaining homeostasis. The cerebellum (A) is involved in coordinating movement and balance, the cerebrum (C) is responsible for higher brain functions like thinking and decision-making, and the thalamus (D) acts as a relay center for sensory information. However, they are not directly involved in controlling involuntary actions like breathing and heart rate.

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: C

Rationale: The correct answer is C because not all macromolecules contain phosphorus. Macromolecules such as proteins, carbohydrates, and lipids contain carbon, hydrogen, and oxygen but not necessarily phosphorus. Proteins and carbohydrates can exist as single chains or be branched, so choices A and B are not characteristics that exclude a macromolecule. Choice D is also incorrect because not all macromolecules are used by the body, as some like cellulose are not digestible by humans.

Correct Answer: B

Rationale: The correct answer is B: Larynx. The voice box, also known as the larynx, is responsible for producing sound by manipulating airflow from the lungs. The other choices are incorrect because: A: Alveoli are small air sacs in the lungs for gas exchange. C: Trachea is the windpipe that carries air to and from the lungs. D: Pharynx is the throat region where the nasal and oral cavities meet.

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.