Practice TEAS Science Test

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.

Correct Answer: B

Rationale: The correct answer is B: Laryngopharynx. The laryngopharynx is part of the pharynx where both the respiratory and digestive systems intersect. It serves as a common passageway for both food and air. When we swallow, the epiglottis covers the larynx to prevent food from entering the trachea. A: The esophagus is solely a passageway for food from the mouth to the stomach. C: The nasopharynx is a part of the upper respiratory tract and not involved in the passage of food. D: The trachea is strictly a passageway for air to enter and exit the lungs.

Correct Answer: B

Rationale: The correct answer is B: Protein. Proteins are macromolecules composed of amino acids, which always contain nitrogen in their structure. Amino acids have an amine group (-NH2), which is where the nitrogen is found. Fatty acids (choice A) do not contain nitrogen in their structure. Lipids (choice C) and carbohydrates (choice D) also do not contain nitrogen in their basic structure. Therefore, protein is the only macromolecule among the choices that will always contain nitrogen.

Correct Answer: D

Rationale: The correct answer is D: Glucose. Glucose is a monosaccharide, not a biological macromolecule. Biological macromolecules are large molecules made up of smaller subunits. Glycoproteins are proteins with attached carbohydrates, DNA is a nucleic acid, and phospholipids are lipids. Glucose, being a simple sugar, is not considered a macromolecule.