Practice Science TEAS Test

Correct Answer: C

Rationale: The correct answer is C: Iron (II). In heme, the central cation is Iron (II) because it forms a coordination complex with the porphyrin ring. Iron (II) has a +2 charge, allowing it to bind to the nitrogen atoms in the porphyrin ring. This binding is crucial for the proper functioning of heme in carrying oxygen in hemoglobin. Choice A (Cr III) is incorrect because chromium (III) does not typically bind to porphyrin rings in heme. Choice B (Cu II) is incorrect because copper (II) is not commonly found at the center of heme. Choice D (Iron III) is incorrect because in heme, iron is usually in the +2 oxidation state to efficiently bind and release oxygen. Iron (III) is not as effective in this role.

Correct Answer: B

Rationale: The correct answer is B: Adhesion. Water is considered a universal solvent because of its strong ability to adhere to other substances and dissolve a wide range of solutes. This property is essential for water to dissolve various molecules and ions, making it an effective solvent in nature. Cohesion (A) refers to water molecules sticking to each other, not to other substances. Molarity (C) is a measure of concentration, not a property of water as a solvent. Dilution (D) refers to the process of reducing the concentration of a solute in a solution, not the reason why water is a universal solvent.

Correct Answer: B

Rationale: The correct answer is B: Glucose. Glucose is a monosaccharide because it is a single sugar molecule, the simplest form of carbohydrates. Starch (A) is a polysaccharide made up of multiple glucose units. Cellulose (C) is also a polysaccharide, not a monosaccharide. Sucrose (D) is a disaccharide composed of glucose and fructose molecules. So, only glucose (B) fits the definition of a monosaccharide in this question.

Correct Answer: B

Rationale: The correct answer is B: To transport food from the mouth to the stomach. The esophagus serves as a muscular tube that carries chewed food (bolus) from the mouth to the stomach through peristalsis, a series of muscle contractions. It does not absorb nutrients (A), break down food (C), or absorb water (D). Absorption of nutrients primarily occurs in the small intestine, food breakdown begins in the mouth and continues in the stomach and small intestine, and water absorption happens mainly in the large intestine.

Correct Answer: B

Rationale: The correct answer is B: Small intestine. The small intestine is primarily responsible for absorbing nutrients due to its large surface area and presence of specialized structures like villi and microvilli. These structures increase absorption efficiency. The stomach mainly breaks down food, the esophagus is a passage for food, and the large intestine primarily absorbs water and salts. Thus, the small intestine is the main site for nutrient absorption in the digestive system.