Biology HESI A2 Practice Exam

Correct Answer: B

Rationale: The correct answer is B: Red blood cells lack nuclei. This is because during their maturation process, red blood cells expel their nuclei to make room for hemoglobin, allowing them to carry oxygen efficiently. Nerve cells (A), liver cells (C), and connective tissue cells (D) all have nuclei because they require genetic material for various functions such as protein synthesis, regulation, and repair. Red blood cells, lacking nuclei, are specialized for their main function of transporting oxygen throughout the body.

Correct Answer: A

Rationale: The correct answer is A: proteins. Enzymes are biological catalysts that facilitate chemical reactions in living organisms. Proteins are made up of amino acids, which are essential for the structure and function of enzymes. Enzymes have specific 3D structures that allow them to interact with substrates and speed up reactions. Lipids (B), starches (C), and simple sugars (D) are not typically components of enzymes. Lipids are fats, starches are carbohydrates, and simple sugars are monosaccharides, none of which provide the structural and functional properties required for enzyme activity.

Correct Answer: A

Rationale: The correct answer is A: Owl. Tertiary consumers are organisms that feed on secondary consumers, which in turn feed on primary consumers. Owls primarily prey on small mammals like shrews, making them tertiary consumers in the food chain. Shrews (choice B) are secondary consumers, grasshoppers (choice C) are primary consumers, and wheat (choice D) is a producer. Therefore, the owl is the only choice that fits the definition of a tertiary consumer in this context.

Correct Answer: C

Rationale: The correct answer is C: Glucose. In photosynthesis, glucose is not a reactant but a product synthesized as a result of the process. Water (A), light energy (B), and carbon dioxide (D) are all reactants in photosynthesis. Water is split into oxygen and hydrogen ions, light energy is absorbed by chlorophyll to initiate the process, and carbon dioxide is converted into glucose through a series of biochemical reactions. Therefore, glucose is the only option that is not a reactant in photosynthesis.

Correct Answer: A

Rationale: The correct answer is A: Sucrose. Sucrose is a disaccharide composed of one molecule of glucose and one molecule of fructose. It is formed by a condensation reaction between these two monosaccharides. Fructose (choice B), glucose (choice C), and galactose (choice D) are all monosaccharides, not disaccharides. Therefore, they are incorrect choices for this question.