Biology HESI A2 Practice Exam

Correct Answer: A

Rationale: The correct answer is A: Anther. The anther is the part of the plant responsible for producing pollen. It is located at the top of the stamen, one of the male reproductive parts of a flower. Pollen contains the male gametes necessary for fertilization. The other choices, B: Style, C: Stigma, and D: Pistil, are all parts of the female reproductive system of a flower. The style is the tube connecting the stigma to the ovary, the stigma is the sticky part that receives pollen, and the pistil is the entire female reproductive structure. Therefore, they are not involved in the production of pollen.

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: D

Rationale: During telophase, the correct answer is D: Two nuclei are formed. This is the final stage of cell division where the nuclear membranes reform around the separated chromosomes, leading to the formation of two distinct nuclei. This process ensures that each daughter cell receives a complete set of chromosomes. Option A is incorrect because the nuclear envelope actually reforms during telophase. Option B is incorrect as organelles do not double in number during telophase. Option C is incorrect because chromosomes actually separate during anaphase, not telophase.

Correct Answer: C

Rationale: The correct answer is C: Capillaries. Capillaries are found in both open and closed circulatory systems as they are the smallest blood vessels where nutrient and gas exchange occurs. In open systems, capillaries allow direct exchange with tissues, while in closed systems, they connect arteries and veins. Arteries (A) are found in closed systems, not open systems. Red blood cells (B) are present in both systems, but this question specifically asks for a structure, not a component. Immune cells (D) are not typically part of the circulatory system.

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.