HESI A2
Biology HESI A2 Practice Test
1. DNA bases include all but which of the following?
- A. Adenine
- B. Thymine
- C. Uracil
- D. Cytosine
Correct answer: C
Rationale: The correct answer is C: Uracil. Uracil is not a DNA base; it is a base found only in RNA. The four bases in DNA are Adenine, Thymine, Cytosine, and Guanine. Choice A, Adenine, is a correct DNA base. Choice B, Thymine, is a correct DNA base. Choice D, Cytosine, is a correct DNA base. Therefore, Uracil is the only incorrect choice among the options provided.
2. What is the most important component of the cell, contributing to protection, communication, and the passage of substances?
- A. Cytoplasm
- B. Cell Membrane
- C. Cytoskeleton
- D. Vacuole
Correct answer: B
Rationale: The cell membrane is the correct answer. It is the most important component of the cell as it provides protection, facilitates communication, and regulates the passage of substances in and out of the cell. The cytoplasm (Choice A) is the gel-like substance within the cell that holds organelles, but it is not primarily responsible for the functions mentioned in the question. The cytoskeleton (Choice C) provides structural support to the cell but is not directly involved in protection, communication, or substance passage. Vacuoles (Choice D) are responsible for storage and maintaining turgor pressure but do not play a primary role in the functions specified in the question.
3. Which of the following is false?
- A. Animal cells use lysosomes to break down old cells
- B. Animal cells use chloroplasts to gain energy
- C. Plant cells have a cell wall to maintain structure
- D. All of the above are true
Correct answer: B
Rationale: The statement "B. Animal cells use chloroplasts to gain energy" is false. Chloroplasts are only present in plant cells and certain algae, where they are responsible for photosynthesis to generate energy from sunlight. Animal cells rely on other organelles, such as mitochondria, for energy production. Choice A is true because animal cells use lysosomes to break down old cells and cellular waste. Choice C is true as plant cells have a cell wall composed of cellulose that provides structural support and protection.
4. Which of the following animals would have the least energy efficiency in nutrient consumption?
- A. Cow
- B. Caterpillar
- C. Coyote
- D. Cricket
Correct answer: A
Rationale: Cows are ruminant animals that have multiple stomachs and require large amounts of food to digest and convert into energy. They have lower energy efficiency compared to insects like caterpillars, coyotes, and crickets, which have more efficient nutrient consumption processes. The digestive system and metabolic functions of cows result in them having the least energy efficiency in nutrient consumption among the given choices. Caterpillars, coyotes, and crickets have more efficient nutrient consumption processes, making them more energy-efficient than cows.
5. Where is the ovary located in a flowering plant?
- A. Anther
- B. Pistil
- C. Stamen
- D. Calyx
Correct answer: B
Rationale: The ovary is located in the pistil of a flowering plant. The pistil is the female reproductive part of the flower, and it consists of the ovary, style, and stigma. The ovary contains ovules, which develop into seeds after fertilization. Choice A, 'Anther,' is incorrect because the anther is the part of the flower's stamen that produces pollen. Choice C, 'Stamen,' is incorrect because the stamen is the male reproductive part of the flower, consisting of the anther and filament. Choice D, 'Calyx,' is incorrect because the calyx is the outermost whorl of a flower, composed of sepals that protect the flower bud.
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