HESI A2
Biology HESI A2 Practice Test
1. Which of the following is true of homozygous traits?
- A. They are haploid
- B. They are denoted AA
- C. They are denoted aa
- D. They are denoted Aa
Correct answer: B
Rationale: Homozygous traits have two identical forms of the gene, either both dominant (AA) or both recessive (aa). Therefore, choices B and C are true for homozygous traits. Choice A is incorrect because being haploid refers to having a single set of chromosomes, not necessarily homozygous traits. Choice D is incorrect as homozygous traits have identical alleles, so they are not denoted as Aa.
2. Which of the following is the best example of a hypothesis?
- A. Dogs like treats
- B. Red is the best color
- C. If I eat 100 donuts, then I will feel sick
- D. If a plant is exposed to red light, then it will show less growth than natural light
Correct answer: D
Rationale: Option D is the best example of a hypothesis because it presents a clear cause-and-effect relationship that can be tested through experimentation. It follows the format of 'If [cause], then [effect]' which is characteristic of a hypothesis in scientific research. The statement is specific, testable, and does not rely on personal opinions or biases, making it a strong and valid hypothesis. Choices A, B, and C do not follow the structure of a hypothesis as they lack the cause-and-effect relationship that can be tested through experimentation. They are more like statements or opinions rather than hypotheses.
3. Select the strand of DNA that would match this segment: ACTTGCA
- A. TGAACGT
- B. GACCATG
- C. ACTTGCA
- D. None of the above
Correct answer: A
Rationale: The correct match for the DNA segment ACTTGCA is TGAACGT. In DNA, adenine (A) always pairs with thymine (T), and cytosine (C) always pairs with guanine (G). Therefore, the complementary strand to ACTTGCA should be TGAACGT, making choice A the correct answer. Choice B (GACCATG) does not follow the base pairing rules; hence, it is incorrect. Choice C (ACTTGCA) is the original segment, not its complementary strand. Choice D is incorrect as well because a matching strand does exist.
4. If a hard-boiled egg is placed in a beaker of saltwater, what will happen to the egg?
- A. Expand because water will move into the egg
- B. Shrivel because water will leave the egg
- C. Remain the same
- D. None of the above
Correct answer: B
Rationale: The correct answer is B. When a hard-boiled egg is placed in a beaker of saltwater, the egg will shrivel because water will leave the egg through osmosis. Osmosis is the movement of water from an area of lower solute concentration to an area of higher solute concentration, in this case, from the egg into the saltwater. The higher concentration of solute in the saltwater causes water to move out of the egg, leading to the egg shrinking or shriveling. Choices A, C, and D are incorrect because the egg will not expand, remain the same, or have an outcome different from shriveling when placed in a beaker of saltwater.
5. What is the process by which cells divide to form two identical daughter cells?
- A. Mitosis
- B. Meiosis
- C. Binary Fission
- D. Cellular Division
Correct answer: A
Rationale: The correct answer is A, Mitosis. Mitosis is the process in which a cell divides to form two identical daughter cells. Choice B, Meiosis, is a type of cell division that results in four non-identical daughter cells with half the number of chromosomes. Choice C, Binary Fission, is a form of asexual reproduction used by prokaryotic organisms. Choice D, Cellular Division, is a general term that encompasses various processes of cell division, but specifically, mitosis refers to the division resulting in two identical daughter cells.
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