HESI A2
Biology HESI A2 Practice Test
1. Which of the following describes the situation where one allele takes a different form from another in a gene?
- A. phenotype
- B. heterozygous
- C. homolog
- D. homozygous
Correct answer: B
Rationale: Heterozygous is the term used to describe the genotype of an individual with two different alleles for a specific gene. In this case, one allele takes a different form from another, resulting in genetic diversity and variation in trait expression. The other choices are incorrect: 'phenotype' refers to the observable traits of an organism, 'homolog' typically refers to chromosomes that are similar in structure, and 'homozygous' describes the genotype where both alleles for a gene are the same.
2. Athletes are often concerned with the question of what they need in their diets to increase muscle mass and strength. What biologic molecule would you recommend that would accomplish this?
- A. carbohydrates
- B. proteins
- C. lipids
- D. nucleic acids
Correct answer: B
Rationale: Proteins are essential for building and repairing muscle tissue. They contain amino acids, which are the building blocks of muscles. Athletes looking to increase muscle mass and strength should focus on consuming adequate amounts of high-quality proteins in their diets. Carbohydrates provide energy for workouts, lipids are important for overall health but do not directly contribute to muscle building, and nucleic acids are involved in genetic activities rather than muscle growth.
3. Which organism reproduces via binary fission?
- A. Mushroom
- B. Blue whale
- C. Rainbow trout
- D. Salmonella
Correct answer: D
Rationale: The correct answer is D, Salmonella. Salmonella bacterium reproduces via binary fission, a form of asexual reproduction where the cell divides into two daughter cells with identical genetic material. This process is common among bacteria and single-celled organisms. Mushrooms reproduce through spores, blue whales and rainbow trout reproduce sexually, involving the fusion of male and female gametes. Therefore, choices A, B, and C are incorrect as they do not reproduce through binary fission.
4. In which phase of mitosis do new nuclear membranes form around sets of chromosomes?
- A. Prophase
- B. Anaphase
- C. Telophase
- D. Interphase
Correct answer: C
Rationale: The correct answer is C, Telophase. During telophase, the final phase of mitosis, new nuclear membranes form around sets of chromosomes at the opposite poles of the cell. This process marks the completion of nuclear division in mitosis. Choices A, B, and D are incorrect because in prophase, chromosomes condense but nuclear membranes are not formed; in anaphase, chromosomes separate and move to opposite poles but no new nuclear membranes are formed; and in interphase, the cell prepares for division but nuclear membranes are not forming around sets of chromosomes.
5. Which of the following is an example of human error in an experiment?
- A. an imperfectly calibrated scale
- B. contaminating a sterile sample by breathing on it
- C. a draft in the laboratory slightly changing the temperature of a liquid
- D. failure to account for wind speed when measuring distance traveled
Correct answer: B
Rationale: Contaminating a sterile sample by breathing on it is an example of human error in an experiment because it involves an action directly caused by the researcher that compromises the integrity of the sample. Breathing on a sterile sample introduces external contaminants that can affect the results. Choices A, C, and D involve factors not directly under the researcher's control or are technical errors that do not involve direct human actions.
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