HESI A2
HESI A2 Biology 2024
1. Which bacteria are spherical in shape?
- A. Clostridia
- B. Bacilli
- C. Spirilla
- D. Cocci
Correct answer: D
Rationale: The correct answer is D, Cocci. Bacteria that are spherical in shape are known as cocci. They can be found in various arrangements such as clusters, chains, or pairs. Examples of cocci bacteria include Staphylococcus aureus and Streptococcus pneumoniae. Choice A, Clostridia, consists of rod-shaped bacteria. Choice B, Bacilli, refers to rod-shaped bacteria as well. Choice C, Spirilla, are spiral-shaped bacteria, not spherical.
2. Huntington’s disease is carried on the dominant allele. In a situation where two heterozygous parents have the disease, what percentage of their offspring are predicted to be disease-free?
- A. 0%
- B. 25%
- C. 50%
- D. 100%
Correct answer: B
Rationale: In this scenario, both parents are heterozygous for Huntington's disease, meaning each carries one dominant allele (representing the disease) and one recessive allele (representing no disease). When they have offspring, there is a 25% chance that each child will inherit two recessive alleles, making them disease-free. The Punnett square for two heterozygous parents (Hh x Hh) yields a 25% probability of offspring being homozygous recessive (hh) and therefore disease-free. Choice A (0%) is incorrect because there is a possibility of disease-free offspring. Choice C (50%) is incorrect as it represents the likelihood of being a carrier. Choice D (100%) is incorrect as all offspring will not be disease-free in this scenario.
3. The apical side of an epithelial cell:
- A. Is exposed to fluid or air
- B. Is on the bottom side of the cell
- C. Does not allow any substances to pass through
- D. None of the above
Correct answer: A
Rationale: The apical side of an epithelial cell is the top side, which is typically exposed to fluids, air, or the inside of an organ. This side allows substances to pass through it, facilitating the absorption, secretion, or excretion of various substances. Choice B is incorrect as the apical side is not on the bottom but the top side. Choice C is incorrect as the apical side does allow substances to pass through. Choice D is incorrect as there are characteristics associated with the apical side.
4. From which component do RNA and DNA derive their names?
- A. From the sugar each contains
- B. From the structure of their nucleotides
- C. From the information they transfer
- D. From their formative processes
Correct answer: A
Rationale: RNA and DNA derive their names from the sugar each contains. RNA stands for Ribonucleic Acid, with 'ribo' indicating the ribose sugar in its structure. DNA stands for Deoxyribonucleic Acid, with 'deoxyribo' referring to the deoxyribose sugar in its structure. The sugars in RNA and DNA molecules distinguish them and are the basis for their names. Choices B, C, and D are incorrect as they do not accurately explain how RNA and DNA derive their names.
5. Cells reproduce by different processes, all of which fall into what two categories?
- A. Sexual reproduction and binary fission
- B. Sexual reproduction and asexual reproduction
- C. Asexual reproduction and binary fission
- D. Asexual reproduction and mitosis
Correct answer: B
Rationale: Cells reproduce through two main processes: 'sexual reproduction and asexual reproduction.' Sexual reproduction involves the fusion of gametes to produce offspring with genetic variation, while asexual reproduction involves the production of offspring genetically identical to the parent. Choice A is incorrect because binary fission is a form of asexual reproduction, not sexual reproduction. Choice C is incorrect because it combines two forms of asexual reproduction. Choice D is incorrect because mitosis is a specific type of cell division, not a form of reproduction involving the production of offspring.
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