HESI A2
HESI A2 Practice Test Biology
1. What is the first step in the conversion of glucose to pyruvate?
- A. Glycolysis
- B. Krebs cycle
- C. Electron transport chain
- D. Aerobic respiration
Correct answer: A
Rationale: The correct answer is Glycolysis. Glycolysis is the initial step in the conversion of glucose to pyruvate. During glycolysis, glucose is broken down into pyruvate through a series of enzymatic reactions. Choice B, the Krebs cycle, occurs after glycolysis in aerobic cellular respiration. Choice C, the Electron transport chain, is the final step in aerobic respiration where the majority of ATP is produced. Choice D, Aerobic respiration, is a broader term that encompasses glycolysis, the Krebs cycle, and the electron transport chain, but it is not the specific first step in the conversion of glucose to pyruvate.
2. Duchenne muscular dystrophy is a recessive sex-linked trait carried on the X chromosome. In an example of an unaffected father and a female carrier who have two daughters and two sons, which is the predicted outcome?
- A. Both daughters will carry the disease.
- B. Both sons will carry the disease.
- C. One daughter may have the disease.
- D. One son may have the disease.
Correct answer: C
Rationale: Duchenne muscular dystrophy is a recessive sex-linked trait carried on the X chromosome. Since the father is unaffected and does not carry the disease, he must have a normal X chromosome. The mother is a carrier, which means she has one normal X chromosome and one X chromosome with the disease allele. The daughters will inherit one X chromosome from each parent; one would be normal, and the other has a chance of carrying the disease allele. So, there is a 50% chance that one daughter may have the disease, as she could inherit the X chromosome with the disease allele. The sons will inherit the Y chromosome from the father and the X chromosome from the mother, so they will not be affected by the disease. Therefore, the predicted outcome is that one daughter may have the disease, while the sons will not carry the disease. This rules out choices A, B, and D.
3. Where is the genetic information of a eukaryotic cell stored?
- A. Mitochondria
- B. Nucleus
- C. Golgi Apparatus
- D. Cytoplasm
Correct answer: B
Rationale: The correct answer is B: Nucleus. In eukaryotic cells, genetic information (DNA) is stored in the nucleus. This organelle acts as the control center of the cell, housing the DNA and regulating gene expression. Choices A, C, and D are incorrect because the genetic information is not stored in the mitochondria, Golgi Apparatus, or cytoplasm. The mitochondria are responsible for energy production, the Golgi Apparatus is involved in protein processing and packaging, and the cytoplasm is where various cellular activities take place, but none of these organelles store the genetic information.
4. Which is true of gametes?
- A. They are diploid cells
- B. They are haploid cells
- C. They are somatic
- D. A & C are true
Correct answer: B
Rationale: Gametes are sex cells (sperm and eggs) that are involved in sexual reproduction. They are haploid cells, meaning they have half the number of chromosomes (n) compared to diploid cells. This is necessary for the formation of a diploid zygote when two gametes unite during fertilization. Somatic cells are non-reproductive cells in the body, so they are not gametes. Choice A is incorrect because gametes are not diploid but haploid. Choice C is incorrect because gametes are not somatic cells.
5. Humans, or Homo sapiens, are part of the family ___________.
- A. Animalia
- B. Hominidae
- C. Mammalia
- D. Chordata
Correct answer: B
Rationale: Humans, or Homo sapiens, are part of the family Hominidae, which includes great apes such as gorillas, chimpanzees, and orangutans. This family belongs to the order Primates within the class Mammalia. Choice A (Animalia) refers to the animal kingdom, not the family of humans. Choice C (Mammalia) is the class to which the family Hominidae belongs, not the family itself. Choice D (Chordata) is the phylum to which humans and other animals with a notochord belong, not the specific family.
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