HESI A2
HESI A2 Practice Test Biology
1. Which of the following describes how a bacterium reproduces?
- A. Mitosis
- B. Meiosis
- C. Binary fission
- D. Cytokinesis
Correct answer: C
Rationale: Bacteria reproduce through a process called 'binary fission.' During binary fission, a bacterium duplicates its DNA and then divides into two identical daughter cells. This method is the primary way bacteria replicate. Choice A, 'Mitosis,' is incorrect because mitosis is a process specific to eukaryotic cells, where the nucleus divides to produce two identical nuclei. Choice B, 'Meiosis,' is incorrect as meiosis is a specialized type of cell division that produces gametes with half the chromosome number. Choice D, 'Cytokinesis,' is not the correct answer as cytokinesis is the physical process of cell division, which occurs after the genetic material has been divided in mitosis or meiosis.
2. Which of the following organelles is responsible for producing ATP in cells?
- A. Nucleus
- B. Mitochondrion
- C. Chloroplast
- D. Lysosome
Correct answer: B
Rationale: The correct answer is 'Mitochondrion.' Mitochondria are known as the powerhouse of the cell and are responsible for producing ATP, the energy currency of the cell. The nucleus is responsible for storing genetic material and controlling cell activities, not for ATP production. Chloroplasts are found in plant cells and are responsible for photosynthesis, not ATP production. Lysosomes are involved in digestion and waste removal, not ATP production.
3. How does water affect the temperature of a living thing?
- A. Water increases temperature.
- B. Water keeps temperature stable.
- C. Water decreases temperature.
- D. Water does not affect temperature.
Correct answer: B
Rationale: Water has a high specific heat capacity, which means it can absorb and release large amounts of heat with minimal temperature change. This property helps water regulate the temperature of living things by maintaining a stable environment. Choice A is incorrect because water does not consistently increase temperature, but rather helps in temperature regulation. Choice C is incorrect as water doesn't typically decrease temperature in living organisms. Choice D is incorrect since water does play a crucial role in regulating temperature.
4. Which of the following is not a product of the Krebs cycle?
- A. carbon dioxide
- B. oxygen
- C. adenosine triphosphate (ATP)
- D. energy carriers
Correct answer: B
Rationale: The correct answer is B: oxygen. Oxygen is not a product of the Krebs cycle. During the Krebs cycle, carbon dioxide, adenosine triphosphate (ATP), and energy carriers like NADH and FADH2 are produced. Carbon dioxide is a byproduct of the cycle, ATP is a form of energy produced, and energy carriers play a crucial role in transferring energy within the cell. Therefore, oxygen is the only option that is not a product of the Krebs cycle, making it the correct answer.
5. What is the typical result of mitosis in humans?
- A. two diploid cells
- B. two haploid cells
- C. four diploid cells
- D. four haploid cells
Correct answer: A
Rationale: The correct answer is A: two diploid cells. Mitosis is a type of cell division that results in two daughter cells, each having the same number of chromosomes as the parent cell. In humans, the typical result of mitosis is the formation of two diploid cells, not haploid or four cells. Choice B, two haploid cells, is incorrect because mitosis produces genetically identical diploid cells. Choices C and D, four diploid cells and four haploid cells, respectively, are incorrect as mitosis results in two daughter cells, not four.
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