HESI A2
Biology HESI A2 Practice Exam
1. A cell containing 12 chromosomes divides into daughter cells in mitosis. How many chromosomes are in each daughter cell?
- A. 3
- B. 6
- C. 12
- D. 24
Correct answer: C
Rationale: During mitosis, the cell undergoes nuclear division without changing the number of chromosomes. Therefore, the daughter cells produced will have the same number of chromosomes as the parent cell. In this case, since the parent cell contains 12 chromosomes, each daughter cell will also have 12 chromosomes. Choices A, B, and D are incorrect because during mitosis, the chromosome number remains the same, and daughter cells inherit the same number of chromosomes as the parent cell.
2. What organelle in the cell produces energy through the process of respiration?
- A. Nucleus
- B. Mitochondria
- C. Golgi Apparatus
- D. Chloroplasts
Correct answer: B
Rationale: The correct answer is B: Mitochondria. The mitochondria are known as the powerhouse of the cell and are responsible for producing energy through respiration in eukaryotic cells. Choice A, the Nucleus, is not involved in energy production but rather houses the cell's genetic material. Choice C, the Golgi Apparatus, is responsible for packaging and processing proteins, not energy production. Choice D, Chloroplasts, are responsible for photosynthesis in plant cells, not respiration for energy production.
3. Why is yeast used to make bread rise?
- A. It engages in photosynthesis, which produces oxygen gas.
- B. Carbon dioxide forms while yeast carries out photosynthesis.
- C. Yeast carries out fermentation, producing ethanol and carbon dioxide.
- D. Yeast breathes in oxygen and produces carbon dioxide through aerobic respiration.
Correct answer: C
Rationale: Yeast is used to make bread rise because it carries out fermentation, producing carbon dioxide gas. The carbon dioxide gas gets trapped in the dough, causing it to rise and create a fluffy texture in the bread. Choices A, B, and D are incorrect because yeast does not engage in photosynthesis, so it does not produce oxygen gas, does not carry out photosynthesis to form carbon dioxide, and does not produce carbon dioxide through aerobic respiration. Yeast's fermentation process is essential for bread rising.
4. The mixture of gases surrounding a planet is referred to as its ______.
- A. Atmosphere
- B. Stratosphere
- C. Biosphere
- D. Troposphere
Correct answer: A
Rationale: The mixture of gases surrounding a planet is referred to as its atmosphere. The atmosphere plays a crucial role in supporting life on Earth by providing oxygen, regulating carbon dioxide levels, and shielding the planet from harmful radiation. While the stratosphere, troposphere, and other layers are part of the atmosphere, the term 'atmosphere' encompasses the entire gaseous envelope surrounding a planet. The stratosphere, troposphere, mesosphere, thermosphere, and exosphere are specific layers within the atmosphere, each with distinct characteristics and functions.
5. A cell from heart muscle would more than likely contain an unusually high proportion of which of the following?
- A. lysosomes
- B. mitochondria
- C. mRNA
- D. ribosomes
Correct answer: B
Rationale: A cell from heart muscle would more than likely contain an unusually high proportion of mitochondria because the heart muscle requires a significant amount of energy to function properly. Mitochondria are the powerhouse of the cell and are responsible for producing energy in the form of ATP through cellular respiration. Therefore, to meet the high energy demands of the heart muscle, it would need a higher concentration of mitochondria compared to other cell types. Choices A, C, and D are incorrect because while lysosomes, mRNA, and ribosomes are essential components of a cell, they do not play as direct a role in meeting the high energy demands of heart muscle as mitochondria do.
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