which if any of the following statements about the biosphere are correct

HESI A2

Biology HESI A2 Practice Test

1. Which, if any, of the following statements about the biosphere is correct?

A. The biosphere is the part of the Earth that supports life.
B. The biosphere encompasses the entire surface of the Earth.
C. A and B are correct.
D. None of these statements is correct.

Correct answer: A

Rationale: Statement A is correct. The biosphere refers to the part of the Earth where life exists, including the land, water bodies, and atmosphere. It is the zone where living organisms and ecosystems exist. Statement B is incorrect because the biosphere covers various ecosystems on Earth but does not encompass the entire surface of the planet. The biosphere includes regions such as the lithosphere (land), hydrosphere (water bodies), and atmosphere, but not every part of the Earth's surface. Therefore, option C, stating both A and B are correct, is inaccurate. The correct answer is option A, as it accurately defines the biosphere.

2. Which of the following cell types has no nucleus?

A. platelet
B. red blood cell
C. white blood cell
D. phagocyte

Correct answer: B

Rationale: The correct answer is B, red blood cell. In humans, red blood cells do not have a nucleus. This unique feature allows them to have more space to carry oxygen efficiently. Platelets (choice A), white blood cells (choice C), and phagocytes (choice D) all have nuclei. Platelets are cell fragments, while white blood cells and phagocytes are types of immune cells that contain a nucleus for DNA and cellular functions.

3. Anaerobic respiration happens in _ because _ .

A. Animals; they need energy
B. Plants; they use sunlight
C. Bacteria; they live in environments with low oxygen
D. None of the above

Correct answer: C

Rationale: Anaerobic respiration happens in bacteria because they live in environments with low oxygen. Bacteria, unlike animals and plants, do not have easy access to oxygen for aerobic respiration and must find alternative ways to produce energy to survive. This makes anaerobic respiration essential for their metabolic processes. Choice A is incorrect because although animals need energy, they generally rely on aerobic respiration when oxygen is available. Choice B is incorrect because plants primarily perform photosynthesis using sunlight to produce energy. Choice D is incorrect as anaerobic respiration does occur in specific organisms like bacteria when oxygen is scarce.

4. 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.

5. Why can animal cells use a contractile ring but plant cells cannot?

A. Plant cells can use both methods to divide
B. Animal cells divide faster, requiring them to pinch apart
C. Plant cells are too rigid to use a contractile ring
D. N/A

Correct answer: C

Rationale: Plant cells have a rigid cell wall surrounding them, which prevents them from using a contractile ring for cell division. The rigid cell wall requires plant cells to form a cell plate during cell division instead of pinching apart like animal cells with a contractile ring. Choice A is incorrect because plant cells cannot use a contractile ring due to their rigid cell wall. Choice B is incorrect as the speed of cell division is not the primary reason for the difference in cell division mechanisms between plant and animal cells. Choice D is not applicable as plant cells indeed have a specific limitation in using a contractile ring for cell division.