Nokea
What are the key differences between cytokinesis in plant and animal cells?
- A. Animal cells utilize an actomyosin ring for cleavage furrow formation, while plant cells lack this mechanism.
- B. Plant cells rely on the assembly of a cell plate in the center of the dividing cell, ultimately separating the cytoplasm.
- C. Cytokinesis in both plant and animal cells is driven by the expansion of the endoplasmic reticulum.
- D. Both types of cells achieve cytokinesis through similar membrane pinching and constriction mechanisms.
Correct Answer: B
Rationale: Rationale:
A) Animal cells utilize an actomyosin ring for cleavage furrow formation, while plant cells lack this mechanism.
- This statement is true. Animal cells use an actomyosin ring to form a cleavage furrow during cytokinesis, while plant cells do not have this mechanism. Instead, plant cells form a cell plate.
B) Plant cells rely on the assembly of a cell plate in the center of the dividing cell, ultimately separating the cytoplasm.
- This statement is correct. Plant cells form a cell plate in the middle of the dividing cell during cytokinesis. The cell plate eventually develops into a new cell wall that separates the two daughter cells.
C) Cytokinesis in both plant and animal cells is driven by the expansion of the endoplasmic reticulum.
- This
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Which of the following can weaken the immune system and increase susceptibility to infections?
- A. Regular exercise
- B. Balanced diet
- C. Chronic stress
- D. Adequate sleep
Correct Answer: C
Rationale: Chronic stress can weaken the immune system by increasing the production of stress hormones like cortisol, which can suppress the immune response. This suppression can make individuals more susceptible to infections and illnesses. Conversely, regular exercise, a balanced diet, and adequate sleep actually support a healthy immune system and help strengthen it. Choices A, B, and D are incorrect as they are factors that generally contribute positively to the immune system. Regular exercise, a balanced diet, and adequate sleep are crucial for maintaining overall health and boosting the immune system rather than weakening it.
The kidneys are bean-shaped organs that perform several vital functions. Which of the following is NOT a primary function of the kidneys?
- A. Filtering waste products from the blood
- B. Regulating blood pressure
- C. Producing red blood cells
- D. Maintaining water balance in the body
Correct Answer: C
Rationale: The correct answer is C. The kidneys do not produce red blood cells. This function is carried out by the bone marrow. The primary functions of the kidneys include filtering waste products from the blood, regulating blood pressure, and maintaining water balance in the body. Red blood cells are produced in the bone marrow, not in the kidneys. Choices A, B, and D are incorrect as they are primary functions of the kidneys, which involve filtering waste products, regulating blood pressure, and maintaining water balance in the body, respectively.
What is the end result of mitosis in animal cells?
- A. The production of two identical daughter cells
- B. The production of four haploid cells
- C. The production of a single diploid cell
- D. The production of a single haploid cell
Correct Answer: A
Rationale: Mitosis is a type of cell division specific to eukaryotic cells that results in the production of two identical daughter cells, each with the same genetic material as the parent cell. This process is crucial for growth, tissue repair, and maintaining a constant number of chromosomes in multicellular organisms. During mitosis, the replicated chromosomes are segregated into two separate nuclei, followed by the division of the cell into two identical daughter cells. Options B, C, and D are incorrect as mitosis does not lead to the production of four haploid cells, a single diploid cell, or a single haploid cell. The correct answer is A because mitosis results in the formation of two daughter cells that are genetically identical to each other and to the parent cell, allowing for growth and replacement of damaged cells in multicellular organisms.
What is the difference between a pure substance and a mixture?
- A. Pure substances have a fixed composition, mixtures don't.
- B. Mixtures have a fixed composition, pure substances don't.
- C. Pure substances can be in any state, mixtures are not always solids.
- D. Pure substances are always elements, mixtures are always compounds.
Correct Answer: A
Rationale: Pure substances have a definite and constant composition, meaning they are made up of only one type of atom or molecule with fixed proportions. This composition does not vary. On the other hand, mixtures are composed of two or more substances physically combined. The components of a mixture can be present in varying proportions, leading to a variable composition. Choice A is correct as it accurately distinguishes between pure substances and mixtures based on the fixed composition of pure substances and the variable composition of mixtures. Choice B is incorrect because mixtures, not pure substances, have variable compositions. Choice C is incorrect as both pure substances and mixtures can exist in different states. Choice D is incorrect because pure substances can be compounds as well, not exclusively elements, and mixtures can contain elements and compounds.
Microfilaments and microtubules are both components of the cytoskeleton, but they have different functions. Which of these describes microfilaments?
- A. Provide structural support and shape
- B. Facilitate cell movement and contraction
- C. Form the mitotic spindle during cell division
- D. Transport materials within the cell
Correct Answer: A
Rationale: Microfilaments are thin, solid rods made of the protein actin and are primarily responsible for providing structural support to the cell and determining its shape. While they also play a role in cell movement, their main function is related to maintaining the structural integrity of the cell. Choice B, 'Facilitate cell movement and contraction,' describes microtubules, which are responsible for facilitating cell movement, providing structural support, and aiding in cell division. Choice C, 'Form the mitotic spindle during cell division,' specifically refers to the function of microtubules in forming the mitotic spindle. Choice D, 'Transport materials within the cell,' is characteristic of microtubules that are involved in intracellular transport of organelles and materials within the cell.