Nokea
What is DNA made of?
- A. Proteins
- B. Nucleotides
- C. Lipids
- D. Carbohydrates
Correct Answer: B
Rationale: DNA is made up of nucleotides, which are the building blocks of genetic material. Choice A (Proteins) is incorrect because while proteins play a crucial role in the body, they are not the building blocks of DNA. Choice C (Lipids) and Choice D (Carbohydrates) are also incorrect as they are not the primary components of DNA.
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How many pairs of chromosomes do all humans have?
- A. 24 pairs
- B. 23 pairs
- C. 22 pairs
- D. 20 pairs
Correct Answer: B
Rationale: All humans have 23 pairs of chromosomes, totaling 46 chromosomes. Choice A is incorrect because humans do not have 24 pairs. Choice C is incorrect as humans have 23 pairs, not 22 pairs. Choice D is incorrect as humans have 23 pairs of chromosomes, not 20 pairs.
During which phase of mitosis do the chromosomes align in the center of the cell?
- A. Prophase
- B. Metaphase
- C. Telophase
- D. Anaphase
Correct Answer: B
Rationale: The correct answer is Metaphase. During Metaphase, the chromosomes line up along the center of the cell's equator, forming the metaphase plate. This alignment ensures that during the subsequent phase, Anaphase, the sister chromatids can separate and move towards opposite poles. Prophase is the initial phase of mitosis where chromosomes condense and the nuclear envelope breaks down. Telophase is the final phase of mitosis where two new nuclei form.
What cycle is the sequence of reactions by which most living cells generate energy during aerobic respiration?
- A. Calvin Cycle
- B. Krebs Cycle
- C. Photosynthesis
- D. Fermentation
Correct Answer: B
Rationale: The Krebs Cycle is the correct answer. It is a series of reactions occurring in the mitochondria and is a crucial part of aerobic respiration. The Calvin Cycle is a part of photosynthesis, not respiration, making choice A incorrect. Photosynthesis (choice C) is the process by which plants, algae, and some bacteria convert light energy into chemical energy. Fermentation (choice D) is an anaerobic process that does not require oxygen and is not the primary energy-generating pathway during aerobic respiration, so it is incorrect.
What provides the cell with the ability to move and propel?
- A. Microfilaments
- B. Microtubules
- C. Flagella
- D. Cilia
Correct Answer: B
Rationale: Microtubules are the cellular structures responsible for cell movement and propulsion. Microtubules are part of the cytoskeleton and play a crucial role in various cellular processes, including cell motility and intracellular transport. While microfilaments also contribute to cell movement by enabling muscle contraction and cell shape changes, they are not primarily responsible for propelling the cell. Flagella and cilia are cellular appendages involved in cell movement, but they are composed of microtubules, making them the structures that move due to the actions of microtubules.
What organelle pushes water out of the cell?
- A. Lysosomes
- B. Vacuoles (contractile)
- C. Mitochondria
- D. Nucleus
Correct Answer: B
Rationale: The correct answer is B: Vacuoles (contractile). Vacuoles (contractile) are responsible for expelling excess water out of the cell. Lysosomes are involved in the digestion and removal of waste materials, mitochondria are the powerhouse of the cell involved in energy production, and the nucleus contains the cell's genetic material but does not play a role in pushing water out of the cell.