Nokea
Why can animal cells use a contractile ring but plant cells cannot?
- A. Plant cells can divide using both methods.
- B. Animal cells divide faster, requiring them to pinch apart.
- C. Plant cells are too rigid to utilize a contractile ring.
- D. Plant cells have a cell wall that hinders the formation of a contractile ring.
Correct Answer: D
Rationale: The correct answer is D because plant cells have a cell wall surrounding them, which provides structural support but makes it challenging for them to form a contractile ring during cell division. The cell wall restricts the flexibility needed for the contractile ring to constrict and separate the cells. In contrast, animal cells do not have a cell wall, allowing them to form a contractile ring composed of actin filaments that constrict during cytokinesis, facilitating cell division.
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Each species has a characteristic chromosome number and most of their cells have a complete set of these chromosomes. However, in the life cycle of humans, only sperm and eggs have which number of chromosomes?
- A. Diploid.
- B. Polyploid.
- C. Haploid.
- D. Monoploid.
Correct Answer: C
Rationale:
Aerobic respiration occurs in the presence of what necessary molecule?
- A. Carbon Dioxide
- B. Water
- C. Glucose
- D. Oxygen
Correct Answer: D
Rationale: Oxygen is essential for aerobic respiration as it acts as the final electron acceptor in the electron transport chain, producing ATP
What is the function of water in photosynthesis?
- A. Combining with carbon dioxide
- B. Absorbing light energy
- C. Supplying electrons in the light reactions
- D. Transporting hydrogen ions in the dark reactions
Correct Answer: C
Rationale: Water is crucial in photosynthesis as it provides electrons during the light reactions. When water molecules are split in the light-dependent reactions, oxygen is released, and electrons are transferred to photosystem II to initiate the electron transport chain. This process is vital for the production of ATP and NADPH, which are necessary for the Calvin cycle to synthesize sugars.
Which method of glucose conversion generates the most usable and efficient form of ATP within the human body?
- A. Aerobic respiration
- B. Anaerobic respiration
- C. Lactic acidosis
- D. Fermentation conversion
Correct Answer: A
Rationale: Aerobic respiration generates the most ATP (around 36-38 ATP molecules per glucose molecule). It uses oxygen and occurs in the mitochondria, making it the most efficient way for the body to produce energy. In contrast, anaerobic respiration and fermentation produce significantly less ATP and are less efficient processes. Lactic acidosis is a medical condition involving the buildup of lactic acid in the body and is not a method of glucose conversion for energy production.
A mother is homozygous recessive for freckles (ff) and a father is heterozygous for freckles (FF). Which genotypic ratio for freckles do their children have?
- A. 50% ff, 50% FF.
- B. 25% ff, 75% Ff.
- C. 25% FF, 75% ff.
- D. 50% ff, 50% Ff.
Correct Answer: A
Rationale: Correct Answer: A (50% ff, 50% FF)
Rationale:
1. The mother is homozygous recessive (ff) and the father is heterozygous (FF).
2. The father can only pass on the dominant allele (F) to all offspring.
3. All offspring will inherit one F allele from the father and one f allele from the mother.
4. The genotypic ratio will be 50% FF (f from father) and 50% ff (f from mother).
Summary:
- Choice B is incorrect because the father cannot pass on the recessive allele.
- Choice C is incorrect as the mother is homozygous recessive.
- Choice D is incorrect because it does not consider the father's genotype.