Nokea
Which cell organelle can be functionally compared to a door of a house?
- A. Endoplasmic reticulum
- B. Cell membrane
- C. Nucleus
- D. Cytoplasm
Correct Answer: B
Rationale: The cell membrane can be likened to a door of a house because it functions to regulate what enters and exits the cell, maintaining internal balance (homeostasis) and safeguarding the cell's interior. Just as a door controls access to a house, the cell membrane controls the passage of substances into and out of the cell, thereby playing a crucial role in maintaining the cell's integrity and functionality.
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What are the three types of muscle tissue?
- A. Cardiac, smooth, skeletal
- B. Smooth, skeletal, cardiac
- C. Neuron, epithelial, collagen
- D. None of the above
Correct Answer: B
Rationale: The correct answer is B: Smooth, skeletal, cardiac. Muscle tissue is classified into three main types: smooth muscle, skeletal muscle, and cardiac muscle. Smooth muscles are found in the walls of internal organs, blood vessels, and the digestive tract. Skeletal muscles are attached to bones and help in body movements. Cardiac muscles are found in the heart and are responsible for its rhythmic contractions.
What are the three types of muscle tissue?
- A. Cardiac, spinal, stomach
- B. Smooth, skeletal, cardiac
- C. Neuron, epithelial, collagen
- D. None of the above
Correct Answer: B
Rationale: The correct answer is B: Smooth, skeletal, cardiac. Muscle tissue in the body is classified into three main types: smooth muscle (found in hollow organs like the digestive tract), skeletal muscle (attached to bones, responsible for voluntary movement), and cardiac muscle (specific to the heart, responsible for its rhythmic contractions). Therefore, option B is the correct answer as it lists the three types of muscle tissue.
Which of the following statements is not true about enzymes?
- A. They catalyze reactions
- B. They raise the activation energy needed
- C. They have an active site
- D. They are typically proteins
Correct Answer: B
Rationale: Enzymes function by lowering the activation energy required for a reaction to occur, not by raising it. This catalytic property allows enzymes to accelerate reactions without being consumed in the process. Enzymes are biological catalysts that are typically proteins and have specific active sites where substrates bind and reactions take place. The statement that enzymes raise the activation energy needed is incorrect as their role is to lower this energy barrier. Therefore, the correct answer is B.
During which phase is the chromosome number reduced from diploid to haploid?
- A. S phase
- B. interphase
- C. mitosis
- D. meiosis I
Correct Answer: D
Rationale: The correct answer is meiosis I. Meiosis is a specialized cell division process that occurs in sexually reproducing organisms to produce gametes (sperm and egg). In meiosis I, the chromosome number is reduced from diploid (2n) to haploid (n) by separating homologous chromosomes. This reduction in chromosome number is crucial for maintaining the correct chromosome count in sexually reproducing organisms and ensuring genetic diversity in offspring.
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.