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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.

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Which term means alternate forms of a gene for the same trait?

  • A. Phenotypes.
  • B. Genotypes
  • C. Alleles.
  • D. Gametes.
Correct Answer: C

Rationale:

What does the mitochondrion produce that causes it to often be called the powerhouse of the cell?

  • A. ATP
  • B. Enzymes
  • C. DNA
  • D. Proteins
Correct Answer: A

Rationale: The mitochondrion produces ATP (adenosine triphosphate), which is the primary energy currency of the cell. This energy production is why mitochondria are referred to as the powerhouse of the cell. ATP generated by mitochondria is essential for various cellular processes, such as muscle contraction, cell division, and macromolecule synthesis, making it a crucial organelle for cell function.

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 utilize a contractile ring.
  • D. Plant cells have a cell wall that hinders the formation of a contractile ring.
Correct Answer: D

Rationale: Plant cells have a rigid cell wall surrounding their cell membrane, which prevents the formation of a contractile ring during cell division. The contractile ring is a structure composed of actin filaments responsible for pinching the cell in two during cytokinesis. Since plant cells cannot form a contractile ring due to the presence of the cell wall, they rely on other methods such as cell plate formation to complete cell division.

Are all bacteria bad, and do they always cause infections?

  • A. TRUE
  • B. FALSE
  • C. Sometimes
  • D. Not sure
Correct Answer: B

Rationale: The misconception that all bacteria are harmful and always cause infections is incorrect. Although some bacteria can lead to diseases, it is essential to note that not all bacteria are harmful. In reality, certain bacteria are beneficial and serve important functions in the body, such as aiding in digestion. Therefore, the correct answer is FALSE.

Osmotic pressure is the tendency for a single solution to absorb what substance?

  • A. Sodium.
  • B. Water.
  • C. Positive ions.
  • D. Negative ions.
Correct Answer: B

Rationale: The correct answer is B: Water. Osmotic pressure is the pressure required to prevent the flow of water across a semipermeable membrane to achieve equilibrium. Water moves from a region of lower solute concentration to higher solute concentration to balance the concentration on both sides of the membrane. Therefore, the tendency for a solution to absorb water is what osmotic pressure refers to. Choices A, C, and D are incorrect because osmotic pressure is specifically related to the movement of water molecules, not sodium, positive ions, or negative ions.

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