Nokea
What will happen to a hard-boiled egg if placed in a beaker of saltwater?
- A. Expand due to water moving into the egg
- B. Shrivel due to water leaving the egg
- C. Remain the same
- D. None of the above
Correct Answer: B
Rationale: When a hard-boiled egg is placed in a beaker of saltwater, a hypertonic solution, water will move out of the egg through osmosis. The saltwater's higher solute concentration causes water to leave the egg in an attempt to balance the concentrations, resulting in the egg losing water and shrinking, leading to it shriveling.
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Why is homeostasis necessary?
- A. To maintain temperature
- B. To maintain pH
- C. To maintain glucose levels
- D. All of the above
Correct Answer: D
Rationale: Homeostasis is essential for the body to maintain internal balance and ensure optimal functioning. It is responsible for regulating temperature to prevent overheating or cooling, controlling pH levels to support biochemical reactions, and managing glucose levels for energy production. Therefore, all the options - maintaining temperature, pH, and glucose levels - are crucial functions of homeostasis.
What does the mitochondrion produce that causes it to often be called the powerhouse of the cell?
- A. ATP
- B. Enzymes.
- C. Proteins.
- D. DNA.
Correct Answer: A
Rationale:
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.
Which term means alternate forms of a gene for the same trait?
- A. Genotypes
- B. Alleles
- C. Gametes
- D. Phenotypes
Correct Answer: B
Rationale: Alleles are different versions of a gene that can exist for a given trait. For example, a gene for flower color may have a red allele and a white allele, representing the alternate forms of that gene. Genotypes refer to the genetic makeup, while phenotypes refer to the observable traits.
How do animal cells divide during cytokinesis?
- A. Contractile ring
- B. Cell plate
- C. Both
- D. None of the above
Correct Answer: A
Rationale: Animal cells divide using a contractile ring during cytokinesis. The contractile ring is composed of actin and myosin filaments and contracts to pinch the cell into two daughter cells. In contrast, cell plate formation is a mechanism observed in plant cells, not animal cells. Therefore, the correct answer is the contractile ring.