1. Which of the following organs is responsible for the mechanical breakdown of food into smaller pieces?

A. Esophagus
B. Stomach
C. Small intestine
D. Mouth

Correct answer: D

Rationale: The correct answer is D: Mouth. The mouth is responsible for the mechanical breakdown of food into smaller pieces through the process of chewing. The teeth in the mouth help to grind and crush food into smaller particles, making it easier for digestion to occur. The esophagus is a muscular tube that transports food to the stomach but does not contribute to mechanical breakdown. The stomach is responsible for further breaking down food using acid and enzymes, while the small intestine is mainly involved in the absorption of nutrients. Therefore, the mouth plays a crucial role in the initial mechanical digestion of food.

2. What is the functional group present in amines?

A. Hydroxyl
B. Carbonyl
C. Amine
D. Nitro

Correct answer: C

Rationale: Amines have the functional group -NHâ‚‚. The other choices are associated with different functional groups.

3. Sunscreen protects the skin from harmful ultraviolet (UV) rays by

A. Reflecting UV rays away from the skin
B. Absorbing UV rays and converting them to heat
C. Blocking UV rays completely
D. Stimulating melanin production

Correct answer: B

Rationale: The correct answer is B: Absorbing UV rays and converting them to heat. Sunscreen contains ingredients that act as filters to absorb UV radiation before it reaches the skin. These filters then convert the UV rays into a less harmful form of energy, usually heat, which is then released from the body. This process helps prevent UV radiation from damaging the skin cells and causing sunburn or long-term skin damage. Reflecting UV rays away from the skin (A) and blocking UV rays completely (C) are not accurate functions of sunscreen. Additionally, stimulating melanin production (D) is not a direct way in which sunscreen protects the skin from UV rays.

4. A medication dosage is listed as 1/2 teaspoon. What is the equivalent dosage in milliliters (1 teaspoon = 5ml)?

A. 1.25ml
B. 2.5ml
C. 3.75ml
D. 5ml

Correct answer: B

Rationale: 2.5ml: Divide the teaspoon dosage (1/2) by the conversion factor (2 teaspoons/5ml).

5. What are the key differences between cytokinesis in plant and animal cells?

A. Animal cells utilize an actomyosin ring for cleavage furrow formation, while plant cells lack this mechanism.
B. Plant cells rely on the assembly of a cell plate in the center of the dividing cell, ultimately separating the cytoplasm.
C. Cytokinesis in both plant and animal cells is driven by the expansion of the endoplasmic reticulum.
D. Both types of cells achieve cytokinesis through similar membrane pinching and constriction mechanisms.

Correct answer: B

Rationale: Rationale: A) Animal cells utilize an actomyosin ring for cleavage furrow formation, while plant cells lack this mechanism. - This statement is true. Animal cells use an actomyosin ring to form a cleavage furrow during cytokinesis, while plant cells do not have this mechanism. Instead, plant cells form a cell plate. B) Plant cells rely on the assembly of a cell plate in the center of the dividing cell, ultimately separating the cytoplasm. - This statement is correct. Plant cells form a cell plate in the middle of the dividing cell during cytokinesis. The cell plate eventually develops into a new cell wall that separates the two daughter cells. C) Cytokinesis in both plant and animal cells is driven by the expansion of the endoplasmic reticulum. - This

6. What checkpoint mechanism ensures all chromosomes are attached to the spindle fibers before anaphase begins?

A. Prometaphase
B. Prometaphase
C. Cyclin degradation
D. Sister chromatid cohesion

Correct answer: A

Rationale: Rationale: A) Prometaphase is the correct answer because it is the stage of mitosis where all chromosomes are attached to the spindle fibers before anaphase begins. During prometaphase, the nuclear envelope breaks down, allowing the spindle fibers to attach to the kinetochores of the chromosomes. This attachment is necessary for proper chromosome alignment and segregation during anaphase. B) Metaphase is incorrect because it is the stage where chromosomes are aligned at the metaphase plate but do not necessarily have all spindle fibers attached. C) Cyclin degradation is incorrect because it is a regulatory mechanism that controls the progression of the cell cycle but is not specifically related to ensuring all chromosomes are attached to spindle fibers. D) Sister chromatid cohesion is incorrect because it refers to the physical connection between sister chromatids that is maintained until anaphase, but it does not ensure that all chromosomes are attached to spindle fibers.