Correct Answer: A

Rationale: To convert centimeters to millimeters, you need to multiply by 10 since 1 centimeter is equal to 10 millimeters. Therefore, 8 cm x 10 mm/cm = 80 mm. The pencil measures 8 cm, which is equivalent to 80 mm when converted. Choice A is correct as it correctly converts 8 cm to mm by multiplying it by 10. Choices B, C, and D are incorrect because they do not apply the correct conversion factor.

Correct Answer: A

Rationale: Epithelial cells have a distinct top (apical) and bottom (basal) side, demonstrating polarity. This polarity is essential for their specialized functions, such as secretion, absorption, and barrier formation. Choice B, 'Neutral,' is incorrect as epithelial cells exhibit polarity. Choice C, 'Larger than other cells,' is incorrect as epithelial cells come in various sizes and are not specifically larger than other cell types. Choice D, 'None of the above,' is incorrect as epithelial cells are indeed polarized.

Correct Answer: D

Rationale: The term "phenotype" refers to the observable characteristics or traits of an organism, which are determined by a combination of genotype (genetic makeup), epigenetic factors (modifications to gene expression), and environmental factors (external influences and experiences). Genotype, epigenetic factors, and environmental factors all play a role in determining an individual's phenotype, making option D the correct statement. Options A, B, and C are incorrect because the phenotype is not the genetic code, the phenotype does not determine the genotype, and it is the genotype that influences the phenotype, not the other way around.

Correct Answer: D

Rationale: There are 206 bones in the human skeletal system. This includes bones in the skull, spine, ribs, arms, legs, hands, and feet. The correct answer is 206 because that is the standard number of bones in an adult human body. Choices A, B, and C are incorrect as they do not reflect the accurate count of bones in the human skeletal system.

Correct Answer: D

Rationale: Tundra, savannas, grasslands, deserts, and rainforests are examples of biomes. A biome is a large geographical area with similar climatic conditions and distinct flora and fauna. Each biome has its unique characteristics, such as temperature, precipitation levels, and types of vegetation, which define the ecosystem within that region. Biomasses refer to the total mass of living organisms in a given area, biospheres are the global ecological system integrating all living beings and their relationships, and biodiversity represents the variety of life forms in a specific habitat.