Correct Answer: C

Rationale: Antibiotic resistance in bacteria is a classic example of microevolution (option C). Microevolution refers to changes in allele frequencies within a population over a relatively short period of time. In the case of antibiotic resistance, bacteria evolve resistance to antibiotics through the natural selection of pre-existing resistant strains. This process does not involve the formation of new species or higher taxonomic groups, which are associated with macroevolution (option D). Convergent evolution (option A) involves different species independently evolving similar traits in response to similar environmental pressures, which is not the case with antibiotic resistance in bacteria. Divergent evolution (option B) refers to related species becoming more dissimilar over time, which also does not apply to the scenario of antibiotic resistance in bacteria.

Correct Answer: B

Rationale: Friction is a force that opposes motion when two surfaces are in contact. It acts in the opposite direction to the direction of motion, causing objects to slow down or come to a stop. Therefore, friction decreases speed rather than increasing it. Choice A is incorrect as friction does not increase speed but rather hinders it. Choice C is incorrect because friction does have an impact on speed by slowing down objects. Choice D is incorrect as friction's effect is not making objects float but rather causing resistance to motion.

Correct Answer: A

Rationale: The correct answer is A: Primary immune response. The primary immune response refers to the initial encounter with a specific pathogen, which triggers the development of the first immune response by the immune system. This response involves activating immune cells like B cells and T cells to produce antibodies and memory cells specific to that pathogen. On the other hand, the secondary immune response occurs upon re-exposure to the same pathogen and is characterized by a faster, stronger, and more effective immune response due to the presence of memory cells from the primary response. Choices B, C, and D are incorrect. The secondary immune response is the response upon re-exposure, hypersensitivity reactions are exaggerated immune responses to antigens, and immunological tolerance is the immune system's ability to recognize and tolerate self-antigens without mounting an immune response.

Correct Answer: C

Rationale: Sweat glands play a crucial role in regulating body temperature by producing sweat that evaporates from the skin surface. This evaporation cools the body when it is hot and helps to maintain a stable internal temperature. Sebaceous glands produce oil to lubricate the skin, hair follicles are responsible for hair growth, and Langerhans cells are a type of immune cell in the skin. Therefore, the correct answer is 'Sweat glands' as they are specifically designed to respond to temperature changes by constricting or dilating to help regulate body temperature.

Correct Answer: C

Rationale: Cellular respiration, the process of converting chemical energy into ATP, takes place in the mitochondria of eukaryotic cells. The mitochondria are known as the powerhouse of the cell because they are responsible for generating most of the cell's ATP through the process of cellular respiration. This process involves the breakdown of glucose and other organic molecules to produce ATP, which is the primary energy currency of the cell. The other organelles listed in the options (nucleus, ribosomes, and Golgi apparatus) do not play a direct role in cellular respiration. The nucleus is responsible for storing genetic material, ribosomes are involved in protein synthesis, and the Golgi apparatus is involved in processing and packaging proteins for secretion or internal use.