The brain is part of which system?

Correct Answer: B

Rationale: The brain is a crucial organ that serves as the command center of the body, making it a key component of the nervous system. It processes sensory information, coordinates movements, and regulates various bodily functions. Therefore, the brain is correctly categorized as part of the nervous system. Choices A, C, and D are incorrect because the integumentary system pertains to the skin, the endocrine system involves hormone regulation, and the respiratory system is responsible for breathing. These systems do not encompass the brain's functions or structure.

Correct Answer: A

Rationale: Cilia and flagella are microtubule-based structures found on the surface of many eukaryotic cells. Their primary function is to facilitate cell movement. Cilia are short, numerous, and move in coordinated waving motions to move substances along the cell's surface. Flagella are longer and usually limited to one or a few per cell, providing a propeller-like movement for the cell. Both cilia and flagella aid in cell motility and are essential for various cellular functions, primarily involved in cell movement rather than protein synthesis, protection, or digestion. Therefore, choice A is correct as it accurately describes the primary function of cilia and flagella. Choices B, C, and D are incorrect as cilia and flagella are not involved in protein synthesis, cell protection, or digestion in cells.

Correct Answer: C

Rationale: The correct answer is 'Cellular differentiation'. Cellular differentiation is the process by which simple cells become highly specialized cells. During cellular differentiation, cells acquire specific structures and functions that allow them to perform particular roles within an organism. This process involves the activation and silencing of specific genes, leading to the development of various cell types with distinct characteristics and functions. 'Cellular complication' (Choice A) is incorrect as it does not describe the specific process of cells becoming specialized. 'Cellular specialization' (Choice B) is not the most precise term for the process, as it does not capture the transformation from simple cells to specialized cells. 'Cellular modification' (Choice D) is incorrect as it is a vague term that does not specifically refer to the process of cellular specialization.

Correct Answer: D

Rationale: Meiosis is the process of cell division that results in the formation of sex cells (gametes) with only half the number of chromosomes as the parent cell, leading to genetically different cells. In contrast, mitosis is a cell division process that produces two daughter cells that are genetically identical to each other and the parent cell, maintaining the same chromosome number. Therefore, the correct answer is D, as meiosis and mitosis differ in their genetic outcomes - meiosis results in genetic diversity, while mitosis maintains genetic identity. Choices A, B, and C are incorrect because they do not accurately distinguish between meiosis and mitosis. Meiosis is not used for repairing the body or asexual reproduction, and the occurrence of both processes in various organisms does not highlight their primary differences in genetic outcomes.

Correct Answer: D

Rationale: The integumentary system, which includes the skin, performs various functions like protecting internal tissues from injury, waterproofing the body, and helping regulate body temperature. The function of returning fluid to the blood vessels is primarily associated with the lymphatic system, not the integumentary system. The skin contributes to fluid balance by regulating sweating and preventing excessive water loss, but it does not directly return fluid to the blood vessels, making this the correct answer. Choices A, B, and C are functions directly related to the integumentary system and are essential for maintaining the body's overall health and well-being.