Correct Answer: B

Rationale: Correct. Positive feedback loops enhance or amplify changes, which can sometimes be harmful as they drive processes further from equilibrium. In contrast, negative feedback loops work to counteract deviations from a set point, promoting stability. Choice A, 'Negative feedback loop,' is incorrect because negative feedback loops inhibit or reduce changes, promoting stability. Choice C, 'Inhibitory feedback loop,' is incorrect as it is synonymous with negative feedback loops. Choice D, 'Stimulating feedback loop,' is incorrect as it inaccurately describes the nature of positive feedback loops.

Correct Answer: B

Rationale: The correct answer is B. Mendel's laws consist of the law of segregation, which states that each parent passes one allele for each trait, and the law of independent assortment, which explains that genes for different traits are inherited independently. Choice A is incorrect because 'law of expression' is not one of Mendel's laws. Choice C is incorrect because 'law of dominance' and 'law of recessiveness' do not represent the two main laws proposed by Mendel. Choice D is incorrect because 'law of mutation' and 'law of crossing over' are not part of Mendel's original laws.

Correct Answer: A

Rationale: Astrocytes are a type of glial cell that provide support and protection for neurons in both the central and peripheral nervous systems. While the term 'Neuroglia' is often used to refer to glial cells collectively, in this context, the question specifically asks for the name of the cells, making 'Astrocytes' the correct answer. Choice B, 'Neuroglia,' is a general term for all glial cells, not a specific type. Choices C and D, 'Oligodendrocytes' and 'Schwann cells,' are also types of glial cells but are not the primary cells responsible for supporting and protecting neurons as described in the question.

Correct Answer: A

Rationale: The correct answer is 'Superior.' 'Superior' refers to a position toward the head, while 'inferior' is the term for a position toward the feet. In the given example, the hand belongs to the superior extremity, which includes structures closer to the head. 'Inferior' is incorrect as it refers to a position away from the head or toward the feet. 'Medial' describes a position closer to the midline of the body, while 'lateral' refers to a position farther away from the midline.

Correct Answer: B

Rationale: The correct answer is B: Thyroid gland. The thyroid gland is responsible for regulating the body's metabolism by producing hormones like thyroxine. These hormones play a key role in controlling the body's metabolic rate and energy production. Choice A, the pituitary gland, is often referred to as the 'master gland' but is not primarily responsible for regulating metabolism. Choice C, the adrenal gland, is involved in producing hormones like adrenaline and cortisol, which are crucial for the body's stress response but not primarily for metabolism. Choice D, the pineal gland, is responsible for producing melatonin, which regulates sleep-wake cycles and not directly related to metabolic regulation.