Correct Answer: A

Rationale: The correct answer is A: Lunulae. The moon-shaped white structures at the base of fingernails are known as lunulae. They are most prominent on the thumb and are situated at the base of the nail matrix. The lunula is the visible part of the nail matrix, which is responsible for generating new nail cells. Choice B, Cuticle, is incorrect as it refers to the thin layer of skin at the base of the nail plate. Choice C, Hyponychium, is incorrect as it is the skin that lies beneath the free edge of the nail. Choice D, Matrix, is incorrect as it is the area where the nail is formed, located under the cuticle.

Correct Answer: C

Rationale: A major consequence of a stroke is brain damage due to interrupted blood flow. Strokes occur when blood flow to the brain is blocked or reduced, leading to the death of brain cells. This interruption in blood flow results in brain damage, which can cause physical and cognitive impairments such as paralysis, speech difficulties, memory problems, and sensory disturbances. The severity and location of the stroke determine the extent of the consequences experienced by the individual. Choices A, B, and D are incorrect. Irregular heart rhythm is not a direct consequence of a stroke but may occur as a complication. Rapid weight gain or loss and chronic fatigue with muscle weakness are not typically considered major consequences of a stroke, which primarily affects the brain due to interrupted blood flow.

Correct Answer: B

Rationale: The correct answer is B: Iron. Hemoglobin, the protein responsible for carrying oxygen in red blood cells, contains iron in its heme group, contributing to the blood's characteristic red color. Magnesium (choice A), copper (choice C), and zinc (choice D) are not responsible for the red color of blood. Magnesium is an essential mineral involved in various physiological processes, copper is a trace element important for enzyme function, and zinc is a micronutrient essential for multiple cellular functions but not related to the red color of blood.

Correct Answer: B

Rationale: - In the reaction, potassium ions (K+) and chloride ions (Cl-) are present on both sides of the equation. They are not involved in the formation of the products and remain unchanged. - Lead ions (Pb2+) and nitrate ions (NO3-) are involved in the formation of the products potassium nitrate (KNO3) and lead(II) chloride (PbCl2). - Therefore, the spectator ions in this reaction are K+ and Cl-.

Correct Answer: A

Rationale: The occipital lobe is the part of the brain responsible for processing visual information. Located at the back of the brain, the occipital lobe contains the primary visual cortex, which plays a crucial role in interpreting visual stimuli received from the eyes. The frontal lobe is primarily involved in higher cognitive functions, decision-making, and motor control, not vision processing. The temporal lobe is responsible for auditory processing, memory, and emotion, not vision. The parietal lobe is involved in sensory integration, spatial awareness, and perception of stimuli, but not specifically for visual processing.