What is the function of the gallbladder?

Correct Answer: B

Rationale: The correct answer is B: To store and concentrate bile. The gallbladder's primary function is to store and concentrate bile, which is produced by the liver. Bile is released into the small intestine to aid in the digestion and absorption of fats. It helps in emulsifying fats and facilitating their breakdown by enzymes for better absorption. Choices A, C, and D are incorrect because the gallbladder does not produce bile (it is produced by the liver), detoxify harmful substances, or directly break down fats. Its main role is to store and concentrate bile before releasing it into the small intestine.

Correct Answer: C

Rationale: Platelets, also known as thrombocytes, play a crucial role in blood clotting. When there is an injury, platelets adhere to the site and release substances that form a clot, preventing excessive bleeding. This function is vital for maintaining hemostasis and preventing blood loss. Choice A is incorrect because red blood cells, not platelets, are responsible for transporting oxygen. Choice B is incorrect as white blood cells are primarily responsible for fighting infections. Choice D is incorrect as nutrients are mainly transported by plasma and red blood cells, not platelets.

Correct Answer: C

Rationale: The alveoli are tiny air sacs in the lungs responsible for the exchange of gases, specifically oxygen and carbon dioxide, during breathing. Oxygen is taken in and carbon dioxide is released through this process, enabling the body to receive oxygen and expel carbon dioxide. Choice A is incorrect because the alveoli do not absorb oxygen but facilitate the exchange of gases. Choice B is incorrect as the alveoli do not remove carbon dioxide but aid in the exchange of gases. Choice D is incorrect as the alveoli are not involved in regulating blood pressure but in gas exchange.

Correct Answer: C

Rationale: The correct answer is C: To clot blood. Platelets, also known as thrombocytes, have a primary function in blood clotting. They help in the process of coagulation, forming clots to prevent excessive bleeding when injuries occur. Platelets play a crucial role in maintaining the integrity of the circulatory system by sealing off damaged blood vessels and promoting wound healing. Choices A, B, and D are incorrect because platelets do not carry oxygen, fight infections, or transport nutrients in the blood.

Correct Answer: B

Rationale: The lens of the eye is responsible for focusing light on the retina. When light enters the eye, it first passes through the cornea, which helps in bending the light, and then the lens further refracts and focuses the light onto the retina at the back of the eye. The retina contains photoreceptor cells that convert light into neural signals, which are then sent to the brain for visual processing. The cornea is the transparent outermost layer of the eye that helps in focusing light, but the main responsibility lies with the lens. The retina is the layer at the back of the eye that receives the focused light and initiates the process of vision. The pupil is the opening in the center of the iris that controls the amount of light entering the eye and is not directly involved in focusing light on the retina.