Nokea
What is the fluid-filled, jelly-like substance within the cell that suspends the organelles called?
- A. Nucleus
- B. Cytoplasm
- C. Plasma membrane
- D. Golgi apparatus
Correct Answer: B
Rationale: The correct answer is B, cytoplasm. Cytoplasm is the fluid-filled, jelly-like substance within the cell that suspends the organelles. The nucleus, not the correct answer, is the organelle that contains the cell's genetic material. The plasma membrane, another incorrect choice, is the outer boundary of the cell that regulates what enters and exits the cell. The Golgi apparatus, also an incorrect choice, is an organelle involved in processing and packaging proteins.
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Which hormone is responsible for lowering blood sugar levels?
- A. Glucagon
- B. Insulin
- C. Adrenaline
- D. Cortisol
Correct Answer: B
Rationale: Insulin is the hormone responsible for lowering blood sugar levels. It is produced by the pancreas and facilitates the entry of glucose into cells, thereby reducing blood sugar levels. Glucagon, adrenaline, and cortisol have roles in increasing blood sugar levels through various mechanisms. Glucagon raises blood sugar levels by stimulating the liver to release stored glucose, adrenaline increases blood sugar in fight-or-flight responses, and cortisol raises blood sugar levels as part of the stress response. Therefore, in the context of lowering blood sugar levels, insulin is the correct answer.
What term refers to the point of contact between a motor neuron and a muscle fiber, where communication occurs to initiate muscle contraction?
- A. Sarcomere
- B. Synapse
- C. Tendon
- D. Myofibril
Correct Answer: B
Rationale: The correct answer is B, 'Synapse.' The synapse is the specific term that refers to the point of contact between a motor neuron and a muscle fiber, where communication occurs to initiate muscle contraction. At the synapse, neurotransmitters are released by the motor neuron, triggering the muscle fiber to contract. Choice A, 'Sarcomere,' is incorrect as a sarcomere is the basic unit of muscle contraction, not the point of contact between a motor neuron and a muscle fiber. Choice C, 'Tendon,' is incorrect as tendons are fibrous connective tissues that connect muscle to bone, not involved in neuronal communication. Choice D, 'Myofibril,' is incorrect as a myofibril is a structure within muscle fibers where muscle contractions occur, not the specific point of contact for communication between a motor neuron and a muscle fiber.
How does sunscreen protect the skin from harmful ultraviolet (UV) rays?
- A. By reflecting UV rays away from the skin
- B. By absorbing UV rays and converting them to heat
- C. By blocking UV rays completely
- D. By stimulating melanin production
Correct Answer: B
Rationale: Sunscreen works by absorbing UV rays and converting them to heat. This mechanism helps to prevent the UV rays from penetrating the skin and causing damage such as sunburn, premature aging, and skin cancer. Reflecting UV rays away from the skin (option A) is not the primary function of sunscreen. While sunscreen does block UV rays, it does not do so completely (option C) as some UV rays may still penetrate the skin. Sunscreen does not stimulate melanin production (option D) as a means of protecting the skin from UV rays.
What is the largest bone in the human body?
- A. Femur (thigh bone)
- B. Tibia (shin bone)
- C. Humerus (upper arm bone)
- D. Scapula (shoulder blade)
Correct Answer: A
Rationale: The femur, also known as the thigh bone, holds the title of the largest bone in the human body. Situated in the upper leg, the femur plays a vital role in supporting the body's weight and enabling movement. While the tibia (shin bone), humerus (upper arm bone), and scapula (shoulder blade) are all essential bones, none of them match the femur in terms of size and importance. The tibia, humerus, and scapula are comparatively smaller bones with specific functions in their respective areas of the body, but they do not surpass the femur in size or significance.
The gland located on top of the kidneys responsible for regulating blood pressure and electrolyte balance is the:
- A. Thyroid gland
- B. Pituitary gland
- C. Adrenal gland
- D. Parathyroid gland
Correct Answer: C
Rationale: The gland located on top of the kidneys responsible for regulating blood pressure and electrolyte balance is the adrenal gland. The adrenal gland produces hormones such as cortisol and aldosterone, which play a crucial role in regulating blood pressure and electrolyte balance in the body. The other choices, thyroid gland (choice A), pituitary gland (choice B), and parathyroid gland (choice D), do not have a primary role in regulating blood pressure and electrolyte balance. The thyroid gland is responsible for regulating metabolism, the pituitary gland controls various endocrine functions, and the parathyroid gland regulates calcium levels in the body.