Nokea
Which gland produces the hormone melatonin?
- A. Pineal gland
- B. Thyroid gland
- C. Pituitary gland
- D. Adrenal gland
Correct Answer: A
Rationale: The correct answer is the Pineal gland. The pineal gland is responsible for producing melatonin, a hormone that helps regulate the sleep-wake cycle. Melatonin secretion is influenced by light exposure. Higher levels are observed at night to promote sleep, while lower levels during the day encourage wakefulness. Choices B, C, and D are incorrect as they are not associated with the production of melatonin. The thyroid gland produces hormones like thyroxine and triiodothyronine, the pituitary gland controls various other glands, and the adrenal gland produces hormones like adrenaline and cortisol.
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What is the primary function of hemoglobin in the blood?
- A. Transporting oxygen
- B. Carrying nutrients
- C. Clotting blood
- D. Removing carbon dioxide
Correct Answer: A
Rationale: The correct answer is A: Transporting oxygen. Hemoglobin, a protein found in red blood cells, plays a crucial role in transporting oxygen in the blood. It binds to oxygen in the lungs forming oxyhemoglobin and carries it to tissues and organs throughout the body. Once at the destination, hemoglobin releases the oxygen for cellular respiration, providing energy for various physiological processes. Choices B, C, and D are incorrect as hemoglobin's primary function is not carrying nutrients, clotting blood, or removing carbon dioxide. These functions are carried out by other components in the blood such as plasma proteins, platelets, and red blood cells, respectively.
Nerve tissue is composed of neurons and connective tissue cells that are referred to as which of the following?
- A. Osteoblasts
- B. Neuroglia
- C. Osteocytes
- D. Arterioles
Correct Answer: B
Rationale: Neuroglia are specialized connective tissue cells that provide support and protection to neurons in the nervous system. They assist in the proper functioning of neurons and are essential for maintaining the overall health of nerve tissue. Therefore, in the context of nerve tissue composition, neuroglia are the connective tissue cells associated with neurons. The other choices, osteoblasts, osteocytes, and arterioles, are not the correct types of connective tissue cells found in nerve tissue. Osteoblasts are involved in bone formation, osteocytes are mature bone cells, and arterioles are small blood vessels that supply blood to tissues.
What is the primary function of the digestive system?
- A. To transport oxygen
- B. To break down food and absorb nutrients
- C. To produce hormones
- D. To transport blood
Correct Answer: B
Rationale: The primary function of the digestive system is to break down food into smaller molecules and absorb nutrients such as vitamins, minerals, carbohydrates, proteins, and fats. These nutrients are then utilized by the body for energy, growth, and repair. The digestive system plays a crucial role in the process of extracting essential components from food and distributing them to the body's cells through the bloodstream. Choices A, C, and D are incorrect because transporting oxygen, producing hormones, and transporting blood are functions associated with other body systems like the respiratory system, endocrine system, and circulatory system, respectively, not the digestive system.
What is the primary function of the nervous system?
- A. To transmit signals and coordinate body activities
- B. To fight infections
- C. To produce hormones
- D. To regulate body temperature
Correct Answer: A
Rationale: The primary function of the nervous system is to transmit signals and coordinate body activities. It controls and regulates body functions by sending and receiving signals between different parts of the body, enabling responses to internal and external stimuli. This intricate network allows for communication between the brain, spinal cord, and the rest of the body, ultimately facilitating movement, sensation, thoughts, and various bodily functions. Choices B, C, and D are incorrect as they do not represent the primary function of the nervous system. Fighting infections is primarily the role of the immune system, producing hormones is the function of the endocrine system, and regulating body temperature involves mechanisms of thermoregulation within the body, not directly controlled by the nervous system.
Which organ in the digestive system absorbs nutrients?
- A. Stomach
- B. Small intestine
- C. Large intestine
- D. Esophagus
Correct Answer: B
Rationale: The small intestine is the primary site for nutrient absorption in the digestive system. It plays a crucial role in absorbing digested food into the bloodstream, where the nutrients are then circulated to the body's cells for energy and other functions. The stomach primarily breaks down food through the action of acids and enzymes, while the large intestine absorbs water and salts, not nutrients. The esophagus is a muscular tube that connects the mouth to the stomach and does not participate in nutrient absorption.