Nokea
Which of the following respiratory structures is affected by a disease that disrupts gas exchange, such as emphysema?
- A. Trachea
- B. Alveoli
- C. Secondary bronchi
- D. Primary bronchi
Correct Answer: B
Rationale: Emphysema is a condition that primarily affects the alveoli in the lungs. Alveoli are tiny air sacs where the exchange of oxygen and carbon dioxide occurs. In emphysema, the walls of these air sacs break down, reducing the surface area available for gas exchange. This leads to impaired respiratory function, making it harder for oxygen to enter the bloodstream and for carbon dioxide to be removed. Therefore, the correct answer is the alveoli (Choice B).
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Which organelle in a eukaryotic cell is responsible for producing ATP?
- A. Mitochondria
- B. Lysosomes
- C. Nucleus
- D. Centrioles
Correct Answer: A
Rationale: The correct answer is A, Mitochondria. Mitochondria are commonly referred to as the powerhouse of the cell because they play a crucial role in generating energy in the form of ATP through cellular respiration. Lysosomes are mainly involved in cellular waste management, the nucleus houses genetic material, and centrioles aid in cell division. Thus, among the organelles listed, the mitochondria is primarily responsible for ATP production in eukaryotic cells.
The triple point of a substance is the temperature and pressure at which the substance exists as which of the following?
- A. As a gel with solid and liquid trapped in gas
- B. Simultaneously in sol, gel, and plasma phases
- C. Simultaneously in solid, liquid, and gas phases
- D. As a sol with gas and solid trapped in liquid
Correct Answer: C
Rationale: The triple point is a specific condition where a substance can exist simultaneously in all three phases: solid, liquid, and gas. The other options do not accurately describe this state.
Which of the following statements best describes the function of a buffer?
- A. It permanently binds hydrogen ions.
- B. It causes the pH of a solution to become neutral.
- C. It decreases the pH of the solution.
- D. It enables resistance to a change in pH.
Correct Answer: D
Rationale: The correct answer is D: 'It enables resistance to a change in pH.' Buffers function by resisting changes in pH when small amounts of acid or base are added to a solution, thereby maintaining a stable pH. Option A is incorrect because buffers do not permanently bind hydrogen ions; they can release or absorb them as needed to maintain pH. Option B is incorrect because buffers do not necessarily cause a solution's pH to become neutral; they stabilize the pH at a specific value. Option C is incorrect; buffers can increase or decrease pH depending on the conditions to maintain stability. Therefore, the best description of a buffer's function is its ability to resist changes in pH.
Which of the following synthesizes antidiuretic hormone?
- A. Pancreas
- B. Thymus
- C. Hypothalamus
- D. Pineal gland
Correct Answer: C
Rationale: The correct answer is C: Hypothalamus. The hypothalamus, located in the brain, synthesizes antidiuretic hormone (ADH), also known as vasopressin. ADH is crucial in regulating water balance by controlling the reabsorption of water in the kidneys. This action reduces urine production, helping to maintain proper fluid levels in the body and prevent dehydration. While the pancreas, thymus, and pineal gland play important roles in the endocrine system, they are not responsible for synthesizing antidiuretic hormone.
After being absorbed in the small intestines, where do lipids first enter?
- A. Arteries
- B. Veins
- C. Intestinal spaces
- D. Lacteal vessels
Correct Answer: D
Rationale: After being absorbed in the small intestines, lipids first enter lacteal vessels. Lacteal vessels are part of the lymphatic system responsible for transporting dietary fats and fat-soluble vitamins. These vessels aid in the absorption and transport of lipids from the intestines to the bloodstream, playing a crucial role in the body's fat metabolism.