Nokea
Which hormone regulates blood calcium levels?
- A. Growth hormone
- B. Melatonin
- C. Norepinephrine
- D. Parathyroid hormone
Correct Answer: D
Rationale: Parathyroid hormone is the correct answer. It plays a crucial role in regulating blood calcium levels by increasing calcium levels in the blood through stimulating the release of calcium from bones and enhancing calcium absorption in the intestines. Produced by the parathyroid glands, this hormone helps maintain calcium homeostasis in the body.
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Which laboratory method is most useful for separating genomic DNA fragments by size?
- A. Titration
- B. Spectrophotometry
- C. Electrophoresis
- D. Filtration
Correct Answer: C
Rationale: Electrophoresis is the most suitable method for separating genomic DNA fragments by size. In electrophoresis, DNA fragments are separated based on their size through an electric field. The smaller fragments move faster towards the positive electrode, while the larger fragments move slower, allowing for differentiation based on size. Titration is a technique used to determine the concentration of a substance in a solution, not for separating DNA fragments. Spectrophotometry is a method used to measure how much a substance absorbs light at different wavelengths, not for separating DNA fragments. Filtration is a process of separating solids from liquids using a filter, not commonly used for separating DNA fragments by size.
Which of the following vessels carries oxygenated blood?
- A. Pulmonary vein
- B. Superior vena cava
- C. Pulmonary artery
- D. Inferior vena cava
Correct Answer: A
Rationale: The correct answer is A, the pulmonary vein. The pulmonary vein carries oxygenated blood from the lungs back to the heart. It is crucial to differentiate between the pulmonary vein, which carries oxygenated blood, and the pulmonary artery, which carries deoxygenated blood. This understanding is fundamental in comprehending the flow of oxygen-rich and oxygen-poor blood within the cardiovascular system.
Which one of the following structures drains oxygen-depleted blood from the kidneys?
- A. Ureter
- B. Renal artery
- C. Urethra
- D. Renal vein
Correct Answer: D
Rationale: The correct answer is D, Renal vein. The renal vein is responsible for draining oxygen-depleted blood from the kidneys back to the heart for reoxygenation. The ureter carries urine from the kidneys to the bladder, the renal artery supplies oxygenated blood to the kidneys, and the urethra is the tube that carries urine from the bladder out of the body. Therefore, in the context of blood drainage from the kidneys, the renal vein is the correct choice.
Emphysema caused by damage to alveoli from toxins and pollutants is likely to result in the body having difficulty performing which of the following actions?
- A. Exchanging oxygen and carbon dioxide
- B. Absorbing food
- C. Releasing histamine and acetylcholine
- D. Producing enzymes
Correct Answer: A
Rationale: Emphysema is a condition that damages the alveoli in the lungs, leading to the loss of elasticity and reduced surface area for gas exchange. As a result, individuals with emphysema have difficulty in exchanging oxygen and carbon dioxide efficiently. The damage impairs the lung's ability to transfer oxygen from the air into the bloodstream and remove carbon dioxide from the body. Absorbing food (B), releasing histamine and acetylcholine (C), and producing enzymes (D) are not directly affected by emphysema.
To accurately measure the density of a series of small irregular solids made of plastic, wood, fiberglass, and glass, which of the following laboratory tools will a student need?
- A. Graduated cylinder, water, weighing balance
- B. Weighing balance, Bunsen burner, metric ruler
- C. Graduated cylinder, spectrophotometer, water
- D. Graduated beaker, metric ruler, water
Correct Answer: A
Rationale: To accurately measure the density of irregular solids made of various materials, a student needs specific laboratory tools. Firstly, a graduated cylinder is required to measure the volume of the irregular solids using the water displacement method, which allows for precise volume determination. Secondly, a weighing balance is necessary to measure the mass of the irregular solids accurately. Density is calculated by dividing the mass by the volume, hence the need for both mass and volume measurements. Therefore, the essential tools for this task are a combination of a graduated cylinder, water, and weighing balance (Choice A). These tools together provide the necessary measurements for calculating the density of the irregular solids accurately.