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Which of the following organs filters excess solutes from the blood?
- A. Stomach
- B. Kidney
- C. Gallbladder
- D. Spleen
Correct Answer: B
Rationale: The correct answer is B: Kidney. The kidneys are vital organs responsible for filtering excess solutes, wastes, and toxins from the blood to produce urine. The stomach's primary function is digestion, the gallbladder stores bile, and the spleen aids in blood filtration and fighting infections. However, it is the kidneys that specifically filter solutes from the blood, making them crucial for maintaining proper fluid and electrolyte balance in the body.
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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.
How many times stronger is the hydrogen-ion concentration of a pH 4 solution compared with a pH 9 solution?
- A. 50
- B. 100,000
- C. 0.000001
- D. 5
Correct Answer: B
Rationale: The pH scale measures the concentration of hydrogen ions in a solution, where each pH unit change represents a tenfold difference in concentration. In this case, the pH 4 solution is 5 units lower than the pH 9 solution. Therefore, the difference of 5 pH units translates to a 10^5 times (or 100,000 times) increase in hydrogen-ion concentration in the pH 4 solution compared to the pH 9 solution. The pH scale is logarithmic, with each unit representing a tenfold change, so a 5-unit difference results in a 100,000-fold difference in hydrogen-ion concentration. Hence, option B, 100,000, is the correct answer.
When an organism with an unknown genotype is crossed with another organism displaying the recessive trait (aa), the Punnett square shown above illustrates the outcomes. What is the unknown genotype?
- A. a
- B. Aa
- C. AA
- D. aa
Correct Answer: B
Rationale: In the provided Punnett square, the recessive trait (aa) is displayed. This means the known organism must be homozygous recessive (aa). When crossed with the unknown genotype, which is represented by a capital letter (A), it results in a 50% chance of producing heterozygous offspring (Aa). As the recessive trait is expressed in the outcomes, the unknown genotype must carry the dominant allele (A) alongside the recessive allele (a), making it heterozygous (Aa). Therefore, the correct answer is B, Aa.
From which region of the intestine does the vermiform appendix extend, known as which of the following?
- A. Ischium
- B. Cecum
- C. Rectum
- D. Jejunum
Correct Answer: B
Rationale: The correct answer is B, Cecum. The vermiform appendix, a small tube-like structure, extends from the cecum, located in the lower right quadrant of the abdomen. Knowing the anatomical relationships among different intestinal parts is essential for identifying the appendix's origin.
A student conducts an experiment where they dissolve 1 g each of several substances in 50 mL of water. They have 12 identical plastic cups of water and place 1 g of salt into three of the cups, 1 g of sugar into three of the cups, and 1 g of baking soda into three of the cups. The three remaining cups contain only water. All the cups are put in a freezer, and the temperature of the solution in each cup is recorded every 15 minutes for 4 hours. What question is the student most likely investigating?
- A. What effect do different concentrations of solute have on the freezing point of water?
- B. How does the volume of water affect the rate at which it cools?
- C. What effect does cooling have on the solubility of different solutes?
- D. How is the cooling rate of water affected by different solutes?
Correct Answer: A
Rationale: The student is most likely investigating the effect of different concentrations of solutes (salt, sugar, baking soda) on the freezing point of water. By monitoring the temperature changes during freezing, the student can observe how each solute affects the freezing point. This experiment helps understand the concept of colligative properties, where the presence of solutes lowers the freezing point of a solvent like water. Therefore, the correct answer is A: 'What effect do different concentrations of solute have on the freezing point of water?'