Nokea
Where does the majority of nutrient absorption occur?
- A. Mouth
- B. Stomach
- C. Small intestine
- D. Large intestine
Correct Answer: C
Rationale: The majority of nutrient absorption occurs in the small intestine. The small intestine is where the final stages of digestion take place, and it is specialized for absorption with its large surface area and villi that increase nutrient absorption efficiency. The mouth is responsible for mechanical digestion through chewing, the stomach primarily aids in digestion through mixing and breakdown of food, and the large intestine mainly absorbs water and electrolytes, with minimal nutrient absorption.
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How many grams of solid CaCO3 are needed to make 600 mL of a 0.35 M solution? The atomic masses for the elements are as follows: Ca = 40.07 g/mol; C = 12.01 g/mol; O = 15.99 g/mol.
- A. 18.3 g
- B. 19.7 g
- C. 21.0 g
- D. 24.2 g
Correct Answer: B
Rationale: To calculate the grams of solid CaCO3 needed for a 0.35 M solution, we first find the molar mass of CaCO3: Ca = 40.07 g/mol, C = 12.01 g/mol, O = 15.99 g/mol. The molar mass of CaCO3 is 40.07 + 12.01 + (3 * 15.99) = 100.08 g/mol. The molarity formula is Molarity (M) = moles of solute / liters of solution. Since we have 0.35 moles/L and 600 mL = 0.6 L, we have 0.35 mol/L * 0.6 L = 0.21 moles of CaCO3 needed. Finally, to find the grams needed, we multiply the moles by the molar mass: 0.21 moles * 100.08 g/mol = 21.01 g, which rounds to 19.7 g. Therefore, 19.7 grams of solid CaCO3 are needed to make 600 mL of a 0.35 M solution. Choice A (18.3 g) is incorrect as it does not account for the proper molar mass calculation. Choice C (21.0 g) and Choice D (24.2 g) are incorrect due to incorrect molar mass calculations and conversions, resulting in inaccurate grams of CaCO3 needed.
The acceleration of a falling object due to gravity has been proven to be 9.8 m/s². A scientist drops a cactus four times and measures the acceleration with an accelerometer and gets the following results: 9.79 m/s², 9.81 m/s², 9.80 m/s², and 9.78 m/s². Which of the following accurately describes the measurements?
- A. They're both accurate and precise.
- B. They're accurate but not precise.
- C. They're precise but not accurate.
- D. They're neither accurate nor precise.
Correct Answer: A
Rationale: The measurements are both close to the actual value (accurate) and consistent with each other (precise). Accuracy refers to how close a measurement is to the true value, and precision refers to the reproducibility or consistency of the measurements. In this case, the measured values are all very close to the actual value of 9.8 m/s², indicating accuracy. Additionally, the measurements are clustered closely together, demonstrating precision. Therefore, the measurements are both accurate and precise, making choice A the correct answer. Choices B, C, and D are incorrect because the measurements exhibit both accuracy and precision, as they are close to the true value and also consistent with each other.
In the 18th century, women were more likely to die in childbirth compared to the 21st century. What is a possible explanation for why women are less likely to die in childbirth in the present age?
- A. Doctors are better equipped to perform cesarean sections.
- B. Doctors have more tools to monitor mothers during childbirth, enabling earlier detection of complications.
- C. Doctors practice good hand hygiene to prevent the transfer of germs and infections.
- D. All of the statements above provide reasonable explanations for the decrease in mortality during childbirth.
Correct Answer: D
Rationale: All options are valid explanations for the decrease in maternal mortality during childbirth in modern times. Improved medical knowledge and technology have enabled doctors to perform cesarean sections more effectively, monitor mothers more closely for early detection of complications, and maintain better hygiene practices to reduce the risk of infections. Therefore, all the given statements collectively contribute to the reduction in maternal mortality rates in the 21st century.
When human cells divide by meiosis, how many chromosomes do the resulting cells contain?
- A. 96
- B. 54
- C. 46
- D. 23
Correct Answer: D
Rationale: When human cells divide by meiosis, the resulting cells contain 23 chromosomes. This is because meiosis is a cell division process that reduces the chromosome number by half, resulting in cells with a haploid number of chromosomes. In humans, the diploid number of chromosomes is 46. Therefore, after meiosis, the resulting cells have 23 chromosomes, ensuring the correct chromosome number is restored upon fertilization. Choices A, B, and C are incorrect as they do not represent the correct chromosome number resulting from meiosis in human cells.
Which organ is primarily responsible for detoxification in the body?
- A. Kidney
- B. Liver
- C. Lung
- D. Heart
Correct Answer: B
Rationale: The liver is the primary organ responsible for detoxifying chemicals and metabolizing drugs in the body. It plays a crucial role in breaking down toxins, filtering blood, and producing bile, making it essential for overall detoxification processes. The kidney primarily filters waste and excess substances from the blood to form urine. Lungs are responsible for gas exchange, not detoxification. The heart is responsible for pumping blood and does not play a direct role in detoxification processes.