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What is the role of platelets in the blood?
- A. Transport oxygen
- B. Fight infection
- C. Produce antibodies
- D. Clot blood
Correct Answer: D
Rationale: Platelets play a crucial role in blood clotting by forming clots to help stop bleeding. While red blood cells transport oxygen, white blood cells fight infection, and immune cells produce antibodies, platelets specifically function to prevent excessive bleeding by forming clots. Therefore, the correct answer is D. Choices A, B, and C are incorrect as they describe functions of other components of the blood, not platelets.
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How many molecules of NADPH and ATP are required to reduce 6 molecules of CO2 to glucose via photosynthesis?
- A. 6 NADPH and 9 ATP
- B. 12 NADPH and 18 ATP
- C. 18 NADPH and 24 ATP
- D. 24 NADPH and 36 ATP
Correct Answer: B
Rationale: During photosynthesis, 12 molecules of NADPH and 18 molecules of ATP are required to reduce 6 molecules of CO2 to glucose. NADPH and ATP are essential energy carriers in the process of photosynthesis. Choice A is incorrect because it underestimates the required molecules of both NADPH and ATP. Choices C and D overestimate the number of molecules needed, making them incorrect answers.
Which of the following is a function of the kidneys?
- A. To produce digestive enzymes
- B. To filter waste from the blood
- C. To produce white blood cells
- D. To produce red blood cells
Correct Answer: B
Rationale: The correct answer is B: 'To filter waste from the blood.' The kidneys are vital organs responsible for filtering waste products from the blood, regulating fluid and electrolyte balance, and producing urine. Choice A is incorrect because the production of digestive enzymes primarily occurs in the pancreas and salivary glands. Choice C is incorrect as the production of white blood cells mainly takes place in the bone marrow and lymphatic system. Choice D is incorrect as the production of red blood cells occurs in the bone marrow.
What is the role of the kidneys in the body?
- A. To regulate body temperature
- B. To filter waste from the blood
- C. To produce hormones
- D. To transport oxygen
Correct Answer: B
Rationale: The correct answer is B: To filter waste from the blood. The kidneys play a crucial role in filtering waste products and excess substances from the blood to form urine, which helps maintain fluid balance and eliminate toxins from the body. Choice A is incorrect because regulating body temperature is primarily controlled by the skin and other mechanisms. Choice C is incorrect as hormone production is mainly attributed to other organs like the endocrine glands. Choice D is incorrect as the transportation of oxygen is primarily facilitated by the lungs and circulatory system, not the kidneys.
Which region of the small intestine is the primary site of absorption?
- A. Duodenum
- B. Jejunum
- C. Ileum
- D. Cecum
Correct Answer: B
Rationale: The jejunum is the correct answer. It is the primary site of nutrient absorption in the small intestine. The duodenum mainly facilitates digestion, the ileum is responsible for further absorption, while the cecum is part of the large intestine and not involved in nutrient absorption.
What type of bond holds water molecules together?
- A. Covalent bond
- B. Hydrogen bond
- C. Ionic bond
- D. Peptide bond
Correct Answer: B
Rationale: The correct answer is B: Hydrogen bond. Hydrogen bonds are responsible for holding water molecules together. In a water molecule, the oxygen atom is slightly negative, and the hydrogen atoms are slightly positive, creating a partial positive and negative charge. This polarity allows hydrogen bonds to form between adjacent water molecules. Covalent bonds involve the sharing of electrons, ionic bonds involve transfer of electrons between ions, and peptide bonds are specific to linking amino acids in proteins, which are not relevant to water molecule interactions.