Nokea
Through which structure do the kidneys reabsorb water, salts, and nutrients and return them to the body?
- A. Renal artery
- B. Renal vein
- C. Nephron
- D. Glomerulus
Correct Answer: C
Rationale: The question has been corrected to specify the structure responsible for reabsorbing water, salts, and nutrients in the kidneys. The correct answer is the nephron, which is the functional unit of the kidney that performs filtration and reabsorption processes. The renal artery brings blood into the kidney for filtration, the renal vein carries filtered blood away from the kidney, and the glomerulus is a part of the nephron where filtration occurs. Therefore, the nephron is the structure that reabsorbs substances and returns them to the body.
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Which group of antibiotics targets the cell wall of bacteria?
- A. Penicillins
- B. Tetracyclines
- C. Macrolides
- D. Fluoroquinolones
Correct Answer: A
Rationale: Penicillins are a group of antibiotics that target the bacterial cell wall by inhibiting the synthesis of peptidoglycan, a vital component of the cell wall. This inhibition weakens the cell wall, leading to bacterial cell lysis and death. Penicillins are particularly effective against Gram-positive bacteria due to their mechanism of action. Tetracyclines (B) inhibit protein synthesis, Macrolides (C) interfere with bacterial ribosomes, and Fluoroquinolones (D) target bacterial DNA gyrase and topoisomerase IV. Unlike Penicillins, these antibiotics do not directly target the cell wall of bacteria.
Which of the following is an example of a decomposition reaction?
- A. 2H2 + O2 → 2H2O
- B. CaCO3 → CaO + CO2
- C. 2Na + Cl2 → 2NaCl
- D. N2 + 3H2 → 2NH3
Correct Answer: B
Rationale: A decomposition reaction involves a single compound breaking down into two or more simpler substances. In option B, CaCO3 breaks down into CaO and CO2, making it an example of a decomposition reaction. Options A, C, and D involve different types of chemical reactions such as synthesis, combination, and combustion, respectively. Option A represents a synthesis reaction, where two elements combine to form a compound. Option C demonstrates a combination reaction, where two elements combine to form a compound. Option D is an example of a synthesis reaction, where two reactants combine to form a single compound. It is important to recognize the specific characteristics of each type of chemical reaction to identify the correct example of decomposition reaction, where a compound breaks down into simpler products.
Where is the primary site for nutrient absorption from digested food in the human digestive system?
- A. Esophagus
- B. Large intestine
- C. Small intestine
- D. Stomach
Correct Answer: C
Rationale: The small intestine is the primary site for nutrient absorption in the human digestive system. It is where the majority of digestion and absorption of nutrients from food occurs. The walls of the small intestine are lined with tiny finger-like projections called villi, which increase the surface area available for absorption. Nutrients such as carbohydrates, proteins, fats, vitamins, and minerals are absorbed through the walls of the small intestine and into the bloodstream to be transported to cells throughout the body for energy and other functions. The esophagus is a muscular tube that connects the throat to the stomach and plays a role in swallowing, not nutrient absorption. The large intestine primarily absorbs water and electrolytes from the remaining indigestible food matter after the absorption of nutrients in the small intestine. The stomach mainly functions in the mechanical and chemical breakdown of food through muscular contractions and the secretion of digestive enzymes.
Skeletal muscles are attached to bones by tough connective tissues called
- A. Ligaments
- B. Tendons
- C. Cartilage
- D. Fascia
Correct Answer: B
Rationale: Skeletal muscles are attached to bones by tough connective tissues called tendons. Tendons are strong, fibrous cords that connect muscles to bones, allowing for movement and stability in the body. Ligaments (option A) connect bones to other bones, not muscles to bones. Cartilage (option C) is firm and flexible connective tissue found in various parts of the body, but it does not attach muscles to bones. Fascia (option D) is a connective tissue that surrounds muscles, providing support and protection, but it does not directly attach muscles to bones.
Which hormone is produced by the thyroid gland to regulate metabolism?
- A. Adrenaline
- B. Thyroxine
- C. Cortisol
- D. Insulin
Correct Answer: B
Rationale: Thyroxine, also known as T4, is the hormone produced by the thyroid gland to regulate metabolism. It is essential for controlling the body's metabolic rate, heart and digestive function, muscle control, brain development, and bone maintenance. Adrenaline is produced by the adrenal glands, not the thyroid gland. Cortisol is produced by the adrenal cortex, not the thyroid gland. Insulin is produced by the pancreas, not the thyroid gland. Therefore, the correct answer is Thyroxine (B).