Nokea
Which of the following is NOT a property of a catalyst?
- A. Increases the rate of a reaction
- B. Remains unchanged after the reaction
- C. Lowers the activation energy
- D. Creates new products
Correct Answer: D
Rationale: A catalyst is a substance that increases the rate of a chemical reaction without being consumed in the process. It remains unchanged after the reaction, which eliminates option B. A catalyst works by lowering the activation energy required for the reaction to occur, which eliminates option C. A catalyst does not create new products in a reaction; it only facilitates the conversion of reactants into products more efficiently. Therefore, option D is NOT a property of a catalyst.
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The lymphatic system is a network of vessels and organs that plays a vital role in:
- A. Transporting oxygen and nutrients to cells
- B. Carrying waste products away from tissues
- C. Regulating body temperature
- D. Producing red blood cells
Correct Answer: B
Rationale: The correct answer is B: Carrying waste products away from tissues. The lymphatic system functions to maintain fluid balance in the body by removing excess fluid, filtering out harmful substances, and transporting waste products away from tissues. It does not primarily focus on transporting oxygen and nutrients to cells, regulating body temperature, or producing red blood cells. Choices A, C, and D are incorrect as the primary function of the lymphatic system is related to waste removal and maintaining fluid balance in the body, rather than roles such as nutrient transport, temperature regulation, or red blood cell production.
What is the difference between a real image and a virtual image formed by a lens?
- A. Real images can be projected onto a screen, while virtual images cannot.
- B. Real images are always upright, while virtual images can be inverted.
- C. Real images are formed by converging lenses, while virtual images are formed by diverging lenses.
- D. All of the above are true.
Correct Answer: A
Rationale: The correct answer is A. Real images can be projected onto a screen because they are formed by the actual convergence of light rays, while virtual images cannot be projected onto a screen as they appear to diverge from a point behind the lens. Real and virtual images do not have a consistent orientation (upright or inverted), so option B is incorrect. Real images are formed by both converging and diverging lenses depending on the specific scenario, so option C is not a definitive distinction. Option D is incorrect as not all the statements are true. Therefore, the only accurate general distinction between real and virtual images is that real images can be projected onto a screen, while virtual images cannot.
Which vitamin deficiency can lead to a condition called pernicious anemia, affecting vitamin B12 absorption in the digestive system?
- A. Vitamin A
- B. Vitamin B12 (cobalamin)
- C. Vitamin D
- D. Vitamin E
Correct Answer: B
Rationale: Pernicious anemia is caused by a deficiency in vitamin B12 (cobalamin). Vitamin B12 is essential for the production of red blood cells and for the proper functioning of the nervous system. Pernicious anemia occurs when there is a lack of intrinsic factor, a protein produced in the stomach that is necessary for the absorption of vitamin B12 in the digestive system. Vitamin A, Vitamin D, and Vitamin E deficiencies do not lead to pernicious anemia. Vitamin A deficiency can cause night blindness and skin issues, Vitamin D deficiency can lead to rickets or osteomalacia, and Vitamin E deficiency can result in neurological problems and muscle weakness.
What is the process by which muscle tissue wastes away due to disuse or lack of nutrients?
- A. Hypertrophy
- B. Atrophy
- C. Fibrosis
- D. Rigor mortis
Correct Answer: B
Rationale: Atrophy is the correct term for the process by which muscle tissue wastes away due to disuse or lack of nutrients. It is essential to differentiate atrophy from hypertrophy, which is the increase in muscle size due to exercise or strength training. Fibrosis involves the formation of excess fibrous connective tissue, which is distinct from muscle wasting. Rigor mortis, on the other hand, is the stiffening of muscles that occurs after death and is not related to muscle wasting during life.
Which hormone is responsible for regulating blood sugar levels and is produced by the pancreas?
- A. Insulin
- B. Glucagon
- C. Testosterone
- D. Estrogen
Correct Answer: A
Rationale: Insulin is the correct answer. It is the hormone produced by the pancreas that regulates blood sugar levels by facilitating the uptake of glucose from the blood into cells for energy production or storage. Glucagon, also produced by the pancreas, has the opposite effect of increasing blood sugar levels by promoting the release of stored glucose from the liver. Testosterone and estrogen are sex hormones produced by the testes and ovaries, respectively, and are not directly involved in regulating blood sugar levels.