Nokea
What is the difference between isometric and isotonic muscle contractions?
- A. Isometric involves movement, while isotonic does not.
- B. Isotonic involves shortening of muscle, while isometric maintains length.
- C. Isometric uses more energy, while isotonic uses less.
- D. Isotonic involves smooth muscle, while isometric involves skeletal muscle.
Correct Answer: B
Rationale: The correct answer is B. Isometric contractions occur when the muscle generates tension without changing its length, while isotonic contractions involve the muscle changing length to move a load. In isotonic contractions, the muscle shortens to move a load, whereas in isometric contractions, the muscle contracts to hold a position without movement. Choice A is incorrect because isometric contractions do not involve movement, while choice C is incorrect as isotonic contractions typically require more energy due to movement. Choice D is incorrect because the type of muscle involved (smooth or skeletal) is not the defining factor between isometric and isotonic contractions.
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Which of the following is a common characteristic of alkynes?
- A. They have a triple bond between carbon atoms.
- B. They are saturated hydrocarbons.
- C. They contain only single bonds.
- D. They are aromatic compounds.
Correct Answer: A
Rationale: The correct answer is A. Alkynes are hydrocarbons characterized by at least one triple bond between carbon atoms. This triple bond sets them apart from alkanes, which only have single bonds, and alkenes, which feature at least one double bond. The presence of a triple bond makes alkynes unsaturated hydrocarbons. Choice B is incorrect as alkynes are unsaturated hydrocarbons, not saturated. Choice C is incorrect because alkynes contain at least one triple bond, making them different from compounds with only single bonds. Choice D is incorrect because aromatic compounds have a distinct cyclic structure with resonance stabilization, a feature not shared by alkynes.
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.
Differentiate between gene therapy and genetic engineering in the context of human intervention.
- A. Gene therapy aims to modify existing genes within body cells, while genetic engineering manipulates genes in embryos to be passed on to offspring.
- B. Gene therapy focuses on treating genetic diseases, while genetic engineering enhances desirable traits or eliminates undesirable ones.
- C. Both involve directly altering the DNA sequence, but gene therapy targets somatic cells and genetic engineering modifies germline cells.
- D. There is no fundamental difference; both terms are synonymous.
Correct Answer: B
Rationale: A) Incorrect. Gene therapy does aim to modify existing genes within body cells, but genetic engineering does not necessarily manipulate genes in embryos to be passed on to offspring. Genetic engineering can involve modifying genes in any type of cell, not just embryos.
B) Correct. Gene therapy is a medical intervention that aims to treat genetic diseases by correcting or replacing faulty genes within an individual's body cells. On the other hand, genetic engineering involves modifying genes to enhance specific traits or eliminate undesirable ones, often in the context of agriculture or biotechnology.
C) Incorrect. While both gene therapy and genetic engineering involve altering DNA sequences, the distinction lies in the target cells. Gene therapy targets somatic cells (non-reproductive cells), while genetic engineering typically involves modifying germline cells (reproductive cells that can pass on genetic changes to offspring).
D) Incorrect. There is
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.
What is the formula for calculating molarity?
- A. M = n/V
- B. M = n/L
- C. M = mol/L
- D. M = mol/dm³
Correct Answer: A
Rationale: The correct formula for calculating molarity is M = n/V. In this formula, 'M' represents molarity, 'n' represents the number of moles of solute, and 'V' represents the volume of the solution in liters. Molarity is defined as the number of moles of solute per liter of solution, hence the ratio of moles to volume. Choice B, 'M = n/L', is incorrect because 'L' should represent liters instead of the number of moles. Choice C, 'M = mol/L', is incorrect as it does not include the representation of the number of moles 'n'. Choice D, 'M = mol/dm³', is incorrect because 'dm³' is a volume unit equal to a liter, but the correct representation should be in terms of the volume of the solution in liters. Therefore, the correct answer is M = n/V.