Nokea
Which of the following is NOT a mechanism of evolution?
- A. Natural selection
- B. Genetic drift
- C. Lamarckism
- D. Mutation
Correct Answer: C
Rationale: A) Natural selection is a mechanism of evolution where individuals with advantageous traits are more likely to survive and reproduce, passing on those traits to the next generation.
B) Genetic drift is a mechanism of evolution that occurs due to random changes in allele frequencies in a population.
C) Lamarckism, also known as the inheritance of acquired characteristics, is a discredited theory that suggests organisms can pass on traits acquired during their lifetime to their offspring. This mechanism has been largely rejected by the scientific community.
D) Mutation is a mechanism of evolution that introduces new genetic variation into a population, which can lead to the emergence of new traits and adaptations over time.
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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.
Two objects with equal masses collide head-on, both initially moving at the same speed. After the collision, they stick together. What is their final velocity?
- A. Zero
- B. Half their initial velocity
- C. Their initial velocity
- D. Twice their initial velocity
Correct Answer: C
Rationale: In an inelastic collision where two objects stick together after colliding, momentum is conserved. Since the two objects have equal masses and equal initial velocities but opposite directions, their momenta cancel out. Therefore, after the collision, the combined mass will move at the same speed as the initial velocity, but in the direction of one of the objects. Choice A ('Zero') is incorrect because momentum is conserved, and the objects must move after the collision. Choice B ('Half their initial velocity') is incorrect as the final velocity is the same as the initial velocity due to momentum conservation. Choice D ('Twice their initial velocity') is incorrect as the final velocity cannot be twice the initial velocity based on the conservation of momentum principle.
What is the term for the process of a liquid changing into a gas?
- A. Evaporation
- B. Boiling
- C. Condensation
- D. Sublimation
Correct Answer: A
Rationale: The correct answer is 'Evaporation.' Evaporation is the process by which a liquid changes into a gas at any temperature, while boiling specifically refers to the rapid vaporization of a liquid only at its boiling point. Condensation is the opposite process of gas turning into a liquid, and sublimation is the direct transition from solid to gas without passing through the liquid phase.
What is the general formula for an alkene?
- A. CnH2n+2
- B. CnH2n
- C. CnH2n-2
- D. CnH2n+1
Correct Answer: B
Rationale: The general formula for an alkene is \(C_nH_{2n}\), indicating the presence of a double bond between carbon atoms.
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.