Nokea
Which type of wave motion occurs when particles move perpendicular to the direction of wave propagation?
- A. Transverse waves
- B. Longitudinal waves
- C. Electromagnetic waves
- D. Surface waves
Correct Answer: A
Rationale: Transverse waves are characterized by particles moving perpendicular to the direction of wave propagation. In transverse waves, the oscillations of particles are perpendicular to the direction of energy transfer. Longitudinal waves have particles that move parallel to the direction of wave propagation. Electromagnetic waves are a type of transverse wave that do not require a medium for propagation. Surface waves combine both longitudinal and transverse motions and occur at the interface between two different mediums.
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Which of the following can weaken the immune system and increase susceptibility to infections?
- A. Regular exercise
- B. Balanced diet
- C. Chronic stress
- D. Adequate sleep
Correct Answer: C
Rationale: Chronic stress can weaken the immune system by increasing the production of stress hormones like cortisol, which can suppress the immune response. This suppression can make individuals more susceptible to infections and illnesses. Conversely, regular exercise, a balanced diet, and adequate sleep actually support a healthy immune system and help strengthen it. Choices A, B, and D are incorrect as they are factors that generally contribute positively to the immune system. Regular exercise, a balanced diet, and adequate sleep are crucial for maintaining overall health and boosting the immune system rather than weakening it.
Which of the following organs is NOT directly involved in the mechanical breakdown of food?
- A. Mouth
- B. Stomach
- C. Small intestine
- D. Esophagus
Correct Answer: D
Rationale: The correct answer is the esophagus (D). The esophagus is not directly involved in the mechanical breakdown of food. Its primary function is to transport food from the mouth to the stomach through peristalsis, a series of muscular contractions. The mouth is involved in the initial mechanical breakdown by chewing and mixing food with saliva. The stomach mechanically breaks down food through churning movements, and the small intestine further breaks down food through peristalsis and segmentation. Choices A, B, and C are directly involved in mechanical breakdown processes. The mouth helps in chewing and mixing food with saliva, the stomach mechanically breaks down food through churning movements, and the small intestine continues the breakdown process with peristalsis and segmentation.
What is the difference between a germline mutation and a somatic mutation?
- A. Germline mutations are passed to offspring, while somatic mutations are not.
- B. Germline mutations occur in reproductive cells, while somatic mutations occur in body cells.
- C. Germline mutations only affect genes, while somatic mutations can affect any DNA.
- D. Germline mutations are always beneficial, while somatic mutations are always harmful.
Correct Answer: B
Rationale: Rationale:
- Germline mutations are changes in the DNA of reproductive cells (sperm or egg cells) and can be passed on to offspring, affecting all cells in the resulting organism.
- Somatic mutations are changes in the DNA of non-reproductive cells (body cells) and are not passed on to offspring. These mutations only affect the cells that arise from the mutated cell.
- Option A is incorrect because somatic mutations are not passed to offspring.
- Option C is incorrect because both germline and somatic mutations can affect any DNA.
- Option D is incorrect because the effects of mutations, whether germline or somatic, can be beneficial, harmful, or have no significant impact.
A ball is thrown upwards. Which of the following statements is TRUE about its potential energy and kinetic energy at the peak of its trajectory?
- A. Both potential and kinetic energy are zero.
- B. Potential energy is maximum and kinetic energy is minimum.
- C. Potential energy is minimum and kinetic energy is maximum.
- D. Both potential and kinetic energy remain constant.
Correct Answer: B
Rationale: At the peak of its trajectory, the ball momentarily stops moving before falling back down. This means its kinetic energy is at a minimum because it has come to a stop. At the same time, its potential energy is at a maximum because it is at the highest point in its trajectory, where it has the most potential to fall and convert that potential energy into kinetic energy as it descends. Choice A is incorrect because at the peak, the ball still has potential energy due to its height. Choice C is incorrect because kinetic energy is at a minimum when the ball is momentarily at rest. Choice D is incorrect because the energy conversion between potential and kinetic energy occurs at different points in the trajectory.
What is the common name for the organic compound CH₃OH?
- A. Methane
- B. Ethanol
- C. Methanol
- D. Butanol
Correct Answer: C
Rationale: The common name for the organic compound CH₃OH is methanol. Methane (A) has the chemical formula CH₄. Ethanol (B) corresponds to the formula C₂H₅OH. Butanol (D) is a compound with the formula C₄H₉OH. The correct answer is C - Methanol, which is the common name for CH₃OH, while the other options correspond to different organic compounds with distinct formulas. Therefore, methanol is the correct choice when identifying the common name for the compound CH₃OH.