Nokea
Which property of a substance refers to its ability to be stretched into thin wires?
- A. Conductivity
- B. Viscosity
- C. Ductility
- D. Malleability
Correct Answer: C
Rationale: Ductility is the property of a substance that allows it to be stretched into thin wires without breaking. It is a crucial property for materials used in wire production. Conductivity refers to the ability of a substance to conduct electricity or heat, not to be stretched into wires. Viscosity is the measure of a fluid's resistance to flow, not its ability to be stretched. Malleability is the property of a substance that allows it to be hammered or rolled into thin sheets, not stretched into wires.
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What is the scientific term for the involuntary rhythmic contraction and relaxation of the heart muscle?
- A. Peristalsis
- B. Myogenesis
- C. Myocardial contractility
- D. Systole and diastole
Correct Answer: D
Rationale: The correct answer is D: Systole and diastole. Systole and diastole are the two phases of the cardiac cycle where the heart muscle contracts (systole) and relaxes (diastole) rhythmically to pump blood throughout the body. This rhythmic process ensures proper blood circulation by pumping blood to the lungs and the rest of the body. Peristalsis, on the other hand, refers to the involuntary constriction and relaxation of the muscles in the gastrointestinal tract, aiding in the movement of food and waste. Myogenesis is the process of muscle tissue formation, and myocardial contractility pertains to the heart muscle's ability to contract efficiently.
The adaptive immune system has two main branches: humoral and cell-mediated immunity. Which type of immune cell is primarily responsible for antibody production?
- A. Helper T cells
- B. Cytotoxic T cells
- C. B cells
- D. Natural killer cells
Correct Answer: C
Rationale: B cells are primarily responsible for antibody production in the adaptive immune system. When activated, B cells differentiate into plasma cells, which are specialized to produce antibodies. Helper T cells play a crucial role in activating B cells, but they do not directly produce antibodies. Cytotoxic T cells are involved in cell-mediated immunity by killing infected cells, while natural killer cells are part of the innate immune system and target virus-infected and cancerous cells. Therefore, the correct answer is C (B cells) as they are directly involved in the production of antibodies, essential for humoral immunity.
As a water wave approaches a shallow beach, what happens to its speed, wavelength, and frequency?
- A. Speed increases, wavelength decreases, frequency increases.
- B. Speed decreases, wavelength decreases, frequency remains the same.
- C. Speed increases, wavelength increases, frequency decreases.
- D. Speed, wavelength, and frequency remain the same.
Correct Answer: B
Rationale: As a water wave approaches a shallow beach, the speed of the wave decreases due to the change in medium from deep to shallow water. According to the wave equation (speed = frequency x wavelength), if the speed decreases and the frequency remains the same, the wavelength must also decrease to maintain the equation balanced. This phenomenon occurs due to the wavefronts being slowed down by the shallower water, causing the wavelength to decrease while the frequency remains constant. Choice A is incorrect as the speed of the wave decreases in shallow water. Choice C is incorrect because the speed increases in deep water, not in shallow water. Choice D is incorrect as all the wave characteristics change when moving from deep to shallow water.
What is a characteristic property of acids?
- A. Bitter taste
- B. Sour taste
- C. Slippery feel
- D. Sweet taste
Correct Answer: B
Rationale: The correct characteristic property of acids is a sour taste. Acids release hydrogen ions when dissolved in water, giving them a sour taste. Bitter taste is a property associated with bases, not acids. Slippery feel is a characteristic property of bases, due to their soap-like nature. Sweet taste does not accurately describe the characteristic property of acids, as they are known for their sour taste.
Which of the following nutrients is essential for muscle growth and repair?
- A. Vitamin C
- B. Protein
- C. Carbohydrates
- D. Fat
Correct Answer: B
Rationale: Protein is essential for muscle growth and repair as it provides the necessary building blocks (amino acids) for muscle tissue synthesis and repair. While vitamins and minerals are crucial for overall health, protein has a specific role in muscle development. Carbohydrates supply energy for workouts, and fats are important for general health but are less directly involved in muscle growth and repair compared to protein.