Nokea
Which muscle type is characterized by a combination of voluntary and involuntary control, is striated, and is responsible for pumping blood throughout the circulatory system?
- A. Skeletal muscle
- B. Smooth muscle
- C. Cardiac muscle
- D. Connective tissue
Correct Answer: C
Rationale: The correct answer is C, Cardiac muscle. Cardiac muscle is characterized by a combination of voluntary and involuntary control, is striated, and is responsible for pumping blood throughout the circulatory system. Skeletal muscle is primarily under voluntary control, smooth muscle is primarily under involuntary control, and connective tissue is not a muscle type, but rather provides support and structure to the body.
You may also like to solve these questions
What is the relationship between the wavelength (λ) and frequency (f) of a wave with a constant speed (v)?
- A. λ = v / f
- B. λ = f / v
- C. λ = vf
- D. λ is independent of f and v
Correct Answer: A
Rationale: The relationship between wavelength (λ), frequency (f), and speed (v) of a wave is given by the formula λ = v / f. This formula is derived from the wave equation v = fλ, where v is the speed of the wave, f is the frequency, and λ is the wavelength. By rearranging the equation, we get λ = v / f, indicating that the wavelength is inversely proportional to the frequency when the speed of the wave is constant. Therefore, choice A, λ = v / f, correctly represents the relationship between wavelength and frequency when the speed of the wave is held constant. Choice B, λ = f / v, is incorrect because it represents an inverse relationship between wavelength and speed, which is not the case. Choice C, λ = vf, is incorrect as it implies a direct relationship between wavelength, frequency, and speed, which is not accurate. Choice D, λ is independent of f and v, is incorrect as both frequency and speed affect the wavelength of a wave, as shown by the correct formula λ = v / f.
What are the tiny contractile units within muscle cells called?
- A. Myocytes
- B. Myofibrils
- C. Sarcomeres
- D. Tendons
Correct Answer: C
Rationale: Sarcomeres are the smallest contractile units within muscle cells. They consist of overlapping filaments of actin and myosin proteins, which interact to produce muscle contractions. Myocytes are the entire muscle cells, myofibrils are bundles of protein filaments found within muscle cells, and tendons are tough connective tissues that connect muscles to bones. Therefore, sarcomeres specifically represent the contractile units responsible for muscle contraction, making them the correct answer in this context.
Antidiuretic hormone (ADH) plays a crucial role in regulating water balance. When ADH levels are high, what happens to urine production?
- A. Urine production increases significantly
- B. Urine production decreases to conserve water
- C. There is no change in urine production
- D. The kidneys stop producing urine altogether
Correct Answer: B
Rationale: When ADH levels are high, urine production decreases to conserve water. ADH acts on the kidneys to increase water reabsorption, leading to the production of concentrated urine and conservation of water in the body. Choice A is incorrect as high ADH levels lead to increased water reabsorption, reducing urine output. Choice C is incorrect since high ADH levels do influence urine production. Choice D is incorrect as the kidneys do not stop producing urine entirely but rather adjust the reabsorption of water based on ADH levels.
How are the frequency and wavelength of a wave related?
- A. Inversely proportional
- B. Directly proportional
- C. No relationship
- D. Dependent on the medium
Correct Answer: A
Rationale: The correct answer is that the frequency and wavelength of a wave are inversely proportional. This relationship is defined by the wave equation: speed = frequency x wavelength. When the frequency of a wave increases, its wavelength decreases, and vice versa. This means that as one quantity increases, the other decreases in a consistent manner, illustrating an inverse relationship between frequency and wavelength. Choice B, 'Directly proportional,' is incorrect because an increase in frequency does not lead to an increase in wavelength; they move in opposite directions. Choice C, 'No relationship,' is incorrect as frequency and wavelength are interconnected as described above. Choice D, 'Dependent on the medium,' is incorrect because the relationship between frequency and wavelength is a fundamental property of waves and is not solely determined by the medium through which the wave propagates.
Autoimmune diseases occur when the immune system mistakenly attacks healthy body tissues. What is a potential cause of autoimmune diseases?
- A. Deficiency in essential vitamins and minerals
- B. Exposure to environmental toxins
- C. Breakdown in immune cell self-tolerance mechanisms
- D. All of the above
Correct Answer: C
Rationale: Autoimmune diseases result from a breakdown in immune cell self-tolerance mechanisms, leading to the immune system mistakenly attacking healthy body tissues. While deficiencies in essential vitamins and minerals or exposure to environmental toxins can impact overall health, they are not direct causes of autoimmune diseases. Deficiency in essential vitamins and minerals may weaken the immune system, making it more susceptible to various health issues but does not directly cause autoimmune diseases. Exposure to environmental toxins can trigger immune responses, but autoimmune diseases specifically stem from the breakdown of self-tolerance mechanisms within immune cells. Therefore, the correct answer is a breakdown in immune cell self-tolerance mechanisms.