Nokea
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.
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What is the functional group present in aldehydes?
- A. Hydroxyl
- B. Carbonyl
- C. Ester
- D. Amine
Correct Answer: B
Rationale: The correct answer is B: Carbonyl. Aldehydes contain the functional group -CHO, which is a carbonyl group where a carbon atom is double-bonded to an oxygen atom and single-bonded to a hydrogen atom. This distinguishes aldehydes from other functional groups. Choice A, Hydroxyl (-OH), is not characteristic of aldehydes as it is found in alcohols. Choice C, Ester (-COOR), and choice D, Amine (-NH2), represent different functional groups not typically found in aldehydes. Therefore, the correct functional group present in aldehydes is the carbonyl group.
What is the mass number of an element?
- A. The number of protons in an atom's nucleus.
- B. The number of neutrons in an atom's nucleus.
- C. The number of electrons in an atom's valence shell.
- D. The number of isotopes of an element.
Correct Answer: B
Rationale: The mass number of an element represents the total number of protons and neutrons in an atom's nucleus. It specifically focuses on the number of neutrons in an atom's nucleus, which contributes to the overall mass of the atom. Therefore, the mass number is not solely determined by the number of protons, electrons, or isotopes. Choice A is incorrect because it refers to the atomic number, which is the number of protons in an atom's nucleus. Choice C is incorrect as the number of electrons in the valence shell is related to the atom's reactivity and bonding behavior, not the mass number. Choice D is incorrect because the mass number does not represent the number of isotopes of an element, but rather the sum of protons and neutrons in an atom's nucleus. Thus, option B, the number of neutrons in an atom's nucleus, is the correct choice.
Which property of matter remains constant regardless of changes in gravity?
- A. Mass
- B. Weight
- C. Volume
- D. Density
Correct Answer: A
Rationale: Mass is a measure of the amount of matter in an object and remains constant regardless of changes in gravity. Weight, on the other hand, is the force of gravity acting on an object and can vary depending on the strength of gravity. Volume is the amount of space an object occupies, and density is the mass per unit volume of a substance, both of which can change with changes in gravity. Therefore, mass is the property that remains the same regardless of variations in gravitational force. Choice B, Weight, changes with gravity as it is a force dependent on gravity. Choices C and D, Volume and Density, can be affected by changes in gravity as they are related to the space an object occupies and the mass per unit volume, respectively.
Which of the following is an example of a zoonotic disease?
- A. The common cold
- B. Influenza (the flu)
- C. Malaria
- D. HIV/AIDS
Correct Answer: B
Rationale: A zoonotic disease is a disease that can be transmitted from animals to humans. Influenza is an example of a zoonotic disease as it can be transmitted from animals such as birds and pigs to humans. The common cold (option A) is caused by human rhinoviruses and is not considered a zoonotic disease. Malaria (option C) is transmitted through the bite of infected mosquitoes and is not considered a zoonotic disease. HIV/AIDS (option D) is caused by the human immunodeficiency virus and is not considered a zoonotic disease.
Which property of a wave determines its energy?
- A. Wavelength
- B. Amplitude
- C. Frequency
- D. Velocity
Correct Answer: B
Rationale: The energy of a wave is determined by its amplitude, which is the measure of its maximum displacement from the equilibrium position. Waves with higher amplitudes carry more energy as energy is directly proportional to amplitude. Therefore, the correct answer is B) Amplitude.
Choice A (Wavelength) does not determine the energy of a wave; it is related to the spatial length between wave crests. Choice C (Frequency) is not the property that determines a wave's energy; it refers to the number of complete oscillations a wave undergoes in a given time. Choice D (Velocity) is the speed at which a wave propagates through a medium and is not directly related to its energy.