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According to Newton's third law of motion, if you push against a wall with a certain force, the wall will push back with:
- A. A smaller force
- B. An equal force
- C. A greater force
- D. No force at all
Correct Answer: B
Rationale: According to Newton's third law of motion, for every action, there is an equal and opposite reaction. When you push against a wall with a certain force, the wall will push back on you with an equal force in the opposite direction. Choice A is incorrect because the wall exerts an equal force back. Choice C is incorrect as it suggests a greater force, which goes against Newton's third law. Choice D is incorrect as the wall does exert a force back in response to your push.
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Which type of immune cell does the human immunodeficiency virus (HIV) target and destroy?
- A. Neutrophils
- B. Macrophages
- C. Helper T cells
- D. Memory B cells
Correct Answer: C
Rationale: HIV targets and destroys Helper T cells, which are vital for coordinating the immune response against infections. The destruction of Helper T cells weakens the immune system, leading to acquired immunodeficiency syndrome (AIDS). Neutrophils (Choice A) are primarily involved in acute inflammatory responses and fighting bacterial infections. Macrophages (Choice B) play a role in phagocytosis and antigen presentation but are not the primary target of HIV. Memory B cells (Choice D) are responsible for mounting a quicker and more robust antibody response upon re-exposure to a pathogen, but they are not the main target of HIV infection.
Which type of mutation involves a change in the number of chromosomes?
- A. Point mutation
- B. Frameshift mutation
- C. Missense mutation
- D. Aneuploidy
Correct Answer: D
Rationale: A) Point mutation involves a change in a single nucleotide base pair within the DNA sequence.
B) Frameshift mutation involves the insertion or deletion of nucleotides, causing a shift in the reading frame of the genetic code.
C) Missense mutation involves a single nucleotide change that results in a codon that codes for a different amino acid.
D) Aneuploidy involves a change in the number of chromosomes, where an individual may have an extra chromosome (trisomy) or a missing chromosome (monosomy). Aneuploidy can lead to genetic disorders such as Down syndrome (trisomy 21) or Turner syndrome (monosomy X). Changing the number of chromosomes is a characteristic feature of aneuploidy, making it the correct answer. Point mutation, frameshift mutation, and missense mutation do not involve a change in the number of chromosomes and are focused on alterations at the nucleotide level within the DNA sequence.
What is the final stage of both mitosis and meiosis?
- A. Interphase
- B. Telophase
- C. Cytokinesis
- D. G1 phase
Correct Answer: B
Rationale: - Interphase (option A) is not the final stage of mitosis or meiosis; it is the phase before cell division where the cell prepares for division by growing and replicating its DNA.
- Telophase (option B) is the final stage of both mitosis and meiosis. During telophase, the separated chromosomes reach opposite poles of the cell, the nuclear membrane reforms around each set of chromosomes, and the chromosomes begin to decondense.
- Cytokinesis (option C) is the process of dividing the cytoplasm to form two separate daughter cells. While it occurs after telophase, it is not considered the final stage of mitosis or meiosis.
- G1 phase (option D) is the first gap phase in the cell cycle, occurring before DNA replication. It is not the final stage of mitosis or meiosis.
How does an increase in surface area affect the force of friction between two surfaces?
- A. Increases friction
- B. Decreases friction
- C. Has no effect on friction
- D. Causes unpredictable changes in friction
Correct Answer: A
Rationale: An increase in surface area typically increases the force of friction between two surfaces. This is because with a larger surface area in contact, there are more points of contact between the surfaces, leading to a greater frictional force resisting motion. As a result, the correct answer is that an increase in surface area increases the force of friction between two surfaces. Choice B is incorrect because a greater surface area increases the frictional force. Choice C is incorrect because an increase in surface area results in more contact points and greater friction. Choice D is incorrect as the relationship between surface area and friction is predictable - an increase in surface area generally leads to an increase in frictional force.
Which component of the nervous system is responsible for controlling voluntary movements, such as the contraction of skeletal muscles?
- A. Autonomic nervous system
- B. Peripheral nervous system
- C. Somatic nervous system
- D. Sympathetic nervous system
Correct Answer: C
Rationale: The correct answer is C: Somatic nervous system. The somatic nervous system is responsible for controlling voluntary movements, such as the contraction of skeletal muscles. This system consists of motor neurons that send signals from the central nervous system to the skeletal muscles, allowing for conscious control over movement. The autonomic nervous system (A) controls involuntary functions like heart rate and digestion, the peripheral nervous system (B) includes all nerves outside the central nervous system, and the sympathetic nervous system (D) is a division of the autonomic nervous system responsible for the fight-or-flight response. Therefore, choices A, B, and D are incorrect as they do not specifically regulate voluntary movements of skeletal muscles, which is a function of the somatic nervous system.