Nokea
Muscles that work in opposition to each other, producing opposing movements, are called:
- A. Synergists
- B. Antagonists
- C. Agonists
- D. Fixators
Correct Answer: B
Rationale: Antagonist muscles are pairs of muscles that work in opposition to each other, producing opposing movements. When one muscle contracts, the other relaxes to allow the movement to occur smoothly. Synergists are muscles that work together to create a movement, not in opposition. Agonists are muscles primarily responsible for producing a specific movement, not opposing each other. Fixators are muscles that stabilize joints to allow other movements to take place, providing a stable base for muscle actions but do not produce opposing movements.
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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 primary organ responsible for filtering urine?
- A. Kidneys
- B. Bladder
- C. Ureters
- D. Urethra
Correct Answer: A
Rationale: The correct answer is A: Kidneys. The kidneys are the primary organs responsible for filtering urine. They filter waste products and excess substances from the blood to produce urine. Subsequently, urine travels from the kidneys through the ureters to the bladder. The bladder temporarily stores urine until it is expelled from the body through the urethra. The bladder's function is storage, the ureters transport urine, and the urethra is the exit pathway for urine expulsion. Therefore, the kidneys play a vital role in the filtration and production of urine within the urinary system.
Which of the following is NOT a mechanism that can directly cause evolution by natural selection?
- A. Mutations in genes
- B. Differential survival and reproduction based on traits
- C. Inheritance of acquired characteristics (like strong muscles from working out)
- D. Competition for resources in an environment
Correct Answer: C
Rationale: A) Mutations in genes can introduce new genetic variations into a population, which can be acted upon by natural selection.
B) Differential survival and reproduction based on traits is a key component of natural selection, as individuals with advantageous traits are more likely to survive and pass on their genes to the next generation.
C) Inheritance of acquired characteristics, also known as Lamarckism, is not a mechanism of evolution by natural selection. Traits acquired during an individual's lifetime (such as strong muscles from working out) are not passed on to offspring.
D) Competition for resources in an environment can drive natural selection by favoring individuals with traits that help them better compete for limited resources.
Therefore, the correct answer is C) Inheritance of acquired characteristics (like strong muscles from working out), as it is not a mechanism that can directly cause evolution by natural selection.
Which of the following terms refers to a muscle that lengthens while another muscle contracts to produce movement?
- A. Synergist
- B. Agonist
- C. Antagonist
- D. Flexor
Correct Answer: C
Rationale: The correct answer is 'Antagonist.' An antagonist muscle is a muscle that lengthens while another muscle (agonist) contracts to produce movement. The antagonist muscle relaxes to allow the agonist muscle to contract effectively. In this scenario, the antagonist muscle works in opposition to the agonist muscle, providing control and precision to movement. The other choices are incorrect because a synergist muscle assists the agonist muscle in performing a movement, an agonist muscle is the primary muscle responsible for generating movement, and a flexor muscle is a muscle that decreases the angle at a joint.
What determines the frequency of oscillations in a spring-mass system when the spring is stretched and released?
- A. The mass of the object
- B. The stiffness of the spring
- C. The initial displacement of the object
- D. All of the above
Correct Answer: B
Rationale: The frequency of oscillations in a spring-mass system is determined by the stiffness of the spring (spring constant) and the mass of the object. The stiffness of the spring affects how quickly the system oscillates back and forth, while the mass of the object influences the inertia and therefore the frequency. The initial displacement of the object does not impact the frequency of oscillations. Choice A is incorrect because while the mass of the object affects the frequency, it is not the sole determining factor. Choice C is incorrect as the initial displacement affects the amplitude of oscillations, not the frequency. Choice D is incorrect as not all factors listed determine the frequency, making it an incorrect choice.