Nokea
Where does the nerve impulses send neurotransmitters across a synapse to a muscle cell to stimulate muscle contraction?
- A. sarcomere
- B. tendon
- C. myelin sheath
- D. neuromuscular junction
Correct Answer: D
Rationale: The neuromuscular junction is the specific area where nerve impulses trigger the release of neurotransmitters that cross the synaptic gap to bind to receptors on the muscle cell membrane. This binding initiates muscle contraction by stimulating the muscle cell. The sarcomere is the basic contractile unit in a muscle fiber, not the location where nerve impulses communicate with muscle cells. Tendons are connective tissues that attach muscles to bones and are not involved in transmitting nerve impulses. The myelin sheath is a protective covering around nerve fibers but is not directly involved in transmitting neurotransmitters to muscle cells for muscle contraction.
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The above experimental design description is an example of which of the following types of experiments?
- A. field experiment
- B. natural experiment
- C. controlled experiment
- D. observational study
Correct Answer: C
Rationale: The above experimental design description involves the manipulation of an independent variable (light exposure) to observe its effects on the dependent variable (plant growth) under controlled conditions. In a controlled experiment, researchers actively manipulate one or more variables while keeping all other variables constant to establish cause-and-effect relationships.
Choice A, a field experiment, typically takes place in a real-world setting but still involves manipulation and control of variables. Choice B, a natural experiment, involves observing naturally occurring differences in variables without researcher intervention. Choice D, an observational study, does not involve manipulation of variables, making it different from the described experimental design.
Which of the following is NOT a function of the liver?
- A. nutrient processing
- B. blood filtration and detoxification
- C. cholesterol and lipoprotein production
- D. insulin production and blood sugar regulation
Correct Answer: D
Rationale: The correct answer is D. The liver does not produce insulin; instead, insulin is produced by the pancreas. The liver plays a crucial role in regulating blood sugar levels by storing and releasing glucose but does not directly produce insulin. Choices A, B, and C are functions of the liver. Nutrient processing, blood filtration, detoxification, cholesterol, and lipoprotein production are essential roles performed by the liver to maintain overall metabolic balance and health.
Which of the following choices would contain the code for making a protein?
- A. mRNA
- B. tRNA
- C. rRNA
- D. DNA polymerase
Correct Answer: A
Rationale: The correct answer is A: mRNA (messenger RNA). mRNA contains the genetic code or instructions for making a protein. During protein synthesis, mRNA carries the genetic information from DNA in the cell nucleus to the ribosomes, where proteins are synthesized. The sequence of nucleotides in mRNA corresponds to the sequence of amino acids that will be used to build the protein. Choice B, tRNA (transfer RNA), is involved in carrying amino acids to the ribosome during protein synthesis but does not contain the code for making a protein. Choice C, rRNA (ribosomal RNA), is a component of ribosomes where protein synthesis occurs but does not contain the specific code for making a protein. Choice D, DNA polymerase, is an enzyme involved in DNA replication, not in directly coding for protein synthesis.
Where is the pineal gland located in the body?
- A. Below the larynx
- B. Above the kidney
- C. At the center of the brain hemispheres
- D. At the base of the brain
Correct Answer: C
Rationale: The pineal gland is correctly located at the center of the brain, between the two hemispheres. It is a small endocrine gland often referred to as the 'third eye' due to its unique location. Choices A, B, and D are incorrect as the pineal gland is not situated below the larynx, above the kidney, or at the base of the brain.
Which of the following basic mechanisms of evolution is described as the process where organisms with an advantageous trait survive more often and produce more offspring than organisms without the advantageous trait?
- A. gene flow
- B. genetic drift
- C. mutation
- D. natural selection
Correct Answer: D
Rationale: Natural selection is the basic mechanism of evolution that explains how organisms with advantageous traits are more likely to survive and reproduce in a given environment. This leads to the passing on of these favorable traits to their offspring, causing these traits to become more common in the population over time, resulting in evolutionary change. Natural selection is driven by environmental pressures that support the survival and reproduction of individuals with specific traits. Gene flow refers to the movement of genes between populations, genetic drift is the change in allele frequencies due to random events, and mutation is the source of genetic variation but is not the process by which advantageous traits become more prevalent in a population.