Nokea
Which of the following is the control group in the above experiment?
- A. tank A
- B. tank B
- C. tank C
- D. There is no control group in this experiment.
Correct Answer: D
Rationale: The correct answer is D: There is no control group in this experiment. A control group is a group in an experiment that does not receive the treatment being studied in order to serve as a baseline for comparison. In this case, all three tanks (A, B, and C) are being treated with different amounts of fertilizer, and there is no group that is left untreated to serve as a control for comparison. Choices A, B, and C are incorrect because they all represent tanks that are part of the experimental groups receiving different amounts of fertilizer, thus none of them can be considered the control group.
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Which of the following chambers of the heart receives blood returning from the lungs during pulmonary circulation?
- A. left atrium
- B. right atrium
- C. left ventricle
- D. right ventricle
Correct Answer: A
Rationale: The correct answer is A, the left atrium. During pulmonary circulation, oxygenated blood returns from the lungs to the heart and enters the left atrium through the pulmonary veins. The left atrium then contracts, pushing this oxygen-rich blood into the left ventricle. The left ventricle subsequently pumps this oxygenated blood out to the rest of the body through the aorta. Choices B, C, and D are incorrect because the right atrium receives deoxygenated blood from the body, the left ventricle receives oxygenated blood from the left atrium, and the right ventricle pumps deoxygenated blood to the lungs for oxygenation, respectively.
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.
Which of the following is the region of the brain that controls and regulates autonomic functions such as respiration, digestion, and heart rate?
- A. cerebellum
- B. medulla oblongata
- C. temporal lobe
- D. cerebral cortex
Correct Answer: B
Rationale: The medulla oblongata is the correct answer. It is the region of the brain located at the base of the brainstem responsible for regulating autonomic functions such as respiration, digestion, and heart rate. These functions are essential for maintaining life. The cerebellum (Option A), temporal lobe (Option C), and cerebral cortex (Option D) do not control these autonomic functions. The cerebellum is mainly involved in coordination and balance, the temporal lobe is associated with memory and hearing, and the cerebral cortex is responsible for higher brain functions like thinking and decision-making.
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.
What type of reaction is represented by the following equation: 2C₆Hâ‚â‚„ + 19Oâ‚‚ → 12CO + 14Hâ‚‚O?
- A. Substitution reaction
- B. Acid-base reaction
- C. Enzyme reaction
- D. Combustion reaction
Correct Answer: D
Rationale: The given chemical equation represents a combustion reaction. Combustion reactions involve the burning of a hydrocarbon (C₆Hâ‚â‚„) in the presence of oxygen (Oâ‚‚) to produce carbon monoxide (CO) and water (Hâ‚‚O). Combustion reactions typically release heat and light energy. In this case, the reactants are a hydrocarbon and oxygen, resulting in the formation of carbon monoxide and water. Choices A, B, and C are incorrect because the reaction does not involve substitution, acid-base reactions, or enzyme catalysis. Combustion reactions are characterized by the rapid combination of a substance with oxygen, leading to the production of heat and light energy.