Nokea
What type of bond holds water molecules together?
- A. Ionic
- B. Covalent
- C. Hydrogen
- D. Molecular
Correct Answer: C
Rationale: The correct answer is 'Hydrogen.' Water molecules are held together by hydrogen bonds. These bonds form between the slightly positive hydrogen atom of one water molecule and the slightly negative oxygen atom of another water molecule. While hydrogen bonds are weaker than covalent bonds, they play a crucial role in various biological processes, such as the cohesion of water molecules and the unique properties of water as a solvent.
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During protein synthesis, what process uses an RNA strand to produce a complementary strand of DNA?
- A. Transcription
- B. Translation
- C. Transfer synthesis
- D. Codon synthesis
Correct Answer: A
Rationale: The correct answer is transcription. Transcription is the process in which an RNA molecule is synthesized from a DNA template. During transcription, an RNA polymerase enzyme reads the DNA template and produces a complementary RNA strand, not DNA. This RNA strand is used as a template in translation to synthesize proteins, where the mRNA is read to produce a protein.
What's the first step in the process of respiration?
- A. Fermentation.
- B. Glycolysis.
- C. Krebs cycle.
- D. Electron transport chain.
Correct Answer: B
Rationale:
Which term means alternate forms of a gene for the same trait?
- A. Phenotypes.
- B. Genotypes
- C. Alleles.
- D. Gametes.
Correct Answer: C
Rationale:
What term best describes the sum of all an organism's chemical processes?
- A. Respiration.
- B. Anabolism.
- C. Metabolism.
- D. Differentiation.
Correct Answer: C
Rationale: The correct answer is C: Metabolism. Metabolism refers to the sum of all chemical processes in an organism to maintain life. It includes both anabolism (building up molecules) and catabolism (breaking down molecules). Respiration (A) is a specific part of metabolism involving the breakdown of glucose to produce energy. Anabolism (B) is the process of building complex molecules from simpler ones. Differentiation (D) is the process in which cells become specialized for specific functions, not related to the sum of all chemical processes in an organism. Therefore, metabolism is the most appropriate term to describe the overall chemical processes in an organism.
Which of the following options best represents complementary base pairing in DNA?
- A. A and G
- B. A and C
- C. A and A
- D. A and T
Correct Answer: D
Rationale: In DNA, adenine (A) pairs with thymine (T) and guanine (G) pairs with cytosine (C). This is known as complementary base pairing. The correct answer is 'A and T' because they form a complementary base pair in DNA. Adenine always pairs with thymine via two hydrogen bonds, while guanine pairs with cytosine via three hydrogen bonds. This base pairing specificity is crucial for DNA replication and genetic information transfer.