Nokea
What is the building block of RNA?
- A. Amino acid
- B. Nucleotide
- C. Protein
- D. Fatty acid
Correct Answer: B
Rationale: Nucleotide: Nucleotides are the building blocks of RNA. A nucleotide consists of a nitrogenous base (adenine, guanine, cytosine, or uracil in RNA), a sugar (ribose in RNA), and a phosphate group. A) Amino acid: Amino acids are the building blocks of proteins, not RNA. C) Protein: Proteins are made up of amino acids, not nucleotides. D) Fatty acid: Fatty acids are components of lipids, not RNA.
You may also like to solve these questions
What is the difference between mitosis and meiosis?
- A. Mitosis produces haploid cells, while meiosis produces diploid cells
- B. Mitosis involves crossing over, while meiosis does not.
- C. Mitosis results in four daughter cells, while meiosis results in two
- D. Mitosis is responsible for sexual reproduction, while meiosis is responsible for asexual reproduction.
Correct Answer: C
Rationale: - Mitosis is a type of cell division that results in two identical daughter cells with the same number of chromosomes as the parent cell. Therefore, mitosis results in two daughter cells.
- Meiosis is a type of cell division that results in four daughter cells, each with half the number of chromosomes as the parent cell. This reduction in chromosome number is essential for sexual reproduction.
- Option A is incorrect because mitosis produces diploid cells (cells with the same number of chromosomes as the parent cell), while meiosis produces haploid cells (cells with half the number of chromosomes as the parent cell).
- Option B is incorrect because crossing over, the exchange of genetic material between homologous chromosomes, occurs during meiosis and not during mitosis.
- Option D is incorrect because mitosis is not responsible for sexual reproduction; it is a process of asexual reproduction and
Isotopes are variants of a single element that differ in:
- A. Having the same number of protons but varying numbers of neutrons
- B. Having the same number of neutrons but varying numbers of protons
- C. Having the same mass but different atomic numbers
- D. None of the above
Correct Answer: A
Rationale: Isotopes are variants of a single element that have the same number of protons, the defining characteristic of an element. They differ in the number of neutrons they possess, leading to isotopes having different atomic masses while retaining the same chemical properties. Choice B is incorrect because isotopes have the same number of neutrons and differ in the number of protons. Choice C is incorrect because isotopes have different masses due to varying numbers of neutrons, not different atomic numbers. Choice D is incorrect as isotopes do differ in the number of neutrons they possess.
In an SN2 reaction, what affects the rate of the reaction?
- A. Only the concentration of the nucleophile
- B. Only the concentration of the electrophile
- C. Neither the concentration of the nucleophile nor the electrophile
- D. Both the concentration of the nucleophile and the electrophile
Correct Answer: D
Rationale: In an SN2 reaction, the rate of the reaction is affected by both the concentration of the nucleophile and the electrophile. The rate-determining step involves the nucleophile attacking the electrophile, so the concentrations of both species will impact the reaction rate. Increasing the concentration of the nucleophile increases the frequency of nucleophilic attacks, while increasing the concentration of the electrophile provides more opportunities for the nucleophile to react. Therefore, the correct answer is that both the concentration of the nucleophile and the electrophile affect the rate of the SN2 reaction. Choices A, B, and C are incorrect as they do not consider the interplay between the nucleophile and the electrophile in determining the overall reaction rate in an SN2 mechanism.
What happens to the force of gravity between two objects when the distance between them is doubled?
- A. The force increases by a factor of 2
- B. The force increases by a factor of 4
- C. The force decreases by a factor of 2
- D. The force decreases by a factor of 4
Correct Answer: D
Rationale: According to the law of universal gravitation, the force of gravity between two objects is inversely proportional to the square of the distance between them. When the distance is doubled, the force decreases by a factor of 2 squared, which is 4. Therefore, the force decreases by a factor of 4. Choice A is incorrect because the force doesn't increase when the distance is doubled. Choice B is incorrect as the force doesn't increase but actually decreases. Choice C is incorrect as the force decreases by a factor of 4, not 2.
Which of the following is NOT an example of an intermolecular force?
- A. Hydrogen bonding
- B. Dipole-dipole interactions
- C. Ionic bonding
- D. London dispersion forces
Correct Answer: C
Rationale: Ionic bonding is not considered an intermolecular force but an intramolecular force. Intermolecular forces occur between different molecules, while intramolecular forces act within a molecule. Hydrogen bonding, dipole-dipole interactions, and London dispersion forces are intermolecular forces. Hydrogen bonding involves a hydrogen atom bonded to a highly electronegative atom, dipole-dipole interactions occur between polar molecules, and London dispersion forces are temporary attractions between nonpolar molecules.