Nokea
What is the process of converting lactic acid back into pyruvate called?
- A. Glycolysis
- B. Gluconeogenesis
- C. Cori cycle
- D. Oxidative phosphorylation
Correct Answer: C
Rationale: A) Glycolysis is the process of breaking down glucose into pyruvate.
B) Gluconeogenesis is the process of synthesizing glucose from non-carbohydrate sources.
C) The Cori cycle is the process by which lactic acid produced by anaerobic metabolism in muscles is transported to the liver and converted back into glucose or pyruvate.
D) Oxidative phosphorylation is the process by which ATP is synthesized using energy derived from the transfer of electrons in the electron transport chain.
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Which of the following is NOT a type of asexual reproduction in bacteria?
- A. Binary fission
- B. Conjugation
- C. Budding
- D. Transduction
Correct Answer: D
Rationale: A) Binary fission: This is a common method of asexual reproduction in bacteria where a single cell divides into two identical daughter cells.
B) Conjugation: This is a process in which genetic material is transferred between bacterial cells through direct cell-to-cell contact, leading to genetic recombination.
C) Budding: Budding is a form of asexual reproduction where a new organism develops from an outgrowth or bud on the parent organism.
D) Transduction: Transduction is a method of horizontal gene transfer in bacteria where genetic material is transferred from one bacterium to another by a bacteriophage (a virus that infects bacteria). It is not a form of asexual reproduction in bacteria.
Therefore, the correct answer is D) Transduction, as it is not a type of asexual reproduction in bacteria but a mechanism of genetic exchange.
During embryonic development, all tissues originate from
- A. Epithelial tissue only
- B. Muscle tissue only
- C. Connective tissue only
- D. Embryonic germ layers
Correct Answer: D
Rationale: During embryonic development, all tissues originate from the three primary germ layers: ectoderm, mesoderm, and endoderm. These germ layers give rise to various tissues and organs in the developing embryo through a process called gastrulation. Epithelial, muscle, and connective tissues are derived from these germ layers during development. Therefore, choices A, B, and C are incorrect as tissues do not originate from a single type of tissue but rather from the embryonic germ layers which differentiate into various tissues and organs.
How can a single gene mutation lead to multiple phenotypes depending on the organism?
- A. Pleiotropy describes the effect of one gene influencing multiple seemingly unrelated traits.
- B. Epigenetics involves environmental factors modifying gene expression without altering the DNA sequence.
- C. Genetic drift refers to random changes in allele frequencies within a population.
- D. Gene regulation controls the timing and level of gene expression within an organism.
Correct Answer: A
Rationale: A single gene mutation can lead to multiple phenotypes through pleiotropy, where one gene influences diverse traits or functions in an organism. This phenomenon occurs when the mutated gene affects different biochemical pathways, developmental processes, or cellular functions, resulting in a cascade of downstream effects that manifest as a variety of phenotypic outcomes. Choice B, epigenetics, involves modifications in gene expression influenced by environmental factors without altering the DNA sequence, which is not directly related to the question about single gene mutations causing multiple phenotypes. Choice C, genetic drift, refers to random changes in allele frequencies within a population, which is unrelated to the impact of a single gene mutation on multiple phenotypes. Choice D, gene regulation, focuses on controlling the timing and level of gene expression within an organism, which is not directly addressing how a single gene mutation can lead to diverse phenotypes.
Which type of reaction is represented by the equation A + B → AB?
- A. Synthesis
- B. Decomposition
- C. Single Replacement
- D. Double Replacement
Correct Answer: A
Rationale: The correct answer is 'Synthesis.' In a synthesis reaction, two or more reactants combine to form a single product. The equation A + B → AB represents a synthesis reaction where substances A and B combine to form compound AB. Choice B, 'Decomposition,' involves a single compound breaking down into two or more simpler substances, which is not the case in this equation. Choices C and D, 'Single Replacement' and 'Double Replacement,' involve the replacement of elements in compounds or the exchange of ions between compounds, neither of which is depicted in the given equation. Thus, 'Synthesis' is the most suitable classification for the reaction A + B → AB.
What is the general formula for an alkyl halide?
- A. Câ‚™Hâ‚‚â‚™
- B. CₙH₂ₙ₊₂
- C. Câ‚™H₂ₙ₊â‚X
- D. Câ‚™Hâ‚‚â‚™O
Correct Answer: C
Rationale: The correct answer is option C, 'Câ‚™H₂ₙ₊â‚X.' This is the general formula for an alkyl halide, where X represents a halogen atom (such as fluorine, chlorine, bromine, or iodine), and the hydrocarbon chain is represented by Câ‚™H₂ₙ₊â‚. Option A, 'Câ‚™Hâ‚‚â‚™,' is incorrect because it does not account for the presence of a halogen atom. Option B, 'Câ‚™H₂ₙ₊₂,' is incorrect as it represents an alkene, not an alkyl halide. Option D, 'Câ‚™Hâ‚‚â‚™O,' is also incorrect as it suggests the presence of oxygen, which is not characteristic of alkyl halides.