An organism that uses CO2: as its carbon source is a:
Autotroph
Heterotroph
Parasite
The Correct Answer is A
A. Autotroph: Autotrophs are organisms that use carbon dioxide (CO₂) as their primary carbon source, converting it into organic molecules through processes like photosynthesis or chemosynthesis. They are capable of synthesizing all the carbon compounds they need for growth, making them independent of other organisms for carbon.
B. Heterotroph: Heterotrophs obtain carbon by consuming organic compounds produced by other organisms. They cannot fix CO₂ directly and rely on autotrophs or other heterotrophs for their carbon supply, which is why they are considered consumers rather than primary producers.
C. Parasite: Parasites are organisms that live on or within a host organism, deriving nutrients at the host’s expense. While many parasites are heterotrophic, being parasitic describes their lifestyle rather than their carbon source.
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is C
Explanation
A. Glycolysis: Glycolysis produces a small amount of ATP directly through substrate-level phosphorylation, yielding 2 ATP molecules per glucose molecule. While it initiates the breakdown of glucose to pyruvate, the majority of energy is not generated at this stage.
B. All phases produce the same number of ATP molecules: ATP production is not uniform across the phases of cellular respiration. Each phase contributes differently, with oxidative phosphorylation generating the largest share of ATP, making this statement incorrect.
C. Oxidative phosphorylation (Electron Transport Chain): The electron transport chain and chemiosmosis in oxidative phosphorylation produce the majority of ATP during cellular respiration, typically yielding 34 ATP per glucose molecule. High-energy electrons from NADH and FADH₂ drive proton pumping across the mitochondrial membrane, creating a proton gradient that powers ATP synthase to generate large quantities of ATP.
D. Krebs cycle: The Krebs cycle produces a small number of ATP molecules directly through substrate-level phosphorylation (1 ATP per cycle per acetyl-CoA). Its main contribution is generating NADH and FADH₂, which carry electrons to the electron transport chain for the production of most ATP.
Correct Answer is D
Explanation
A. Transduction: Transduction is the transfer of bacterial DNA from one cell to another via a bacteriophage (virus). It does not require direct physical contact between bacterial cells; the virus mediates the DNA transfer.
B. Transformation: Transformation involves the uptake of free DNA fragments from the environment by a bacterial cell. Physical contact between cells is not necessary, as the DNA is incorporated from the surrounding medium.
C. Transduction and conjugation: While conjugation requires physical contact, transduction does not. Therefore, combining the two does not accurately describe a process that exclusively requires cell-to-cell contact.
D. Conjugation: Conjugation is a process in which one bacterial cell transfers DNA directly to another through a pilus (sex pilus). Physical contact is essential for this mechanism, making it the only option listed that requires cell-to-cell interaction for DNA transfer.
E. Transformation and conjugation: Transformation does not require physical contact, so pairing it with conjugation does not correctly reflect the requirement for contact in all listed processes. Only conjugation depends on direct contact.
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