Question

Read the following statements:
(i) Aerobic heterotrophic bacteria use organic matter for carbon source and energy source.
(ii) Aerobic heterotrophic bacteria use carbon dioxide for carbon source and energy source.
(iii) Aerobic autotrophic bacteria use carbon dioxide for carbon source and reduced substances for energy source.
(iv) Aerobic autotrophic bacteria use organic matter for getting energy.
The correct choice is:

• A. (i) is correct; (iii) is correct
• B. (iv) is correct; (i) is incorrect
• C. (i) is correct; (iv) is correct
• D. (ii) is correct; (iv) is incorrect

Hint:

Remember: - Heterotrophs $\Rightarrow$ depend on organic matter. - Autotrophs $\Rightarrow$ fix CO$_2$. - Aerobic autotrophs may use oxygen and reduced inorganic compounds for energy.

Answer 1

The Correct Option is A

Step 1: Analyze statement (i).
Aerobic heterotrophic bacteria obtain both carbon and energy from organic matter (since they cannot fix CO$_2$). Thus, statement (i) is correct.
Step 2: Analyze statement (ii).
Heterotrophs cannot use CO$_2$ as their carbon source. Only autotrophs fix CO$_2$. Thus, statement (ii) is incorrect.
Step 3: Analyze statement (iii).
Aerobic autotrophic bacteria (like nitrifying bacteria) fix CO$_2$ as their carbon source and use reduced substances (like NH$_3$, NO$_2^-$) as their energy source. Thus, statement (iii) is correct.
Step 4: Analyze statement (iv).
Autotrophs do not rely on organic matter for energy; instead, they use inorganic sources or light. Thus, statement (iv) is incorrect. Hence, the correct choice is: (i) and (iii) are correct. Final Answer: \[ \boxed{\text{(A) (i) is correct; (iii) is correct}} \]