Question

The Autotrophic mode of nutrition requires :

• A. \(\text{SO}_2\), sunlight, red pigment and \(\text{H}_2\text{O}\)
• B. \(\text{CO}_2\), sunlight, chlorophyll and \(\text{H}_2\text{O}\)
• C. \(\text{O}_2\), sunlight, chlorophyll and \(\text{H}_2\)
• D. None of the above

Hint:

"Autotrophic" means "self-feeding". Most autotrophs (like plants) use photosynthesis. Think of the ingredients plants need to make their own food (glucose):
{Carbon Dioxide (\(\text{CO}_2\)):} From the air.
{Water (\(\text{H}_2\text{O}\)):} From the soil.
{Sunlight:} For energy.
{Chlorophyll:} The green pigment in leaves that traps sunlight. Oxygen (\(\text{O}_2\)) is a byproduct (released), not a requirement.

Answer 1

The Correct Option is B

Concept: Autotrophic nutrition is a mode of nutrition where an organism produces its own food from simple inorganic substances, typically using an external energy source. The most common form is photosynthesis, used by plants, algae, and some bacteria. Step 1: Understanding Photosynthesis (the primary autotrophic process) Photosynthesis is the process by which green plants and some other organisms use sunlight to synthesize foods (glucose) from carbon dioxide and water. Chlorophyll is the green pigment that captures light energy. The overall simplified chemical equation for photosynthesis is: \[ 6\text{CO}_2 \text{ (Carbon Dioxide)} + 6\text{H}_2\text{O} \text{ (Water)} \xrightarrow[\text{Chlorophyll}]{\text{Sunlight}} \text{C}_6\text{H}_{12}\text{O}_6 \text{ (Glucose)} + 6\text{O}_2 \text{ (Oxygen)} \] Step 2: Identifying the essential requirements for photosynthesis From the equation and process description, the key requirements are:
Carbon Dioxide (\(\text{CO}_2\)): Obtained from the atmosphere. Provides the carbon atoms for glucose.
Water (\(\text{H}_2\text{O}\)): Absorbed from the soil (by plants) or surrounding environment. Provides hydrogen atoms for glucose and is the source of oxygen released.
Sunlight (Light Energy): Provides the energy to drive the chemical reactions.
Chlorophyll: The green pigment found in chloroplasts of plant cells (and in photosynthetic bacteria). It absorbs light energy. Step 3: Analyzing the options
(1) \(\text{SO}_2\), sunlight, red pigment and \(\text{H}_2\text{O}\): \(\text{SO}_2\) (sulfur dioxide) is not a primary reactant for typical plant photosynthesis. "Red pigment" is incorrect; chlorophyll (green) is primary, though other accessory pigments exist.
(2) \(\text{CO}_2\), sunlight, chlorophyll and \(\text{H}_2\text{O}\): This option correctly lists all the essential requirements for photosynthesis in green plants. Correct.
(3) \(\text{O}_2\), sunlight, chlorophyll and \(\text{H}_2\): \(\text{O}_2\) (oxygen) is a {product} of photosynthesis, not a requirement. \(\text{H}_2\) (hydrogen gas) is not a direct input in this form for plant photosynthesis (hydrogen comes from water).
(4) None of the above: Incorrect, as option (2) is correct. Therefore, the autotrophic mode of nutrition (specifically photosynthesis) requires carbon dioxide, sunlight, chlorophyll, and water.