Organisms that generate energy using light are:

Correct option is D

The correct answer is: (d) Photoautotrophs

Explanation:

• Photoautotrophs are organisms that generate energy using light (photo) and synthesize their own food using carbon dioxide (CO₂) as a carbon source.

• They carry out photosynthesis, using light energy to convert CO₂ and water into glucose and oxygen.

• Examples include green plants, algae, and cyanobacteria.

• These organisms contain chlorophyll or similar pigments to capture solar energy.

• Autotrophs: Can synthesize their own food; sub-divided into photoautotrophs and chemoautotrophs.

• Photoautotrophs perform oxygenic photosynthesis (e.g., plants) or anoxygenic (e.g., purple sulfur bacteria).

• Chlorophyll a is the primary pigment in photoautotrophs like plants.

• Photoautotrophs form the base of the food chain in most ecosystems.

• Their energy transformation supports the global carbon and oxygen cycles.

• Light reactions (in thylakoids) and dark reactions (Calvin cycle) are part of the photosynthesis process.

• Oligotrophs: Thrive in environments with low nutrient availability, not necessarily using light for energy.

• Chemoorganotrophs: Obtain energy by oxidizing organic compounds (e.g., glucose); do not use light.

• Chemolithotrophs: Derive energy from inorganic compounds like hydrogen sulfide or ammonia; also do not use light.