Plants obtain their nutrition by various modes. The main mode of nutrition in plants is autotrophic mode of nutrition. Plants are considered to be autotrophs as they synthesise their own food.Photosynthesis is an autotrophic mode of nutrition. Photosynthesis is a process by which green plants can synthesise glucose from raw materials like carbon dioxide and water in the presence of sunlight and chlorophyll. Photosynthesis involves the conversion of solar energy into chemical energy to synthesise starch.*Sunlight is trapped by a green colour pigment called as chlorophyll. This chlorophyll is chiefly present in chloroplasts. As plants synthesise their own food and use the sunlight for this synthesis, their cells possess chloroplasts containing chlorophyll. *Chloroplasts are absent in animal cells because animals do not synthesise their own food.

Why Chloroplasts are Found Only in Plant Cells?
Chloroplasts are specialized organelles found in plant cells that are responsible for photosynthesis, the process by which plants convert sunlight into energy. There are several reasons why chloroplasts are only found in plant cells:

1. Evolutionary Origin:
Chloroplasts are believed to have originated from ancient cyanobacteria through endosymbiosis. This means that chloroplasts were once independent bacteria that were engulfed by a primitive plant cell and eventually developed a symbiotic relationship. This evolutionary history explains why chloroplasts are unique to plant cells.

2. Function in Photosynthesis:
Chloroplasts contain chlorophyll, a pigment that captures sunlight and converts it into chemical energy through photosynthesis. This process is essential for plants to produce glucose and oxygen, which are vital for their survival. Since animals do not undergo photosynthesis, they do not require chloroplasts.

3. Structural Adaptations:
Chloroplasts have a double membrane structure, which is believed to be a result of their bacterial origin. This structure allows chloroplasts to carry out photosynthesis efficiently by separating different stages of the process. The presence of this unique structure further supports the idea that chloroplasts are specific to plant cells.
In conclusion, chloroplasts are found only in plant cells due to their evolutionary origin, specialized function in photosynthesis, and unique structural adaptations. These organelles play a crucial role in the survival and growth of plants, making them an essential component of plant biology.