Cell Walls
* Support and Structure: Plant cells need rigid cell walls to maintain their shape and provide structural support. This is crucial for plants to stand upright and grow tall, especially against gravity.
* Protection: Cell walls also protect the delicate cell membrane from damage and provide a barrier against invading pathogens.
* Turgor Pressure: The cell wall helps maintain turgor pressure, the internal pressure within the cell that keeps the plant rigid and upright.
Chlorophyll
* Photosynthesis: Chlorophyll is the green pigment that allows plants to capture light energy from the sun and convert it into chemical energy (sugars) through the process of photosynthesis. This is how plants make their own food.
* Essential for Survival: Without chlorophyll, plants would not be able to produce their own energy and would not be able to survive.
Why Animals Don't Need These:
* Animals Obtain Energy from Food: Animals obtain energy by consuming other organisms, either plants or other animals. They don't need to make their own food, so they don't need chlorophyll.
* Internal Support Systems: Animals have developed internal support systems, like bones and muscles, which provide structure and allow them to move. They don't rely on rigid cell walls like plants do.
In Summary:
Plant cells have cell walls and chlorophyll because they need to be strong, supported, and able to create their own food. Animal cells do not need these structures because they obtain their energy from food and have evolved different mechanisms for structure and movement.
