Question

How does a plant get food after the stored food in the cotyledon is used up?

Answer 1

After the stored food in the cotyledon is used up the nutrition is provided by the endosperm of the seed. The endosperm is starchy and is separated from the embryo using an epithelial layer. After the germination of the seed is completed and the leaves are formed then the plant uses the process of photosynthesis to gain nutrition. With the help of water, sunlight, carbon dioxide, and chlorophyll it produces glucose.

Complete answer:
Initially the reserve food material is provided by the cotyledon. The main form in which the cotyledon stores food is polysaccharide starch which is then converted into glucose by specific enzymes. The formed glucose is utilized in mitochondria during cellular respiration. After the food stored in the cotyledon is used up fully the food is supplied by the endosperm. In the case of dicot seeds endosperm is also known as albumen. So the seeds can be classified as endospermic seeds and non-endospermic seeds. In the case of monocot seeds, the major portion of the seed is found to be endosperm. It is white. Just below the endosperm layer in the monocot seeds, there is another layer present known as the aleurone layer which stores protein.

Note:
Seeds are classified based on the number of cotyledons they have. On this basis, the seeds are classified into two types– monocotyledonous (monocot) and dicotyledonous (dicot). Endospermic seeds contain a kernel which is made up of embryo and endosperm but in the case of non-endospermic seeds, the kernel contains only the embryo. Sometimes food matter is not stored in the cotyledon.