How do new plants obtain the energy needed for growth?
New plants obtain energy for growth from the reserve food stored in seed.
Seed germinates to form young seedling. The germination involves cell division in apical meristems in plumule and radicle, representing embryonic shoot and embryonic root , respectively.
Plumule grows to form young shoot and radicle grows to form young shoot.
The young seedling requires energy for all these activities like cell division, cell elongation and differentiation into different parts of the plant.
The seed stores the food needed for the growth of seedling till the green leaves of young shoot are able to synthesize sufficient food during photosynthesis.
The food is stored in the seed, either in cotyledons as in most of the dicotyledonous seeds (e.g. gram, pea, beans, etc.) or in a special tissue, endosperm as in most of the monocotyledonous seeds (e.g. Maize, wheat, rice, etc.)