Why does the zygote begin to divide only after the division of Primary endosperm cell (PEC)?

Why does a rubber band become loose after repeated use?

Why does the growth of a plant occur only at specific parts of the plant body?

Give reason : Why does a hot substance not remain hot after two or three hours in a thermos flask?

Why does an individual have only two alleles even if a character shows multiple allelism?

Why does this happen? Fruits, flowers fall off after a certain period of time.

In medium where E. coli was growing lactose was added, which induced the lac operon. But why does lac operon shut down after some time after addition of lactose in the medium?

Mention the ploidy of the following protonemal cell of a moss primary endosperm nucleus in dicot, leaf cell of a moss prothallus cell of a fern, gemma cell in Marchantia, meristem cell of monocot, ovum of a liverwort, and zygote of a fern.

Does the parent cell exist after asexual reproduction fission?

Read the statements (A) Meiosis is a special kind of cell division which occurs in the zygote of algae (B) Meiosis is a special kind of cell division which occurs in the spore mother cells of bryophyte to higher plants (C) Meiosis is a special kind of cell division which occurs in the primary spermatocyte and oocyte during gamete formation in animals

Why doensn't the stone move up all the time? Why does it fall down after reaching a certain height?