Question

Why egg cell is larger than sperm cell

Answer 1

That is the major reason why egg is so much larger. In addition, egg contains almost all organelles, materials, and nutritions for zygote growth. However, a sperm only contains haploid chromosome and certain mitochondria for movement. This is the second reason why egg is larger than sperm.

Answer 2

due to meiosis the sperm cell contains only haploid number of chromosomes ( n number of chromosomes)
egg cell contains diploid number of chromosomes ( 2n number of chromosome) egg cell contains many organelles ( mitochondria, etc.)
whereas sperm cells whose function is to fuse with ova doesn't contain many organelles