SEXUAL AND ASEXUAL

Apuntes

SEXUAL AND ASEXUAL REPRODUCTION IGCSE Biology Reproduction in humans Reproduction Sexual Asexual Copyright © 2014 Henry Exham Asexual reproduction • Cells in one part of the body divide by mitosis and then break off from the parent to form a new organism. • All the offspring are genetically identical. • These organisms all reproduce asexually. Yeast (Fungi) E-coli (Bacteria) Animal (Hydra) http://commons.wikimedia.org/wiki/User:Dietzel65 Copyright © 2014 Henry Exham Example of asexual reproduction Asexual reproduction: advantages and disadvantages Sexual Reproduction • Sex cells called gametes are produced. • There are two types, a male gamete and a female. • The male gamete must move to the female gamete and fuse. • This is called fertilisation. • The new cell formed is called a zygote. Copyright © 2014 Henry Exham gametes ► A gamete is a sex cell (in animals: sperm and ovum; in plants pollen nucleus and ovum) ► Gametes differ from normal cells as they contain half the number of chromosomes found in other body cells - we say they have a haploid nucleus ► This is because they only contain one copy of each chromosome, rather than the two copies found in other body cells. E...