3.19 a+b

3.18 a+b

Website for genetics questions

http://click4biology.info/c4b/4/gene4.3.htm#eleven

3.2

understand that fertilisation involoves the fusion of a male and female gamete to produce a zygote that undergoes cell division and develops into an embryo

fertilisation
adult male + female. cells have complete number of chromosomes (diploid. 2n)
in human male they divide in testis in human female in ovary to produce gametes which are haploid (n) only have 23 chromosomes instead of usual 46.
in sexual reproduction the egg and sperm (haploid gametes) join/fuse to form 1 cell called the zygote. this process is called fertilisation. (n+n=2n>>hapliod+haploid=diploid) 23+23=46
then zygote undergoes mitosis (cell division). all contain all 46 chromosomes. 2n. diploid. once many have formed the mass of celles is known as an embryo.

3.9b

recall structure and function of female reproductive system.
before pregnancy uterus is small, no larger than an orange.

ovary - meiosis occurs, production of female gamete (egg)
oviducts - carry eggs to uterus, also location of fertilisation
uterus -
wall made of muscle which expands and contracts during pregnancy and just after to accomodate unborn child.
lining accepts and develops the fertilised egg
space allows the egg to turninto a embryo and then an unborn child.
development of placenta in uterus too.
cervix - enterance to uterus (where the sperm cells enter)
vagina - collects sperm cells, allows them to pass.

3.9a

recall structure and function of male reproductive system



bladder - stores urine
testes - carry out proces of miosis, producing male gametes (sperm cells)
epydidymus - stores sperm cells
vas deferens - carry sperm cells to penis during sexual stimulation
prostate - 20-30 percent of semen (alkali mix containing sugars)
seminal vesicles - produce sugar based alkali 70 percent of semen
urethra - common tube connects L+R testes and vas deferens. takes semen down penis and also takes urine.
penis - carries sperm cells into vagina during sexual intercourse.