Sexual reproduction

Question 1

Outline the stages of sprematogenesis

Answer 1

Primordial germ cell undergoes mitosis forming sprematogonia after a growth period of sprematogonia forms primary spermatocytes .
-The primary sprematocytes undergo meisosis
~Meiosis 1 :diploid secondary sprematocytes
~M2 :Haploid sprematids (4 they are undifferentaited )
The sprematids differentiate to fain the flageluum ,acrosome and many mitochondira

Question 2

What do sprematids differentiate to form ?

Answer 2

The sprematids differentiate to fain the flageluum ,acrosome and many mitochondira

Question 3

How do primary oocytes form

Answer 3

The primordinal germ cell in the ovaries ,divides by mitosis to form oogonia,after a period of growth the oogonia form the primary oocytes ,they remain in the prophase 1 in folicles until puberty

Question 4

what is formed during the first meiotic divison during oogenieis

Answer 4

1 Secondary oocyte with all the cytoplam forms
1 polar body buds off and sticks to the oocyte.

Question 5

What happens during the second meiostic division during oogenesis

Answer 5

Secondary oocyte divides into the hapolid ootid and polar body ,this polar body divides into 2.
Overall 3 polar bodies form ,they degenerate as ootid develops

Question 6

How does the ovum form

Answer 6

Meiotic division in prophase 1 ,fertilisation triggers an influx of calcium ions ,this stimulates meiosis 2 to form the ovum

Question 7

Describe the structre of the ovum

Answer 7

Outer layer of follicle cells
Zona pellucida :coating above the cytoplams preventing polsprermy and hardens when a cortical reaction occurs

Question 8

describe the structre of the sprematozoon

Answer 8

Acrosome ,nucleus ,spiral shapes mitochondira and the flagellum bound by a plasma membrane

Question 9

what happens during fertilisation

Answer 9

The enzymes in the acrosomes head digest zona pellucida
Sprem head fuses with ovum cell membrane ,allowing sprem nucleus to enter
Cortical reaction takes place causing the zona pellucid a to harden
The nuclei fuse ,forming a diploid zygote

Question 10

Outline the early stage if embryo development

Answer 10

Zygote - morula -blastocyst-implantaion

Question 11

how does the blastocyst form

Answer 11

Seeveral mitiotic divisions of zygote prouce the morula (solid ball of cells) the morula divides further then undergoes differentation forming the blastocyst .

Question 12

describe the strutre of the blastocyst

Answer 12

Inner cells mass develops into embryo ,outer layer trophoblast develops into placenta and a fluid filled cavity (blastocoele)