Fertilisation & meiosis

Question 1

Name the steps of fertilization

Answer 1

1. Sperm transport
2. Capacitation
3. Acrosome
4. Penetration
   5.Cortical Reaction
5. Nuclear fusion

Question 1

What is the fundamental idea of Fertilisation?

Answer 1

Sperm and egg create a zygote

Question 2

What are the two stages of development?

Answer 2

Embryonic and Fetal

Question 2

Describe the process of fertilisation.

Answer 2

The sperm capacitates at the zona pellucida of the egg, triggering an acrosome reaction. Once it penetrates, the egg undergoes cortical reaction to ensure no other sperm get in. Then, the sperm and egg nuclei fuse to form a diploid zygote with a complete set of chromosomes.

Question 2

How does an embryo develop?

Answer 2

Cleavage: After fertilisation, the zygote undergoes rapid cell divisions (mitosis) without increasing in size, forming a ball of cells called a morula.

The morula becomes a blastocyst, which has a fluid-filled cavity. The blastocyst implants into the uterine wall around day 6-7.

Question 3

What is meiosis?

Answer 3

Formation of egg and sperm cells that divide twice to form 4 daughter cells

Question 4

Explain what the first meiotic division is

Answer 4

2 genetically different daughter cells have 4 chromatids. The chromosomes exchange genes by crossing over, inheriting a random assortment of genetic material.

Question 5

Explain what the second meiotic division is

Answer 5

Amount of genetic material is halved; centromeres halved; 2 sister chromatids separate to opp. sides of cell and divide into 4 haploid daughter cells

Question 6

2 identical forms of gene

Answer 6

Homozygous

Question 7

2 different forms of gene

Answer 7

Heterozygous

Question 8

Explain Prophase in PMAT

Answer 8

Prophase = chromosones condence and line up with homologous pairs (crossing over = genetic exchange)

Question 9

Explain the MAT in PMAT

Answer 9

Metaphase = chromosones in the middle
Anaphase = chromosones are pulled away by spindle fibres
Telophase = 2 newly formed nuclei

Question 10

In Meiotic 2, there is no ___

Answer 10

Crossing over or lining up in pairs

Question 11

Prometaphase is

Answer 11

disappearance of envelope, fastening of sister chromatids and kinetochore function

Question 12

What hormone is released during parturition?

Answer 12

Increase in Oxytocin - uterine contractions

Question 13

In labour, there is a decline in

Answer 13

progesterone

Question 14

Phenotype

Answer 14

appearance or observable characteristic

Question 15

Genotype

Answer 15

genetic makeup of organism - individual collection

Question 16

If an egg is fertilised, it will burrow __

Answer 16

into the endometrium during implantation.

Question 17

When LH is present, the oocyte leaves the ruptured follicle, and it becomes

Answer 17

a corpus luteum which produces progesterone

Question 18

What does GnRH release in men?

Answer 18

Released by the hypothalamus and stimulates production of luteinizing hormone (LH) from the anterior pituitary.

Question 19

What does the ovary release?

Answer 19

Controlled by hypothalamus - it releases FST and LH - gonadotropins

Question 20

The release of oxytocin from posterior pituitary gland during labour is

Answer 20

a positive feedback loop - stimulates muscular contractions to push the baby