2.19b F1 x F1 Cross

3.19a P1 x P1 Cross

3.18b Genotypes

3.18a Phenotypes

3.10

1. The ovary produces Oestrogen which flows through the blood stream to the lining of the uterus. The effect of oestrogen is the thickening of the wall of the endometrium. This occurs during the first day of the cycle to around the thirtieth.

2. The oestrogen then flows from the bloodstream to the brain where it releases another hormone called luteinising hormone. The release of the LH reaches its peak at around day thirteen which causes the ovary to release an egg. This happens because during the first half of the menstrual cycle a circular structure known as a follicle becomes increasingly larger. Inside the follicle is the egg. The cells around the follicle produce the Oestrogen. At around day thirteen the follicle reaches its largest size. When the LH causes the lining around the ovary to rupture and the egg is released. The egg will come out of the ovary and into the oviduct where it becomes possible for fertilisation to occur.

3. The empty follicle changes function. It turns a yellow colour. This is called Corpus Luteum ‘Yellow Body’. The yellow body produces progesterone. Progesterone travels through the blood steam to the lining of the Uterus. The progesterone prevents the lining of the uterus from breaking down. Here, it is possible for the fertilised egg to implant into the wall and develop into a pregnancy.

4. If there is no implantation of a fertilised egg then the corpus Lutuem breaks down and progesterone levels fall. The fall of progesterone levels causes the break down in the lining of the Uterus. This is known as the menstrual period or the menstrual bleeding. Once the lignin had fully broken down then the cycle begins over again.

Life Cycle

2.4

Plants and Animals:
N – Nucleus
C- Cytoplasm
Cm – Cell Membrane

Plants only:
CW –Cell Wall
C- Chloroplast
CV – Large Central Vacuole

Shape:
- Plant cells tend to be more regular
- Animal store the molecule: Gycogen
- Plant store the molecule: starch

Differences:
- Form of carbohydrate (glycogen/starch)
- Plant have the additional CW, C, CV

3.12

Amniotic Fluid:

- In the Uterus is a fluid called The Amniotic Fluid (largely water)

- The fluid protect developing embryo as it cannot be compressed.

- It absorbs the pressure. Any force applied to the uterus wall, the amniotic fluid will absorbs the pressure to prevent damage to the unborn child.

3.11

Placenta:

-The wall of the Uterus is called the Placenta.
- When the child is in the uterus, it is full of embryotic fluid
- The child cant digest or breath or excrete whilst in the mother.
- The placenta grows out of the developing embryo, does not grow out of the mother.
- The Blood vessels inside the placenta are the child’s blood vessels (arteries, veins)
- Placenta grows into the wall of the uterus.
- Glucose amino acids, fats, travel through the bloodstream of the mother and into the wall of the uterus.
- The Sugars, amino acids and fats will cross into the child’s blood at the placenta and then taken into the child.
- Placenta has a large surface area.
-The barrier between the mother’s blood and the child’s blood is very thin.

3.9b

3.9a