3.12 understand the roles of oestrogen and testosterone in the development of secondary sexual characteristics.

Secondary sexual characteristics develop during puberty

Oestrogen- females
The beginning of the menstrual cycle
Body mass increases and redistributed- to hips and breasts
Body hair- pubic
Voice deepens slowly
Development of sexual organs

Testosterone- males
Production of sperm
Growth of sexual organs
Body hair- pubic, arms and face
Body mass will increase, including muscle mass
Voice breaks (becomes deeper)
Development of a sexual drive

3.11 understand how the developing embryo is protected by amniotic fluid

The fluid (mainly water) cannot be compressed- it absorbs pressure- so any force on the uterus wall will not harm the embryo.

3.10 describe the role of the placenta in the nutrition of the developing embryo

The embryo can't breath, digest or excrete.
Blood vessels inside the placenta can absorb the digested food molecules and oxygen that the embryo needs to survive. Waste products will be taken out of the embryo and put back into the mothers blood stream for her to excrete.

3.9 understand the roles of oestrogen and progesterone in the menstrual cycle

The menstrual cycle

Oestrogen and progesterone are both hormones which effect the menstrual cycle.

Oestrogen: produced in the ovaries; thickens the womb lining; prompts the release of LH.

Progesterone: produced in the corpus lutiem; maintains the lining of the womb

3.8 describe the structure and explain the function of the male and female reproductive systems

Male reproductive system
Testis- produce sperm cells, they are stored in the epididymus
Vas deference- carries sperm to the penis
The prostate- adds fluid to the sperm, creating semen (as does the seminal vesicles)
The urethra- carries sperm to the end of, and out of the penis.

Female reproductive system
Ovaries- produce eggs
Oviducts- carry the eggs to the uterus, is the site of fertilisation
Uterus- develops the fertilised egg on the placenta
Cervix- entrance to uterus

3.7 understand that plants can reproduce asexually by natural methods (illustrated by runners) and by artificial methods (illustrated by cuttings)

Asexual reproduction only involves one parent, this can be achieved in two ways by plants:
Runners- eg strawberries- a second stem extend, when it reaches the ground cells specialise into root cells and a new plant develops.
Cuttings: a clipping is put in to plant hormones, encouraging the ends to become roots, when placed in soil it will then create another plant.

3.6 understand how germinating seeds utilise food reserves until the seedling can carry out photosynthesis

Food reserves are in the cotyledons, sustain the plant growth until leaves are able to photosynthesis to support the plant.

3.5 understand the conditions needed for seed germination

Water, warm temperatures (enzymes eg to break down starch in to maltose) and oxygen for respiration

3.4 understand that the growth of the pollen tube followed by fertilisation leads to seed and fruit formation

A pollen will travel down the stigma through a pollen tube, in to the ovule in the carpel. Here the pollen will fertilise the ovule, forming a zygote (the seed). The carpel (reproductive organ) becomes a fruit.

3.3 describe the structures of an insect-pollinated and a wind-pollinated flower and explain how each is adapted for pollination

Insect
Brightly coloured, larger petals
Nectar
Scents

Wind
Anthers stick out- past other parts of the flower
Stamen will have large surface area.

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

Gametes are sex cells: the male one being sperm; the female one being an egg.
When they join together it is know as fertilisation. At this point the fused gametes become a zygote.
A the zygot then divides repeatedly, at this stage it becomes an embryo.

3.1 understand the differences between sexual and asexual reproduction

In sexual reproduction two parents create non-identical offspring, inheriting characteristics from both parents.
In asexual reproduction a single parent creates genetically identical offspring.