Edexcell ppt Biology 3.8 - 3.12 Used in lessons to scaffold class teaching and as a revision resource for students

1. REPRODUCTION
3.1 understand the differences between sexual and asexual reproduction
There are two types of reproduction;
• Sexual: reproduction in which two gametes (sex
cells) fuse to create a new offspring that is
genetically different to the parents. Two parents
are involved.
• Asexual: reproduction without fusion of gametes. It
involves one parent only and produces offspring
that are genetically identical to the parent (clones).

2. Fertilization
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
Definitions
• Fertilization:
• Zygote:
• Embryo:
A male and a female gamete fuse
to form a zygote
a cell that is the result of
fertilization. It will divide by mitosis
to form an embryo
An organism in its early stages of
development, especially before it
has reached a distinctively
recognizable form.

3. Structure and Function of Reproductive systems
3.8 describe the structure and explain the function of the male and female reproductive systems

4. Structure and Function of Reproductive systems
3.8 describe the structure and explain the function of the male and female reproductive systems

5. Structure and Function of Reproductive systems
3.8 describe the structure and explain the function of the male and female reproductive systems
DRAW IN YOUR OWN DIAGRAM
LABLE

6. MENSTRUAL CYCLE
3.9 understand the roles of oestrogen and progesterone in the menstrual cycle
The menstrual cycle in women is a recurring process, taking around 28 days.
During the process, the lining of the uterus - womb - is prepared for pregnancy.
If pregnancy does not happen, the lining is then shed at menstruation.
Several hormones control this cycle.
Oestrogen
The hormone oestrogen is secreted by the ovaries.
Oestrogen makes two things happen:
it stops more ovum being matured
it causes the thinkening of the uterus lining
Progesterone
Progesterone is a hormone secreted by ovaries.
It maintains the lining of the uterus during the middle part of the menstrual cycle and during
pregnancy.

7. MENSTRUAL CYCLE
3.9 understand the roles of oestrogen and progesterone in the menstrual cycle

8. MENSTRUAL CYCLE
3.9 understand the roles of oestrogen and progesterone in the menstrual cycle

9. PLACENTA
3.10 describe the role of the placenta in the nutrition of the developing embryo (TA)
Diffuse from
foetus to mother:
1) CO2
2) water,
3) Urea
Diffuse from
mother to foetus:
1) O2
2) glucose,
3) amino acids,
4) minerals

10. PLACENTA
3.10 describe the role of the placenta in the nutrition of the developing embryo (TA)
The placenta is
adapted for diffusion
in much the same
way as other
exchange organs:
1. Huge surface area (it
has lots of villi-like
projections)
2. Only a few cells thick
3. Blood supplies keep
the concentration
gradients high
4. Counter-current
system

11. AMNIOTIC FLUID
3.11 understand how the developing embryo is protected by amniotic fluid (TA)

12. SECONDARY SEXUAL CHARACTERISTICS
3.12 understand the roles of oestrogen and testosterone in the development of secondary sexual characteristics.