1. Reproduction and Inheritance
National 5 Unit 2
Multicellular Organisms
Reproduction and Inheritance

2. Learning Outcomes Explain that gametes (sex cells) are haploid.
State that sperm are the male gametes in animals and that they are produced in the testes.
Describe the structure of sperm
State that pollen are the male gametes in plants and that they are produced in anthers.
Describe the structure of pollen
State that eggs (ova) are the female sex cell in animals and that they are produced in ovaries.
State that eggs (ovules) are the female sex cell in plants and that they are produced in ovaries.
State that fertilisation is the fusion of the nucleus of the male gamete with the nucleus of the female gamete resulting in a diploid cell called a zygote.

3. What is Reproduction? All living things reproduce.
Humans use sexual reproduction to produce their young.
In order to do this, the two parents (male and female) have different reproductive systems and organs that produce different sex cells.

4. The female reproductive system

5. The male reproductive system

6. Roles of the reproductive system

7. nucleus containing DNA
Sex cells – sperm
In males, the sex cells are called sperm.
tail
middle piece
head
cell membrane
nucleus containing DNA
Sperm are produced in sex organs called testes.

8. nucleus containing DNA
Sex cells – egg
In females, the sex cells are called eggs.
nucleus containing DNA
cytoplasm
membrane
jelly coat
Eggs are produced in sex organs called ovaries.

9. Female Male Sex cells - Gametes egg / ovum sperm
does not move on its own
large
foodstore present
made in ovaries
Male
sperm
swims using tail
very small
no foodstore
made in testes

10. Ovulation and fertilisation
In a female, one of the ovaries produces an egg approximately every 28 days. This is called ovulation.
During sexual intercourse, millions of sperm are ejaculated into the vagina.
If a sperm meets the egg, the sperm’s nucleus can join with the egg’s nucleus.
The fusing of the two nuclei is called fertilisation.

11. Fertilisation and implantation

12. Fertilisation in Mammals

13. Sexual Intercourse and Fertilisation
(3) Egg divides in two
(2) Sperm fertilises egg
(5) Embryo implants in uterus and grows
(4) Ball of cells formed
(1) Egg released from ovary

14. Fertilisation in Mammals
Day 3
Day 0
Egg released by ovary
Day 4
Day 7

15. Menstruation
An important part of puberty for girls is the beginning of their monthly cycle. This is known as the menstrual cycle.
The menstrual cycle involves the preparation of the uterus lining so that it can receive a fertilized egg.
If an egg is fertilized, it can implant itself in the prepared uterus lining.
If the egg is not fertilized, the lining of the uterus breaks down and is lost from the body. This is called menstruation, or a period.

16. Asexual reproduction in plants
It is possible for plants to reproduce asexually i.e. without flowers or fertilisation.
It can occur naturally or as a result of propagation by growers
Sexual reproduction also occurs in plants
The FLOWER contains the both the male and female reproductive organs of a plant.
Flowers of different plants may not be exactly alike, but they are built to the same basic plan.

17. Asexual Reproduction
Asexual reproduction only needs one parent, unlike sexual reproduction, which needs two parents. Since there is only one parent, there is no fusion of gametes and no mixing of genetic information. As a result, the offspring are genetically identical to the parent and to each other: in other words, they are clones.
Runners

18. Looking Inside a Flower

19. Flower Show Petals Petals Stigma attract insects catches pollen grains
Style
Anther
pollen tube grows down through this
pollen made here
Ovary
Ovule
contains ovules
becomes a seed when joined with pollen

20. Structure Function Sepal Petal Stamen Anther Stigma Ovary Nectaries
protect the unopened flower bud
Petal
may be brightly coloured to attract insects
Stamen
the male parts of the flower consisting of the anther held up on the filament
Anther
produce male sex cells (pollen grains).
Stigma
the top of the female part of the flower which collects pollen grains
Ovary
produces the female sex cells (ovules)
Nectaries
produce sugary nectar which attracts insects

21. Flowers are the organs of sexual reproduction in plants.
Gamete formation in flowering plants
Flowers are the organs of sexual reproduction in plants.
Usually the male and female reproductive organs are both present in the same flower.
Pollen grains contain the plant's male sex cells and are produced in the anthers. Ovules contain the plant's female sex cells and are produced in the ovary.

22. Insect Pollination
These plants often have flowers that are brightly coloured
and scented . The pollen from the anther sticks
to the insect’s body while it is sucking nectar from the
flower. The pollen gets brushed on to the style of the
flower.

23. Wind Pollination Feathery stigma
The wind blows the smooth pollen off the anther onto the feathery stigmas, which hang outside the flower so they can easily catch the pollen. As these plants don’t rely on insects, the petals are in colour.

25. Fertilisation Pollen grain Stigma Style Pollen tube Nucleus Ovary
Ovule

26. The zygote formed becomes an embryo which later grows into a plant containing genetic material from both the male and the female parents