1. Passing It On Topic 3 Biological Diversity

2. Passing It On Heritable: a genetic characteristic that can be passed on from parent to offspring. Reproductive Strategies: the method an organism uses to reproduce and pass on genetic information to offspring

3. Reproductive Strategies Asexual Reproduction: –When only one parent supplies genetic information to offspring –Seen in bacteria and fungi Sexual Reproduction: –When two parents supply genetic material to offspring

4. Asexual Reproduction Offspring are genetically identically to parent. Benefits: –There is no need to find a mate –It can occur quite rapidly

5. Types of Asexual Reproduction Binary Fission –Happens only in single-celled organisms –Cell Duplicates its contents, including nucleus and other organelles. –Cell Divides, each new cell has a copy of genetic material and half the cytoplasm. –Offspring are genetically identical.

6. Types of Asexual Reproduction Asexual Spores –Organism produces many single-celled reproductive structures called spores. –Asexual spores contain genetic material from only one parent. –Many spores produced to ensure survival. –Zoospores are spores which move using a tail-like flagella. –Some organisms that produce asexual spores also reproduce sexually.

7. Types of Asexual Reproduction Asexual Reproduction in Plants –At the tips of roots and stem plants have areas of rapidly reproducing cells called meristem. –Meristematic cells are able to make repairs when activated. –Asexual reproduction can occur in plants by activating merstematic cells in different plant structures. –You can then take cuttings from the plants and plant it. –Offspring are clones (exact copies) of parents.

8. Types of Asexual Reproduction Budding –A cell (usually near the base of the organism) produces a new group of cells called a bud. –When developed the bud detaches itself and becomes independent.

9. The Best of Both Worlds Many organisms are able to reproduce both asexually and sexually. Zygospores contain genetic material from two different sources, therefore is a form of sexual reproduction.

10. Sexual Reproduction Offspring not identical to either parent, but will be a combination of characteristics from both parents. Benefit: sexual reproduction leads to a greater genetic diversity.

11. Types of Sexual Reproduction Bacterial Conjugation –A transfer of genetic material directly from one cell to another. –Primitive form of sexual reproduction because 2 parent cells involved. –Benefit because a new combination of inherited characteristics. –Bacterial conjugation is a genetic recombination but not a reproduction because there is no increase in number of cells.

12. 12 Sexual Reproduction in Plants and Animals Sexual Reproduction occurs when an egg (female gamete) and a sperm cell (male gamete) join together to form a new cell called a zygote. 12

13. Types of Sexual Reproduction Plant Sexual Reproduction: –Angiosperms and Gymnosperms reproduce sexually by forming seeds. –Angiosperms are flowering plants. –Gymnosperms do not produce flowers.

14. Angiosperms 14

15. Gymnosperms 15

16. Sexual Reproduction in Plants

17. Sexual Reproduction in Plants Pistil: female reproductive organ. Made up of the ovary, style and stigma. Stamen: male reproductive organ. Made up of the filament and anther

18. 18 Sexual Reproduction in Plants Pollination –Pollen grains are produced in the stamen. –Pollination occurs when the pollen grain reaches the pistil of the flower. –The pollen grain grows a pollen tube which when it reached the ovule, the sperm nucleus fertilizes the egg. –When fertilization happens a zygote forms. 18

19. Sexual Reproduction in Plants

20. 20 Sexual Reproduction in Plants Plants can: Self-pollinate When the sperm and egg come from the same plant. Cross-pollinate When due to wind, water, insects, birds or other animals carry pollen from one plant to another. This means that the sperm and egg come from two different plants. 20

21. 21 Sexual Reproduction in Plants The zygote formed during fertilization undergoes many cell divisions to form a multicellular embryo. The embryo contains a miniature leaf, root and stem. Food is supplied to the embryo by one or two cotyledons (seed leaves). The seeds will only germinate when the growing conditions are good. 21

22. Sexual Reproduction in Plants

23. 23 Sexual Reproduction in Plants In angiosperms the seeds are surrounded by a fruit. The fruit usually develops from the wall of the ovary. 23

24. 24 Sexual Reproduction in Animals For Sexual Reproduction to be successful some conditions must be met: –the male and female gametes need to arrive at the same place, at the same time for fertilization to occur. –after fertilization the zygote needs to have enough nutrition, moisture and in some cases warmth and protection. 24

25. 25 Sexual Reproduction in Animals Gametes are delicate and so timing is important. Fertilization can take place: – outside the body of the female e.g. sponges, worms, some fish, some amphibians –inside the body of the female e.g. insects, reptiles, mammals, birds, some fish, some amphibians 25

26. 26 Sexual Reproduction in Animals Mammals have a high rates of successful fertilization (reproductive success) due to internal fertilization. In internal fertilization eggs are protected inside the body of the female. Sperm is deposited and when a mature egg is present fertilization may occur. When the egg and sperm join a zygote is formed. The zygote divides to form an embryo. The embryos are protected by being close to or in the female’s body. 26