Plant Reproduction

1. Plant Reproduction Angiosperms, mosses, and ferns

2. Plant reproduction • Plants use both asexual (one) and sexual (two) reproduction to pass their genes onto the next generation.

3. Plant reproduction • Plants use both asexual (one) and sexual (two) reproduction to pass their genes onto the next generation. • Lower plants – sexual repro. produces spores from meiosis

4. Plant reproduction • Plants use both asexual (one) and sexual (two) reproduction to pass their genes onto the next generation. • Lower plants – sexual repro. produces spores from meiosis • Higher plants – gametes fuse to form a zygote which develops into an embryo inside a seed.

5. Plant reproduction • Plants use both asexual (one) and sexual (two) reproduction to pass their genes onto the next generation. • Lower plants – sexual repro. produces spores from meiosis • Higher plants – gametes fuse to form a zygote which develops into an embryo inside a seed. • http://www.youtube.com/watch?v=FsBQQDg5GIw

6. Plant reproduction • Plants use both asexual (one) and sexual (two) reproduction to pass their genes onto the next generation. • Lower plants – sexual repro. produces spores from meiosis • Higher plants – gametes fuse to form a zygote which develops into an embryo inside a seed. • http://www.youtube.com/watch?v=FsBQQDg5GIw • http://www.youtube.com/watch?v=drcnTg7ZCoc

7. Plant reproduction • Seeds are dispersed by

8. Plant reproduction • Seeds are dispersed by • http://www.youtube.com/watch?v=zbQ1jWl3AOM

9. Plant reproduction • Seeds are dispersed by birds and wind etc to a range of habitats.

10. Plant reproduction • Seeds are dispersed by birds and wind etc to a range of habitats. • Some habitats may be suitable for the germination of the seed, but some may not – this results in large losses of seeds and genes from those parent plants.

11. Plant reproduction • Seeds are dispersed by birds and wind etc to a range of habitats. • Some habitats may be suitable for the germination of the seed, but some may not – this results in large losses of seeds and genes from those parent plants. • Some seeds will tolerate the habitat because it is similar to the one their parents were in.

12. Plant reproduction • Asexual plants produce offspring by mitotic cell division – all offspring are genetically identical to their parent.

13. Plant reproduction • Asexual plants produce offspring by mitotic cell division – all offspring are genetically identical to their parent. • Eg Strawberries produce horizontal stems called runners.

14. Plant reproduction • Asexual plants produce offspring by mitotic cell division – all offspring are genetically identical to their parent. • Eg Strawberries produce horizontal stems called runners. • Eg daffodils and onions produce bulbs underground.

16. Plant reproduction • Conditions are usually ideal for the new plants growing through asexual reproduction.

17. Plant reproduction • Conditions are usually ideal for the new plants growing through asexual reproduction. • This can cause problems because of the dense population of the plant. Eg old man’s beard.

18. Plant reproduction • Conditions are usually ideal for the new plants growing through asexual reproduction. • This can cause problems because of the dense population of the plant. Eg old man’s beard. • However, colonising new habitats is difficult for asexual reproducers because there is no dispersal mechanism.

19. Alternation of generations • Where a diploid (double set of chromosomes) asexual generation is followed by a haploid (one set of chromosomes) sexual generation.

20. Alternation of generations • Where a diploid (double set of chromosomes) asexual generation is followed by a haploid (one set of chromosomes) sexual generation. • Gametes from gametophytes fuse to form a zygote, which grows into a sporophyte.

21. Alternation of generations • Where a diploid (double set of chromosomes) asexual generation is followed by a haploid (one set of chromosomes) sexual generation. • Gametes from gametophytes fuse to form a zygote, which grows into a sporophyte. • Sporophytes produce haploid spores from meiosis which grow into gametophytes.

22. Alternation of generations • Sporophytes contain double the genetic info as gametophytes and also produce spores which are genetically unique, so the trend in plant evolution has to be; increase the size and development of the sporophyte at the gametophyte’s expense.

23. Mosses • Spores produced by the sporophyte are resistant to drying out, and are blown until they settle and germinate into gametophytes.

24. Mosses • Spores produced by the sporophyte are resistant to drying out, and are blown until they settle and germinate into gametophytes. • Gametophyte is the dominant generation, being larger and with a longer lifespan than that of the sporophyte. • http://www.youtube.com/watch?v=jcWYAnmm-QE

25. Mosses • Spores produced by the sporophyte are resistant to drying out, and are blown until they settle and germinate into gametophytes. • Gametophyte is the dominant generation, being larger and with a longer lifespan than that of the sporophyte. • Gametophytes produce sperm from a male gametangium and eggs from the female gametangium.

26. Mosses • Spores produced by the sporophyte are resistant to drying out, and are blown until they settle and germinate into gametophytes. • Gametophyte is the dominant generation, being larger and with a longer lifespan than that of the sporophyte. • Gametophytes produce sperm from a male gametangium and eggs from the female gametangium. • Reproduction requires water, because sperm must swim to an egg for fertilisation to occur.

27. Ferns • The sporophyte is the dominant generation.

28. Ferns • The sporophyte is the dominant generation. • Fern spores are produced on the underside of fronds and germinate in damp conditions into very small heart-shaped gametophytes.

29. Ferns • The sporophyte is the dominant generation. • Fern spores are produced on the underside of fronds and germinate in damp conditions into very small heart-shaped gametophytes. • Gametophytes survive for just a few weeks. Sperm need water to swim to the egg of a nearby female.

30. Ferns • The sporophyte is the dominant generation. • Fern spores are produced on the underside of fronds and germinate in damp conditions into very small heart-shaped gametophytes. • Gametophytes survive for just a few weeks. Sperm need water to swim to the egg of a nearby female. • The sporophyte formed after fertilisation draws nourishment from the gametophyte only until the sporophyte begins to photosynthesis.

31. Ferns • The sporophyte is the dominant generation. • Fern spores are produced on the underside of fronds and germinate in damp conditions into very small heart-shaped gametophytes. • Gametophytes survive for just a few weeks. Sperm need water to swim to the egg of a nearby female. • The sporophyte formed after fertilisation draws nourishment from the gametophyte only until the sporophyte begins to photosynthesis. • The fern sporophyte is well adapted to the land environment. Ferns – the ponga and silver fern have evolved to colonise a number of habitats even though they still require water for reproduction.

32. Ferns • http://www.youtube.com/watch?v=eZ40LDWt678

33. Questions • A plant reproduced asexually for two generations. What must be assumed about the chromosome number of the second generation?