1. Plants: Reproduction, Growth, & Sustainability
Chapter 14
Plants: Reproduction, Growth, & Sustainability

2. Learning Goal
To learn more about the details of plant reproduction

3. Introduction Plants undergo BOTH sexual and asexual reproduction
Recall: sexual reproduction occurs when the male gamete (sperm cell) unites with the female gamete (egg cell) – resulting in Fertilization
All plants go through a life cycle called alternation of generations

4. Alternation of Generations

5. Task: pg. 582
Make summary notes on the phases of the life cycle of the Fern:
Notice how the top shows the haploid generation (1n), which is responsible for the gamete-making individuals (gametophyte)
Notice how the bottom shows the diploid generation (2n), which is responsible for the spore-making individual (sporophyte)

6. Summary Notes

7. Sexual Reproduction in Seedless Plants
Some plants like mosses and ferns do not produce seeds
Seedless plants depend on diffusion and osmosis to transport water and nutrients into the plant
For fertilization, sperm must swim from the male gametophyte to the female gametophyte (the egg)

8. Sexual Reproduction in Seedless Plants
A) Seedless Plants without Vascular Tissues
In seedless plants, the gametophyte is the dominant generation
It is larger and lives longer than the sporophyte – like Mosses

9. Sexual Reproduction in Seedless Plants
In seedless plants with vascular tissues, the sporophyte is the dominant generation
Here, the gametophyte is smaller and does not live as long
In ferns, the leafy part is the sporophyte

10. Sexual Reproduction – Pollination
In seed plants – the gametophytes are not free-living plants
The MALE gametophytes are small structures that develop into pollen grains that produce sperm cells and do not have tiny flagella (~) to help them move during pollination
The FEMALE gametophytes produce eggs
Here, the whole male gametophyte (not just the sperm) travels to the female gametophyte

11. Sexual Reproduction – Pollination
Pollination occurs when the pollen (male) lands on the female reproductive structure of a plant of the same species
The pollen grain encase the cells that develop into the sperm and protects them from drying out when they travel to the female gametophyte
Does not require water to transport them

12. Plant Reproduction

13. Sexual Reproduction in Seed Plants
Sexual reproduction in seed plants involves pollination
Plants that produce seeds include gymnosperms and angiosperms

14. Sexual Reproduction in Seed Plants
Gymnosperms
Angiosperms
Are plants that contain vascular tissue and produce seeds that are not covered by a protective layer of tissue
Include coniferous trees (pine trees, firs, spruce, and redwoods)
Produce seeds on the surface of cone scales
are plants that contain vascular tissue and produce seeds that do have a protective tissue around them
Include flowering plants (roses, dandelion, and magnolias) and trees (oak, maples, & birch)

15. Sexual Reproduction in Gymnosperms
Conifers are gymnosperms that reproduce using cones
During sexual reproduction in conifers, large amounts of pollen grains are released by wind
When a pollen grain lands on a female cone, the sperm fertilizes the eggs
After fertilization, the zygote develops into an embryo
After some time, it is matured and then released into the wild by wind or animals, where they may grow into new sporophytes plants depending on the conditions they are in

17. Sexual Reproduction in Angiosperms
Angiosperms are the most diverse and widespread plants on Earth
The most important factor in why there are so many of them is because of how they reproduce, as their reproductive organs is within the flower
Flowers have 4 organs: sepals, petals, stamens, and pistole(s)

18. Sexual Reproduction in Angiosperms
Use pg. 584 to review the function of each organ:
Organs of the Flower
Description
1. Sepals
2. Petals
3. Stamens
4. Pistils

19. Sexual Reproduction in Angiosperms

20. Checking for Understanding
Based on the reproductive organs of the flower, which are the female reproductive organs?
Which are the male reproductive organs?

21. Online Activity: Fertilization

22. Pollination Mechanisms
Pollination is the transfer of pollen from the male anther to the female stigma
Most plants are cross-pollinated – which means they receive pollen from another plant, which helps create genetic diversity in plants
Cross pollination can take place though the use of wind or animals
However, some plants can self-pollinate

23. Pollination Mechanisms

24. Pollination Mechanisms
Self- Pollination
Cross -Pollination
Animal Pollination
Wind Pollination
Where such plants can pollinate themselves or another flower on the same plant
This can cause inbreeding and loss of genetic variation
Occurs with most Angiosperms
They receive pollen from another plant and undergo fertilization
The Male and Female plants must be close enough for the male to pollinate the female plant
This allows for genetic diversity
Occurs when an insect or small animal move from flower to flower (usually looking for nectar) and carry some pollen from one flower to another
Usually occurs with plants that are lightly coloured (like a Lilly) or do not smell as much
But they do create a lot of pollen
The large amount of pollen is then carried by wind to other plants

25. Pollination Mechanisms

26. Life Cycle of Angiosperms (Flowering Plants)
Whether or not a plant develops male or female gametophytes, begins early in an undeveloped flower
Inside the flower’s ovary, an ovule containing the embryo sac begins to grow
Inside the ovule, meiosis results in 4 haploid megaspores
Usually of the 4 megaspores, only 1 develops into a female gametophyte and the other 3 degenerate

27. Life Cycle of Angiosperms (Flowering Plants)
Mitosis occurs 3x in the remaining megaspore until one megaspore has 8 haploid nuclei divided into seven cells
1 of the seven cells has 2 nuclei, which are called polar nuclei
In the Anther, specialized cells undergo meiosis to produce microspores
Each microspore then undergoes mitosis to form a tube cell and a generative cell
A thick protective cell wall forms around each microspore called a pollen grain

28. Life Cycle of Angiosperms (Flowering Plants)
When the pollen grain lands on the stigma of the correct species, the tube cells form a pollen tube
This pollen tube grows as generative cells undergo mitosis and evolve into 2 sperm cells
When the pollen tube reaches the ovule, it releases these sperm cells,
where 1 fuses with the egg (forming a zygote), and the other fuses with the polar nuclei (forming a nutrient-rich tissue called endospore)
The Endospore provides nutrition for the embryo as it grows

29. Life Cycle of Angiosperms (Flowering Plants)
The fertilization of an angiosperm egg is called double fertilization (as 2 fertilizations occur)
When do these 2 fertilizations take place?
1. ______________________________________________
2. ______________________________________________
After fertilization, the ovule develops into the seed, and the ovary develops into the fruit

30. Life Cycle of Angiosperms (Flowering Plants)
Video:

31. Results of Reproduction
Fertilization is the beginning of a long process in reproduction that ends when a seed is formed
In angiosperms, a seed is part of a fruit that develops from the ovary or other flower organs

32. Seed and Fruit Development
The Sporophyte begins as a Zygote (or a 2n cell)
Numerous cells divisions produce a cluster of cells that eventually develop into an elongated embryo where:
1 cotyledon forms Monocots (like coconuts)
2 cotyledons form Dicots (like a Daisy)

33. Seed and Fruit Development
As the endosperm matures, the outside layers harden and form a protective tissue called a seed coat
Depending on the plant, the ovary can contain 1 ovule or 100s
As the ovule develops into a seed, changes occur in the ovary that leads to the formation of a fruit
A fruit forms from the ovary wall, and the juice tissues develop from other flower parts

34. Seed Dispersal
As well as protecting seeds, fruits help disperse them increasing the rate of offspring survival
Fruits that are attractive to animals can be moved quite a bit from the parent plant
Some seeds have structural modifications that help them to be transported by water, animals, or wind

35. Seed Germination
Once seeds have been dispersed and land in an area that provides enough water, warmth, and oxygen they can begin growing seedlings, or remain dormant
As a seed matures, it loses water and rests in a state of dormancy
Only when conditions become ideal does the seed resume growth and enter germination

36. Seed Germination
The first part of the embryo to be seen outside the seed itself is called the Radicle
The Radicle develops into the plants’ roots
The Hypocotyl is the part of the stem closest to the seed and often the 1st part of the seedling to appear
Photosynthesis begins as soon as the seedling’s cells that have chloroplasts are above the ground and have access to sunlight

37. Seed Germination
Video:

38. Asexual Reproduction in Angiosperms
In asexual reproduction, a parent plant produces offspring that is genetically IDENTICAL to it and each other
Asexual reproduction can be an advantage when environmental conditions are stable and an organism is well adapted to its environment

39. Artificial Propagation
In asexual reproduction, new individuals are grown from a portion of the roots, stems, or leaves of the existing plant
This helps farmers and gardeners to select from the parent plant for specific traits

40. Task
Use pgs. 590 – 591 to learn more about the common techniques of artificial propagation

41. Types of Artificial Propagation
Purpose or Advantage
Examples
Division (Splitting)
Grafting
Leaf Cutting
Stem Cutting

42. Types of Artificial Propagation
Purpose or Advantage
Examples
Root Cutting
Simple Layering
Air Layering
Cell Culturing