1. Plant Life Cycles CHAPTER 30

2. Animals vs. Plants Plant Reproduction Animal Reproduction Life cycle
Alternation of generations
No alternation of generations
Gametes
Haploid gametes
Spores
Haploid spores
No spores
Gametes made by
Haploid gametophyte, by mitosis
Diploid organism, by meiosis
Spores made by
Diploid sporophyte, by meiosis

3. Alternation of Generations
Plants have a double life cycle with two distinct forms:
Sporophyte: diploid, produce haploid spores by meiosis.
Gametophyte: haploid, produce gametes by mitosis.

4. Non-flowering plants
Mosses, ferns, and related plants have motile, swimming sperm.
What kind of environmental conditions would be required for reproduction in these plants?
What kinds of limits does external reproduction impose on these plants?
Reproduction in these plants requires wet conditions, and requires having male and female parts close together.
Living conditions, plant size, and genetic mixing is limited.

5. Life cycle of mosses
Follow the link and write down in your notes 1 page on the life cycle of mosses

6. Moss Life Cycle

7. Life cycle of ferns
Ferns, unlike some other plants, do not flower in order to propagate. Instead, they reproduce sexually from spores.
The life cycle of a fern is very different from the life cycle of many other plants.
While many plants grow a mature adult form straight out of the seed, ferns have an intermediate stage, called a gametophyte, which then grows into a mature fern.
There are two distinct stages in the life cycle of ferns. The first stage is that of the gametophyte.
Spores are produced on the underside of mature plants. These will germinate and grow into small, heart-shaped plants called gametophytes.
The gametophytes produce both sperm and egg cells, and will fertilize itself, or others. Once the fertilization occurs, the adult fern will begin growing.
The second stage in the life cycle of a fern is the adult stage. The fertilized gametophytes begin to look like a mossy growth.

9. Conifers
Conifers (also non-flowering plants) have reduced gametophytes.
Male gametophyte is contained in a dry pollen grain.
Female gametophyte is a few cells inside of the structures that become the seed.

10. Conifer life cycle

11. Conifer pollination Conifers are wind-pollinated plants.
Chance allows some pollen to land on the scales of female cones.
Pollen germinates, grows a pollen tube into the egg to allow sperm to fertilize the egg.
What are some advantages and disadvantages to wind pollination?

12. Flowering Plant Reproduction

13. Angiosperms (flowering plants)
Plants that protect their seeds within the body of a fruit.
Make up ¾’s of all plants, including:
Trees, shrubs, herbs,
grasses, water plants…

14. Structure of a Flower 1. Pistil 2. Stigma 3. Style 4. Ovary 5. Stamen
6. Filament
7. Anther
8. Petal
9. Sepal
10. Receptacle
11. Stem

15. Male Reproductive Structure
The stamen consists of two parts: Anther and Filament
The anther is where meiosis occurs to produce haploid pollen
The filament is a stalk that supports the anther

16. Female Reproductive Structure
The pistil consists of the stigma, style and ovary
The sticky stigma receives the pollen from the anther
The pollen grows a tube down through the style
Meiosis occurs in the ovary to produce haploid ovules

17. Reproductive Structures
Petals: colourful
structures that attract pollinators.
Sepals: surround and protect the flower bud.

18. Pollination
Wind, insects or other animals transfer pollen from the anther of one flower to the stigma of another
Flowers vary depending on pollination mechanism

19. Pollination Animation

20. Pollination Vectors Wind Pollination: Dull, scentless
flowers with reduced petals
Bees/Butterfly Pollination: Bright
color, nectaries, scent.
They sip nectar, get pollen on coats,
transfer pollen from flower to flower
Bird Pollination: Nectaries, bright
colors, tube-like flowers
Moth Pollination: White petals,
open at night
Fly Pollination:Rank odor, flesh
colored petals

21. Pollen Grain Anther Sac
Pollen grains contain two haploid cells produced through meiosis.
1- The Tube cell – will grow the pollen tube.
2- The Generative cell – will go through mitosis to create two sperm cells.

22. Ovary
Each ovule within an ovary has a micropyle (an opening for the pollen tube).
The ovules’ megasporangium undergo meiosis to produce four haploid cells (3 die leaving 1 megaspore)
The megaspore undergoes mitosis 3 times to produce 8 haploid cells within the embryo sac.

24. Fertilization
After pollen lands on the stigma, a pollen tube grows down through the style to ovary
Generative cell creates the two sperm nuclei
Double fertilization occurs:
one sperm fertilizes the egg
one sperm the two polar nuclei together

25. Result of Double Fertilization
The sperm nucleus and egg nucleus join to form a 2n (diploid) embryo
The other sperm nucleus and the two polar nuclei join to form a 3n (triploid) endosperm. The endosperm is the food supply for the embryo.
First link

26. Seed and Fruit Development
After fertilization, the petals and sepals fall off flower
Ovary “ripens” into a fruit
The ovule develops into a seed

27. Seed Dispersal Mechanisms- Allow plants to colonize new areas and avoid shade of parent plant
Wind Dispersal - Flight mechanisms,
like parachutes, wings, etc.
Ex. Dandelion, maples, birch
Animal Dispersal - Fleshy fruits which
animals eat, drop undigested seeds in
feces or burrs which stick to
animals’ coats

28. Gravity Dispersal - Heavy nuts fall to ground and roll
ex. acorns
Water Dispersal - Plants
near water create floating
fruits
ex. coconuts

29. Plant Responses CHAPTER 31
How plants move and communicate

30. Plant Hormones

31. Plant Hormones Plant hormones can be divided into two classes:
Growth promoters: Auxins, Gibberellins, Cytokinins
Growth inhibitors: Ethylene gas, Abscisic acid

32. Growth promoters Hormones can promote plant growth in two ways:
Stimulating cell division in meristems to produce new cells.
Stimulating elongation in cells.

33. Auxins

34. Auxin activity
Auxins stimulate genes in cells associated with plant growth.

35. Auxin roles
Auxins carry out multiple roles having to do with plant growth including:
Tropisms
Apical dominance
Growth of adventitious roots
Fruit growth

36. Tropisms
Tropisms are the growth of a plant toward or away from a stimulus, including:
Phototropism: in response to light
Gravitropism: in response to gravity
Thigmotropism: in response to touch

37. Nastic Movements

38. Nastic movement in the sensitive plant (Mimosa pudica)

39. Hinge control in Venus Fly Trap - Nastic movement

40. How it works
Nastic movements are rapid, reversible movements in a plant.
Electrical potentials across cell membranes, similar to those in our nerve cells, signal plant cells at the base of the Mimosa leaf to rapidly lose water. This causes the leaf to droop.

41. Movies Sensitive Plant: http://www.youtube.com/watch?v=BVU1YuDjwd8
Venus Fly Trap:

42. Other examples Sunflowers follow the sun during the day.
Leaves of many plants turn to follow the sun.

43. Day/Night length
Some plants flower in response to the length of periods of darkness.
Spring-blooming flowers are long night (short day) plants, while summer-blooming flowers are short night (long day) plants.
Some plants are day-neutral.

45. Plant Communication Plants communicate chemically.
Injured plants send out chemical signals that may
signal other plants to prepare for an attack.
attract other insects that eat the insects that are attacking the plant.