1. Deirdre Jeter Biology II, 2013
Plants
Deirdre Jeter
Biology II, 2013

2. Plants
Multicellular eukaryotes, cell walls (cellulose), most are autotrophs
Use photosynthesis (chloroplasts); provides oxygen necessary for life
Very diverse group
Provide materials for buildings, paper, furniture, clothing, & medicines

3. Surviving on Land To survive on land plants have to be able to:
Absorb nutrients from their surroundings
Avoid dehydration/drying out
Be able to disperse without using water

4. Surviving on Land, cont. 2 major groups:
Nonvascular plants—no roots/vascular systems
Vascular plants—have roots and vascular systems
Fungi help plants absorb nutrients (mycorrhizae)

5. Surviving on Land, cont. Cuticle—waxy covering on outside of plants
Makes it easier for plants to retain water
Disperse using spores or seeds that can float on the wind or be carried by animals

6. Life Cycles Has alternation of generations
Haploid gametophytes alternate with diploid sporophytes
Zygotes divide through mitosis to produce sporophytes
Diploid sporophytes produce haploid spores through meiosis

7. Life Cycles, cont.
Spores grow into haploid gametophytes that produce haploid gametes through mitosis
End first set of notes!

8. Nonvascular Plants Small plants that reproduce using spores
Do not have true roots, stems, and leaves (vascular system)

9. Nonvascular Plants, cont.
Water & nutrients transported by osmosis & diffusion
Slow & only over small distances
Limits the size of the plants

10. Mosses Most common nonvascular plants
Green parts we recognize are gametophytes

11. Mosses, cont. Sporophytes grow from tips of gametophytes
Are not green
Have bare stalks topped by spore capsules (sporangia)
Most have a cuticle, stomata (openings that allow gas exchange in plants), and simple conducting cells

12. Liverworts Like mosses, grow in mats of individual plants
Have no stomata, cuticle, or conducting cells

13. Liverworts, cont. Some species have flat gametophytes with lobes
Made of structures that resemble stems & leaves
Sporophytes are very small & consist of a short stalk with a sporangium on top

14. Hornworts Like liverworts, have no conducting cells
Sporophytes have stomata & a cuticle
Hornlike; grow up from flat gametophytes

15. Nonvascular Plant Reproduction
Like all plants, life cycles have an alternation of generations
Gametophytes must be covered in water for fertilization to occur
Gametophytes that produce eggs are archegonia
Gametophytes that produce sperm are antheridia

16. Nonvascular Plant Reproduction, cont.
Spores are produced by sporophytes in a sporangium
Sporophytes are smaller than gametophytes
Grow from gametophytes & depend on them for nutrients

17. Moss Life Cycle
Diploid sporophytes produce haploid spores through meiosis
Mature spores are released & spread by wind or water
Spores settle to the ground & grow into haploid gametophytes

18. Moss Life Cycle, cont.
Gametophytes produce eggs & sperm through mitosis
When water covers mosses, sperm swim to nearby archegonia to fertilize eggs

19. Seedless Vascular Plants
Do not produce seeds
Sporophytes have vascular tissue; gametophytes do not
Vascular systems allow them to develop true roots, stems, & leaves
Grow much larger than nonvascular plants

20. Seedless Vascular Plants, cont.
Gametophytes grow on or below surface of the soil
Water required for fertilization
2 major groups:
Lycophytes (club mosses)
Monilophytes (ferns & related species)

21. Club Mosses Not true mosses because they have roots, stems, & leaves
Stems branch from underground rhizome

22. Club Mosses, cont.
Spores develop in sporangia that form on specialized leaves
Some species form cones
Clusters of non-green, spore-bearing leaves

23. Ferns & Related Species
Most common seedless vascular plants
Sporophytes are what we recognize as ferns
Have a rhizome that is anchored by roots & leaves

24. Ferns & Related Species, cont.
Leaves, called fronds, that have small sporangia that grow on their underside

25. Seedless Vascular Plant Reproduction
Like nonvascular plants, must have water for fertilization to occur
Sporophytes much larger than gametophytes
Archegonia & antheridia develop on lower surface of gametophytes

26. Seedless Vascular Plant Reproduction, cont.
Most species have egg & sperm produced by the same individual (has archegonia & antheridia)
Some produce gametes in separate structures

27. Spores Haploid; produced by meiosis
Capable of growing into an adult without fusing with another cell
Has thickened walls that help prevent drying out & help withstand adverse conditions

28. Spores, cont. Form in sporangia
Cluster of sporangia in ferns called a sorus
Can be used to identify fern species
End second set of notes

29. Seed Plants Vascular plants that produce seeds
Development of seeds enhanced the survival & dispersal of offspring

30. Seed Plants, cont. 2 groups: Gymnosperms Angiosperms
Seeds do not develop within a fruit
Most develop within a cone
Angiosperms
Seeds develop within fruits (ripened ovary)
Flowering plants

31. Reproduction in Seed Plants
Does not require water
Sporophyte is dominant; gametophyte is microscopic

32. Reproduction in Seed Plants, cont.
Sporophytes produce 2 types of spores that produce 2 types of gametophytes
Female gametophyte develops inside an ovule
Male gametophyte develops inside a pollen grain

33. Reproduction in Seed Plants, cont.
Pollination—the transfer of pollen grains from the male reproductive structures to the female reproductive structures
Pollen tube grows into the female gametophyte & sperm passes directly to the egg for fertilization

34. Seeds Ovule that contains a fertilized embryo
Outer ovule layers harden to form the seed coat
Protects embryo from mechanical injury & harsh environment

35. Seeds, cont. Contain tissue that provides nutrients to embryos
In gymnosperms, tissue forms from female gametophyte
In angiosperms, tissue called endosperm

36. Seed Dispersal
May prevent competition for water, nutrients, light, & living space
Some seeds have wing-like structures so they can float on the wind
Dandelion & milkweed seeds have parachute-like structures to help them drift

37. Seed Dispersal, cont.
Some fruits have hooks that cling to animals’ fur
Some fruits are food for animals
Seeds dispersed through animals’ feces

38. Gymnosperms One of the most successful groups of plants
4 major groups:
Conifers
Cycads
Ginkgoes
Gnetophytes

39. Conifers Most familiar gymnosperms
Needle-like leaves or leaves that are reduced to tiny scales
Grow in cool, dry regions
Pollen grains dispersed by wind

40. Cycads Short stems & palm-like leaves
Cones that produce pollen & those that produce seeds develop on different plants
Grow in tropical areas
Pollen grains dispersed by insects

41. Ginkgoes Only living species is the maidenhair tree Fan-shaped leaves
Male & female gametophytes develop on separate trees
Seeds do not develop in a cone
Pollen grains dispersed by wind

42. Gnetophytes Diverse group of trees, shrubs, & vines
Produce seeds & pollen in cones

43. Conifer Life Cycle
Diploid zygote develops when sperm fertilizes an egg
Becomes dormant while seeds form
Seeds are released when they mature & grow when conditions are favorable

44. Cones Whorls (circles) of modified leaves called scales
Gametophytes of most gymnosperms develop inside cones
Male (pollen) cones produce pollen grains
Female (seed) cones produce ovules

45. Cones, cont.
Many gymnosperms produce male & female cones on the same plant
Female cones open for pollination, then close until seeds mature
End 3rd set of notes

46. Angiosperms Divided into 2 groups: Monocots
Seeds have 1 seed leaf (cotyledon)
Long, narrow leaves with parallel veins
Flowers with parts in multiples of 3

47. Angiosperms Dicots Seeds have 2 seed leaves
Leaves with branching veins
Flowers with parts in multiples of 4 or 5

48. Angiosperm Reproduction
Occurs within flowers
Specialized reproductive structures of angiosperms
Promote pollination and fertilization more efficiently than cones

49. Flower Structure & Kinds of Flowers
Arranged in 4 concentric whorls (circular swirls)
Outermost whorl consists of the sepals
Protect flowers from damage while they are buds

50. Flower Structure & Kinds of Flowers, cont.
Second whorl consists of the petals
Attract pollinators
Third whorl consists of stamens
Produce pollen in anthers

51. Flower Structure & Kinds of Flowers, cont.
Fourth whorl consists of 1 or more pistils
Produce ovules in ovaries (swollen lower portion of pistils)
Complete flowers
Have all 4 basic flower parts

52. Flower Structure & Kinds of Flowers, cont.
Incomplete flowers
Lack 1 or more of the basic flower parts

53. Angiosperm Life Cycle
Sporophytes produce haploid spores through meiosis
Spores form gametophytes
Female gametophytes grow inside ovules
Male gametophytes grow in anthers of stamens

54. Angiosperm Life Cycle, cont.
Pollination occurs when pollen grain is moved from anther to stigma

55. Angiosperm Life Cycle, cont.
Pollen tube grows into style to release 2 sperm into the ovule (double fertilization)
1 sperm fertilizes an egg
The other joins with 2 haploid nuclei to form a triploid cell
Develops into endosperm to provide nutrients for the embryo

56. Pollination 2 types of plants
Self-fertilizers—fertilize their own ovules
Cross-fertilizers—fertilized by pollen from other plants

57. Pollination, cont.
Cross-fertilizing plants adapted for pollination by wind or animals
Strong odors, bright colors, nectar, or shapes used to attract animals
Wind-pollinated plants small without bright colors, strong odors, or nectar

58. Fruits The ovary of a plant after fertilization
Help to protect developing seeds
Primary function is seed dispersal
Eaten by animals
Structures for wind dispersal
Some plants forcefully eject their seeds

59. Vegetative Reproduction
Asexual reproduction involving non-reproductive parts (stems, roots, leaves)
Occurs through modified stems, such as bulbs, tubers, and stolons
Faster than sexual reproduction
Allows single plants to rapidly populate an area