1. Inquiry into Life Twelfth Edition
Lecture PowerPoint to accompany
Inquiry into Life Twelfth Edition
Sylvia S. Mader
Chapter 10
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

2. 10.1 Sexual Reproduction in Plants

3. 10.1 Sexual Reproduction in Plants
Plants have two stages in their life cycle.
A diploid stage alternates with a haploid stage.
The diploid plant is called the sporophyte.
The haploid plant is called the gametophyte.

4. 10.1 Sexual Reproduction in Plants
Flowers are the reproductive structures of angiosperms.
Flowers produce two kinds of spores.
Microspores develop into the male gametophyte.
The male gametophyte produces sperm.
Megaspores develop into the female gametophyte.
The female gametophyte produces an egg.

5. 10.1 Sexual Reproduction in Plants
Upon fertilization, a zygote is formed. The zygote develops into an embryo.
A seed forms contains the embryo and stored food.
When a seed germinates, a new sporophyte emerges.

6. Alternation of Generations in Flowering Plants

7. 10.1 Sexual Reproduction in Plants
Parts of a Flower
Sepals - leaf-like structures that protect the developing bud
Petals - attract pollinators
Stamens - male portion of the flower
Anther - produces pollen grains
Filament - a slender stalk that supports the anther
Carpel - female portion of the flower
Stigma - an enlarged stick knob
Style - a slender stalk
Ovary - encloses one or more ovules

8. Anatomy of a Flower

9. 10.1 Sexual Reproduction in Plants
Flower parts occur in three’s (or multiples) in monocots.
Flower parts occur in four or five’s (or multiples) in eudicots

10. 10.1 Sexual Reproduction in Plants
Flowers may have one or multiple carpels (which may be fused).

11. 10.1 Sexual Reproduction in Plants
Flowers that have sepals, petals, stamens and carpels are called complete flowers. Flowers that do not are called incomplete.

12. 10.1 Sexual Reproduction in Plants
A monoecious plant has both staminate and carpellate flowers. If staminate and carpellate flowers are on separate plants, the plant is dioecious.

13. 10.1 Sexual Reproduction in Plants
Life Cycle of Flowering Plants
Flowering plants produce:
Microspores
Megaspores

14. 10.1 Sexual Reproduction in Plants
Life Cycle of Flowering Plants
Microspores become mature male gametophytes (sperm-bearing pollen grains)
Megaspores become mature female gametophytes (egg-bearing embryo sacs)

15. 10.1 Sexual Reproduction in Plants
Life Cycle of Flowering Plants
During fertilization, one sperm nucleus unites with the egg nucleus, producing a zygote.
The other sperm unites with the polar nuclei, forming a 3n endosperm cell.

16. Life Cycle of Flowering Plants

17. 10.1 Sexual Reproduction in Plants
Pollination -
The transfer of pollen from an anther to a stigma.
Self-pollination (pollen is from the same plant)
Cross-pollination (pollen is from a different plant)

18. Pollinators

19. 10.2 Growth and Development

20. 10.2 Growth and Development
Development of the Eudicot Embryo
The endosperm cells divides to produce endosperm tissue.
The zygote divides into two cells.
One cell will become the embryo.
Embryonic cells near the suspensor become the root, and those at the opposite end form the shoot
The other cell will give rise to the suspensor.
The suspensor anchors the embryo and transfers nutrients to it.

21. Development of the Eudicot Embryo

22. 10.2 Growth and Development
Development of the Eudicot Embryo
The embryo changes from a ball of cells to a heart-shape
Cotyledons (seed leaves) appear
The embryo next becomes torpedo-shaped, and the root tip and shoot tip become visible
The epicotyl portion of embryo contributes to shoot development
The hypocotyl portion contributes to stem development
The radicle contributes to root development

23. 10.2 Growth and Development
Monocots Versus Eudicots
Eudicots (two cotyledons)
Cotyledons store nutrients that the embryo uses
Monocots (one cotyledon)
Cotyledon absorbs food molecules from the endosperm and passes them to the embryo

24. 10.2 Growth and Development
Fruit Types and Seed Dispersal

25. 10.2 Growth and Development
Fruit Types
Fruits are derived from an ovary
Fruits protect and help disperse offspring
The ovary wall thickens to become the pericarp.

26. 10.2 Growth and Development
Fruit Types
Simple fruits are derived from a simple ovary or from a compound ovary.
Legumes
Dry fruits
Fleshy fruits
Accessory fruits

27. 10.2 Growth and Development
Fruit Types
Compound fruits develop from several individual ovaries.
Aggregate fruits
Multiple fruits

28. 10.2 Growth and Development
Dispersal of Seeds
Seeds may have hooks or spines that attach to fur or clothing
Seeds may pass through the digestive tract of animals
Seeds may be gathered and buried by animals
Seeds may be carried by wind or water

29. 10.2 Growth and Development
Germination of Seeds
Some types of seeds remain dormant until conditions are favorable for growth.
Temperature
Moisture
Regulatory Factors (stimulatory and inhibitory)
Mechanical Action (examples: water or fire)

30. 10.2 Growth and Development
Eudicot Versus Monocot Germination
Eudicots
Cotyledons shrivel and degrade
Epicotyl produces immature leaves and is called a plumule
Young shoot is hook-shaped as it emerges through the soil
Monocots
Cotyledon does not have a storage function
Plumule and radicle are protected by sheaths
Plumule and radicle burst through the sheaths when germination occurs
Young shoot is straight, not hooked

31. Germination of Eudicots and Monocots

32. 10.3 Asexual Reproduction

33. 10.3 Asexual Reproduction
Plants contain non-differentiated meristem tissue that allows them to reproduce asexually by vegetative propagation.
Offspring may arise from the nodes of stolons or rhizomes. Stems and roots can also give rise to new plants.

34. 10.3 Asexual Reproduction Tissue Culture
The growth of tissue in an artificial liquid or solid culture medium.
Plant cells are totipotent, each cell can become an entire plant.
Large numbers of plants with desired characteristics and genotypes can be propagated rapidly.

35. Tissue Culture of Plants

36. 10.3 Asexual Reproduction Genetic Engineering of Plants
Traditionally, different varieties of plants have been crossed to produce offspring with desirable traits.
Today it is possible to directly alter the genes of organisms, producing new varieties of plants with desirable traits.
Plants that have a foreign gene are called transgenic or genetically modified plants.

37. 10.3 Asexual Reproduction Agricultural Plants with Improved Traits
Corn, cotton, soybean and potato plants have been engineered to be resistant to either herbicides or insect pests.
Ongoing research is expected to yield different variety of crops that will be salt tolerant, cold tolerant, drought resistant or blight resistant.

38. Transgenic Crops of the Future

39. 10.3 Asexual Reproduction Commercial Products
Single gene transfers have produced plants that can manufacture various products
Hormones
Clotting Factors
Antibodies

40. 10.4 Control of Growth and Responses
Hormones are small organic molecules that serve as chemical signals between cells and tissues.

41. 10.4 Control of Growth and Responses
Hormones are small organic molecules that serve as chemical signals between cells and tissues.
Groups of Plant Hormones
Auxins
Gibberellins
Cytokinins
Abscisic Acid
Ethylene

42. Plant Hormones: Mode of Action
Plant hormones bind to a specific protein in the plasma membrane. This brings about a physiological response.

43. 10.4 Control of Growth and Responses
Auxins
Auxins affect many aspects of plant growth and development. Auxins:
May promote apical dominance
Increase the development of adventitious roots
Promote the growth of fruits
Are involved with phototropism and gravitropism.

44. 10.4 Control of Growth and Responses
How Auxins Work
H+ is pumped out of cells
Auxins are acidic and weakens cell wall structure
Water moves into the cell and turgor pressure causes the cell to bend toward the light (away from auxin)

45. 10.4 Control of Growth and Responses
Gibberellins
Gibberellins are growth-promoting hormones that promote elongation.

46. 10.4 Control of Growth and Responses
Cytokinins
Promote cell division
Prevent senescence (aging)
Initiate growth
The ratios of auxins to cytokinins play a role regarding the differentiation of plant tissues.

47. 10.4 Control of Growth and Responses
Abscisic Acid
Produced by green portions of plant
Closes stomata and maintains seed and bud dormancy
Considered a plant “stress” hormone
A decrease in abscisic acid and an increase in gibberellins breaks dormancy

48. 10.4 Control of Growth and Responses
Ethylene:
Is a gas that moves freely through the air
Is involved with abscission (leaf drop)
Promotes the ripening of fruit

49. 10.4 Control of Growth and Responses
Plant Responses Are Influenced By:
Light
Day length
Gravity
Touch

50. 10.4 Control of Growth and Responses
Plant Tropisms:
Phototropism: Growth in response to light
Gravitropism: Growth in response to gravity
Thigmotropism: Growth in response to touch

51. Positive Negative Phototropism Gravitropism

52. 10.4 Control of Growth and Responses
Flowering
Short-day plants
Long-day plants
Day-neutral plants

53. Photoperiodism and Flowering

54. 10.4 Control of Growth and Responses
Phytochrome and Plant Flowering
Phytochrome is a plant pigment that responds to light
Pr is active form; Pfr is inactive
Direct sun contains more red light than far red light; Pfr is present in plant leaves during the day
At dusk, there is more far red light; Pfr is activated to Pr
Phytochrome conversion allows plant to detect photoperiod changes

55. Phytochrome

56. Phytochrome Control of A Growth Pattern