Presentation is loading. Please wait.

Presentation is loading. Please wait.

End Show Slide 1 of 24 Copyright Pearson Prentice Hall Biology.

Similar presentations


Presentation on theme: "End Show Slide 1 of 24 Copyright Pearson Prentice Hall Biology."— Presentation transcript:

1 End Show Slide 1 of 24 Copyright Pearson Prentice Hall Biology

2 End Show Slide 2 of 24 Copyright Pearson Prentice Hall 24-2 Seed Development and Germination

3 End Show 24-2 Seed Development and Germination Slide 3 of 24 Copyright Pearson Prentice Hall Seed and Fruit Development How do fruits form?

4 End Show 24-2 Seed Development and Germination Slide 4 of 24 Copyright Pearson Prentice Hall Seed and Fruit Development As angiosperm seeds mature, the ovary walls thicken to form a fruit that encloses the developing seeds.

5 End Show 24-2 Seed Development and Germination Slide 5 of 24 Copyright Pearson Prentice Hall Seed and Fruit Development A fruit is a ripened ovary that contains angiosperm seeds. As seeds mature, the ovary walls thicken to form a fruit that encloses the developing seeds.

6 End Show 24-2 Seed Development and Germination Slide 6 of 24 Copyright Pearson Prentice Hall Seed Dispersal How are seeds dispersed?

7 End Show Slide 7 of Seed Development and Germination Copyright Pearson Prentice Hall Seed Dispersal Seeds are dispersed by animals, wind, and water. Seeds dispersed by animals are typically contained in fleshy, nutritious fruits.

8 End Show 24-2 Seed Development and Germination Slide 8 of 24 Copyright Pearson Prentice Hall Seed Dispersal Seeds of many plants are eaten by animals. These seeds are covered with tough coatings that protect them from digestive chemicals, allowing them to pass through an animal’s digestive system unharmed. The seeds then sprout in the feces eliminated from the animal.

9 End Show 24-2 Seed Development and Germination Slide 9 of 24 Copyright Pearson Prentice Hall Seed Dispersal Seeds dispersed by wind or water are typically lightweight, allowing them to be carried in the air or to float on the surface of the water.

10 End Show 24-2 Seed Development and Germination Slide 10 of 24 Copyright Pearson Prentice Hall Seed Dispersal Some seeds are encased in winglike structures that spin and twirl, helping them glide from their parent plants. A coconut is buoyant enough to float in seawater within its protective coating for many weeks. Tumbleweed plants break off at their roots and scatter their seeds as they are blown by the wind.

11 End Show 24-2 Seed Development and Germination Slide 11 of 24 Copyright Pearson Prentice Hall Seed Dormancy Many seeds will not grow when they first mature. These seeds enter a period of dormancy, during which the embryo is alive but not growing. The length of dormancy varies in different plant species.

12 End Show 24-2 Seed Development and Germination Slide 12 of 24 Copyright Pearson Prentice Hall Seed Dormancy What factors influence the dormancy and germination of seeds?

13 End Show 24-2 Seed Development and Germination Slide 13 of 24 Copyright Pearson Prentice Hall Seed Dormancy Environmental factors such as temperature and moisture can cause a seed to end dormancy and germinate. Seed dormancy can be adaptive in several ways: allows for long-distance dispersal allows seeds to germinate under ideal growth conditions

14 End Show 24-2 Seed Development and Germination Slide 14 of 24 Copyright Pearson Prentice Hall Seed Germination Seed germination is the early growth stage of the plant embryo. When seeds germinate, they absorb water which causes food-storing tissues to swell and crack open the seed coat. The young root grows through the cracked seed coat.

15 End Show 24-2 Seed Development and Germination Slide 15 of 24 Copyright Pearson Prentice Hall Seed Germination In most monocots, the single cotyledon remains underground. The growing shoot emerges while protected by a sheath.

16 End Show 24-2 Seed Development and Germination Slide 16 of 24 Copyright Pearson Prentice Hall Seed Germination Corn (monocot) Young shoot Germinating seed Primary root Foliage leaves

17 End Show 24-2 Seed Development and Germination Slide 17 of 24 Copyright Pearson Prentice Hall Seed Germination In dicots, germination takes place in one of two ways. In some species, the cotyledons emerge above ground, protecting the stem and first foliage leaves. In other species, the cotyledons stay underground and provide a food source for the growing seedling.

18 End Show 24-2 Seed Development and Germination Slide 18 of 24 Copyright Pearson Prentice Hall Seed Germination Cotyledons Bean (dicot) Germinating seed Primary root Young shoot Cotyledons Seed coat Foliage leaves

19 End Show - or - Continue to: Click to Launch: Slide 19 of 24 Copyright Pearson Prentice Hall 24-2

20 End Show Slide 20 of 24 Copyright Pearson Prentice Hall 24-2 A germinating corn seedling has a.a single cotyledon, which remains below ground. b.two cotyledons, which push above ground. c.a single cotyledon, which pushes above ground. d.two cotyledons, which remain below ground.

21 End Show Slide 21 of 24 Copyright Pearson Prentice Hall 24-2 Angiosperm fruits develop from a.the ovary wall of the flower. b.seed endosperm. c.swollen sepals of the flower. d.flower stamens.

22 End Show Slide 22 of 24 Copyright Pearson Prentice Hall 24-2 An example of a seed that is transported by water is a a.coconut. b.tumbleweed. c.blackberry. d.maple seed.

23 End Show Slide 23 of 24 Copyright Pearson Prentice Hall 24-2 The seeds of many plants that form fruits are dispersed mainly by a.animals. b.water. c.wind. d.the plant itself.

24 End Show Slide 24 of 24 Copyright Pearson Prentice Hall 24-2 An environmental condition that can cause the activation of a dormant seed is a.a sharp drop in temperature. b.the heat from a forest fire. c.an extended drought. d.falling from a great height.

25 END OF SECTION


Download ppt "End Show Slide 1 of 24 Copyright Pearson Prentice Hall Biology."

Similar presentations


Ads by Google