1. Sheryl Searcy Ninth Grade Center  2012 CONES & FLOWERS Reproduction in Seed Plants Chapter 24

2. Sheryl Searcy Ninth Grade Center  2012 REPRODUCTION WITH CONES & FLOWERS Section 24-1

3. Sheryl Searcy Ninth Grade Center  2012 Life Cycle of Gymnosperms  Reproduction of gymnosperms takes place in cones which are produced by a mature sporophyte plant. –Pollen cones –Seed cones

4. Sheryl Searcy Ninth Grade Center  2012 Life Cycle of Gymnosperms

5. Sheryl Searcy Ninth Grade Center  2012 Structure of Flowers  Flowers are reproductive organs that are composed of four kinds of specialized leaves: –Sepals: outermost part, green, resembles leaves. –Petals: brightly colored, attract insects and other pollinators. –Stamens: male gametophyte; the anther and a filament inside the ring of the petals. –Carpel (pistils): female gametophyte; consists of ovary, ovule, style, and stigma.

6. Sheryl Searcy Ninth Grade Center  2012 Structure of Flowers Carpel

7. Sheryl Searcy Ninth Grade Center  2012  Flowers vary enormously in structure.  Some flowerlike structures are actually clusters of many individual flowers. Structure of Flowers Day LillyWisteria

8. Sheryl Searcy Ninth Grade Center  2012 Cycle of Angiosperms

9. Sheryl Searcy Ninth Grade Center  2012 SEED DEVELOPMENT & GERMINATION Section 24-2

10. Sheryl Searcy Ninth Grade Center  2012 Seed Development  As angiosperm seeds mature, the ovary walls thicken to form a fruit that enclosed the developing seeds.

11. Sheryl Searcy Ninth Grade Center  2012 Seed Dispersal  Dispersal by animals –Seeds dispersed by animals are typically contained in fleshy, nutritious fruits.  Dispersal by wind and water –Seeds dispersed by wind or water are typically lightweight, allowing them to be carried in the air or float on the surface of the water.

12. Sheryl Searcy Ninth Grade Center  2012 Seed Dormancy  Contributing environmental factors –Temperature –Moisture  Seed dormancy… –Can allow for long-distance dispersal (weeks or months). –Can allow seeds to germinate under ideal conditions. –Can allow seeds to reclaim a forest after a fire (pine trees).

13. Sheryl Searcy Ninth Grade Center  2012 Seed Germination  The early growth phase of plant embryo.

14. Sheryl Searcy Ninth Grade Center  2012 GROWTH RESPONSE IN PLANTS

15. Sheryl Searcy Ninth Grade Center  2012 Tropism  A directional growth movement made by a part of a stationary plant response to unilateral stimulus.

16. Sheryl Searcy Ninth Grade Center  2012 Graviotropism/Geotropism  Importance: –Provide firm anchorage for roots. –Ensure the plant gets adequate water & mineral salts  The root tip produces hormones which diffuse to the elongation region. –The hormones diffuse to the lower side due to gravity. –High hormone concentration inhibits growth in root. –The lower side grows slower than the upper side. –The root bends downward.

17. Sheryl Searcy Ninth Grade Center  2012 Phototropism  Importance: –Enables leaves to be in a position to receive as much sunlight as possible for photosynthesis.  The shoot tip produces hormones which diffuse downward: –The hormones diffuse to the shaded side due to the presence of one-sided light. –High hormone levels stimulate growth in shoot. –The shaded side grows faster than the lighted side. –The shoot bends towards the light.

18. Sheryl Searcy Ninth Grade Center  2012 Thigmotropism  The directional response of a plant organ to touch or physical contact with a solid object. –This directional response is generally caused by the induction of some pattern of differential growth. –This phenomenon is clearly illustrated by the climbing tendrils of some plants, such as the sweet pea.  The tendrils actually "feel" the solid object, which results in the coiling/closing response.

19. Sheryl Searcy Ninth Grade Center  2012 Hydrotropism  Importance –Ensures that a plant gets enough water as a raw material for photosynthesis & enough mineral salts to maintain normal growth.

20. Sheryl Searcy Ninth Grade Center  2012 Photoperiodism  Physiological reaction of organisms to the length of day or night.  Occurs in plants and animals.  The developmental responses of plants to the relative lengths of the light and dark periods. –Many flowering plants use a photoreceptor protein, such as phytochrome or cryptochrome, to sense seasonal changes in night length, or photoperiod, which they take as signals to flower.

21. Sheryl Searcy Ninth Grade Center  2012 Plant Hormones  Chemicals that regulate plant growth.  Auxins: most common plant hormone –Regulate growth & other physiological processes in plants. –Produced by root tip / shoot tip. –Affect the elongation region of the tip.

22. Sheryl Searcy Ninth Grade Center  2012 Herbicides  All pesticides work by disrupting some natural mechanism within the biology of the targeted plant, insect or animal species. –Most of these natural or man-made chemicals kill their targets. –Some protect crops or livestock by repelling pests. –The ultimate goal for pesticide researchers is to find chemicals that kill or repel the target pests without affecting other organisms in the environment or humans.  Herbicides – chemicals that kill weeds; are the most widely used pesticides in farming. –Each year, they account for about 70 percent of all agricultural pesticide use in the U.S.

23. Sheryl Searcy Ninth Grade Center  2012 Herbicide Groups  Modern herbicides can be grouped. 1.The way they act:  Herbicides are active in the weed either through contact or in a systemic way. 2.The way they're used:  Herbicides can be categorized by their use. 3.How they kill the weeds they're meant to kill:  Herbicides can be classified by their mechanism of action.  Herbicides work on different enzymes, proteins or biochemical steps.  Synthetic auxins