The document discusses plant reproduction and development. It describes how flowering plants produce male gametophytes (pollen grains) containing sperm in anthers and female gametophytes (embryo sacs) containing egg cells in ovules. Pollination involves pollen grains landing on the stigma and growing a pollen tube to deliver sperm for double fertilization within the ovule. After fertilization, the ovule develops into a seed containing an embryo and endosperm. The ovary develops into a fruit protecting the seeds. Seed germination continues the life cycle as the embryo resumes growth using nutrients from the endosperm.

1. Chapter 31 (Part 2) Plant Structure, Reproduction, and Development 0

2. REPRODUCTION OF FLOWERING PLANTS 31.9 Overview: The sexual life cycle of a flowering plant The angiosperm flower consists of Sepals, petals, stamens, and carpals Figure 31.9A Stigma Style Ovary Anther Filament Stamen Petal Ovule Sepal Carpel

3. Pollen grains develop in anthers At the tip of stamens

4. The tip of the carpel, the stigma Receives pollen grains The ovary, at the base of the carpel Houses the egg-producing structure, the ovule Figure 31.9B Ovary, containing ovule Fruit, (mature ovary), containing seed Mature plant with flowers, where fertilization occurs Seedling Germinating seed Seed Embryo

5. 31.10 The development of pollen and ovules culminates in fer tilization In the diploid sporophyte of an angiosperm Haploid spores are formed within ovules and anthers

6. The spores in the anthers Give rise to male gametophytes, pollen grains, which produce sperm A spore in an ovule Produces the embryo sac, the female gametophyte, which contains an egg cell

7. Pollination Is the arrival of pollen grains onto a stigma A pollen tube grows into the ovule And sperm pass through it and fer tilize both the egg and a second cell in a process called double fer tilization

8. Gametophyte development and fertilization in an angiosperm Figure 31.10 Development of male gametophyte (pollen grain) Development of female gametophyte (embryo sac) Anther Cell within anther Meiosis Four haploid spores Single spore Wall forms Mitosis (of each spore) Two cells Pollen grain released from anther Ovary Ovule Surviving cell (haploid spore) Pollen germinates Mitosis Embryo sac Egg cell Two sperm in pollen tube Pollen tube enters embryo sac Two sperm discharged Triploid (3 n ) endosperm nucleus Double fer tilization occurs Diploid (2 n ) zygote (egg plus sperm) Pollination Meiosis

9. 31.11 The ovule develops into a seed After fertilization, the ovule becomes a seed And the fertilized egg within it divides and becomes an embryo Figure 31. 11A Growth Secondary xylem (wood) Cork Cork cambium Secondary phloem Shed epidermis Triploid cell Ovule Zygote Embryo Endosperm Shoot Cotyledons Seed coat Seed Root Two cells

10. The other fertilized cell Develops into the endosperm, which stores food for the embryo

11. The internal structures of dicot and monocot seeds Differ in a variety of ways Figure 31.11B Embryonic leaves Embryonic root Seed coat Cotyledons Embryonic shoot Common bean (dicot) Cotyledon Embryonic leaf Sheath Fruit tissue Seed coat Endosperm Embryonic Shoot Embryonic root Corn (monocot)

12. 31.12 The ovary develops into a fruit Angiosperms form fruits Which help protect and disperse the seeds Figure 31.12B Figure 31.12A 1 2 3 Upper part of carpel Ovule Sepal Ovar y wall Seed Pod (opened)

13. Angiosperm fruits May differ in size and development Figure 31.12C

14. 31.13 Seed germination continues the life cycle A seed starts to germinate When it takes up water and star ts to expand The embryo resumes growth And absorbs nutrients from the endosperm An embryonic root emerges And a shoot pushes upward and expands its leaves

15. In dicot germination, the root emerges first Followed by the shoot, which is covered by a protective hook Figure 31.13A Foliage leaves Embryonic shoot Embryonic root Cotyledons

16. In monocot germination A protective sheath surrounding the shoot breaks the soil Figure 31.13B Foliage leaves Protective sheath enclosing shoot Embryonic root Cotyledon

17. 31.14 Asexual reproduction produces plant clones Asexual reproduction can be achieved via Bulbs, sprouts, or runners Figure 31.14A Figure 31.14B Figure 31.14D Figure 31.14C

18. CONNECTION 1.15 Asexual reproduction is a mainstay of modern agriculture Propagating plants asexually from cuttings or bits of tissue Can increase productivity but can also reduce genetic diversity Figure 31.15

19. Chapter 32 Plant Nutrition and Transport 0

20. Plants That Clean Up Poisons Dr. Lena Ma studies certain species of ferns That are able to absorb and thrive on the poison arsenic

21. The ferns and other plants are being used in phytoremediation The use of plants to help clean up polluted soil and groundwater Sunflower plants absorbing radioactive metals from a contaminated pond.

22. THE UPTAKE AND TRANSPORT OF PLANT NUTRIENTS 32.1 Plants acquire their nutrients from soil and air As a plant grows Its roots absorb water, minerals, and some O 2 from the soil Its leaves absorb CO 2 from the air Figure 32.1A Minerals CO 2 O 2 H O 2

23. Plants use the sugars made by photosynthesis To construct all the organic materials they need, including the cellulose in the trunks of trees Figure 32.1B

24. 32.2 The plasma membranes of root cells control solute uptake Root hairs Greatly increase a root’s absorptive surface Figure 32.2A

25. Water and solutes can move through the root’s epidermis and cortex By going either through the cells or between them Figure 32.2B Key Dermal tissue system Ground tissue system Vascular tissue system Root hair Epidermis Cortex Phloem Xylem Endodermis Root hair Xylem Epidermis Endodermis Casparian strip Casparian strip Extracellular route, via cell walls; stopped by Casparian strip Intracellular route, via cell interiors, through plasmodesmata Plasmodesmata Cortex

26. However, all water and solutes Must pass through the selectively permeable plasma membranes of cells of the endodermis to enter the xylem for transport upward

27. 32.3 Transpiration pulls water up xylem vessels Transpiration can move xylem sap Which consists of water and dissolved organic nutrients, to the top of the tallest tree Figure 32.3 Root hair Flow of water Soil particle Water Water uptake from soil Adhesion Cell wall Cohesion, by hydrogen bonding Xylem cells Cohesion and adhesion in the xylem Xylem sap Mesophyll cells Air space within leaf Stoma Outside air Transpiration Water molecule

28. 32.4 Guard cells control transpiration The leaf stomata of plants, which can open and close Are adaptations that help plants regulate their water content and adjust to changing environmental conditions

29. A pair of guard cells Flank each stoma Figure 32.4 H 2 O H 2 O H 2 O H 2 O H 2 O H 2 O H 2 O H 2 O H 2 O H 2 O K + Stoma Guard cells Stoma opening Stoma closing Vacuole

30. 32.5 Phloem transports sugars Phloem contains food-conducting cells That aid in the transport of phloem sap Figure 32.5A Sieve- tube member Sieve plate TEM 2,700 

31. Phloem transports food molecules made by photosynthesis By a pressure flow mechanism Figure 32.5B 1 2 3 4 Low water pressure High sugar concentration High water pressure SUGAR SOURCE PHLOEM XYLEM Sugar Water Source cell Sieve plate Sugar Water Sink cell SUGAR SINK Low sugar concentration Low water pressure

32. At a sugar source Sugar is loaded into a phloem tube The sugar raises the solute concentration in the tube And water follows, raising the pressure in the tube

33. The increase in pressure at the sugar source and the decrease at the sugar sink Cause phloem sap to flow from source to sink

34. Aphids, which feed on phloem sap Have allowed plant biologists to study the contents of the sap and its flow Figure 32.5C Honeydew droplet Stylet of aphid Aphid feeding on a small branch Aphid’s stylet inserted into a phloem cell Severed stylet dripping phloem sap LM 760 

35. PLANT NUTRIENTS AND THE SOIL 32.6 Plant health depends on a complete diet of essential inorganic nutrients Plants must obtain usable sources Of the chemical elements it requires, “nutrients,” from its surroundings

36. If any nutrient is not available Normal growth may not occur Figure 32.6 Complete solution containing all minerals (control) Solution lacking potassium (experimental)

37. Macronutrients, such as carbon and nitrogen Are needed in large amounts, mostly to build organic molecules Micronutrients, including iron and zinc Act mainly as cofactors of enzymes