PLANTS

1. PLANTS Chapters 23-26

2. All Plants… • multicellular, eukaryotic, autotrophic Evolution of Plants

3. Angiosperms • Monocots vs. Dicots • named for the number • of cotyledons present on • the embryo of the plant • + monocots • - orchids, corn, • lilies, grasses • + dicots • - roses, beans, • sunflowers, oaks

4. Alternation of Generations • Sporophyte (diploid) • produces haploid • spores via meiosis • Gametophyte (haploid) • produce haploid • gametes via mitosis • Fertilization • joins two gametes to • form a zygote

5. Plant Morphology • Morphology (body form) • - shoot system • + stems, leaves, flowers • - root system • + taproot, lateral roots • vascular tissues • + transport materials between • roots and shoots • - xylem/phloem

6. Plant Anatomy • Anatomy (internal structure) • division of labor • + cells differ in structure and function • - parenchyma, collenchyma, sclerenchyma(below) Parenchyma St: “typical” plant cells Fu: perform most metabolic functions Collenchyma St: thick walls Fu: provide support but allow growth in young parts of plants Sclerenchyma St: hardened secondary walls (LIGNIN) Fu: specialized for support; dead

7. WATER-CONDUCTING CELLS OF THE XYLEM SUGAR-CONDUCTING CELLS OF THE PHLOEM Sieve-tube members: longitudinal view Tracheids Vessel Companion cell Sieve-tube member Sieve plate Tracheids and vessels Nucleus Vessel element Tracheids Companion cell Cytoplasm Plant cell types • Xylem • Phloem

8. Water- and Food-conducting Cells • Xylem (water) • dead at functional maturity • Phloem (food) • alive at functional maturity • sieve-tube cells- arranged • end to end with sieve plates & • Companion cells

9. Plant Tissues • Three Tissue Systems • dermal tissue • + epidermis (skin) • - single layer of cells that • covers entire body • - waxy cuticle/root hairs • vascular tissue • + xylem and phloem • - transport and support • ground tissue • + mostly parenchyma • - filler tissue • - photosynthesis, storage, • support

10. Meristems • embryonic tissues located at regions of growth • - apical meristems (primary growth- length) • + located at tips of roots and shoots • - lateral meristems (secondary growth- girth) Plant Growth

11. Figure 35.3 Roots • A root • Anchors the plant • Absorbs minerals and water • Stores organic nutrients • Taproots: vertical • Lateral roots: horizontal branches • Fibrous root system in monocots (e.g. grass)

12. (a) Prop roots (b) Storage roots (c) “Strangling” aerialroots (d) Buttress roots (e) Pneumatophores Modified Roots • Many plants have modified roots (b) Storage roots (a) Prop roots

13. (a) Stolons Storage leaves (d) Rhizomes Stem Node Root Bulbs Rhizome (c) Tubers Root Modified Stems

14. Buds • An axillary bud • Forms a lateral shoot • A terminal bud • Causes elongation of a young shoot Gardening tip: Removing the terminal bud stimulates growth of axillarybuds (e.g. makes plants bushier)

15. The leaf • Is the main photosynthetic organ of most vascular plants

16. Tendrils Spines Storage leaves Bracts Reproductive leaves. The leaves of some succulents produce adventitious plantlets, which fall off the leaf and take root in the soil. Modified Leaves

17. Leaf Anatomy • Epidermal Tissue • upper/lower epidermis • guard cells (stomata) • Ground Tissue • mesophyll • +palisade/spongy • parenchyma • Vascular Tissue • veins • + xylem and phloem

18. The Vascular Cambium and Secondary Vascular Tissue • The vascular cambium • Is a cylinder of meristematic cells one cell thick • Develops from parenchyma cells

19. Secondary Growth • As a tree or woody shrub ages • The older layers of secondary xylem, the heartwood, no longer transport water and minerals • The outer layers, known as sapwood • Still transport materials through the xylem

20. Plant Reproduction

21. Plant Reproduction • Sporophyte (diploid) • produces haploid • spores via meiosis • Gametophyte (haploid) • produce haploid • gametes via mitosis • Fertilization • joins two gametes to • form a zygote

22. Flowers

23. Double Fertilization • Double Fertilization • pollen grain lands on stigma • + pollen tube grows toward ovule • + 2 sperm discharged down the tube • - egg and one of the sperm • produce zygote • - 2 polar nuclei and sperm • cell produce endosperm • + ovule becomes the seed coat • + ovary becomes the fruit

24. Seed Structure and Development

25. Asexual Reproduction in Plants: Vegetative Propagation • Budding and Grafting: smaller stems from one plant are attached to another plant • Taking cuttings: pieces of one plant are used to grow another • Stems can be modified: • Runners: horizontal stems aboveground • Rhizome: horizontal stems belowground • Tuber: swollen underground stem

26. Plant nutrition

27. Plant Nutrition What does a plant need to survive?

28. Atmosphere N2 N2 Atmosphere Nitrate and nitrogenousorganiccompoundsexported inxylem toshoot system Soil Nitrogen-fixingbacteria N2 Denitrifyingbacteria H+ (From soil) NH4+ NH3 (ammonia) Soil NO3– (nitrate) NH4+ (ammonium) Nitrifyingbacteria Ammonifyingbacteria Organicmaterial (humus) Root Soil Bacteria and Nitrogen Availability • Nitrogen-fixing bacteria convert atmospheric N2 • plants absorb ammonium (NH4+), nitrate (NO3-)

29. Nutritional Adaptations • Symbiotic Relationships • Mycorrhizae • + symbiotic associations of fungi and roots • - mutualisticrelationship: fungus receives food from plant and plant receives increased surface area for root absorption

30. Unusual nutritional adaptations

31. Plant Transport

32. 1 3 4 2 Sugars are produced by photosynthesis in the leaves. Through stomata, leaves take in CO2 and expel O2. Transpiration, the loss of water from leaves, pulls xylem sap upward. 6 5 7 Water and minerals are transported upward in the xylem. Roots absorb water and minerals from the soil. Roots exchange gases with the soil, taking in O2 and discharging CO2 in cellular respiration • A variety of physical processes • Are involved in the different types of transport CO2 O2 Light H2O Sugar Sugars are transported via phloem to otherparts of the plant. O2 H2O CO2 Minerals

33. Water and minerals ascend from roots to shoots through the xylem • Plants lose an enormous amount of water through transpiration, the loss of water vapor from leaves • The transpired water must be replaced by water transported up from the roots

34. Control of Transpiration • Water enters guard cells and causes cells to swell, opening stomata. • Water leaves guard cell and they shrink, closing stomata

35. Translocation through Phloem • Translocation • Is the transport of organic nutrients in the plant • Phloem sap • Is an aqueous solution that is mostly sucrose • Travels from a sugar source to a sugar sink

36. Sugar Source & Sink • A sugar source • Is a plant organ that is a net producer of sugar, such as mature leaves • A sugar sink • Is an organ that is a net consumer or storer of sugar, such as a tuber or bulb

37. Write down as many ways you can think of in your lab notebook. How do plants respond to the environment?

38. Tropisms • Growth toward or away from a stimulus • Gravitropism (Gravity) • Phototropism (Light) • Thigmotropism (Touch)

39. Plant hormones help coordinate growth, development, and responses to stimuli • Hormones • Are chemical signals that coordinate the different parts of an organism

41. Photoperiod, the relative lengths of night and day • + Is the environmental stimulus plants use most often to detect the time of year and when to flower