Plants: Structure & Function

1. Plants: Structure & Function

2. Plant Cell Plants are: Eukaryotic Autotrophic– havechloroplasts Multicellular Cell walls of cellulose

3. BRIEF HISTORY OF PLANTS • Theory: many scientists believe that photosynthetic green algae (protist) living near land adapted to life on land. Supporting evidence: • Plants and green algae both have cellulosein their cell walls. • Both use chlorophyllfor photosynthesis. • Both store food (glucose) by linking them into long chains of carbohydrates known as starch.

4. Brief History of Plants • The earliest plant fossils are 450 million years old and were of small simple plants that grew close to the ground and were still dependentonwaterto complete their life cycle….even AFTER they made the move to land • Over time plants developed specialized structures that allow them to grow larger and survive further from water. • Plants have evolveddifferent adaptations that there are now many different classifications within the plant kingdom

5. Plants that live in nitrogen poor soils trap and break down insects with enzymes to obtain nitrogen Venus fly trap Pitcher plant

6. Cladogram – Evolutionary History

7. Plant Diversity • Vascular tissues: larger plants need a way to move H2O and nutrients throughout the plant. Vascular tissue in plants carries water and sap, just like our vascular tissue carries blood. • Seed type: seeds can form on the surface of a cone or in a protective layer of tissue. • Flowers: many plants have flowers as their reproductive structures. The bight colors and sweet smells can attract pollinators to help in the process. Flowers come in many shapes, sizes and colors..

8. 4 Main Plant Groups: 1. Bryophytes: non-vascularmosses & other small plants • Non-vascular plants, so they must be low to the ground near water because water must travel into & out of these bryophytes by osmosis.

9. Only live in moist areas. Reproduction has to occur in water. • Commercial Value: Moss (peat moss) is commonly added to the soil when gardening to help retain water for the other plants and also to acidify the soil. • Examples: mosses, liverwort, & hornwort

10. 4 Main Plant Groups: 2. Ferns:seedless vascular plants • Vascular tissue allows water and nutrients to be easily moved farther distances so ferns can grow larger than non-vascular plants. • All vascular plants contain true roots, stems, and leaves. • Examples:ferns, horsetails Whisk fern Horsetail Fern

11. 4 Main Plant Groups: • Ferns reproduce using spores instead of seeds. These spores are made on the underside of the leaf in specialized structures called sporangia.

12. 4 Main Plant Groups: 3. Gymnosperm:vascular plants with unprotectedseedson cones • Exposed “naked” seeds on the surface of a cone • There are both male and female cones

13. Ovulate cone from a pinetree (female) Staminate cone from a pinetree (male)

14. Gymnoperms • Can live nearly anywhere, because seeds can form without water and remain dormant until water is available. • Many have special needle shaped leaves to minimize water loss • Examples: Cycads, Ginkgoes, Conifers (pine, spruce, cedars, redwoods, junipers, etc.)

15. Cycad Ginkgo

16. 4 Main Plant Groups: 4. Angiosperm: vascular plants with flowers, and seeds protected by layers of tissue called the fruit • Flowers are unique reproductive organs in angiosperms. The flowers contain an ovary that protects the developing seed. After pollination the ovary develops into a fruit.

17. Grassesandtreesare also flowering plants. Grass flowers

18. Flower (male) (female) pistil

19. Pollen grains containsperm. They are produced in the anthers of the flowers in angiosperms.

20. Ovaries with ovules become fruits with seeds after the ovule (egg) is fertilized by sperm from the pollen

21. Fruits help the seeds to spread by traveling through an animals digestive tract. • Angiosperms (vascular plants with flowers) are divided into 2 classes: monocot and dicot

23. Cotyledons– non-photosynthetic leaves of an immature plant; provide source ofnutrientsuntil plant can produce its own food

24. Water Conducting Tissue of Vascular Plants

25. Stems – cross sections through a dicot and a monocot showing the vascular bundles

26. Angiosperm: Stems: • Woody: stems composed of cells with thick cell walls - includes trees, bushes, vines. • Herbaceous: these are smooth non-woody stemmed plants - include dandelions, petunias, sunflowers

27. Angiosperm: Life span: • Annuals: plants that complete a life cycle within one year. Ex: zinnias, petunias, and marigolds. • Biennial: plants with a two-yearlife span. Typically they germinate and establish roots in the first year. Then flower and reproduce in the second. Ex: celery, parsley, and carrots. • Perennials: plants that usually live for many years. Some have stems that die back every winter, but grow back from the roots in the spring. Ex: all trees, peonies, honeysuckle, and most grasses.

28. Organ Systems in Plants • All plants have 3 main organ systems 1. Roots: absorbs water & dissolved nutrients, anchors plant to the ground, protectsthe plant from harmful bacteria/fungi in the soil

29. Organ Systems in Plants Shoot System: 2. Stems: connects roots to leaves, gives the plant support & strength and transports materialsthroughout the plant. 3. Leaves: structure responsible for photosynthesis in plants, also controls exchange of O2 and CO2 through tiny holes in the underside of leaves called stomata. Remember that plants need CO2to make glucoseglucose in photosynthesis and O2to break down the glucose during cellular respiration.

30. Organ Systems in Plants • Together these organs perform important functions for the plant including transport, protection, and coordination of plant activities.

31. Plant Tissue Types • Plants are composed of 3 types of tissue: dermal, vascular, & and ground tissue. • These 3 types of tissues combine in different arrangements to form roots, stems, and leaves.

32. Plant Tissues 1. Dermal Tissue: • The outer layer of the plant. You can think of it as the “skin” of the plant. • This layer of cells is also known as the epidermis. The epidermis excretes a waxy covering known as the cuticle, which helps prevent water from evaporating out of leaves. The cuticle does not cover the rootsbecause plants need to let water into root cells. • In roots the epidermis includes root hairs, and in leaves the dermis can also include the trichomes, special projections that protect the leaf and gives it a fuzzy appearance.

33. Plant Tissues 2. Vascular Tissue: • Vascular tissue forms a transport system made up of several specialized cells that transport water and nutrients throughout the plant. • (a) Xylem: transport system that carries waterand dissolved nutrientsupward from the roots to all parts of the plant.

34. Plant Tissues (b) Phloem: transport system that moves nutrients and carbohydrates(sap) made in photosynthesis throughout the plant. Plants store carbohydrates in areas called sugar sinks but then must transport them back to every cell forcell growth.

35. Plant Tissues 3. Ground Tissue: • The tissue that lays between the dermal and vascular tissue. Different types of ground tissue cells perform different functions. Some ground tissue cells are responsible for photosynthesis while others add strength to the plant.

36. Other Types of Plant Tissues Meristematic Tissue: • Unlike other plant tissues, meristematic tissue does not make up plant organs. Meristematic tissue is responsible for plant growth. It is the only plant tissue that can make new cells by mitosis.

37. Plant Tissues 2 types of meristematic tissue: • Apical meristem: located at the tips of stemsand roots. Apical meristem is responsible for lengtheningplants. It allows plants to grow taller and form deeper roots. The lengthening of plants is known as primary growth. • Lateral meristem: responsible for secondarygrowth, which thickens stems and roots. Lateral meristematic tissue surrounds vascular tissue.

38. Plant Tissues • Once the meristematic tissues form new cells, the cells have to mature into the differenttypes of cells that the plant needs. This process of cells maturing into different types is called differentiation.

39. Roots • Plant organ that extends underground to: - anchor the plant in place - absorb water and nutrients from the soil -protectsplant by preventing bacterial and fungal diseases from entering • 2 types of roots: • Taproot : the primary, thick and long root that other small roots may grow from. Oak trees have long taproots to help them reach water and prevent them from blowing over in the wind. Carrots and radishes store sugar in their taproots. A taproot is a common characteristic of dicots.

40. Roots - Fibrous Root: branching roots where there is no one large root. Found in grasses and other plants that prevent soil erosion. A fibrous root is a common characteristic of monocots.

41. The root has a water proof boundary called the Casparian stripwhich allows water and dissolved nutrients into the vascular cylinder but prevents if from seeping back out of the root. • The Casparian strip also prevents disease causing bacteria, viruses and fungi from entering the plant • This one-way movement of water causes root pressure which pushes water out of the root and up the stem

42. Nitrogen fixation– occurs in the roots and in the soil around the roots of plants; performed by bacteria

43. Stems • Three functions: (a) Produce leaves, branches andflowers (b) Holdleaves up to the light (c) Transportsubstances between the roots and leaves through the vascular system (xylem and phloem)

44. Stems • Monocot vs. dicot stems have their vascular tissue arranged differently • Monocot: scattered vascular bundles • Dicot: vascular bundles arranged in rings

45. Formation of Wood and Bark • The rings within the stem (trunk) of a tree cannot only tell you how old the tree is but it can also show years of drought and years with good growing conditions. Theringscan tell the tree’s life story. Formation of Wood • Most of what we call “wood” is actually layers of xylem • As a woody stem grows thicker, the older xylem near the center of the stem no longer conducts water and will become heartwoodto help support the tree • Heartwood is surrounded by sapwood which contains active xylem that transfers water and dissolved nutrients

46. Formation of Wood and Bark

47. Formation of Bark • Bark: all of the tissues outside the vascular cambium; includes phloem, cork cambium and cork • Vascular Cambium : a meristem that produces new xylem and phloem to increase stem width • Cork Cambium: a meristem that produces the protective layer of cork • Cork: contains phloem that no longer functions

48. Stems Parts of a stem: • Node: place where the leaves are attached and also an area where budsform which will produce new stems and leaves • Internodes: regions betweennodes

49. Leaves • Leaves are the primary structure for absorbing light & performing photosynthesis • Leaf Structure: • Blade: flattened part of leaf, designed to catch waves of light • Petiole: thin stalk thatattaches the leaf to the stem

50. Leaves • Leaves can be simple or compound which contain many leaflets.