Download to read offline
Lecture 2 Plant Structure and Function.pdf
- 1. PLANT STRUCTURE andFUNCTION
- 2. KEY CONCEPT Plants havespecialized cells and tissue systems.
- 3. Plant tissues aremade of three basic cell types. • Parenchyma cells are the most common plant cell type. – store starch, oils and water – help heal wounds to the plant – have thin flexible walls
- 4. – they arestrong and flexible. – celery strings are strands of collenchyma. – they have unevenly thick cell walls. • Collenchyma cells provide support to a growing plant.
- 5. – second cellwall hardened by lignin – die when they reach maturity – used by humans to make linen and rope • Sclerenchyma cells are the strongest plant cell type.
- 6. Plant organs aremade of three tissue systems. • Dermal tissue covers the outside of a plant. – protects the plant – secretes cuticle of leaves – forms outer bark of trees
- 7. – provides support –stores materials in roots and stems – most commonly made of parenchyma • Ground tissue is found inside a plant.
- 8. stem leaf root – two networksof hollow tubes – xylem transports water and minerals – phloem transports photosynthetic products • Vascular tissue transports water, minerals and organic compounds.
- 9. KEY CONCEPT The vascularsystem allows for the transport of water, minerals, and sugars.
- 10. Water and dissolvedminerals move through xylem. • Xylem contains specialized cells. – vessel elements are short and wide – tracheid cells are long and narrow – xylem cells die at maturity vessel element tracheid
- 11. – Plants passivelytransport water through the xylem. – Cohesion is the tendency of water molecules to bond with each other. • The cohesion-tension theory explains water movement. – Adhesion is the tendency of water molecules to bond with other substances.
- 12. – absorption occursat roots • Water travels from roots to the top of trees. – cohesion and adhesion in xylem – transpiration at leaves
- 13. – water vaporexits leaf stomata – helps pull water to the top branches • Transpiration is the loss of water vapor through leaves.
- 14. Phloem carries sugarsfrom photosynthesis throughout the plant. • Phloem contains specialized cells. – sieve tube elements have holes at ends – companion cells help sieve tube elements – unlike xylem, phloem tissue is alive
- 15. – plants activelytransport sugar from the source – sugar flows to the sink due to pressure differences sugars phloem xylem water Sugars move from their source, such as photosynthesizing leaves, into the phloem. 1 The sugars move into the sink, such as root or fruit, where the are stored. 3 Water moves from the xylem into the phloem by osmosis, due to the higher concentration of the sugars in the phloem. The water flow helps move sugars through the phloem. 2 • The Pressure-flow model explains sugar movement.
- 16. KEY CONCEPT Roots andstems form the support system of vascular plants.
- 17. Roots anchor plantsand absorb mineral nutrients from soil. • Roots provide many functions. – support the plant – absorb, transport, and store nutrients – root hairs help absorption
- 18. root cap – rootcap covers the tip • There are several parts of a root.
- 19. apical meristem – rootcap covers the tip • There are several parts of a root. – apical meristem is an area of growth
- 20. – vascular cylindercontains xylem and phloem vascular cylinder – root cap covers the tip • There are several parts of a root. – apical meristem is an area of growth
- 21. – Fibrous rootsystems have fine branches. Fibrous root Taproot • There are two main types of roots. – Taproot systems have one main root.
- 23. Roots – monocots versusdicots. Monocot Dicot
- 24. Stems support plants,transport materials, and provide storage. • Stems have many functions. – support leaves and flowers – house most of the vascular system – store water Baobab trees Cactus
- 25. – grow undergroundfor storage Ginger rhizomes Potato tubers Stems support plants, transport materials, and provide storage. • Stems have many functions. – support leaves and flowers – house most of the vascular system – store water
- 26. – grow undergroundfor storage Stems support plants, transport materials, and provide storage. • Stems have many functions. – support leaves and flowers – house most of the vascular system – store water – form new plants Strawberry stolons
- 27. • Some stemsare herbaceous and conduct photosynthesis.
- 28. • Some stemscan be woody, and form protective bark.
- 29. • Secondary growthincreases a plant’s width. • Primary growth increases a plant’s length.
- 30. • Tree ringshelp determine the age of a tree. heartwood bands bark one year of growth sapwood
- 31.
- 32. KEY CONCEPT Leaves absorblight and carry out photosynthesis.
- 33. Most leaves sharesome similar structures. • The blade is usually broad and flat. – collects sunlight for photosynthesis – connects to the stem by a petiole blade petiole
- 34. • Mesophyll isbetween the leaf’s dermal tissue layers. cuticle upper epidermis palisade mesophyll spongy mesophyll lower epidermis
- 35. – Stomata openand close when guard cells change shape. – When stomata are open, water evaporates and gas exchanges. – Stomata close at night and when plant loses too much water. guard cells stoma • Guard cells surround each stoma.
- 36. • Leaves maybe simple, compound, or double compound. Simple leaf Compound leaf Double compound leaf
- 37. • Leaf veinsmay be parallel or pinnate. Pinnate veins Parallel veins
- 38. • Leaf marginsmay be toothed, entire, or lobed. Toothed margin Entire margin Lobed margin
- 39. Most leaves arespecialized systems for photosynthesis. • There are two types of mesophyll cells. – both types contain chloroplasts – palisade mesophyll absorbs sunlight – spongy mesophyll connects to stomata xylem phloem cuticle upper epidermis palisade mesophyll spongy mesophyll stomata lower epidermis
- 40. – for extremetemperatures, ex: pine needles • Leaves have many adaptations.
- 41. • Leaves havemany adaptations. – for extreme temperatures, ex: pine needles – for water loss, ex: cactus spines
- 42. – for aquaticenvironments, ex: water lily • Leaves have many adaptations. – for extreme temperatures, ex: pine needles – for water loss, ex: cactus spines
- 43. – for aquaticenvironments, ex: water lily – for getting food, ex: Venus’ flytrap • Leaves have many adaptations. – for extreme temperatures, ex: pine needles – for water loss, ex: cactus spines
- 44.
- 45.