21.1 Plant Cells and Tissues TEKS 5B, 10B, 10C The student is expected to: 4B investigate and explain cellular processes, including homeostasis, energy conversions, transport of molecules, and synthesis of new molecules; 5B examine specialized cells, including roots, stems, and leaves of plants...; 10B describe the interactions that occur among systems that perform the functions of transport, reproduction, and response in plants; 10C analyze the levels of organization in biological systems and relate the levels to each other and to the whole system

21.1 Plant Cells and Tissues TEKS 5B, 10B, 10C KEY CONCEPT Plants have specialized cells and tissue systems.

21.1 Plant Cells and Tissues TEKS 5B, 10B, 10C Plant organs are made of three tissue systems. Dermal tissue covers the outside of a plant. –protects the plant –secretes cuticle of leaves –forms outer bark of trees

21.1 Plant Cells and Tissues TEKS 5B, 10B, 10C –provides support –stores materials in roots and stems –most commonly made of parenchyma Ground tissue is found inside a plant.

21.1 Plant Cells and Tissues TEKS 5B, 10B, 10C stem leaf root –two networks of hollow tubes –xylem transports water and minerals –phloem transports photosynthetic products Vascular tissue transports water, minerals and organic compounds.

21.1 Plant Cells and Tissues TEKS 5B, 10B, 10C Water and dissolved minerals 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

21.1 Plant Cells and Tissues TEKS 5B, 10B, 10C –Plants passively transport 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.

21.1 Plant Cells and Tissues TEKS 5B, 10B, 10C –absorption occurs at roots Water travels from roots to the top of trees. –cohesion and adhesion in xylem –transpiration at leaves

21.1 Plant Cells and Tissues TEKS 5B, 10B, 10C –water vapor exits leaf stomata –helps pull water to the top branches Transpiration is the loss of water vapor through leaves.

21.1 Plant Cells and Tissues TEKS 5B, 10B, 10C Phloem carries sugars from 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

21.1 Plant Cells and Tissues TEKS 5B, 10B, 10C –plants actively transport sugar from the source –sugar flows to the sink due to pressure differences sugars phloemxylem 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.

21.1 Plant Cells and Tissues TEKS 5B, 10B, 10C Most leaves share some similar structures. The blade is usually broad and flat. –collects sunlight for photosynthesis –connects to the stem by a petiole blade petiole

21.1 Plant Cells and Tissues TEKS 5B, 10B, 10C Mesophyll is between the leaf’s dermal tissue layers. cuticle upper epidermis palisade mesophyll spongy mesophyll lower epidermis

21.1 Plant Cells and Tissues TEKS 5B, 10B, 10C –Stomata open and 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 cellsstoma Guard cells surround each stoma.

21.1 Plant Cells and Tissues TEKS 5B, 10B, 10C Leaves may be simple, compound, or double compound. Simple leaf Compound leaf Double compound leaf

21.1 Plant Cells and Tissues TEKS 5B, 10B, 10C Leaf veins may be parallel or pinnate. Pinnate veins Parallel veins

21.1 Plant Cells and Tissues TEKS 5B, 10B, 10C Leaf margins may be toothed, entire, or lobed. Toothed marginEntire marginLobed margin

21.1 Plant Cells and Tissues TEKS 5B, 10B, 10C Most leaves are specialized 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

21.1 Plant Cells and Tissues TEKS 5B, 10B, 10C –for extreme temperatures, ex: pine needles Leaves have many adaptations.

21.1 Plant Cells and Tissues TEKS 5B, 10B, 10C Leaves have many adaptations. –for extreme temperatures, ex: pine needles –for water loss, ex: cactus spines

21.1 Plant Cells and Tissues TEKS 5B, 10B, 10C –for aquatic environments, ex: water lily Leaves have many adaptations. –for extreme temperatures, ex: pine needles –for water loss, ex: cactus spines

21.1 Plant Cells and Tissues TEKS 5B, 10B, 10C –for aquatic environments, 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

21.1 Plant Cells and Tissues TEKS 5B, 10B, 10C Roots anchor plants and absorb mineral nutrients from soil. Roots provide many functions. –support the plant –absorb, transport, and store nutrients –root hairs help absorption

21.1 Plant Cells and Tissues TEKS 5B, 10B, 10C root cap –root cap covers the tip There are several parts of a root.

21.1 Plant Cells and Tissues TEKS 5B, 10B, 10C apical meristem –root cap covers the tip There are several parts of a root. –apical meristem is an area of growth

21.1 Plant Cells and Tissues TEKS 5B, 10B, 10C –vascular cylinder contains xylem and phloem vascular cylinder –root cap covers the tip There are several parts of a root. –apical meristem is an area of growth

21.1 Plant Cells and Tissues TEKS 5B, 10B, 10C –Fibrous root systems have fine branches. Fibrous root Taproot There are two main types of roots. –Taproot systems have one main root.

21.1 Plant Cells and Tissues TEKS 5B, 10B, 10C 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

21.1 Plant Cells and Tissues TEKS 5B, 10B, 10C –grow underground for 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

21.1 Plant Cells and Tissues TEKS 5B, 10B, 10C –grow underground for 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 Straw berry stolon s

21.1 Plant Cells and Tissues TEKS 5B, 10B, 10C Some stems are herbaceous and conduct photosynthesis.

21.1 Plant Cells and Tissues TEKS 5B, 10B, 10C Some stems can be woody, and form protective bark.

21.1 Plant Cells and Tissues TEKS 5B, 10B, 10C Secondary growth increases a plant’s width. Primary growth increases a plant’s length.

21.1 Plant Cells and Tissues TEKS 5B, 10B, 10C Tree rings help determine the age of a tree. heartwood bands bark one year of growh sapwood