Plant Structure

Transport

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3) Vascular Tissues - transport water and food through the plant.

a. Phloem: straw-like tubes conducting food downward in a plant.

b. Xylem: straw-like tubes conducting water and minerals upward in a plant.

A. Roots1) Function

- Roots support and anchor the plant (Similar to Rhizoids)- Roots absorb water and minerals from the soil- Roots store glucose (starch)

– Root cell growth pattern: Division, elongation, and differentiation

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

b. Structure: Roots are made up of many tissues

• Dermal Tissue-covers the outside of a plant. – protects the plant –the root cap– Absorbs water from the soil-the root hairs• Ground Tissue-found inside-provides support

-stores materials in roots • Vascular Tissue-contains xylem and phloem

– Xylem transports water– -Phloem transports food and minerals

Types of roots- Taproot- Fibrous- Aboveground(epiphytes)

Fibrous root systems have fine branches. They are usually extensive and shallow.

Taproot systems have one main root.

Fibrous root

Taproot

Ex. Grasses Ex.carrots

EpiphytesPlants that are not rooted in soil but instead grow directly on the bodies of other plants. Most are found in tropical rainforest biomes and they are NOT parasitic.

OrchidSpanish Moss

B. Stems1) Function- stems support the plant- stems hold the leaves toward the sunlight- inside the stem water and nutrients travel to other plant parts- stems of some plants store glucose in the form of starch

Types of Tissues in Stems• Dermal Tissue- Outer bark of woody stems• Ground Tissue• Vascular tissue- xylem and phloem• Meristematic Tissue-contain both apical

and lateral meristematic tissue for growth

Annual RingsThe width of tree rings help determine the amount and conditions of growth.

. Tree rings help determine the age of a tree

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C. Leaf1) Function

- leaves capture light from the sun- leaves make glucose through photosynthesis- leaves take-in CO2 release oxygen O2

2) Structure- top layer is made of a waxy cuticle (prevents H2O loss) and epidermis(dermal layer)-middle layer is the mesophyll (ground tissue)contains most of the chloroplasts-bottom layer exchanges gases through the stomata

Stomata

Stomata visual concept: Guard cells

Guard Cells

Image of a Stomata

Plant AdaptationsAquatic plants To take in sufficient oxygen, aquatic plants, have tissues with large air-filled spaces through which oxygen can diffuse. Stomata located on top of leaf!

Desert plants Have extensive roots, reduced leaves, and thick stems that can store water.

Leaves are modified to reduce evaporative water loss and, often, to deter herbivores.

Transport in Plants

• KEY CONCEPT The vascular system allows for the transport of water, minerals, and sugars.

Water and dissolved minerals move through xylem.

U V W XUp / vascular tissue/water travels / in xylem

Water travels from roots to the top of trees.3 main ways

Transport of Water

• animation of water transport• -1- Absorption

• -2- Capillary action(cohesion-tension theory)

• -3- Transpiration

Capillary ActionThe cohesion-tension theory explains water movement

– Plants passively transport water through the xylem.

– Cohesion is the tendency of water molecules to bond with each other.

– Adhesion is the tendency of water molecules to bond with other substances.

Transpiration is the loss of water vapor through leaves.

– water vapor exits leaf stomata– helps pull water to the top branches

– Factors that affect transpiration:– Temperature

– -Wind

– -Humidity

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

• PH-F-Food

The Pressure-flow model explains sugar movement

2sugars

phloem xylem

water

1.Sugars move from their source, such as photosynthesizing leaves, into the phloem.

2.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 phloem3. The sugars move into the sink, such as root or fruit, where the are stored.