Plants: Cells, tissue and organs

Plants: Transport system and nutrition

Outline1. Key concepts2. Cells

Chloroplasts, Cell walls, and Central Vacuole

3. Vegetative Tissues4. Vegetative Organs: Roots, Stems, Leaves5. Transport system and nutrition6. Conclusions

Key Concepts:

1. There are three major categories of tissue systems in these plants: ground, vascular, and dermal

2. Plants grow by way of mitotic cell divisions

3. Each growing season, shoots and roots lengthen and thicken

4. Water absorbed from soil moves on up through xylem and into leaves

5. By the energy-requiring process of translocation, sucrose and other organics are distributed in the plant

Vegetative Tissues1. Dermal tissue: A. Simple epidermis (a.

barrier b. reduce H2O loss) B. Specialized epidermal cells – guard cells in pairs, stoma (pl. stomata) for gas exchange and H2O vapor outC. Root hairs – absorption of H2O

2. Ground tissue: leaves – photosynthesisother plant part –store water, structural support, and store sugars in the form of starch

3. Vascular tissue: A. Xylem (Vessels and Tracheids) : conducts water and dissolved mineralsB. Phloem (Sieve tube elements, companion cells) conducts dissolved sugars from leaves

Xylem

Phloem

A Plant

Vegetative Organs1. Roots

a. Taproots vs. fibrous rootsb. Root functions-anchorage, absorption, storagec. Root tip structure: root cap, meristem, elongation zoon and maturation zoond. cross section at the zoon of maturation:epidermis, root hair, cortex (ground tissue), endodermis, vascular cylinder (pericycle, xylem and phloem)

Vegetative Organs2. Stems

a. Stem functions-support for leaves, conductionb. Tissues: epidermis, cortex, vascular bundles, pithc. Monocot versus dicot stem structured. Secondary growth of woody stems-xylem rings and seasons

Vegetative Organs3. Leaves

a. Leaf (Leaf components-blade and petiole) functions:

Photosynthesis, Gas exchange, Water transportb. Leaf structure

1) Epidermis-cuticle and stomata2) Mesophyll-palisade and spongy3) Vascular tissue-veins

Plant growth

a. primary growth = elongation of shoots & roots

b. secondary growth = thickening of structures

Root tip

Root tip

Root tip

Xylem and Phloem

Monocot stem

Dicot stem

Vascular bundles

Stem structure

Stem

Secondary growth

Year rings

Leaf structure

Leaf structure

A Maple leaf

The growth of plants

Transport system and nutrition1. Vascular system:

Xylem - conducts water and dissolved mineralsPhloem - conducts dissolved sugars

2. Water movementmore than 90% of water not used in metabolic

activitieswater needs:

a. replace water lost through stomatab. to transport mineralsc. to maintain turgord. metabolic activities

Transport system and nutrition2. Water movement

The lost of water through leaf is called transpirationTranspirational flow of water – water pulled onto surface of leaf from xylem by cohesion (water molecules stick to each other), tension (ability to pull column of water without breaking), and adhesion (water sticks to other things)

3. Movement of sugar – translocationfrom source to sinksource = source of photosynthesis products

(leaf & root)sink = site where sugars are moved to (roots, fruits, flowers, leaf buds)

Transpiration

Transpiration

In Conclusion

1. Plant growth originates at meristems

2. Stems function in support of upright growth and in conducting substances through the plant body by way of vascular bundles

3. Leaves contain veins and mesophyll between the upper and lower epidermis

4. Roots absorb water and ions for distribution to plant parts

In Conclusion5. Distribution of water and mineral ions occurs

through xylem

6. Plants lose water through transpiration: evaporation of water from leaves and other parts exposed to air

7. Plants distribute organic compounds through sieve tubes

8. The pressure flow theory states that translocation is driven by differences in solute concentration and pressure between source and sink regions

See you later