Plant Anatomy and Physiology

Roots, Shoots and Leaves

Roots - anchor the plant, absorb water/minerals, stores nutrients

Shoots - everything above ground (stems + leaves), support and transport

Leaves - Photosynthesis (light capture + gas exchange)

3 Major Tissue Types in Plants

Dermal - protective outer layer (like skin) (epidermis, root hair)

Vascular - Transport (xylem and phloem) (core of roots, in vascular bundles of stems/leaves)

Ground - photosynthesis, storage, and support (fill space between derm and vascular, endodermis, cortex,mesophyll)

Turgid Cells

full of water and are firm, important for structure and help the plant stand upright

• in guard cells, changes in turgor pressure open/close the stomata.

Transpiration and Negative Pressure

transpiration: water evaporates from the leaves through the stomata

• negative pressure as it pulls water up from the roots

• cohesion tension method

Properties of water helping transport

Cohesion: Water sticks to itself

Adhesion: water stick to xylem walls

Surface tension and hydrogen bonding help forms a continuous water column

Symplastic and Apoplastic

Symplastic: water moves through cytoplasm via plasmodesmata (Symplastic - straight through)

Apoplastic: water moves through the cell walls

Casparian Strip: blocks apoplastic pathway at endodermis → forces water into the symplast so it can be filtered before entering the vascular cylinder which is the stele

Xylem

transports water/minerals up, dead tissue at maturity, and thick walls/hollow tubes

Phloem

Transports sugars, living tissue at maturity, and has sieve tubes with companion cells

Guard Cells and Stomata

Guard cells open and close in response to stomata based on turgor pressure.

They open when the cell is turgid (water will enter), close when flaccid (water leaves) —> controls gas exchange and water loss

Four types of Major Meristems

Apical - Primary growth (growth in length), found at root/shoots → upward in shoots and downward in roots

• primary growth happens in all plants event the non-woody

Axillary - Branching (side shoots)

Vascular Cambium - adds secondary xylem(wood), and phloem (inner bark)

Cork Cambium - produces outer bark (protective covering)

Secondary Growth

adds thickness, especially in woody plants

Involves vascular and cork cambium

common in dicots and gymnosperms