bio - leaves

Parenchyma (mesophyll)

-Vascular tissues with a THIN cell wall
-In leaves

Mesophyll

Specialized ground tissue-bulk of leaves

Palisade Mesophyll

-Top layer
-Contains chloroplasts
-Absorbs light for photosynthesis
-Photosynthesis occurs

Adhesion

Different substances sticking to each other (water sticking to anything else)

Cohesion

Same substances sticking to each other (water sticking to water)

active transport

causes water to move from soil into roots

3 methods of active transport

-Root pressure
-capillary action
-transpiration

root pressure

causes mercury to rise in the manometer

capillary action

allows water to move up the xylem (uses cohesion and adhesion, provides osmotic and turgor pressures)

transpiration

pulls water upward

What happens in transpiration?

High transpiration rates lead to loss of turgor pressure and wilting. Water is lost, vacuoles shrink and cell walls bend inward.

Loss of osmotic pressure causes the guard cells to close which will slow down transpiration.

What are the 3 functions of a leaf?

1.Respiration
2.Photosynthesis
3.Transpiration

Respiration

is the interchange of gases (carbon dioxide and oxygen)

Photosynthesis

the process of creating sugar and oxygen from carbon dioxide, water and sunlight.

Transpiration

the process where water is released from the pores of a leaf

What does the structure of the leaf enable?

The structure of the leaf enables the leaf to absorb light and can carry out photosynthesis

Sclerenchyma

-Vascular tissue with a THICK cell wall
-In stem

Spongy Mesophyll

-Contain chloroplasts
-Photosynthesis can occur here
-Loose tissue with many air spaces between its cells

Stomata

-Openings in the underside of leaf
-Transpiration occurs
-Allow O2 and CO2 to diffuse into leaf
-Usually closed at night

Guard Cells

-Epidermal cells
-Controls the opening and closing of the stomata
-Responds to changes in water, wind, and temperature

Why must a plant have its stomata open at least part of the time?

-allow for gas exchange
-allow photosynthesis to occur
-conserve water during transpiration

Phloem

-Carries nutrients and sugars produced in the leaves
-Cells have end walls
-Two way flow

Xylem

-Carries water upward from the roots to the leaves
-Thick walls
-One way one
-No end walls
* only adhesion and cohesion take place in here

What is the role of the phloem?

Phloem carries out seasonal movement of sugars within a plant. Food can be pushed from the leaves into stems and roots for storage.