plant cell organisation

How does the level of water in the plant affect the opening and closing of stomata?

• each stomata is formed from gap between 2 guard cells.

• When plant has lots of water (so some to spare) the guard cell becomes turgid making gap larger so more CO2 can diffuse through

• when plant is short of water the plant cell will lose water through osmosis and guard cell will become flaccid and the gap for co2 to diffuse through will become smaller/closed to conserve water

they are also sensitive to light so close at night and at lower surface it’s more shaded and cooler so less water evaporates

Why does the spongy mesophyll layer have so many air gaps?

So gas can diffuse through to next layer

Is a guard cell, spongy mesophyll , leaf an organ system, organ, tissue, or cell?

guard cell- cell

Spongy mesophyll - tissue

Leaf-organ

Why is the upper epidermis transparent?

Because sunlight needs to pass through to get to chloroplast in palisade cells

What is the function of leaves and what does it require

Function- photosynthesis

Requires- a lot of carbon dioxide and water to make sugars .

Water come from soil and is transported to leaves from roots and xylem

Carbon dioxide diffuses directly into leaf from outside air through stomata.

Which structures help to minimise water loss?

Leaf has waxy cuticle which is a thin waterproof layer of lipids

Leaf also have guard cells which can close to prevent water from escaping

Where is meristem tissuefound?

Found at growing tips of roots and shoots and can differentiate into different types of cells

What is meristem tissue?

Plant tissue composed of actively dividing, unspecialized cells that are responsible for plant growth, repair, and adaptation

What does xylem and phloem do

Phloem - carries sugar to plant and amino acids from the leaves to other parts of the plant

Xylem- continuously brings water from the roots for the palisade cell to use in photosynthesis

What is the main problem that leaves face

Water loss

Where in plant can water be lost

Top - waxy cuticle

Bottom-stomata

What’s the function of palisade mesophyll

Where photosynthesis occurs palisade cells are full of chloroplasts

What is epidermal tissue covered with

A waxy cuticle which helps reduce water loss by evaporation

Structure of leaf