6.4: Gas exchange in the leaf of a plant Flashcards
Upper epidermis

The upper epidermis is a protection layer from any kind of damage

The upper epidermis is a protection layer from any kind of damage. What does the upper epidermis do?

The upper epidermis protects the internal tissues from:
- Mechanical damage
- Bacterial and fungal invasion

Cuticle

The cuticle is a waxy layer that prevents water loss from the leaf surface

What does the palisade mesophyll layer contain?
The palisade mesophyll layer contains many chloroplasts
The palisade mesophyll layer contains many chloroplasts.
Describe the palisade mesophyll cells
The palisade mesophyll cells are columnar cells that are closely packed together to absorb light more efficiently
What allows gases to move in and out of the leaf?
The spongy mesophyll layer allows gases to move:
- In
- Out of
the leaf
Spongy mesophyll layer
The spongy mesophyll layer is irregular cells loosely packed together to leave numerous large air spaces to allow rapid diffusion of gases throughout the leaf
Lower epidermis

The lower epidermis is the same as the upper epidermis, except the cuticle is thinner

The lower epidermis is the same as the upper epidermis, except the cuticle is thinner.
Why is the cuticle thinner?

The cuticle is thinner, because it’s on the bottom of the leaf

The lower epidermis is the same as the upper epidermis, except the cuticle is thinner.
The cuticle is thinner, because it’s on the bottom of the leaf and therefore it is what?

The cuticle is thinner, because it’s on the bottom of the leaf and therefore it is less exposed to the Sun

The lower epidermis is the same as the upper epidermis, except the cuticle is thinner.
The cuticle is thinner, because it’s on the bottom of the leaf and therefore it is less exposed to the Sun, so what?

The cuticle is thinner, because it’s on the bottom of the leaf and therefore it is less exposed to the Sun, so there will be less evaporation

Stomata
The stomata are an opening that allows gases to pass through it to go:
- Into
Or,
- Out of the leaf
The stomata are an opening that allows gases to pass through it to go into or out of the leaf.
What do stomata also do?
Stomata also let water out during respiration
The stomata are an opening that allows gases to pass through it to go into or out of the leaf.
Stomata also let water out during respiration.
What is this process called?
This process is called transpiration
What is the vascular bundle (vein) made up of?

The vascular bundle (vein) is made up of:
- Xylem
- Phloem

What is the function of xylem?

The function of xylem is to transport:
- Water
- Mineral salts
towards the leaf

What is the function of phloem?

The function of phloem is to transport organic substances away from the leaf

The function of phloem is to transport organic substances away from the leaf.
What does phloem generally transport?

Phloem generally transports sucrose

What do guard cells do?
Guard cells control the:
- Opening
- Closing
of the stomata
What do guard cells have?
Guard cells have a:
- Thin outer wall
- Thick, inelastic inner wall
Guard cells have a thin outer wall and a thick, inelastic inner wall.
What is the thick, inelastic inner wall fundamental for?
The thick, inelastic inner wall is fundamental for movement
When the guard cells are flaccid (lack of water), what are the stoma?
When the guard cells are flaccid (lack of water), the stoma are closed
When the guard cells are turgid (plenty of water), what are the stoma?
When the guard cells are turgid (plenty of water), the stoma are open
When the guard cells are turgid (plenty of water), the stoma are open, why?
When the guard cells are turgid (plenty of water), the stoma are open, because the inside thick, inelastic wall doesn’t open as much as it should