Gas Exchange In Plants Flashcards
What is a chloroplast
Part of the plant cell that is used for photosynthesis
What is chlorophyll
A green compound that absorbs light
What is an epidermis
Thin layer of cells (top + bottom)
What does the phloem do
Transport sugars around the plant
What does the xylem do
Transports water + mineral ions around the plant
What is respiration
A process which uses glucose to make energy
What are stomata
Minute pores which open to allow co2 to diffuse into the leaf
What is the function of the vein
To transport xylem and phloem and support the leaf
Which cell contains chloroplasts
Palisade cell
Which part of the plant contains chloroplasts
Chlorophyll
Where are the xylem and the phloem cells contained
Veins
What is transpiration
The process by which water vapour is lost from leaves
There are lots of stomata on the _________ surface of the lower epidermis. Why?
Upper surface because otherwise they lose water
____________ triggers the movement of minerals into the guard cells. This makes water move into the guard cells by __________. As water moves in, the guard cells become swollen or ‘________’ and the cell bends because the inner cell wall is thicker making the stomata _______
Sunlight
Osmosis
Turgid
Open
In the dark, water _________ the guard cells and they become ____________ making the stomata ____________
Leaves
Flaccid
Close
What is transpiration
The loss of water by evaporation through the stomata.
It is a side-effect of the way leaves are adapted for photosynthesis
Either side of the stomata are 2 banana-shaped _________ cells
Guard cells
The part of the cell wall nearest to the stoma is __________ than the cell wall elsewhere in the cell. As the guard cell becomes more turgid, this uneven thickness of cell wall causes the cell to bend outwards which opens the _________
Thicker
Stomata
In the light, water ________ the guard cells by osmosis from the surrounding epidermis cells
Enters
In the light, the guard cells use energy to accumulate solutes in their _________ which causes water to be drawn into them by osmosis
Vacuoles
Name the equipment that can be used to measure the rate of transpiration
Potometer
Transpiration is the evaporation of _______ from leaves. It escapes through tiny pores called __________
Water
Stomata
How does light affect the rate of transpiration and why
It increases because the stomata open wider to allow more carbon dioxide into the leaf for photosynthesis
How does high temperature affect the rate of transpiration and why
It is faster in higher temperatures because evaporation and diffusion are faster at higher temperatures
How does wind affect the rate of transpiration and why
It is faster in windy conditions because water vapour is removed quickly, so more water vapour diffuses out of the leaf
What will happen to the rate of transpiration if it is humid
It is slower because diffusion of water vapour out of the leaf slows down if the leaf is already surrounded by moist air
Why is transpiration important
- It supplies water for the leaf cells to carry out photosynthesis
- Carries mineral ions dissolved in water
- Provides water to keep the plant cells turgid
- Allows evaporation form the leaf surface which cools the leaf, in a similar way that sweat cools the human skin
Inside a plant, water moves from cell to cell by __________
Osmosis
The long thin outer projection of the _____ ______ cells penetrates between the soil water particles, reaching the soil water. The soil water has a a higher potential than the inside of the cell which allows water to enter the cell by ___________
Root hair cells
Osmosis
Water leaves the cells of the leaf mesophyll and evaporates into the air spaces between the _________ _____________ cells
Spongy mesophyll cells
Why is it important that root hair cells have a large surface area
It means that more mineral ions can be diffused into it - efficient absorption
What does the term partially permeable mean
Will allow certain solutes (e.g water) through
Suggest a reason for the large numbers of mitochondria present in cells involved in active transport
Make energy for respiration
_____________ are not found in all plant cells. For example, they are not found in root hair cells
Chloroplasts
What colour does hydrogen-carbonate indicator if there are high levels of Co2
Yellow
What colour does hydrogen-carbonate indicator if there are low levels of Co2
Purple
What colour does hydrogen-carbonate indicator if there are normal levels of Co2
Red
Word equation for photosynthesis
Carbon dioxide + Water –> Glucose + Oxygen
Symbol equation for photosynthesis
6CO2 + 6H2O –> C6H12O6 + 6O2
How are leaves adapted for photosynthesis (3)
Large surface area
Chloroplasts on palisade layer
Upper epidermis is transparent
Thin for gas exchange
What is a limiting factor
Something which stops photosynthesis from happening any faster
Palisade mesophyll layer
These have the most chloroplasts - where most photosynthesis takes place
Spongy mesophyll layer
Cells with big air spaces around them for gas exchange
Waxy cuticle
A transparent, waterproof layer that lets light through.
Water runs off it.
It also acts as a barrier to the entry of disease causing microorganisms
Upper epidermis
Like the cuticle
Single, transparent, layer of cells with no chloroplasts - allows sunlight through to the epidermis where there are chloroplasts
Vascular bundle
Transport vessels of xylem and phloem
Lower epidermis
Has lots of tiny holes called stomata which allow gases to diffuse in and out
Guard cell
A pair of curved cells that surround a stoma
How are leaves adapted for efficient gas exchange
Broad leaves
Thin leaves
Air spaces inside leaf
Stomata on lower surface for gas exchange
What will a plant do if there is a lack of water from the roots
Stop photosynthesising (bad) But if they didn't, the plant might dry out and die (worse)
