Plants Flashcards
What happens when xylem cells mature?
They add lignin to their walls
What happens to the xylem cell when it lignifies?
- they die
- it makes the cells waterproof
- it makes the cells stronger and able to withstand water pressure
Where are xylem and phloem located in leaves?
The phloem is on the lower surface
The xylem is on the upper surface
Where are xylem and phloem located in roots?
The vascular bundles are in the center of the root, xylem on the inside, phloem on the outside
Where are xylem and phloem located in stems?
The vascular bundles are arranged in a circle around the center. the xylem is in the middle and the phloem is on the edge.
What is the top layer of a leaf?
Waxy cuticle
What is the third-to-top layer of a leaf?
Palisade mesophyll
What is the third-to-bottom layer of a leaf?
spongy mesophyll+air space+ vascular bundle
What is the third-to-top layer of a leaf?
palisade mesophyll
What is the second-to-bottom layer of a leaf?
lower epidermis
What is the bottom layer of a leaf?
cuticle
Which layer of a leaf has the most chloroplasts?
Palisade mesophyll
What type of growth does the apical meristem cause and where is it found?
Primary growth (lengthening), found in tips of roots and shoot, makes new plants and leaves
What type of growth does the cateral meristem cause and where is it found?
Secondary growth (widening), found in cambium, produces bark on trees
What is the purpose of the flower?
reproduction
What is the purpose of the root?
anchorage, absorption, storage
What is the purpose of the stem?
support, vessels for transport
What is the purpose of the leaf?
photosynthesis
the roots, stem and leaves form…
a plant organ structure that transports substances around plants
What is the purpose of the waxy cuticle?
Stops water loss by evaporation,
What is the purpose of the upper epidermis?
Transparent, lets light through
protection for palisade mesophyll
What is the purpose of the palisade mesophyll?
Photosynthesis, has lots of choroplasts. Regular shape so maximum photosynthesis. nearer to top to increase sunlight
What is the purpose of the spongy mesophyll?
irregular shaped cells to increase surface area for gas exchange, many air spaces in between. some photosynthesis
What is the purpose of the air space?
stores CO2 and lets it move towards the palisade cells for photosynthesis
What is the purpose of the guard cells?
Prevents transpiration at night by closing to decrease water loss. Found in pairs
What is the name of the gap between the guard cells?
Stomata
How does light affect transpiration?
In bright light, transpiration increases because the stomata open wider to allow in more carbon dioxide for photosynthesis
How does wind affect transpiration?
The transpiration rate is higher in windy conditions because water vapour is removed faster , speeding up the rate of diffusion as it means a steep concentration gradient can be maintained
How does temperature affect transpiration?
Transpiration rate is higher in high temperatures because evaporation and diffusion are higher in higher temperatures as the water molecules have more kinetic energy
How does humidity affect transpiration?
The transpiration rate is lower in high humidity as diffusion of water from the leaf slows down when there is already more water outside the leaf (shallow concentration gradient)
What are the special adaptions of guard cells?
The inner wall is thicker, so the cell can curve and make a hole
How do the stomata open?
1) potassium ions move into the guard cell
2) this makes the cell more concentrated than surrounding tissue
3) water moves into the guard cells via osmosis
4) the cell swells unevenly because the thicker inner wall is less flexible than the outer wall
Why is water pulled up the transpiration stream?
Because water is very cohesive because of hydrogen bonding
What does the reservoir in a potometer do?
Resets the experiment
What do you use to measure the rate of transpiration?
A potometer
Are there more stomata on the upper or lower surface of the plant?
lower
What shape does the lignin grow in?
a spiral
What is transpiration?
The evaporation of water from the leaves
