Plant Adaptations Flashcards
Adaptations of the root hair cell
(Eukaryote)
Long projections :
Root hair cells have long projections that increase the surface area that the plant can use to absorb water and minerals.
No chloroplasts :
These cells are located underground.This means that they do not contain chloroplasts (there is no light for photosynthesis).
Why are the adaptations of the Root hair cells vital for plant survival ?
Their structure allows the plant to absorb more water. They also allow a plant to take in the minerals it needs to survive.
Adaptations of the xylem vessel (dead / prokaryote)
Open ended cells :
Xylem vessels are made up of a series of connected dead xylem cells.The end walls of the dead cells are broken to allow water to move through.
Lignin : (a substance) strengthens the cell walls of xylem cells.
What is the function of the xylem vessel ?
The xylem is specialised to transport water up the stem of a plant and into the leaves.
Why are the xylem cells end walls broken ?
The end walls of the dead xylem cells are broken to allow water and dissolved minerals to move through.
Where is the stomata found ?
in the lower epidermis of leaves that facilitate (make easier) the diffusion of gases, including evaporated water, in and out of the leaf. Guard cells can open and close the stomata:
When does the stomata close to prevent water loss ?
AT NIGHT, stomata close because, in the absence of sunlight, carbon dioxide is not required for photosynthesis.At this time, their only objective is to prevent water loss.
When WATER IS SCARCE (rare), stomata close in order to prevent further water loss.This is achieved by guard cells returning to a limp state after they lose water.
Why is the state of the stomata important ?
The state of stomata (open or closed) achieves a balance between allowing gases for photosynthesis into the leaves, and conserving water in the plant
During transpiration, which way is water (and minerals dissolved in water) transported?
Water moves in one direction only: from the roots to the leaves.
How is water carried up the xylem ?
Once H2O reaches the leaves, the majority of water evaporates and the water vapour diffuses out (is lost) through open stomata, this results in a vacuum that pulls the water up the xylem to replace the lost water in the leaf.
How does air flow affect transpiration ?
Increased air flow carries water away from the plant’s leaves, encouraging more water to evaporate (replaces a high concentration gradient).
Increased air flow increases the rate of transpiration.
How does temperature affect transpiration ?
Increased temperature makes water evaporate faster, which increases the rate of transpiration - more energy for change of state.
How does light intensity affect transpiration ? (Look into this)
Increased light intensity makes water evaporate faster, which increases the rate of transpiration
How does humidity affect transpiration?
Increased humidity increases the amount of water in the air. This makes it more difficult for more water to evaporate (lower concentration gradient between leaves and air).
Increasing humidity decreases the rate of transpiration.
How to measure the rate of transpiration using a potometer.
As water is lost through the plant’s leaves, the air bubble moves, as water will transpire up the xylem to replacr lost water. The speed of the bubble’s movement shows the rate of water uptake.This is only an estimation (guess) as a small amount of the water taken up by the shoot is used in the leaves.
Why is measuring the rate of water transpiration using a potometer only an estimate ?
A small amount of the water taken up by the shoot is used in the leaves and is not transpired.
What is the use of the phloem ?
To move sucrose and amino acids (nutrients) up and down the plant, where they are needed.
Why are there small holes in the phloem ?
To allow allow sucrose and amino acids to move throughout the plant - soluble so small enoght to move between small holes.
Describe translocation
Translocation is the process by which nutrients (sucrose) produced in photosynthesis is transported from the leaves to the growing regions of plants and storage organs.
What is the structure of the phloem tubes like ?
Translocation happens through phloem tubes.
Phloem tubes are made up of columns of elongated cells that have holes in the end walls.
These holes allow cell sap (a liquid in plants that stores sugars, salts and amino acids) to pass between the cells.
What is unique of the movement of translocation to water transport?
Unlike water transport (transpiration), translocation is bidirectional (movement is both up and down the plant).
What is palisade mesophyll and where is it located ?
Palisade mesophyll is a row of cells located BELOW THE UPPER EPIDERMIS.
The cells are exposed to a lot of sunlight.
The cells have lots of chloroplasts (where photosynthesis takes place) to maximise the energy created by photosynthesis.
What is a feature of mesophyll that allows for gas exchange ? (Seperate from palisade mesophyll)
Spongy mesophyll contains many air spaces, which help with gas exchange throughout the leaf.
Where is epidermal tissue located ?
Epidermal tissue covers the outer surface of leaves (as well as the rest of the plant).
