Transport and coordination in plants Flashcards
Why do plants require water?
- structure (turgid cells)
- transport medium
- chemical reactions
When is osmosis used in plants?
Used to uptake water
When is active transport used in plants?
When mineral ions are absorbed at the root hairs
What is glucose made for?
energy - growth + repair
What type of sugar is sucrose and what is it made from?
Disaccharide, made of glucose and fructose
Name of plants’ networks of tubes
Vascular bundles
Where is water absorbed?
At root hair cells
Is the xylem a one-way or two-way journey for water?
One-way
What is transported in the xylem?
Mineral ions and water ONLY
Where is sugar made?
In the leaf
Where is sugar stored?
In the roots (as starch) or the leaf
Where is water requires?
Leaf, palisade cells (for photosynthesis)
Xylem = water or sugar?
Water
Phloem = water or sugar?
Sugar
What is transported in the phloem?
Amino acids and sucrose ONLY
Where will the sugar solution be in the plant?
All over the plant
Is the phloem a one-way or two-way system?
Two-way
Why does the xylem have no cytoplasm or organelles and how does this help?
Because the cells are dead - no obstruction to flow of water
From where is the movement in the xylem?
From roots to shoot
How does the xylem form?
- end walls removed
- cells join to form long tubes
What are the walls of the xylem thickened with and why?
Lignin - waterproof + strong, stops cells collapsing inwards and gives stem support
What is special about the end of the cell in the phloem?
Acts like a sieve - allows contents to pass through cells
Does the phloem have a cytoplasm?
Yes - thin layer (cell needs to be kept alive to help transport)
Which vessel has companion cells: xylem or phloem?
Phloem
What do companion cells not transport?
Sugars
What do companion cells do?
Help with the life processes of the phloem
Where is the xylem located in the leaf and why?
near the surface - delivers water for photosynthesis
Where is the xylem located in the stem and why?
Towards the middle - helps provide support
Where is the xylem located in the root and why?
Close to the edge for quick transport
Where is the phloem located in the root and why?
Close to edge to allow for sugar storage as starch
What are nitrate ions needed for?
needed to make amino acids and proteins
What are magnesium ions needed for?
Needed to make chlorophyll
What is the benefit of having no end walls in the xylem?
Forms a continuos transport system
What are the cell walls in the phloem made from?
Cellulose
From where are substances transported in the phloem and where to?
From leaves to growing points/storage areas
How do root hairs reach the soil water?
Long thin outer projection penetrates between soil particles
Is the water absorbed pure?
No - has some solutes in it
What is the concentration of the solutes in the water compared the concentration of the root hair cells’ solutes?
Water solutes’ concentration is much lower
Why does water enter the cell by osmosis?
Soil water has a higher concentration of water molecules
What is the effect of osmosis?
- dilutes contents of the cell
- increases concentration of water molecules
Where does the water move to from the root hair cells?
Into the cortex of the root
Explain the concentration gradient that the water travels along
- travels down water concentration gradient
- from an area of more water molecules to an area of fewer water molecules
Does the water concentration gradient stay the same and why/
- gradient is maintained
- water is continually being taken up by xylem in middle of the root
What is the epidermis covered by and what is the effect of this?
Covered by waxy cuticle so is impermeable to water
What is transpiration?
The evaporation of water from the surface of a plant.
What does most water pass out of the stomata as?
Water vapour
What happens after water leaves the mesophyll cells?
Evaporates into air spaces between the spongy mesophyll
Where does the water vapour go and by what process?
Diffuses out through the stomatal pores
What is the result of the lack of water at the mesophyll cells?
Cells have lower concentration of water molecules
What is the result of a lower concentration of water molecules?
Draws water by osmosis from mesophyll cells
What supplies the leaf mesophyll tissues with water?
Xylem vessels
What does transpiration cause?
Causes water to be pulled up the xylem in the stem + roots in continuos flow (transpiration stream)
What is cohesion?
Ability of water to attach to other water molecules
What is adhesion?
Ability of water to stick to other tissues
What are the functions of the transpiration stream?
- carry mineral ions for synthesis of amino acids and chlorophyll
- keep turgor pressure high in leaves
- evaporation cools the leaves
- allows O2 and CO2 to diffuse freely
How does temperature affect the rate of transpiration?
- hot - energy of particles = high
- hot - rate of transpiration = fast
How does humidity affect the rate of transpiration?
- humid - rate of transpiration = slow
- humid - concentration gradient = low
How does wind speed affect the rate of transpiration?
- still air - transpiration slows down
- moving air - transpiration speeds up, concentration gradient high
What is the concentration of transpiration in general?
High to low
How do leaves make carbohydrates?
By photosynthesis
What do leaves use carbohydrates for?
To make amino acids, proteins and oils
What is the transport in the phloem called?
Translocation
Why is translocation an active process?
Energy is needed to make sap move through phloem tubes
What is phototropism?
Plant growth movement with light as the stimulus
What is geotropism?
Growth of parts of a plant in response to gravity
What are tropisms?
Plant growth movements and how they respond to certain stimuli
