Transpiration and translocation Flashcards
How does water enter plant roots?
osmosis
How do mineral ions enter plant roots?
active transport
What is the function of the xylem?
Transport water and mineral ions from roots to leaves
What is the function of phloem?
transport sucrose around the plant
Why do xylem cells have lignin in them?
To strengthen the cell
Are xylem cells living or dead?
Dead
Are phloem cells living or dead?
Dead
Which type of transport takes place in the xylem?
transpiration
Which type of transport takes place in the phloem?
translocation
What are stomata?
Pores/holes in the underside of the leaf
Why does a plant need stomata?
For gas exchange
Which cells control opening and closing of stomata?
Guard cells
How do guard cells control opening and closing of stomata?
When there is lots of water, water enters guard cells by osmosis and causes them to become plump and turgid. This opens the stomata. When there is less water, water leaves the guard cells by osmosis causing them to become thin and flaccid, closing the stomata
Does transpiration need energy?
No
Does translocation need energy
yes
How do phloem cells get energy for translocation?
Companion cells next to the phloem provide the energy.
What is transpiration?
movement of water from the roots of a plant up to the leaves where it evaporates through stomata.
Which factors can increase transpiration?
High temperature, low humidity, high air movement, high light intensity
Why does increasing temperature increase transpiration?
More water molecules evaporate from the leaf through the stomata. Rate of diffusion is increased
Why does decreasing humidity increase transpiration?
Makes a greater concentration gradient between the leaf and the air so diffusion is faster
Why does increasing air movement increase transpiration?
Maintains concentration gradient between leaf and air, increasing rate of diffusion
Why does increasing light intensity increase transpiration?
Rate of photosynthesis increases and stomata open for gas exchange, causing water to diffuse out.
Which piece of equipment can measure rate of transpiration?
potometer
How does a potometer work?
Potometer measures how much water a plant takes up, therefore how much is lost through transpiration
