Topic 6- Transport in plants and transpiration Flashcards
How do the microscopic hairs on a root help it absorb water?
It gives the plant a large surface area so it can absorb more minerals (by active transport- the concentration of mineral ions is higher in the hair cell than it the soil) and water by osmosis.
What substances do the phloem tubes transport?
They transport food substances (mostly sucrose)
Identify 1 feature of the structure of the phloem tubes
They have end walls with small pores to allow substances to flow through
What process do the phloem tubes use to transport substances?
Translocation. This requires energy and goes in both directions.
What substances do the xylem tubes transport and in which direction?
Water and mineral ions up
Identify the stages of how water moves through the plant
Root hair cells - cells in the root - xylem - leaf
What is transpiration?
The loss of water from the plant
What is transpiration caused by?
Evaporation and diffusion
Explain how water moves through a plant in the transpiration stream
Water is lost from the plants leaves by evaporation and diffusion. This creates a slight shortage in the leaves so more water is absorbed to replace it.
The water is cohesive, so as water evaporates from the leaf, it creates a pull motion and pulls water up the xylem. This along with the tension between the water and the walls of the xylem, helps the water travel up the tube. This is cycle is continuous.
What are stomata and where are they found?
Tiny pores on the surface of a plant that are mostly found on the lower surface of the leaf
What do stomata do?
They allow carbon dioxide and oxygen to diffuse in and out of the leaf as well as water vapour (transpiration).
What role do stomata play in transpiration?
Transpiration is a side affect. Leaves must have stomata for gas exchange but because there’s more water inside the plant than outside, water escapes by diffusion
How do guard cells control the size of the stomata?
The change shape. When guard cells are turgid (swollen with water) the stomata are open and when they are flaccid (low on water, limp) the stomata are closed.
How is the transpiration rate affected by light intensity?
The brighter the light, the greater the transpiration rate. Stomata begin to close as it gets darker. Photosynthesis cant happen in the dark so they don’t need to open for carbon dioxide, therefore little water can escape.
How is the transpiration rate affected by temperature?
The warmer it is, the faster transpiration is because the water particles have more energy to evaporate and diffuse out of the stomata.
