gas exchange and transport in flowering plants Flashcards
The role of diffusion in gas exchange for plants
It allows gases such as oxygen and carbon dioxide for chemical reactions trough usually the stomata in the leaf.. It enters the leaf through diffusion
How is the structure of the leaf adapted to gas exchange
Flattened shape, Larger surface area to absorb light and carbon dioxide
Thin, Short diffusion distance for carbon dioxide to diffuse into leaf cells, and oxygen to diffuse out of leaf cells
Stomata, Can open to allow diffusion of carbon dioxide into the leaf from the atmosphere, and the diffusion of oxygen and water vapour out of the leaf
Internal air spaces in spongy mesophyll layer, Increases surface area of leaf to absorb more carbon dioxide
Guard cells around stomata, Allows the size of stomata to be adjusted (eg they close the stomata to prevent wilting)
The role of stomata in gas exchange.
It opens and closes to allow diffusion for carbon dioxide and oxygen to come in
What is the role of the phloem?
The phloem transports sucrose and amino acids (food) between the leaves and other parts of the plant.
It is a type of transport tissue in the plant
What is the role of the xylem?
The xylem transport water and mineral ions from the roots to other parts of the plant
It is a type of transport tissue in the plant
How is water absorbed by root hair cells
Plants absorb water from the soil by osmosis. Root hair cells are adapted for this by having a large surface area to speed up osmosis.
What is transpiration?
Transpiration explains how water moves up the plant against gravity in tubes made of dead xylem cells without the use of a pump.
Water on the surface of spongy and palisade cells (inside the leaf) evaporates and then diffuses out of the leaf. This is called transpiration. More water is drawn out of the xylem cells inside the leaf to replace what’s lost. As the xylem cells make a continuous tube from the leaf, down the stem to the roots, this acts like a drinking straw, producing a flow of water and dissolved minerals from roots to leaves.
What factors affect transpiration?
Light In bright light transpiration increases The stomata (openings in the leaf) open wider to allow more carbon dioxide into the leaf for photosynthesis
Temperature Transpiration is faster in higher temperatures Evaporation and diffusion are faster at higher temperatures
Wind Transpiration is faster in windy conditions Water vapour is removed quickly by air movement, speeding up diffusion of more water vapour out of the leaf
Humidity Transpiration is slower in humid conditions Diffusion of water vapour out of the leaf slows down if the leaf is already surrounded by moist air
