Transport (plants) Pg25-27 Flashcards
why do organisms need transport systems
to transport things, organisms need substances such as: water, minerals and sugars and get rid of waste substances
why is unicellular organisms diffusion rates quicker
because the substances can diffuse directly into and out of the cell across the cell membrane
Why is diffusion rates in multicellular organisms slower and why do they need transport systems
direct diffusion from the outer surface would be slow because substances would have to travel large distances to reach every single cell. That is why multicellular organisms require transport systems to move substances to and from individual substances quickly
What are the 2 main transport systems in plants
Xylem and phloem
What does the xylem do
the xylem carries water and mineral ions from the roots up the shoots and to the leaves with the transpiration pull (one-way)
What does the phloem do
The phloem transports sugars, like sucrose and amino acids from where they are made in the leaves to other parts of the plant (goes both directions)
What is translocation
The movement of food substances around the plant
What do root hairs do
Takes in water by osmosis as higher water concentration in the soil than the plant so water is drawn into the root hair cell by osmosis
How are root hair cells adapted to take in water
they grow into long hairs which stick out into the soil. Each branch of a root will be covered in millions of these microscopic hairs. This gives the plant a high surface area for absorbing water from the soil
what is transpiration caused by
transpiration is caused by evaporation and diffusion of water from a plant’s surface
what are the 4 factors affecting transpiration
temperature, light intensity, wind speed, humidity
how does light intensity affect rate of transpiration
the brighter the light, the greater the transpiration rate. Stomata closes in the dark as they don’t need to let carbon dioxide in, when stomata are closed, very litte water can escape.
how does temperature affect rate of transpiration
The warmer it is, the faster the rate of transpiration. When it is warmer the water particles have more energy so they evaporate and diffuse out of the stomata
how does wind speed affect rate of transpiration
The higher the wind speed, the faster the rate of transpiration. When a wind speed is low, water vapour is left surrounding the outside of a leaf so there is no high concentration of water particles outside the leaf as well as inside it, so diffusion doesn’t happen as quickly. When wind speeds are high, water vapour is swept away, meaning there is a low water concentration gradient outside the leaf so diffusion happens quicker from an area of high concentration to a area of low concentration.
how does humidity affect rate of transpiration
the drier the air, the faster the rate of transpiration. If it is very humid, there is already water vapour outside the leaf so diffusion happens slower. But, if there is low humidity, diffusion increases as there is a lower concentration of water particles outside the leaf compared to higher concentration inside the leaf
