3a.2 - Diffusion through Membranes, Active Transport and Water Flow through Plants Flashcards
Where does gas exchange happen?
The lungs
What is the job of the lungs?
To transfer oxygen to the blood and to remove waste carbon dioxide from it
How do the lungs exchange gas?
They contain millions of little air sacs called alveoli
How are alveoli specialised to maximise the diffusion of oxygen and carbon dioxide? (4)
- Have an enormous surface area
- Moist lining
- Thin walls
- Good blood supply
Where are villi found?
Small intestine
Why do the small intestines contain villi?
So digested food is absorbed much more quickly into the blood
How are villi specialised for absorbing in the small intestine? (2)
- Single layer of cells
- Good blood supply
What are root hair cells specialised for?
Absorbing water and minerals
How are root hair cells specialised for absorbing water and minerals?
- Big surface area
What process do plants do to absorb water and minerals?
Active transport
Why do plants need to use active transport to absorb water and minerals?
The concentration of minerals is usually higher in the root hair cell than the soil so normal diffusion doesn’t work
What is active transport?
Absorbing something that goes against the concentration gradient
Where does active transport happen? (3)
- Root hair cells - minerals
- Gut - glucose
- Kidney tubules - glucose
What does active transport need to make it work?
Energy from respiration
What do phloem tubes transport?
Food
What are phloem tubes made from?
Made of columns of living cells with small holes in the ends to allow stuff to flow through
Where to phloem tubes transport food to? (2)
- Growing regions
- Storage organs
Which direction does transport go in phloem tubes?
Both directions
What do xylem tubes transport?
Water and minerals
What are xylem tubes made of?
Dead cells with no end walls between them with a hole in the middle
What direction does transport go in xylem tubes?
Up
What is transpiration?
Loss of water from the plant
What is transpiration caused by?
Evaporation and diffusion of water from inside the leaves
What is the transpiration stream?
Through shortages of water on the leaves (because of transpiration), so more water is drawn up through the xylem from the roots to replace it
