Exchanging substances

Question 1

What’s the job of the lungs?

Answer 1

To transfer oxygen to the blood and to remove waste carbon dioxide from it

Question 2

Where does gas exchange take place in the lungs?

Answer 2

Alveoli

Question 3

How are alveoli specialised to maximise the diffusion of oxygen and carbon dioxide ?They have:

Answer 3

1.An enormous surface area
2. A moist lining for dissolving gases
3. Very thin walls
4. A good blood supply

Question 4

Where is villi found?

Answer 4

Inside the small intestine

Question 5

What do villi do ?

Answer 5

They increase the surface area so hat digested food is absorbed much more quickly into the blood

Question 6

How are they adapted to absorb food quickly into the blood? They have:

Answer 6

1. A single layer of surface cells
2. A very good blood supply to assist quick absorbtion

Question 7

How is the leaf’s structure adapted to difffusion?

Answer 7

1. Underneath the leaf is an sxchange surface. Its covered with little holes called stomata which carbon dioxide diffuses on through
2. Stomata are controlled by guard cells. These close the stkmata if the plant is losing water faster than it is being replaced by the roots (without them the plant will wilt)
3. The flattened shape of the leaf increase the area of this exchange so that its more effective
4. The walls of the cells . The air spaces inside the leaf increase the area of this surface so there’s more chance for carbon dioxide to get into the cells.

Question 8

How are gills adapted for gas exchange?

Answer 8

1. Each gill is made of lots of thin plates called gill filaments, which give a big surface area for exchabge of gases
2. Gill is covered in tiny structures called lamellae, which increase the surface area even more
   2.5. The lamellae have lots of blood capillaries to speed up diffusion. They also have a thin surface layer of cells to minimise the distance that the gases have to diffuse
3. Blood flows through the lamellae in one direction and water flows over in the opposite direction. This maintains a large concentration gradient between the water and the blood
4. The concentration od oxygen in the water is always higer than that in the blood, so as much oxygen as possible diffuses from the water into the blood.