B5 Human Exchange Surfaces

Question 1

How do substances move through human exchange surfaces?

Answer 1

Diffusion, osmosis and active transport

Question 2

What is the job of the lungs?

Answer 2

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

Question 3

Where do the gas exchanges take place in the lungs?

Answer 3

Alveoli

Question 4

What are alveoli?

Answer 4

Millions of little air sacs in the lungs which is where the exchange of gases take place.

Question 5

What are the alveoli surrounded by?

Answer 5

A network of tiny blood vessels called capillaries

Question 6

What are capillaries?

Answer 6

Ta network of tiny blood cells that surround the alveoli

Question 7

Complete the sentence

……… diffuses from the air in the ………. into the blood in the ……….

Answer 7

Oxygen
Alveoli
Capillaries

Question 8

See p68 for diagram of how O2 and CO2 diffuse between alveoli and capillaries

Answer 8

.

Question 9

How does carbon dioxide diffuse?

Answer 9

From the blood in the capillaries to the air in the alveoli

Question 10

What are the alveoli specialised to maximise?

Answer 10

The rate of diffusion of O2 and CO2

Question 11

List the features of alveoli that make it specialised to increase the rate of diffusion 4

Answer 11

An enormous surface area (about 75 m2 in humans)

A moist lining for dissolving gases

Very thin walls (consisting of cells with partially permeable cell membranes)

A good blood supply

Question 12

How are dissolved food and water absorbed?

Answer 12

In the digestive system

Question 13

Where is dissolved food absorbed?

Answer 13

In the small intestine

Question 14

What are the millions and millions of tiny protections that cover the inside of the small intestine called?

Answer 14

Villi

Question 15

What do villi do?

Answer 15

Increase the surface area in a big way so that digested food is quickly absorbed into the blood by active transport and diffusion.

Question 16

Complete the sentence

When there’s a higher concentration of glucose in the intestine, it ……. naturally into the …….

Answer 16

Diffuses

Blood

Question 17

Complete the sentence

When there’s a lower concerns of glucose in the intestine, it is…………..into the blood.

Answer 17

Actively transported

This allows glucose to be taken into the blood, despite the fact that the concentration gradient is the wrong way.

Question 18

What do villi have to assist quick absorption?

Answer 18

A single layer of surface cells

A very good blood supply

Question 19

What do the surface cells do to assist quick absorption?

Answer 19

They have a partially permeable cell membrane (like all cells)

This regulates the movement of substances across them.

Question 20

How is water absorbed into the blood from the large intestine?

Answer 20

By osmosis

Question 21

Where does osmosis of water take place?

Answer 21

Large intestine

Question 22

Give one way in which alveoli are adapted for gas exchange (1 mark)

Answer 22

They have a large surface area

They have a moist lining for dissolving gases

They have very thin walls

(1 mark for any one)

They have a good blood supply