Unit 3: 1 - Exchange of Materials

Question 1

What is osmosis?

Answer 1

The diffusion of water through a semi-permeable membrane, which moves from a high to a low concentration.

Question 2

What is osmosis?

Answer 2

The diffusion of water through a semi-permeable membrane, which moves from a high to a low concentration.

Question 3

Why does the cell membrane allow osmosis?

Answer 3

Because it is partially permeable.

Question 4

What is different about active transport compared to osmosis and diffusion? (3)

Answer 4

It requires energy released in respiration, it goes from a low to high concentration and requires a carrier protein.

Question 5

What is different about active transport compared to osmosis and diffusion? (3)

Answer 5

It requires energy released in respiration, it goes from a low to high concentration and requires a carrier protein.

Question 6

What does isotonic mean?

Answer 6

If the content of a drink matches the body fluids, the solution is called isotonic.

Question 7

What does isotonic mean?

Answer 7

If the content of a drink matches the body fluids, the solution is called isotonic.

Question 8

Large, complex organisms have special _______ to obtain all the food and oxygen they need.

Answer 8

Exchange surfaces

Question 9

What is the scientific term for soluble food materials?

Answer 9

Solutes.

Question 10

Give 3 features of efficient exchange surfaces.

Answer 10

Large surface area, thin walls or short diffusion path, and an efficient transport system (in humans, the blood supply).

Question 11

What 3 features of alveoli make them good for absorbing oxygen and releasing carbon dioxide?

Answer 11

Thin walls, a large surface area and a good blood supply.

Question 12

What 3 features of alveoli make them good for absorbing oxygen and releasing carbon dioxide?

Answer 12

Thin walls, a large surface area and a good blood supply.

Question 13

What are the blood vessels that oxygen diffuses to?

Answer 13

Capillaries.

Question 14

What are the blood vessels that oxygen diffuses to?

Answer 14

Capillaries.

Question 15

The lungs are situated in the …

Answer 15

Thorax.

Question 16

What muscle separates the lungs and the abdomen?

Answer 16

The diaphragm.

Question 17

Give the steps our muscles take when we breathe in.

Answer 17

When we breathe in…

• The intercostal muscles (between the ribs and diaphragm) contract;
• The ribcage moves up and out and the diagram flattens;
• The volume of the thorax increases;
• The pressure of the thorax decreases and air is drawn in.

Question 18

Give the steps our muscles take when we breathe out.

Answer 18

When we breathe out…

• The intercostal muscles (between the ribs) and the diaphragm relax;
• The ribcage moves down and in and the diaphragm becomes domed;
• The volume of the thorax decreases;
• The pressure of the thorax increases and air is forced out.

Question 19

The movement of air in and out of the lungs is known as…

Answer 19

Ventilation.

Question 20

Give the 3 main reasons why a person would have difficulties getting oxygen into the bloostream.

Answer 20

1. If the alveoli are damaged, the surface area for gas exchange is reduced;
2. If the tubes leading to the lungs are narrowed, less air can be moved through them;
3. If the person is paralysed, their muscles will not work to pull the ribcage up and out.

Question 21

What was the ‘iron lung’ used for? How did it work?

Answer 21

It was used for people with polio who were paralysed. It involved the person lying in a large metal cylider with their chest sealed. When air was drawn out of the cylinder, the vacuum created a negative pressure, causing the person’s chest moved out as they breathed in. When air was pumped back in, it created pressure on the person’s chest, forcing the air out of the lungs.

Question 22

How do breathing aids work?

Answer 22

Bags linked to masks force measured amounts of air down the trachea using positive pressure.

Question 23

Why are positive pressure aids more useful than traditional breahting aids, like the iron lung?

Answer 23

They are often smaller, easier to manage in the home, and they can be linked to computers for control.

Question 24

What are villi?

Answer 24

Finger-like projections which greatly increase the surface area of the intestine for absorption to take place.

Question 25

Discuss the features that make villi (and microvilli) suitable for their jobs. (3)

Answer 25

Question 26

How are substances absorbed from the intestine into the villi?

Answer 26

Using either diffusion or active transport.

Question 27

How do gases diffuse out of leaves?

Answer 27

Through the stomata.

Question 28

How do plants lose water vapour?

Answer 28

By evaporation in the leaves, which then leaves out of the stomata.

Question 29

How are leaves optimised to absorb CO₂ and release oxygen?

Answer 29

They are flat and very thin, so have a large surface area to volume ratio.

Question 30

How are roots optimised to absorb lots of water and mineral ions?

Answer 30

Root hair cells increase the surface area of roots for absorption of water and mineral ions.

Question 31

What happens to the stomata when a leaf is losing more water than is being replaced by the roots?

Answer 31

The stomata are closed by the guard cells to prevent wilting.

Question 32

What do we call the system that moves water through the plant?

Answer 32

The transpiration system.

Question 33

Give the weather conditions where evaporation is more rapid.

Answer 33

Hot, dry, windy and bright conditions.

Question 34

Why does wilting help prevent water loss?

Answer 34

The leaves collapse and hang down, which reduces the surface area.

Question 35

What is a potometer? Draw a diagram.

Answer 35

A tool used to show how the uptake of water by a plant changes with different conditions.