B3 - Exchange of materials

Question 1

What is osmosis

Answer 1

The diffusion of water through a partially permeable membrane. From a high concentration of water to a low. So from a dilute to concentrated solution

Question 2

What’s active transport

Answer 2

Cells use active transport to absorb substances over a concentration gradient. Usually by using energy from respiration

Question 3

Give an example of active transport

Answer 3

Glucose reabsorbed by active transport in the kidney tubes

Question 4

Why is glucose used during exercise

Answer 4

Glucose is used for respiration and when you exercise your muscles respire to release energy

Question 5

What is lost from the body when you exercise

Answer 5

Ions, water through sweat and sugars through respiration

Question 6

What’s an isotonic sports drink and it’s function

Answer 6

A drink that contains water and ions to rehydrate cells after exercise. Isotonic means the concentration of the drink matches the concentration of the body fluids.

Question 7

Are isotonic drinks the best option

Answer 7

Not always, water works just as well

Question 8

What is an exchange surface

Answer 8

Surfaces in the body that absorb the food and oxygen needed

Question 9

How would an exchange path be efficient

Answer 9

Large surface area
Thin walls
Short diffusion pathway

Question 10

What exchange happens in the lungs

Answer 10

Gaseous exchange, surface area is increased by the alveoli

Question 11

What are alveoli and how are they well adapted

Answer 11

Air sacs in the lungs that help to ventilate the air and absorb required substances. They have thin walls, a large surface area and a good blood supply

Question 12

Describe the gaseous exchange that goes on in the alveoli

Answer 12

Oxygen diffuses into the surrounding capillaries and carbon dioxide diffuses back into the lungs to be breathed out

Question 13

Describe the movement of breathing in

Answer 13

Lungs - Move up and out
Volume - Increases
Diaphragm - Flattens
Pressure - Decreases, so the outside air is forced in

Question 14

Describe the movement of breathing out

Answer 14

Lung - Move in and down
Volume - Decreases
Diaphragm - Arches
Pressure - Increases, so the air is forced out

Question 15

Give 2 ways a person might not be able to get enough oxygen into their bloodstream

Answer 15

Paralysed so the muscles are unable to contract and move the ribcage

Alveoli are damaged, surface area for gas exchange is reduced

Question 16

What are villi

Answer 16

Line the inside of the small intestine and exchange the material from the digestive system to the blood

Question 17

Explain how villi are adapted to increase efficiency

Answer 17

Large surface area and thin walls. Many capillaries and can absorb via active transport or diffusion

Question 18

Describe the structure of a leaf cell

Answer 18

Waxy cuticle - waterproof layer to stop water loss
Upper epidermis
Palisade
Mesophyll
Lower epidermis
Stomata - with guard cells that control water loss

Question 19

Describe the exchange in a plant

Answer 19

Gases diffuse from the stomata at the bottom of the leaf, and the size is controlled by the size of the guard cells.

Oxygen needed for respiration and waste from photosynthesis, vice versa with carbon dioxide

Water vapour is also diffused from the stomata

Question 20

What is the transpiration stream

Answer 20

The movement of water through a plant

Starting at the root where the water is taken by the root until it is wasted through evaporation from the stomata

Question 21

What increases the rate of evaporation and what could this mean for the plant

Answer 21

Hot, dry, windy or bright conditions

Plant could dehydrate if more water is lost than is taken in