exchange

Question 1

Describe how a large difference in oxygen concentration is maintained between a fish gill and the surrounding

Answer 1

1. fish ventilation system which replaces water
2. highly oxygenated water
3. blood removes oxygen and so it has a low concentration of oxygen
4. blood is counter current to the flow of water over the gills
5. therefore a concentration gradient is maintained (across theg

Question 2

describe the adaptations of a mammalian LUNG which ensures a short diffusion pathway pathway for respiration

Answer 2

1. the aveloli are one cell thin. 1 epithelium thin
2. capillaries surrounding by single layer of cells and the capillaries and the aveoli are close
3. thin diffusion pathway between the aveloli and the capillaries so faster rate of diffusion

Question 3

a thin surface and a diffusion both feature of gas exchange surfaces

Describe how there are achieved at the gas exchange surfaces of a mammal

Answer 3

1. Ventilation maintains high oxygen and blood flow/circulation
2. there is a low oxygen concentration in blood due to cells using it for respiration
3. and so a concentration gradient is maintained

Question 4

explain how excess water from the gas exchange is prevented

Answer 4

a mammal

1. enclosed within body cavity/ limited contact with outside
2. the guard cells close stomata

Question 5

many of the mammals found in this part of Finland have a larger size and body mass than related species found in warmer regions

Explain the importance of their survival

Answer 5

The larger size means that they have more fat

fat is a good insulator of heat

large animals have a small surface area to volume ratio

so less heat is loss to the environment

Question 6

explain how diffusion results in the aveoli having a moist surface

Answer 6

2. aveolar epithelium is permeable to small molecules

water us a small molecule

Question 7

why is blood important in exchange

Answer 7

gas exchange surfaces are a long distance from the respiring cells

so blood allows transport for these substances

Question 8

in the lungs, oxygen gases form the aveloi to the blood

Describe and explain that features that make this process rapid efficient

Answer 8

1. large surface area for diffusion thin aveolar wall/ one cell thick
2. flattened cells in capillary wall
3. ventilation keeps oxygen concentration high in aveoli and circulation of the blood keeps oxygen concentration low
4. this maintains a concentration gradient/ a high concentration gradient

4.