gas exchange

Question 1

if you have a lung disease and it resduces the amount of air inhaled and exhaled, how does this affect the exchange of carbon dioxide in the blood and the aveoli?

Answer 1

• less carbon dioxide exhaled so more stays in the lungs
  -reduces diffusion concentration gradient of carbon dioxide moving out of the blood into the alveoli.

Question 2

Explain how the counter-current principle allows efficient oxygen uptake in the fish gas exchange system

Answer 2

1. Blood and water flow in opposite directions;
2. Diffusion/concentration gradient (maintained) along
   (length of) lamella/filament;

Question 3

Describe and explain the mechanism that causes lungs to fill with air.

Answer 3

Diaphragm (muscle) contracts and external intercostal muscles
contract;
2. (Causes volume increase and) pressure decrease;
3. Air moves down a pressure gradient

Question 4

• Haematoxylin solution stains DNA a blue colour.
• Iodine solution stains starch a blue-black colour.
  The scientist used haematoxylin solution and not iodine solution to stain
  the lung tissue.
  Suggest why.

Answer 4

no starch in lung
steins DNA in nucleus

Question 5

Use your knowledge of gas exchange in leaves to explain why plants
grown in soil with very little water grow only slowly

Answer 5

stomata close so less photosynthesis which produces glucose which is needed for proteins so plant grows.

Question 6

) Describe the pathway taken by an oxygen molecule from an alveolus to the blood.

Answer 6

(Across) alveolar epithelium;
/ epithelium of capillary;

Question 7

) Describe the gross structure of the human gas exchange system and how we breathe in and out.

Answer 7

Named structures – trachea, bronchi, bronchioles, alveoli;
Breathing in – diaphragm contracts and external intercostal muscles
contract;
(Causes) volume increase and pressure decrease in LUNGS/ THORAX
(to below atmospheric, resulting in air moving in);
Breathing out - Diaphragm relaxes and internal intercostal muscles
contract;
(Causes) volume decrease and pressure increase in LUNGS/THROAX

Question 8

Explain three ways in which an insect’s tracheal system is adapted for
efficient gas exchange.

Answer 8

tracheoles are branched- increasing surface area
tracheoles are thin- reduced diffusion pathways
body muscles contract to maintain concentration gradient

Question 9

Explain two ways in which the structure of fish gills is adapted for efficient gas exchange.

Answer 9

Many lamellae / filaments so large surface area;
Filament is Thin (surface) so short diffusion pathway;

Question 10

how do you work out percentage uncertainty?

Answer 10

• uncertainty divided by value.

Question 11

Explain how the counter current mechanism in fish gills ensures the
maximum amount of the oxygen passes into the blood flowing through the
gills.

Answer 11

Water and blood flow in opposite directions;
Blood always passing water with a higher oxygen concentration;
Diffusion gradient maintained throughout length of the lamellae