Gas Exchange Flashcards
Describe and explain 2 feature of the alveolar epithelium that makes it well adapted for gas exchange (4)
Flattened cells- reduces diffusion distance
Permeable- allows diffusion of oxygen
Tidal volume is the volume of air inhaled and exhaled during a single breath when a person is resting. Tidal volume is reduced in a person with emphysema
Suggest and explain how a reduced tidal volume affects the exchange of CO2 between blood and alveoli (3)
- Less CO2 exhaled
- So reduced diffusion gradient between blood and alveoli
- Less movement of CO2 out the blood
Explain how the counter current principles allows oxygen uptake in the fish gas exchange system (2)
- blood and water flow in opposite directions
- diffusion gradient maintained along length of lamella
Describe and explain the mechanism that causes the lungs to fill with air (3)
- Diaphragm contracts and external intercostal muscles contract
- Causes volume increase and pressure decrease
- Air moves down a pressure gradient
Haemotoxylin stains DNA blue
Iodine solution stains starch blue-black
A scientist used haemotoxylin solution and not iodine solution to stain the lung tissue, suggest why (2)
- Lung tissue does not contain starch
- Makes nucleus visible
Higher concentration of particulate matter results in death of some alveolar epithelium cells, if they die they are replaced by non-specialised, thick tissue
Explain why death of alveolar epithelium cells reduces gas exchange in the human lungs (3)
- Reduced surface area
- Increased distance for diffusion
- Reduced rate of gas exchange
Describe and explain the advantage of the counter current principle in has exchange across a fish gill (3)
-Water and blood flow in opposite directions
-Maintains diffusion gradient of oxygen
-Diffusion along length of lamellae
Explain why plants grown in soil with little water grow only slowly (2)
Stomata close
Less CO2 uptake for less photosynthesis
Describe the pathway taken by an oxygen molecule from an alveolus to the blood (2)
- Across alveolar epithelium
- Across endothelium of capillary
Explain how 1 feature of an alveolus allows efficient gas exchange to occur (2)
- alveolar epithelium is one cell thick
- creates a short diffusion pathway
describe the gross structure of the human gas exchange system and how we breathe in and out (6)
- and 2. trachea, bronchi, bronchioles, alveoli (correct order)
- breathing in- diaphragm contracts and external intercostal muscles contract
- volume increase and pressure decrease in thoracic cavity below atmospheric, air moves in
- breathing out- diaphragm relaxes and internal intercostal muscle contract
- volume decrease and pressure increase in thoracic cavity above atmospheric, air moves out
explain three ways in which an insects tracheal system id adapted for gas exchange (3)
tracheoles have thin walls so short diffusion distance to cells
large number of tracheoles so short diffusion distance to cells
large number of tracheoles so large surface area for gas exchange
damselfly larva actively hunt prey, has gills to obtain oxygen from water.
Explain how the presence of gills adapts the damselfly to its way of life (2)
-damselfly larvae has high metabolic rate
- so uses more oxygen per unit time
explain 2 ways in which the structure of a fish is adapted for efficient gas exchange (2)
-many lamellae so large surface area
-thin surface so short diffusion pathway
Describe how the structure of the insect gas exchange system:
* provides cells with sufficient oxygen
* limits water loss.
Explain your answers (5)
- Spiracles, tracheae, tracheoles;
- Spiracles allow diffusion (of oxygen)
- Tracheoles are highly branched so large
surface area (for exchange);
4. Tracheole (walls) thin so short diffusion
distance (to cells)
- Tracheole permeable to oxygen/air;
- Cuticle/chitin/exoskeleton (impermeable) so
reduce water loss; - Spiracles (can) close so no/less water loss
- Hairs around spiracles reduce water loss;
