Topic 4 Biology Flashcards
Why must organisms be able to exchange substances in/out?
- To be able to receive oxygen for aerobic respiration and nutrients such as glucose and amino acids.
- Organisms must remove waste products such as urea and CO2.
What happens to the SA:V ratio as an organism increases in structure?
- Its volume increases faster than its surface area.
What happens to the amount of material the organism can exchange when the structure increases?
- The amount it needs to exchange increases by a lot but the amount it is able to exchange only increases by a little.
What are 3 characteristics of single-celled organisms?
1) Large SA:Volume ratio
2) Reliance heavily on the diffusion of substances in/out of the cell.
3) Diffusion is quicker as there is only a small distances the substances have to travel.
What are 3 characteristics of large-celled organisms?
1) Don’t rely on diffusion alone as SA:V ratio is too small.
2) Don’t exchange enough substances to supply the large volume of an organism through a large volume of organisms.
3) Distances are too large
What are the 3 main adaptations of organisms to deal with small SA:V ratio?
- Large SA
- Good blood supply maintains concentration gradient.
- Thin membrane for a small diffusion distance.
What is the gas exchange system in insects called?
- The tracheal system
How does gas exchange happens in insects?
- Air moves into the tracheae via spriracles which are openings on the surface of the insect.
- Oxygen diffuses down a concentration gradient, towards cells.
- Tracheae branch off into tracheoles, which have thin, permeable walls that border respiring cells.
- Oxygen diffuses from tracheoles directly to the respiring cells.
- Carbon dioxide diffuses from cells towards spiracles to be released into the atmosphere.
What are the adaptations of the tracheal system?
- Spiracles close to prevent water loss.
- Hairs trap humid air creating a low concentration gradient between the inside/outside of cells, reducing the process of osmosis.
- Air sacs around trachease provide an extra supply of oxygen.
Why do Fish need an efficient gas exchange system?
- There is a lower concentration of oxygen in the water and diffusion of oxygen and carbon dioxide is a lot slower in water than in the air.
What are the adaptations of fish?
1) Gill filament - Large surface area for gas exchange. Gill filaments contain lamellae which further increase the SA.
2) Short diffusion distance as the surface of lamellae only made of thin layers of cells.
3) Good blood supply: lamellae have lots of blood capillaries to maintain a favourbale concentration gradient.
What is the counter current mechanism?
- Blood and water move in opposite directions, allowing the diffusion gradient to be maintained across the entire length of the gill lamellae.
How does the flow of air happen in lungs?
1) As you breathe in, air enters the tracheae.
2) The tracheae splits into 2 bronchi.
3) Bronchi split into bronchioles.
4) This then leads to the alveoli.
5) The diaphgram, internal and external intercostal muscles work together to perform inspiration and expiration.
How does oxygen and carbon dioxide diffuse inwhen
