gas exchange

Question 1

insect adaptions for gas exchange)

Answer 1

1) fluid in ends of trachea where it joins tissues- gas exchange from from air to liquid allows gases to diffuse to tissues faster
2) muscles can pump body to force air in and out - maintains concentration gradient for gases
4) tracheoles are highly branched
- increases surface area for gas exchange
5) Short distance between tracheoles + muscle fibres
- shortens diffusion distance of gases to cells

Question 2

insect adaptations to prevent water loss

Answer 2

1) insects have a small SA:V ratio - where water can evaporate from
2) insects have a waterproof exoskeleton ( bc it is made of chitin)
3) spiracles can open and close to reduce water loss

Question 3

what are the three methods of moving gases in the tracheal system

Answer 3

1) diffusion - cell respiration establishes a conc gradient from tracheoles to the atmosphere
2) mass transport - insect contracts and relaxes their abdominal muscles to move gases on mass
3)- in flight, cells respire anaerobically to produce lactate.
- this lowers water potential therefore water moves from tracheoles into cells by osmosis
- this decreases the volume in tracheoles so air from atmosphere is drawn in

Question 4

explain the process of fish ventilation

Answer 4

1) mouth opens, operculum shuts
2) water enters cavity due to decreased pressure/increased volume
3) mouth closes, operculum opens
4) results in decreased volume so increased pressure
5) increased pressure forces water out over gills

Question 5

fish adaptations for gas exchange

Answer 5

1) thin epithelium/walls of lamellae
- shortens diffusion distance of gases from water to blood
2) large number of filaments and lamellae
- increases surface area for gas exchange
3) countercurrent flow system where blood and water flow in opposite directions
- maintains concentration gradient was water always next to blood with lower concentration of oxygen
4) large number of capillaries around lamellae
- circulation constantly removes oxygenated blood to maintain steep concentration gradient
5) ventilation by operculum
- ensure constant fresh water flows over gills to replace lost oxygen and maintain steep concentration gradient

Question 6

What is countercurrent flow

Answer 6

When water flows over the gills in the opposite direction to the flow of blood in capillaries
- ensures that equilibrium is not reached
- ensures diffusion gradient is maintained across the entire length of lamellae

Question 7

what is tricks law (rate of diffusion calculation)

Answer 7

diffusion = surface area x difference in concentration/ length of diffusion path

Question 8

outline the inhalation breathing mechanism

Answer 8

• external intercostal contract, internal intercostal muscles relax
• ribcage moves upwards and outwards, diaphragm contracts and flattens
• volume of thorax increases
• pressure in the lungs decreases
• so air rushes into lungs

Question 9

what is pulmonary ventilation

Answer 9

total volume of air that is moved into the lungs during one minute