Gas exchange adaptations

Question 1

Factors that contribute of gas exchange

Answer 1

Large SA to volume ratio
Moist surface (gases can dissolve in it)
Distance pathway
Large concentration gradient
Permeable to o2 and co2

Question 2

Why do large active animals with high metabolic rates need a ventilating system?

Answer 2

To maintain gradients across respiratory surfaces

Question 3

Describe adaptations of Amoeba for gas exchange and method of delivery of o2

Answer 3

Single celled organism (very small), so less o2 demand
Large SA to vol. ratio
Simple diffusion

Question 4

Describe adaptations of a flatworm for gas exchange and method of delivery of o2

Answer 4

Dorso-ventrally flattened organism (thin and flat) for shorter diffusion distance
Simple diffusion

Question 5

Describe adaptations of a earthworm for gas exchange and method of delivery of o2

Answer 5

Elongated and round
Has haemoglobin and circulatory system to carry o2 by diffusion across skin
Outer skin is moist and thin

Question 6

Gas exchange surface features for amphibians

Answer 6

Moist skin for larger respiratory surface when inactive, lungs when active

Question 7

Gas exchange surface features for reptiles

Answer 7

Pair of lungs and no diaphragm

Question 7

Draw out and label the structure of the lungs

Answer 7

Larynx, trachea, bronchi, bronchioles alveoli, pleural membranes, pleural cavity, ribs, external and internal intercostal muscles, diaphragm

Question 8

Gas exchange surface features for birds

Answer 8

Counter-current exchange that helps birds handle energy demands for flying
Air sacs which act as bellow

Question 8

Advantage of internalised lungs

Answer 8

Minimises heat and water loss

Question 9

Function of elastic fibres

Answer 9

To stretch when inhaling and recoil when breathing out

Question 9

Explain the process of inspiration

Answer 9

External intercostal muscles contract, ribcage goes up and outwards (volume increases) therefore pressure down
Diaphragm contracts, goes from doomed to flattened shape
Air enters, travelling down conc gradient

Question 9

What are the rings of cartilage around the trachea, bronchi and alveoli used for?

Answer 9

So during inspiration, the tubes wouldn’t collapse

Question 9

Why are the rings of cartilage “c” shaped?

Answer 9

So that the oesophagus can expand during digestion

Question 9

Cells/ structures and function in human gas exchange system?

Answer 9

Goblet cells (make mucus)
Ciliated epithelial cells (Cilia wafts mucus + dust)
Cartilage (support)
Elastic fibres (stretch in inhalation and recoil in exhalation)
Smooth muscle (adjust size of airway, relax in exercise to let air in)

Question 10

Describe process of expiration, forced and relaxed

Answer 10

External intercostal muscles relax, ribcage falls down
Diaphragm relaxes, volume decreases so pressure increases, and goes back to domed shape
Elastic fibres recoil
Air is forced out
In forced, internal intercostal muscles contract and abdominal muscles contracts pushing the diaphragm upwards

Question 10

5 ways alveoli are efficient at gas exchange

Answer 10

-Provide large SA
-Moist, gasses diffuse faster)
-Maintain conc grad (blood has low conc on o2 etc)
-Thin, short diff pathway
-Permeable to o2 and co2

Question 11

Function of surfactant in lungs? (similar to water for gill filaments)

Answer 11

Reduces surface tension of water molecules to stop lungs from collapsing

Question 12

Explain respiration system in insects

Answer 12

-Thorax spiracles open, abdomen expands, increase vol decrease pressure, o2 in through valves
-Travels through thin trachea tubes, with cuticular thickenings for support, linked to air sacs
-Travels to tracheoles that are moist and thin and enter tissues
-CO2 goes through same tubes (disadvantage)
-Abdomen contracts, vol down pressure up, air flows out through abdomen spiracles

Question 13

How do insects reduce water loss?

Answer 13

By spiracles closing

Question 14

What is the purpose of air sacs in insects?

Answer 14

Storage of o2 when spiracles closed

Question 15

Explain ventilation in fish

Answer 15

-Mouth cav lowered (vol up press down)
-Water in buccal cav
-Floor of mouth cav raised (vol down press up)
-Water pushed out and flows across the gills, gill cover opens

Question 16

Explain the structure of gills and functions of parts

Answer 16

-Gill arch, support
-Gill filament, lots for large SA
-Gill rakes, filter water and trap prey

Question 17

Explain counter-current flow and its advantages

Answer 17

The water flows over the lamellae (gill plate) in an opposite direction to the blood in the capillaries in the lamellae so that blood always has a low conc of oxygen then water and diffusion grad is maintained across the whole lamellae

Question 18

Explain parallel flow

Answer 18

-Blood in lamellae flows in the same direction then the water -This means that only 50% of the oxygen will be absorbed as the diffusion grad isn't maintained -This is less efficient then counter current flow

Question 19

Explain why fish with gills have to be in water

Answer 19

The moistness of gill filaments makes them spread apart, out of water they would stick together because of the cohesion of water mole.

Question 20

Difference between bony and cartilaginous fish

Answer 20

Bony: -More active -Larger -Have gills and counter current system Cartilaginous: -Smaller -Have gill clefts -Have parallel flow