Adaptation for Gas Exchange

Question 1

What is gas exchange?

Answer 1

The diffusion of gases down a concentration gradient across a respiratory surface, between an organism and it’s environment

Question 2

Diffusion

Answer 2

Movement of molecules from a region of high concentration to a region of lower concentration until they are equally distributed (reach equilibrium)

Question 3

What gases are involved in gas exchange?

Answer 3

Oxygen
Carbon Dioxide

Question 4

Flatworm

Answer 4

• Aquatic, flat, larger surface area than spherical worms
• Large surface area to volume ratio - every part of body close to surface
• Short diffusion pathway

Question 5

Earthworm

Answer 5

-Terrestrial organism, cylindrical so m
smaller SA:VR than flatworms
- Skin is the respiratory surface - keeps moist by secreting mucus
- It has a low oxygen requirement because it’s slow moving + low metabolic rate
- Hemoglobin -blood caries oxygen around the body - maintains steep concentration gradient

Question 6

Amoeba

Answer 6

• Cell membrane is thin = rapid diffusion
• Single celled = short diffusion pathway + large SA:VR

Question 7

Amphibians

Answer 7

• Inactive amphibian uses its moist skin for gas exchange
• Skin is moist and permeable - well developed capillary network just below skin
• Active amphibians use simple lungs - surface is highly folded which increases SA

Question 8

Reptiles

Answer 8

-Skin is impermeable - they have lungs
- More complex folding in lungs than amphibians
- Ribs helps ventilation

Question 9

Birds

Answer 9

• Worm blooded - high respiration rate
• lungs processes large amount of oxygen - flight requires a lot of energy
• Ribs and wing muscles ventilates the lungs

Question 9

Birds

Answer 9

• Worm blooded - high respiration rate
• lungs processes large amount of oxygen - flight requires a lot of energy
• Ribs and wing muscles ventilates the lungs

Question 10

How do mammals ventilate their lungs?

Answer 10

Mammals ventilate their lungs by negative pressure breathing. For air to enter the lungs, the pressure inside the lung needs to be under atmospheric pressure

Question 11

Inspiration

Answer 11

Ribs and sternum raised
Diaphragm pulled down

Question 12

Expiration

Answer 12

Ribs and sternum fall
Diaphragm raised

Question 13

When inhaling

The external muscles …
Ribs move …
Diaphragm …
Thorax volume …

Answer 13

Contract
Upwards and Outwards
Contracts and flatten
Increase

Question 14

When exhaling

The external muscles …
Ribs move …
Diaphragm …
Thorax volume …

Answer 14

Relax
Downwards and inwards
Relax and dome upwards
Decrease

Question 15

When inhaling

Pressure in lungs …
Atmospheric air pressure…
Movement of air…

Answer 15

Reduce
Greater than pressure in lungs
Into lungs

Question 16

When exhaling

Pressure in lungs …
Atmospheric air pressure…
Movement of air…

Answer 16

Increase
Less than pressure in lungs
Out of lungs

Question 17

What is the gas exchange surface in mammals?

Answer 17

Alveoli

Question 18

Describe alveoli

Answer 18

Provide a large surface area relative to volume of the body
Moist for gasses to dissolve
Thin walls - squamous epithelium - short diffusion pathway
each alveolus covered by and extensive capillary network
Oxygenated blood is carried away from the alveolus and CO2 returns - maintains a steep concentration gradient

Question 19

What is Surfactant?

Answer 19

(anti sticking chemical) covers each surface of the alveoli
Its prevents the alveoli from collapsing
- Often given to premature babies to provent immature lungs from sticking together

Question 20

Gas exchange in the alveolus

Answer 20

1. Deoxygenized blood enters the capillaries surrounding the alveoli
2. Oxygen diffuses out of the air in the alveoli into the red blood cells in the capillary
3. CO2 diffuses out of blood plasma in the capillary into the alveolar air, from where it is exhales

Question 21

The 2 different types of fish

Answer 21

Cartilaginous fish - made of cartilage e.g sharks

Bony fish - got bones

Question 22

Where do boney fish live?

Answer 22

Fresh or sea water

Question 23

What is the flap covering the gills in bony fish called?

Answer 23

Operculum

Question 24

Ventilation in bony fish

Answer 24

To take water in 1. Mouth opens 2. Operculum closes 3. Floor of mouth is lowered 4. Volume inside mouth cavity increased 5. Pressure inside mouth cavity decreases 6. Water flows in (external pressure is greater than internal pressure)

Question 25

How to force water over gills in bony fish?

Answer 25

1. Mouth closes 2. Operculum opens 3. Floor of the mouth is raised 4. Volume inside mouth cavity decreased 5. Pressure inside mouth cavity increases 6. Water flows out over gills (internal pressure is greater than external pressure)

Question 26

What is each gill supported by?

Answer 26

gill arch/ gill bar

Question 27

What are the thin projections along each gill called?

Answer 27

gill filaments

Question 28

On the gill filaments are the gas exchange surface. What is the gas exchange surface called?

Answer 28

Gill lamellae/ gill plates

Question 29

Gill lamellae / Gill plates

Answer 29

They provide a large surface area for gas exchange (in water lamellae's are separated, out of water they stick together causing the gills to collapse

Question 30

What is the flow mechanism in bony fish called?

Answer 30

Counter current flow mechanism Blood from the gill capillaries flows in the opposite direction to water

Question 31

What is the flow mechanism in bony fish called?

Answer 31

Counter current flow mechanism Blood from the gill capillaries flows in the opposite direction to water

Question 32

Counter current flow

Answer 32

Water always has a higher concentration of oxygen than the blood. Oxygen will move from a higher concentration in water, into the blood by diffusion, down a concentration gradient. Blood will always come across water that has a higher oxygen concentration than it.

Question 33

Cartilaginous fish

Answer 33

less efficient than bony fish - they have to keep swimming for ventilation to happen

Question 34

Direction of blood flow and water in bony fish

Answer 34

Opposite - counter current flow

Question 35

Direction of blood flow and water in cartilaginous fish

Answer 35

Same direction - parallel flow

Question 36

Parallel flow

Answer 36

Oxygen diffuses from a higher concentration in water into blood untill the cons=centration of oxygen in blood (has reached equilibrium).

Question 37

Insects

Answer 37

Terrestrial To reduce water loss they have evolved rigid waterproof exoskeleton made of chitin which is covered by a waxy cuticle They have a small SA:Vol ratio so can't use diffusion for gas exchange

Question 38

What is the name of the holes that insects require for gas exchange

Answer 38

Spiracles - holes running along the side of the body

Question 39

Spiracles

Answer 39

They can open and close like valves which allows gas exchange to take place and they reduce water loss

Question 40

Spiracles lead into a system of ......

Answer 40

Branched, chitin lined air-tubes called tracheae, which branch into smaller tubes called tracheoles

Question 41

During periods of activity, such as flight what helps ventilate the tracheae?

Answer 41

Movement of the abdoment

Question 42

Explain gas exchange in insects

Answer 42

Gas exchange takes place at the end of the tracheoles. Oxygen dissolves into the fluid and diffuses directly into the cells so no respiratory pigment pr blood circulation is needed. CO2 diffuses out by the reverse prosses

Question 43

Gas exchange pathway in insects

Answer 43

ENTERS through the thorax spiracles When the abdomen is expanded the thorax spiracles are open and the abdominal spiracles are closed. As the abdomen is compressed the thorax spiracles close and the abdominal ones open Exits through the abdominal spiracles