Exchanging Substances Part 1- Gas Exchange

Question 1

What is breathing

Answer 1

Movement of air into and out of the lungs

Question 2

What is respiration

Answer 2

Chemical reaction to release energy in the form of ATP

Question 3

What does the rate of diffusion depend upon

Answer 3

Sa x conc. difference / diffusion distance

Question 4

What substances do organsims need to exchange with their environment

Answer 4

Oxygen, co2
Glucose, amino acids, minerals, vitamins
Urea, ammonia
Heat

Question 5

What are the key features of an effective exchange surface

Answer 5

High sa;v ratio
Short diffusion distance
Ability to maintain concentration gradient
Circulatory system

Question 6

Describe gas exchange in single-cell organisms

Answer 6

Large sa;v ratio
Oxygen is absorbed by diffusion over the cell surface membrane
CO2 diffuses in opposite directions

Question 7

Gas exchange in insects
How do they reduce water loss

Answer 7

Waterproof coating over their body - their exoskeleton is covered
Small sa;v ratio - area in which water is lost is reduced

Question 8

Gas exchange in insects
Desicbe how air enters

Answer 8

Air enters through pores in their outer surface of their abdomen called spiracles
They open and close by valve
When they open water vapour evaporates

Question 9

Gas exchange in insects
How does gas move in and out of the tracheal system

Answer 9

When oxygen is used- the concentration towards the en dot the tracheoles falls
This creates a diffusion gradient that diffuses into cell

CO2 is produced creating a diffusion gradient in the opposite direction
- this causes co2 to diffusion along the tracheoles and tracheae into the atmosphere

Contraction of muscle squeezes the trachea enabling mass movement of gas

Question 10

Gas exchange in insects
Why are the end of the tracheoles filled with water

Answer 10

During activity, muscle cells anaerobically respire and produce lactate
Lactate is soluble and reduces the water potential of the muscle cells
Water moves into the cells by osmosis and more air is drawn in

Question 11

What are the adaptations of gas exchange in insects

Answer 11

Tracheoles have thin walls- short diffusion distance
Highly branched - short diffusion distance e
Tracheae provides tubes full of air - fast diffusion
Fluid in the end

Question 12

What are the features of gills

Answer 12

4 gills on either side of their head
Each gill is separated by a gill slit
Gill rakes protect the gills from food entry
Gills are covered with an operculum

Question 13

What are gills good for for gas exchange

Answer 13

Provid enlarge sa
Gill filaments - series of flat projection at right angles to filaments called lamellae

Vast capillary network - good blood supply
Good vascular supply - short diffusion distance, conc. gradient maintained

Permeable membrane - gases to diffuse

Question 14

Describe the counter current exchange in fish

Answer 14

Water an dblood flow in opposite directions
Diffusion/ conc. gradient maintained along length of filament/ lamellae

Prevents equilibrium being reached
Blood always passing water with higher o2 concentration

Question 15

How are different plants adapted for efficient gas exchange

Answer 15

Thicker leafs - lower sa;v - prevent loss of water
Thicker waxy cuticle
Sunken stomata - traps most air next to leaf - reduces water potential radiant
(+ spines, hairs)
Deep roots, shallow lots

Question 16

What is ventilation

Answer 16

Air is constantly being moved in and out of the mounts

Question 17

What is inspiration (inhalation)

Answer 17

When the air pressure of the atmosphere is greater than the air pressure inside lungs
Active

Question 18

What is expiration (exhalation )

Answer 18

Air pressure in lungs is greater than that of the atmosphere

Question 19

What happens during inhalation

Answer 19

Diaphragm contracts and flattens
Ribcage moves up and out
Internal intercostal muscle contracts

Increases volume in thorax
Resulting is lowering ai rpressure (atmospheric pressure in high than thorax
Reduced pressure causes air to flow into our lungs

Question 20

What happens during exhalation

Answer 20

Diaphragm relaxes, forms a dome shape
Ribcage moves down and in
Internal intercostal muscles contract
External intercostal muscles relax

Volum eof thorax decreases (pressure in thorax is higher than atmosphere)
Increases lung air pressure
Forcing air out of lungs

Question 21

Describe and explain one feature of the alveolar epithelium that makes the epithelium well adapted as a surface for gas exchange. Do not refer to surface area or moisture in your answer.

Answer 21

Flattens cells - reduces diffusion distance

Permeable - allow diffusion for o2/co2

Question 22

Describe and explain the mechanism that causes lungs to fill with air

Answer 22

Diaphragm contracts
External intercostal muscles contact

Pressure decreases
Air moves down pressure gradient
Air enters from higher atmospheric pressure

Question 23

The adult damselfly uses a tracheal system for gas exchange.
Explain three ways in which an insect’s tracheal system is adapted for efficient gas exchange.

Answer 23

Tracheoles have thin walls so short diffusion distance to cells;

Highly branched / large number of tracheoles so short diffusion distance to cells;
Highly branched / large number of tracheoles so large surface area (for gas exchange):

Trachee provide tubes full of air so fast diffusion (into insect tissues):

Fluid in the end of the tracheoles that moves out (into tissues) during exercise so faster diffusion through the air to the gas exchange surface;
OR
Fluid in the end of the tracheoles that moves out (into tissues) during exercise so larger surface area (for gas exchange);
Body can be moved (by muscles) to move air so maintains diffusion / concentration gradient for oxygen / carbon dioxide;