Module 3

Question 1

How do microorganisms obtain nutrients and remove waste

Answer 1

By exchange via their surface
Nutrients ( eg glucose , oxygen ) move in by diffusion via their surface
Waste ( eg co2 ) move out by diffusion via their surface

Question 2

Why are microorganisms able to perform exchange via their surface

Answer 2

Have a large surface area to volume ration
Have a short diffusion pathway/ distance
Have a low demand

Question 3

Why can’t animals and plants perform exchange via their surface

Answer 3

Have a small surface area to vol ratio
Multicellular ( large diffusion distance )
Impermeable surface ( Prevents pathogens entering and reduces water lost)
Therefore require specialised exchange and transport systems

Question 4

Exchange system

Answer 4

Increases rate of diffusion of nutrients in and wastes out

Question 5

Transport system

Answer 5

Deliver nutrients and remove waste from all cells

Question 6

Why do fish have specialised gas exchange

Answer 6

Multicellular organism

So cannot perform gas exchange via their surface , so they have gills

Question 7

Structure of gills in fish

Answer 7

Many gill filaments and gill lamellae= large SA
Gill lamellae have a thin wall and are permeable
Ventilation brings in pure water ( high o2 ) and circulation brings in deoxygenated blood , the water and blood pass over in opposite directions ( countercurrent flow )
Which maintains conc grad all the way along the gill lamellea

Question 8

Structure of tracheal system in insects

Answer 8

Starts with openings on body surface called spiricles
Spircles contain valves, open = gas exchange , closed= prevent water loss
Spircles connect to trachea
Trachea connects to tracheoles
Tracheoles connect directly to respiring cells ( delivering o2 and removing co2)

Question 9

How does gas exchange occur in tracheal system of insects

Answer 9

At rest = down a conc grad , o2 moves in and co2 moves out by simple diffusion
When active = by ventilation , air inhaled for mass flow of o2 in and air exhaled for mass flow of co2 out

Question 10

Function of lungs

Answer 10

Site of gas exchange in mammals

Question 11

What are lungs made up of

Answer 11

Trachea , bronchi, bronchioles , alveoli ( + capillaries )

Question 12

Structure of trachea / bronchi

Answer 12

Wall made of c shaped cartilage to give flexibility
Cartilage is strong so trachea / bronchi do not Collapse
Lining made of goblet cells and ciliates epithelial cells

Question 13

Goblet cells

Answer 13

Make mucus, which traps pathogen / particles

Question 14

Ciliates epithelial cells

Answer 14

Have Celia which pushes mucus up and out of lungs

Question 15

Structure of bronchioles

Answer 15

Walls made of smooth muscle which contacts , lumen narrows , bronchioles constrict
Lining made of goblet cells and ciliated epithelial cells

Question 16

Adaptation of alveoli

Answer 16

Millions of tiny alveoli that are folded ( large SA).
Thin wall/one cell thick/ squamous epithelial cells ( shirt diffusion )
Elastic tissue in wall ( stretches when breathing in to increase SA. , recoils when breathing out to push the air out )
Be ventilation maintains conc grad ( high o2, low co2 )

Question 17

Adaption of capillaries

Answer 17

Millions of tiny capillaries ( large SA )
Thin wall
Narrow lumen ( increases diffusion time , deceases diffusion distance )
Circulation maintains conc grad ( low o2 and high co2 )