Gas Exchange

Question 1

aHow is gas exchanged in smaller organisms?

Answer 1

They have a large SA:Vol
Short diffusion pathway
Gases can directly diffuse across their membranes

Question 2

What are the adaptations of fish to increase gas exchange?

Answer 2

1) A large surface area- gills are covered in many filaments covered in many lamellae
2) Short diffusion pathway- thin epithelium of capillaries and thin walls of lamellae
3) Concentration gradient- continuous flow of blood replaces deoxygenated blood + countercurrent mechanism

Question 3

What is the countercurrent mechanism?

Answer 3

Water flows over the gills in the opposite direction of the continuous flow of blood
Equilibrium is not reached = higher concentration of oxygen in water than in the blood
Diffusion gradient is maintained over the ENTIRE gill = constant diffusion

Question 4

What are antagonistic muscles?

Answer 4

Pair of muscles that work opposite to each other

Question 5

What happens during inspiration?

Answer 5

Inhale
External intercostal muscles contract
Internal intercostal muscles relax
Ribcage moves up and out = diaphragm is pulled down
Increases volume = decreases pressure
Air moves from a higher pressure outside to a lower pressure inside down a pressure gradient

Question 6

What happens during expiration?

Answer 6

Exhale
External intercostal muscles relax
Internal intercostal muscles contract
Ribcage moves down and in = diaphragm relaxes
Decreases volume = increases pressure
Air moves from a higher pressure inside to a lower pressure outside down a pressure gradient

Question 7

How is the alveolar epithelium adapted for gas exchange?

Answer 7

Large surface area- millions of alveoli to increase surface area
Short diffusion pathway- walls alveoli epithelium cells and blood capillaries are one cell thick
Concentration gradient- continuous flow of blood network of capillaries

Question 8

Define tidal volume

Answer 8

The volume of air breathed in and out of the lungs at a normal breathing rate

Question 9

Define ventilation rate

Answer 9

The number of breaths in and out in a minute

Question 10

Formula of pulmonary ventilation

Answer 10

PV = TV x VR
dm3min-1 = dm3 x min-1

Question 11

Why do humans need gas exchange?

Answer 11

Produce ATP to release energy for respiration
Remove CO2 to prevent pH of blood decreasing

Question 12

What is the exoskeleton of an insect made up of?

Answer 12

Chitin

Question 13

How do insects prevent water loss from their bodies?

Answer 13

Outermost layer is waxy and waterproof

Question 14

Gas exchange in insects

Answer 14

Tracheoles are the site of gas exchange
O2 diffuses into the cell whilst CO2 diffuses out
Spiracles > trachea > tracheoles > cells

Question 15

How is the gas exchange system in insects adapted?

Answer 15

Large surface area- Many tracheoles
Short diffusion pathway- Thin walls of tracheoles and close proximity to the cell

Question 16

How are the spiracles adapted?

Answer 16

Open and close to minimise water loss
Hairs to trap moisture to reduce water loss

Question 17

When does abdominal pumping occur?

Answer 17

When the insect is flying

Question 18

How is the trachea adapted?

Answer 18

Contains rings for support

Question 19

How are the tracheoles adapted?

Answer 19

Deliver O2 to cells
Short diffusion pathway- thin walls, close proximity to cells
Large surface area- huge network of tracheoles

Question 20

What is abdominal pumping?

Answer 20

Ventilation by contraction of the muscles can force air in and out of the spiracles
Steeper concentration gradient
More O2 = More ATP = needed for muscle contraction

Question 21

How does an insect reduce water loss?

Answer 21

Waxy waterproof outermost layer
Spiracles are surrounded by valves which open and close spiracles
Spiracles are surrounded by hairs which trap moisture to minimise water loss