Bio Component 3

Question 1

Why do large organisms not use diffusion to get oxygen?

Answer 1

• The surface are to volume ratio is to low
• Diffusion through the membrane would be to slow meaning the cells in the body would not get the supplies they need. There is also a high metabolic rate so high amounts of O2 needed. Therefore they need specialised gas exchange

Question 2

Describe amphibians gas exchange?

Answer 2

• Larvae live in water and have gills
• The adult uses moist skin as a respiratory surface except when active where some ( like frogs) use lungs respiratory surface

Question 3

Describe reptiles gas exchange?

Answer 3

• Reptails have lungs with an in out bellows arrangement
• They have growth of tissue to increase SA

Question 4

Describe gas exchange of birds?

Answer 4

• Birds have lungs with air sacs attached

Question 5

What is the function of the smooth muscle?

Answer 5

• Adjust size of airway, can contract, causing constriction of airway which restricts air flow
• Found in trachea, bronchi and bronchioles

Question 6

Describe the gas exchange of amoeba?

Answer 6

• Very small so simple diffusion can provide enough oxygen
• Live in water where oxygen is dissolved

Question 7

Describe the gas exchange of a flat worm?

Answer 7

• Extremely flattered organism
• Simple diffusion across body shape

Question 8

Describe the gas exchange of an earthworm?

Answer 8

• Elongated and round
• Has haemoglobin which takes up oxygen
• Circulatory system that carries oxygenated blood away from surface to cells deep in body

Question 9

Describe the gas exchange in insects?

Answer 9

• Have tracheol tubes throughout the body
• Spiracles (openings at the side of the body) that opens into a branching system of trachea
• Smallest tubes are tracheoles
• At end of each tracheole is a small amount of fluid where the gases dissolve
• Tracheol system gives insects a large surface area for gas exchange

Question 10

Describe the ventilation for insects?

Answer 10

1. Abdomen expands and thoracic spiracles open
2. Air enters through thoracic spiracles
3. Abdomen contracts and forces air out of the open abdominal spiracles

Question 11

What happens to insects during flight and at rest?

Answer 11

• During flight, the fluid at the end of the tracheoles is drawn into the tissue, supplying oxygen
• When the muscle is at rest, fluid released back into the tracheoles so CO2 can be removed
• During exercise there is less fluid, during rest there is more

Question 12

Describe the gills?

Answer 12

• Made up of numerous folds, providing a large surface area to maximise gas exchange
• 4 pairs of gills in pharynx (throat)
• Each gill supported by bony gill arch

Question 13

Describe the parts of the gills?

Answer 13

• Gill filaments = provide a large surface area, filled with blood, short diffusion path
• Gill arch = bony structure to support gill filaments and rakers
• Gill rakers = filter water and trap prey

Question 14

How do fish breathe in?

Answer 14

• Mouth opens and operculum (gill cover) closes the opening at the back of the pharynx
• Floor of mouth cavity is lowered
• Volume of mouth cavity increases and pressure falls
• Water flows in

Question 15

How do fish breathe out?

Answer 15

• Mouth closes
• Floor of mouth cavity is opened
• Volume of mouth cavity decreases and pressure rises
• Water flows across gills
• Operculum (gill cover) forced open

Question 16

Describe the counter current flow?

Answer 16

• Blood and water flow in the opposite direction
• Efficient as blood flowing through the gills always meets water that has a high % saturation of oxygen so diffusion is constant
• Diffusion gradient maintained across all of the gill plate

Question 17

Describe parallel flow?

Answer 17

• Water and blood flow in the same direction
• Halfway across the gill plate the % saturation of oxygen in blood and water reaches equilibrium

Question 18

Why do alveoli have a good blood supply?

Answer 18

• They are covered in capillaries

Question 19

Describe some features of the alveoli?

Answer 19

• Good blood supply
• Ensures diffusion gradients are maintained as blood is always moving
• Large surface area due to may alveoli
• Thin as walls of alveoli are only one epithelial cell thick so there is a short diffusion pathway

Question 20

Describe pleural membranes?

Answer 20

• Pleural membranes surround each lung and line the thorax
• In between each membrane is pleural fluid which prevents friction between the inner wall of the thorax and the lungs

Question 21

What is surfactant?

Answer 21

• Surfactant covers the surface of alveoli and prevents them from collapsing when breathing out by reducing surface tension

Question 22

Describe inhalation of humans?

Answer 22

• External intercostal muscles contract, pulling ribcage upwards and outwards (forced inspiration only)
• This pulls out the outer pleural membrane, reduces pressure in the pleural cavity and the inner pleural membrane moves outwards
• This pulls on the surface of the lungs and causes the alveoli to expand (forced inspiration only)
• Diaphragm contracts, pulling it from a domed to a flattered shape
• Causes volume of thorax and lungs to increase and pressure is reduced
• Air rushes into lungs down a pressure gradient

Question 23

Describe relaxed exhalation?

Answer 23

• External intercostal muscles relax and the ribcage falls under its own weight
• Diaphragm relaxes and gut pressure pushes it back into its domed shape
• Elastic recoil of lung tissue
• Causes volume of thorax and lungs to decrease, pressure is increased and air is forced out

Question 24

Describe forced exhalation?

Answer 24

• Internal intercostal muscles contract, pulling the ribcage down and in
• Abdominal muscle contracts, pushing the diaphragm upwards
• Causes volume of thorax and lungs to decrease, pressure is increased and air is forced out
• Used in exercise, singing, playing an instrument