Chapter 6

Question 1

PVR equation

Answer 1

PVR = tidal volume x breathing rate

Question 2

path of air in humans

Answer 2

mouth/nose, trachea, bronchi, bronchioles, alveolus

Question 3

During inspiration what muscles do what

Answer 3

external intercostal muscles contract (rib cage moves up), diaphragm contracts (flattens)

Question 4

During expiration what muscles do what

Answer 4

external intercostal muscles relax and diaphragm relaxes

Question 5

4 main features of alveoli

Answer 5

large SA:V, moist, rich blood supply, thin cell walls

Question 6

asthma

Answer 6

airways narrow

Question 7

bronchitis

Answer 7

inflammation of the lung lining, excess mucus

Question 8

2 main functions of the mesophyll in gas exchange

Answer 8

moist surfaces, air spaces

Question 9

4 adaptations of xerophytes

Answer 9

thicker cuticle, reduced leaf surface area, fewer stomata, rolled leaves

Question 10

path of air in insects

Answer 10

spiracle, trachea, tracheoles, muscles

Question 11

3 adaptations of gills

Answer 11

large SA:V, rich blood supply, counter-current flow

Question 12

exopeptidases

Answer 12

hydrolyse terminal peptide bonds

Question 13

endopeptidases

Answer 13

hydrolyse central peptide bonds

Question 14

3 adaptations of the ileum

Answer 14

large surface area, good blood supply, thin walls

Question 15

lipid absorbtion

Answer 15

when a micelle reaches the ileum it breaks down, releasing the fatty acids and monoglycerides which then diffuse into the epithelial cell, these then re-join in the endoplasmic reticulum and in the golgi apparatus are associated with cholesterol and lipoproteins into a chlyomicron which is then released by exocytosis to the lacteal, then via the lymphatic system travel into the blood

Question 16

5 main adaptations for specialised exchange surfaces

Answer 16

large SA:V, thin, selectively permeable, ventilation to maintain gradient, efficient transport system to maintain gradient

Question 17

Rate of diffusion equation

Answer 17

= SAD/TOES
SA = surface area
D = difference in concentration gradient
TOES = Thickness of exchange surface

Question 18

What happens in the tracheoles during anaerobic respiration

Answer 18

lactate is produced making the cell more acidic, therefore water in the end of the tracheoles is drawn into the muscle reducing the volume of water in the tracheoles drawing more air in.

Question 19

Structure of the gill

Answer 19

made up of gill filaments, which are stacked in a pile. Perpendicular to the filaments is lamellae which increase the surface area

Question 20

Main adaptations of a plant for gaseous exchange

Answer 20

short diffusion pathway, large SA:V, many stomata, air spaces so gas can diffuse in

Question 21

Digesting starch

Answer 21

saliva enters the mouth and mixes with food during chewing, amylase in the saliva starts hydrolysing the starch into maltose, food is then swallowed and enters the stomach which is acidic and denatures the amylase, the food is then passed into the small intestine and mixes with pancreatic amylase to continue the hydrolysis of starch, the epithelial lining in the ileum produces disaccharidases like maltase which hydrolyses the maltose into alpha-glucose

Question 22

Role of bile

Answer 22

Bile salts emulsify lipids into tiny droplets increasing surface area, mineral salts neutralise stomach acid