gas exchange and digestion

Question 1

what is the definition for metabolic rate?

Answer 1

amount of energy expended by that organism in a time period

Question 2

what is the SA:V in a larger organism?

Answer 2

lower

Question 3

what is the metabolic rate in a larger organism and why?

Answer 3

the metabolic rate is higher
>require more efficient delivery of oxygen
>more respiration needed
>have more advanced exchange surfaces

Question 4

what does the definition for metabolic demand?

Answer 4

how much oxygen and nutrient an organism needs to take in daily to respire enough to maintain its metabolic rate

Question 5

what is the SA:V in a smaller organism?

Answer 5

greater

Question 6

why is the metabolic rate in a smaller organism lower?

Answer 6

as they loose heat more easily

Question 7

in terms of per unit of body mass, which organism has a higher metabolic rate? why?

Answer 7

smaller organisms
> loose heat more easily so they need more energy
> higher metabolic rate is required

Question 8

give 2 physical adaptions in a cold environment

Answer 8

• streamline body (smaller SA:V)
• thick fur (insulate to reduce heat loss)
  > smaller mammals with higher SA:V

Question 9

give a behavioural adaptation in a cold environment

Answer 9

• will eat more food/ hibernate (maintain constant temp so they don’t loose heat as easily)
  > smaller mammals with higher SA:V

Question 10

give 2 physical adaptations in a hot/dry environment

Answer 10

• large ears (increase SA to loose heat to maintain constant temp)
  > large organisms with lower SA:V
• kidney adaptations (produce less urine, less water is lost)
  > small organisms with high SA:V

Question 11

give a behavioural adaptation in a hot/dry environment

Answer 11

• nocturnal (cooler at night)

Question 12

give the structures of the fish

Answer 12

gills, gill filaments, gill arch, lamella

Question 13

what do gills increase?

Answer 13

surface area for water to flow over

Question 14

what is lamella? what does it also contain?
what occurs in the lamella?

Answer 14

lots of tiny folds on the gill filaments.
> contains lots of capillaries and thin layer of cells
- gas exchange occurs (water flows over them)

Question 15

what is concurrent flow?

Answer 15

where blood and H2O flow over the lamella in the same direction
> large conc gradient between the blood and H2O (diffusion of oxygen to blood occurs)
> conc decreases until equilibrium is reached (diffusion of oxygen to blood stop)

Question 16

what is countercurrent flow?

Answer 16

where blood and H2O flow over the lamella in the opposite direction
> diffusion occurs throughout the whole lamella as blood always flows alongside H2O
> maintains steep conc gradient across the whole length of gills

Question 17

why is there large number of capillaries around lamella

Answer 17

removes oxygenated blood to maintain steep conc gradient

Question 18

what is the function of the operculum?

Answer 18

ventilation. ensure constant fresh water flow over gills to replace lost oxygen
> maintain steep conc gradient

Question 19

describe the ventilation within a fish

Answer 19

1. mouth opens, operculum shuts.
2. water enters the cavity due to decreased pressure, increases the volume.
3. mouth shuts, operculum opens
4. increased pressure, decreased volume.
5. increased pressure forces water out over gills.

Question 20

give the structures in an insect

Answer 20

trachea, tracheoles and spiricoles

Question 21

why do insects have tracheoles?

Answer 21

increase the surface area for efficient gas exchange

Question 22

why can spiracles open and close?

Answer 22

to prevent water lost and keeps the organism waterproof

Question 23

describe the ventilation of a insect

Answer 23

1. muscles contract, compressing trachea.
   >maintain steep conc gradient to pump gases out and in body
2. increases pressure, forces air out of spiracles down the pressure gradient
   > increase the removal of CO2 when energy demands increase

Question 24

what do small intestines contain to maximise absorption of nutrient?

Answer 24

villi

Question 25

what are the features of villi and how does it contribute to the absorption of nutrients?

Answer 25

- one cell thick (to keep diffusion pathway short) - lots of capillaries (maintain conc gradient, constantly transporting absorbed nutrients around body)

Question 26

what are epithelial cells?

Answer 26

cells that line the ileum (intestines)

Question 27

what are the adaptations of epithelial cells? what are the functions of these?

Answer 27

- microvilli (increase SA for diffusion) - many mitochondria (provide energy for ATP) - have membrane bound enzymes as monosaccharides are produced close to the ileum (increase absorption rates)

Question 28

what enzyme does the salivary glands produce?

Answer 28

amylase

Question 29

what role does amylase play within the digestive system?

Answer 29

hydrolyse glycosidic bonds within amylose and amylopectin (starch) into maltose

Question 30

what enzyme does the pancreas produce?

Answer 30

pancreatic amylase which is released into the small intestines >digestive enzymes for absorption

Question 31

in the ileum there are membrane bound enzymes, what do they digest?

Answer 31

hydrolyse glycosidic bonds in disaccharides into monosaccharides

Question 32

how is glucose and galactose transported?

Answer 32

uses sodium ions through co transporter proteins

Question 33

how is fructose transported?

Answer 33

through facillated diffusion using different transporter proteins

Question 34

where does protein digestion occur?

Answer 34

small intestines and stomach

Question 35

what acid does the stomach contain, what is its function?

Answer 35

hydrochloric acid > creates optimum pH (7) for enzyme pepsin to work

Question 36

how is pepsin secreted?

Answer 36

secreted from other cells that line the stomach

Question 37

what are the enzymes that digest proteins?

Answer 37

endopeptidases, exopeptidases and dipeptidases

Question 38

what is the function of endopeptidases?

Answer 38

hydrolyse peptide bonds in large polypeptide chains into smaller polypeptide chains. >create more terminal ends for exopeptidases (increase SA)

Question 39

what is the function of exopeptidases?

Answer 39

hydrolyse terminal peptide bonds between amino acid. >remove individual amino acids and create smaller polypeptide chains (dipeptide)

Question 40

what is the function of dipeptidases?

Answer 40

hydrolyse peptide bonds in dipeptides >creates 2 single amino acids to be absorbed

Question 41

how are amino acid transported?

Answer 41

through active transport with sodium ions

Question 42

why is endopeptidase important for digestion?

Answer 42

- hydrolyses peptide bond in the middle of large polypeptide chain - increase number of terminal ends - more rapid hydrolysis of polypeptide

Question 43

what are lipases and what is its function?

Answer 43

lipases are digestive enzymes > hydrolyse ester bonds in triglycerides

Question 44

where are lipases produced and where is it released?

Answer 44

produced: pancreas released: small intestines

Question 45

where are bile salts produced and where is it released?

Answer 45

produced: liver released: small intestines

Question 46

what is the function of bile salts?

Answer 46

- help break down large fat globules by emulsifying them into smaller droplets

Question 47

how does bile salts effect lipase action?

Answer 47

bile salts speed up the action of lipase by increasing SA of lipids to be exposed to lipase

Question 48

what is a triglyceride a type of?

Answer 48

lipid

Question 49

what are the products of triglycerides when they are hydrolysed by the lipase?

Answer 49

monoglycerides and fatty acids (non polar molecules)

Question 50

are fatty acids lipid soluble? if so, why?

Answer 50

yes - they can diffuse through the plasma membrane which is made phospolipids >non polar molecules diffuse thorough membrane >small enough

Question 51

what do the products from the hydrolysis of a lipid attach to? what do they form?

Answer 51

they attach to bile salts and form micelles

Question 52

what is the function of micelles?

Answer 52

they help absorption of fatty acids and monoglycerides in bloodstream

Question 53

how are fatty acids transported?

Answer 53

by the lymphobic system

Question 54

describe the lymphobic system (how fatty acids are transported)

Answer 54

1. micelles hit the epithelial cell and breakdown --> so monoglyceride + fatty acid can diffuse across membrane 2. monoglyceride + fatty acid get transported to the ER --> recombine to form triglycerides again. 2. triglyceride gets transported to golgi where they bind with cholestrol and proteins --> packaged to form chylomicrons 3. chylomicrons travel in a vesicle to cell membrane and exocytosed from epithelial cell. 4. chylomicrons enter lymphatic capillaries called lacteals --> transport away from small intestines to tissues --> triglycerides can be hydrolysed again to be used by tissues