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biology > 6 exchange > Flashcards

6 exchange Flashcards

1
Q

when an object gets bigger, will it have a bigger or smaller surface area to volume ratio?

A

smaller

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2
Q

what do all organisms rely on for respiration?

A

diffusion

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3
Q

do single celled organisms have a big or small SA:V?

A

big

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4
Q

what can single celled organisms do due to their big SA:V?

A

diffuse all O2 and CO2

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5
Q

do large organisms have a big or small SA:V?

A

small

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6
Q

what have large organisms had to do due to their small SA:V?

A

adapt to ensure rapid movement of gas

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7
Q

how would an amoeba respirate?

A

diffuse O2 through cell membrane and diffuse CO2 out of cell membrane

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8
Q

what does fick’s law state?

A

diffusion pathway

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9
Q

what makes a good exchange surface?

A

large surface area
large conc grad
small exchange surface

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10
Q

how do some insects limit water loss?

A

waterproof covering
small SA:V

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11
Q

name the feautures of an insects gas exchange system

A

tracheoles
tracheae
spiracles

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12
Q

what are spiracles?

A

small pores on exoskeleton that open and close

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13
Q

what are tracheae?

A

tubes supported by strengthened rings

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14
Q

what are tracheoles?

A

small branched tubes that come off the tracheae through to the body tissues

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15
Q

how does oxygen move through an insect?

A
  1. oxygen enters the insect through spiracles and into the tracheae
  2. spiracles close
  3. oxygen diffuses through tracheae into tracheoles
  4. oxygen is delivered directly to the respiring tissues.
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16
Q

why do the spiracles open and close?

A

to prevent water loss by evaporation

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17
Q

what is the structure and function of the tracheoles?

A
  • small tubes with THIN walls so the diffusion distance is small
  • highly branched so large surface area
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18
Q

what is the structure and function of the tracheae?

A

tubes full of air so diffusion is fast

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19
Q

why does diffusion happen within the insect?

A

large amount of O2 outside insect, small amount of O2 at respiring tissues
large amount of CO2 at respiring tissues, small amount of CO2 outside insect

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20
Q

why does insect movement speed up the rate of gas exchange?

A

muscles contract around the tracheae pushing air into tracheoles

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21
Q

what happens when an insect is resting?

A

water can build up in tracheoles

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22
Q

what may happen when insects are at flight?

A

anaerobic respiration producing lactic acid

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23
Q

how does lactic acid help water travel through tissues via osmosis in insects?

A

lowers water potential

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24
Q

why does lactic acid ultimately help the diffusion of oxygen in insects

A

lowers diffusion distance by allowing water to travel through muscles by osmosis

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25
what is the gas exchange organ in fish?
gills
26
why are gills good for gas exchange?
large surface area
27
describe the structure of the fish gas exchange system
- gill arch - blood vessels - gill filaments - lamellae - lamellae contain capillaries
28
explain how the structure of the fish gas exchange system is adapted to its function
1. many filaments- large surface area 2. lamellae thin- short diffusion pathway
29
what is countercurrent flow?
the blood and water in the lamellae flow in different directions
30
why does a countercurrent flow increase the fish’s ability to absorb oxygen from the water?
diffusion gradient is always maintained across the whole length of the lamellae
31
which has a higher oxygen concentration- blood or water?
blood
32
what is the equation for photosynthesis?
6CO2 + 6H2O -> 6O2 + C6H12O6
33
describe the structure of a leaf
- cuticle - upper epidermis cells - palisade mesophyll cells - spongy mesophyll cells - air space - lower epidermis cells (guard cells) - stomata
34
what is the function of a waxy cuticle?
minimise evaporation
35
what are some adaptations of the leaf for gas exchange?
many stomata- allow air to move in and out flat- large SA:V air spaces- short distance between mesophyll cells and air
36
how do you calculate rate of diffusion?
conc grad + surface area / diff distance
37
how does CO2 diffuse in leaves?
1. mesophyll cells photosynthesise, reducing CO2 conc 2. CO2 diffuses from air spaces into cells 3. reduces CO2 conc in air spaces causing CO2 to move into air spaces from outside leaf through stomata
38
explain O2 diffusion in leaves
1. mesophyll cells produce O2 as a result of photosynthesis 2. O2 diffuses to air spaces 3. this raises the O2 conc in air spaces allowing it to leave the stomata into the air outside the leaf
39
what does a dicotyledonous plant do?
flower
40
what happens to guard cells at night?
they close the stomata to prevent water loss
41
what are xerophytic plants?
dry plants like cacti
42
how do xerophytic plants adapt to reduce water loss?
1. lower number of stomata - less SA 2. sunken stomata - reduced water potential 3. hairs to trap water - reduced water potential 4. rolled leaves - reduce water potential
43
what is the structure of the lungs?
- trachea - bronchi - bronchioles - alveoli
44
what is the trachea in humans?
tube like structure that carries air from mouth to lungs
45
what are bronchi?
trachea splits into 2 bronchi allowing air to travel to both lungs
46
what are bronchioles?
bronchi further divide into bronchioles which supply alveoli with air
47
what are alveoli?
small sacs at the end of the bronchioles barrier between air in lungs and blood
48
how do alveoli maintain a large conc gradient?
rich blood supply
49
what are alveolar squamous epithelium?
one cell thick layer on alveoli that have a thin diffusion distance
50
describe the process of inhalation
1. external muscles contract pulling rib cage up and out 2. diaphragm contracts and pulls down 3. thoracic cavity volume increases 4. pressure in lungs lower than outside 5. air moves into lungs down a pressure gradient
51
describe the process of exhalation
1. external muscles relax 2. diaphragm relaxes and moves up 3. thoracic cavity volume decreases 4. pressure in lungs greater than outside 5. air moves out down a pressure gradient
52
what are the main parts of the digestive system?
salivary gland oesophagus stomach pancreas small intestine large intestine rectum
53
what is the function of the salivary glands?
secretes saliva containing salivary amylase that breaks down starch into maltose
54
what is the function of oesophagus?
carries food to stomach
55
what is the function of the stomach?
mixes food with gastric juice which is acidic and contains endopeptidases and exopeptidases
56
what is the function of the pancreas?
secretes pancreatic juice that contains pancreatic amylase, lipases and proteases
57
what is the function (and structure) of the small intestine?
folded into villi and microvilli for a large surface area for absorption
58
what is the function of the large intestine?
to absorb water
59
what is the function of the rectum?
faeces removed through egestion
60
name enzymes involved in the digestion of starch
amylase (salivary and pancreatic) maltase
61
what is the first stage of starch digestion, before enzyme action?
mechanical digestion- breaking up of food by the teeth
62
what does amylase hydrolyse and produce?
starch to maltose
63
explain the role of pancreatic and salivary amylase
hydrolyses glycosidic bonds in starch
64
why aren't salivary and pancreatic amylase the same enzyme?
salivary amylase gets denatured in the stomach due to acidic pH
65
what does maltase hydrolyse and produce?
maltose to glucose
66
where is maltase located?
membrane of epithelial cells in ileum
67
name enzymes involved in the digestion of proteins
proteases; - endopeptidases - exopeptidases - dipeptidases
68
where are proteases located?
stomach
69
what do endopeptidases hydrolyse and produce?
polypeptides into smaller chains of polypeptides
70
explain the how endopeptidases hydrolyse polypeptides
hydrolyse peptide bonds within polypeptide chain
71
why is it important that endopeptidases produce smaller chains of polypeptides?
smaller chains provide increased surface area for faster and more efficient digestion
72
what do exopeptidases hydrolyse and produce?
polypeptides into single amino acids or dipeptides
73
explain how exopeptidases hydrolyse polypeptides
exopeptidases are specifically complementary to N and C terminal ends so they hydrolyse polypeptides at terminal ends
74
where are dipeptidases located?
cell surface membrane of epithelial cell
75
what do dipeptidases hydrolyse and produce?
dipeptides into amino acids
76
where are lipids digested?
lumen of ileum
77
what do lipids need to turn into in order to be digested?
fat droplets
78
why do lipids need to be in the form of fat droplets in order to be digested?
needs to be emulsified for increased surface area for faster and more efficient digestion
79
how are lipids in the form of fat droplets emulsified?
by bile salts
80
what are bile salts made from?
bile
81
where is bile produced, stored and released?
produced in liver stored in gall bladder released in ileum
82
name enzymes involved in lipid digestion
lipases
83
what do lipases hydrolyse and produce?
lipids into glycerol, fatty acids and monoglycerides
84
what can mammals not digest?
cellulose
85
why are mammals not able to digest cellulose?
no cellulase present in mammals
86
how are carbohydrates absorbed?
1. only monosaccharides can be transported across epithelial cell membrane 2. because monosaccharides are small enough and specifically complementary to carrier proteins 3. move across membrane by co transport/ facilitated diffusion
87
how are proteins absorbed?
1. only amino acids can be transported across epithelial cell membrane 2. because amino acids are small enough and specifically complementary to carrier proteins 3. move across membrane by co transport
88
how are lipids absorbed?
1. after digestion, glycerol and fatty acids form micelles 2. micelles enter epithelial cells by simple diffusion 3. at SER, fatty acids and glycerol recombine to form triglycerides 4. at golgi apparatus, proteins are added to triglycerides to form chylomicron and is packaged into vesicles 5. chylomicron transported into lymph vessel by exocytosis and absorbed into blood
89
what type of molecule is chylomicron?
lipoprotein

biology (23 decks)

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