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Biology A level AQA > Chapter 6 - Exchange > Flashcards

Chapter 6 - Exchange Flashcards

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1
Q

what are the features of a specialised exchange surface? (5)

A
  • large SA:Vol
  • thin, short DP
  • selectively permeable
  • movement of environmental medium to maintain DG
  • transport system to maintain DG
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2
Q

What is the calculation for diffusion?

A

surface area x difference in concentration
_________________________________

     length of diffusion pathway
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3
Q

How are single celled organisms able to survive with no transport system?

A

large SA:Vol
simple diffusion
no part too far from external substances

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4
Q

what is the main factor in conflict with gas exchange in terrestrial organisms?

A

water conservation

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5
Q

list the structures of insects gas exchange system in order from smallest to largest (4)

A

fluid filed ends
tracheoles
trachea
spiracles

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6
Q

How do gases move in/out of the tracheal system? (3)

A
  • along a diffusion gradient, oxygen used by surrounding cells
  • mass transport, muscle contraction
  • fluid filled ends, water enters surrounding cells by osmosis during times of activity meaning a lower vol. of water in the system leaving a shorter diffusion pathway for gas exchange in times of high metabolic activity
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7
Q

What are the limitations of the tracheal system? (2)

A
  • rely solely on diffusion

- needs short diffusion pathway therefore limits insect size

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8
Q

state the structures of the gills from largest to smallest

A

gill bar
gill filaments
gill lamella

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9
Q

What is the importance of the counter-current exchange system for diffusion?

A
  • maintains a constant favourable diffusion gradient for oxygen to diffuse into the blood e.g. when blood with little oxygen meets water with little oxygen the oxygen still diffuses down the gradient into the blood
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10
Q

how do gases enter/exit the leaf of a plant (the process)?

A

diffusion

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11
Q

how are leaf tissues gas exchange systems similar to that of an insect? (2)

A
  • cells not far from external air, short DP

- diffusion takes place in gas phase, more rapid

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12
Q

State an adaptation of a leaf for rapid diffusion

A

stomata -short DP
air spaces throughout mesophyll
large SA of mesophyll = large SA

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13
Q

state the structures of a leaf from top to bottom (5)

A 
waxy cuticle
upper epidermis
mesopyhll
air spaces
lower epidermis
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14
Q

How are stomata adapted for limiting water loss?

A

when flacid due to low water potential stomata close, when turgid they remain open

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15
Q

state 3 adaptations of insects to reduce water loss

A
  • small SA:Vol
  • waterproof coverings
  • spiracles, open/close
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16
Q

adaptations of non-xerophitic plants to limit water loss? (2)

A
  • waxy cuticle

- close stomata

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17
Q

adaptations of xerophytes? (5)

A
  • thick cuticle
  • rolling up of leaves
  • hairy leaves
  • stomata in pits/grooves
  • reduced SA:Vol e.g. cactus
18
Q

state the structures of the lungs passed through by air entering the lungs (mouth onwards) (4)

A

trachea
bronchus
broncheole
alveoli

19
Q

why must the lungs be located inside the body?

A
  • air not dense enough to support the delicate structure

- significant water loss, body would dry out

20
Q

describe the structure of the trachea

A

flexible airway supported by ‘c’ shaped cartilage, lined by goblet cells

21
Q

describe the structure of the bronchi

A

less cartilage as bronchi get smaller

22
Q

describe the structure of bronchioles

A

muscle walls able to constrict, lined with epethelial cells

23
Q

describe the structure of alveoli

A

air sacs with collagen and elastic fibres between to allow it to expand and recoil

24
Q

state the 3 sets of muscle involved with the mechanism of breathing

A
  • internal intercostal muscles
  • external intercostal muscles
  • diaphragm
25
Q

describe the diaphragm

A

sheet of muscle separating thorax from abdomen

26
Q

outline the process of inspiration (6)

A
  • external contract, internal relax
  • ribs pull upwards and outwards
  • volume of thorax is increased
  • diaphragm contracts and flattens
  • reduction of pressure in lungs
  • atmospheric pressure is then greater than in lungs = air flows into lungs
27
Q

adaptations of alveoli for diffusion into blood (5)

A
  • red blood cells slowed as they move through capillaries - more time for diffusion
  • red blood cells flattened against walls of capillaries
  • thin walls of both - shorter DP
  • both have large SA
  • constant ventilation, constant heartbeat maintains DG
28
Q

state the risk factors for lung disease (5)

A
  • smoking
  • air pollution
  • genetics
  • infections
  • occupation (chemicals)
29
Q

what is the difference between a correlation and a causation?

A 
correlation = change of one variable reflected by change in other variable
causation = one variable is the result of the change in the other variable
30
Q

state the major parts of the digestive system (5)

A 
oesophagus
stomach
ileum
large intestine
rectum
(salivary glands)
(pancreas)
31
Q

what is the difference in function of the ileum and the large intestine?

A

ileum:
- food digested
- absorbs products of digestion
large intestine:
- absorbs water

32
Q

outline the process of carbohydrate digestion (chemical). (5)

A
  • saliva enters mouth from salivary glands, mixes with food through chewing (contains salivary amylase, breaks down starch to maltose)
  • acid in stomach denatures salivary amylase
  • food passes into ileum, mixes with pancreatic juice containing pancreatic amylase
  • muscles in intestine push food along ileum
  • membrane-bound disaccharidase maltase hydrolyses maltose to alpha glucose
33
Q

what is the term used to describe enzymes that hydrolyse carbs?

A

carbohydrases

34
Q

what the the two other types of hydrollytic enzymes other than maltase for carbs?

A

sucrase

lactase

35
Q

what is the optimum pH for amylase?

A

around neutral

36
Q

outline the process of lipid digestion (3)

A
  • bile salts split lipids into micelles
  • process called emulsification
  • increases SA for action of lipases
37
Q

name of protein enzymes?

A

peptidases

38
Q

name the 3 types of peptidases

A

endopeptidases
exopeptidases
dipeptidases

39
Q

state adaptations of the exchange surface of the ileum + function of adaptation (5)

A
  • villi, SA
  • microvilli, SA
  • thin walls, DP
  • muscle walls for movement//mixing, DG
  • capillary network, DG
40
Q

how are amino acids absorbed in the ileum?

A

co-transport using sodium and co-transport carrier proteins

41
Q

outline how lipids are absorbed (5)

A
  • micelles associated with bile salts
  • contact epethelial cells and break down releasing monoglycerides and fatty acids (lipid soluble) pass through PB-L
  • transported to ER reform into triglycerides
  • continue to Golgi where they become associated with cholesterol and lipoproteins to form chylomicron
  • excytosis out of cell into lymphatic capillaries which drain into blood

Biology A level AQA (19 decks)

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