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AQA A-level Biology Year 1 > Chapter 6 - Exchange between organisms + their environment > Flashcards

Chapter 6 - Exchange between organisms + their environment Flashcards

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1
Q

What exchange is done passively?

A

Diffusion + osmosis

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2
Q

What exchange is done actively?

A

Active transport

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3
Q

What is the relationship between SA:V?

A

As the side Increases, Vol increases + SA increases.

Relationship between SA:VOL

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4
Q

What is the features of specialized exchange surfaces?

A

Large SA:Vol = Increases rate of exchange
Very thin = short diffusion pathway
Selectively permeable
Maintenance of conc gradient

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5
Q

How have some organisms have evolved to increase the rate of exchange?

A

Flattened shape = no cell far from surface (flatworm, leaf)

Large area = increased SA:VOL

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6
Q

What is the equation for the rate of diffusion?

A

Rate of diffusion is proportional to SA X conc gradient

divided by length of diffusion pathway

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7
Q

What are an adaptation for the exchange of gas in single celled organisms?

A

Small = large SA:VOL
O2 absorbed by diffusion across body surface
Covered by CSM
CO2 diffuses out

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8
Q

How have insects evolved to allow efficient exchange if gases?

A

Evolved Tracheae + tracheoles

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9
Q

What are tracheae and their function?

A

They are supported by strenth rings
They prevent collapsing
They are then divided into tracheoles

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10
Q

What are tracheoles and their function?

A

they extend throughout all body tissues
atmospheric air + O2 brought directly to respiring tissues by a short diffusion pathway
(tracheole + body cells)

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11
Q

How do respiratory gases move in + out of the tracheal system along a diffusion gradient?

A

when cells respire O2 is used up -> conc towards end of tracheoles fall
- this creates a diffusion gradient
(O2 -> tracheae -> tracheoles -> cells)

CO2 produced from respiration
-Creates diffusion gradient in opposite direction
(CO2 -> TRACHEOLES -> TRACHEAE)

Respiratory gases exchnaged quickly

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12
Q

How do respiratory gases move in + out of the tracheal system through mass transport?

A

Contraction of muscles squeeze tracheae enabling air in + OUT
Speeds exchange of respiratory gases

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13
Q

How do respiratory gases move in + out of the tracheal system through the ends of tracheoles filled with water??

A

Periods of major activity cause muscles to respire (anaerobically)
Produces lactose
H2O, therefore, moves into cells from tracheoles by osmosis
H2O at ends of tracheoles -> low VOL -> draws air further into them
Final diffusion is in a gas therefore more RAPID DIFFUSION
HIGHER rate of air in tracheoles -> but greater water evaporation

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14
Q

How do gases enter + leave the tracheae?

A

Through spiracles
Open (Water evaporates) + closes (prevents water loss) by valve

Periodically keep it open for gas exchange

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15
Q

What are the limitaions of a tracheal system?

A

Relies mostly on diffusion for gas exchange
Diffusion needs to be short to be effective (insect small)
Short diffusion path (small insect)

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16
Q

How have fish adapted for gas exchange?

A

Have waterproof therefore gas tight, outer covering covering
Relatively larger = small SA:VOL
Body surface therefore not adequate for gas exchange (not evolved)

HAVE EVOLVED GILLS

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17
Q

What are gill filaments?

A

they are stacked up in a pile

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18
Q

What are right-angled to gill filaments?

A

Gill lamellae

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19
Q

what are gill lamellae?

A

Increase SA of gills

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20
Q

What is the process of how the gills work?

A

H2O taken through mouth + forced over gills + out through the opening on each side of body

Flow of H2O over gill lamellae + flow of blood within are in opposite direction

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21
Q

What is countercurrent flow?

A

Flow of H2O over gill lamellae + flow of blood within are in opposite direction

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22
Q

What are the countercurrent exchange principles?

A

LOOK AT GRAPH IN BOOK

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23
Q

What happens when plants photosynthesize?

A

most CO2 obtained from air
Most O2 used in respiration diffuses out
When photosynthesis doesn’t occur (in dark e.g) O2 diffuses into leaf constantly for respiration

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24
Q

How does the structure of the leaf allow better gas exchange?

A

No living cell far from external air
Diffusion takes place in air (rapid)

= short, fast diffusion pathway
air spaces = large SA

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25
Q

What adaptations in leaf have for rapid diffusion?

A

Stomata (small pores) - Short DP
Numerous Interconnecting air spaces occur throughout mesophyll gases readily in contact with mesophyll cases
-> large SA = Rapid diffusion (mesophyll cells)

26
Q

How are stomata structured?

A

Minute pores
Each STOMA surrounded by guard cells
open + close STOMATAL PORE
Controls rate of gas exchange

27
Q

Why are stomata important?

A

Lose H2O by evaration
Evolved to balance gas exchnage + H2O loss
Do this by open + closing

28
Q

How is water loss limited in insects?

A

SMALL SA:VOL
Water proof coverings
Spiracles

29
Q

How is water loss limited in plants?

A

Transpiration -> XEROPHYTES

Adapted to live in areas with short H2O supply

30
Q

How have xerophytes adapted to live in areas with short H2O supply?

A

Thick cuticle - waxy cuticle not enough, makes it thicker
Rolling up leaves - protects lower epidermis
Hairy leaves - traps moist air on L.epidermis
Stomata in pits/groves - traps moist air
Reduced in SA:VOL

31
Q

What are lungs?

A

pair of lobed structures made of bronchioles, which end in alveoli

32
Q

What are tracheae?

A 
Flexible airway supported by rings cartillage (prevents tracheae collapsing)
Tracheal walls (made of muscle lined with ciliated epithelium + goblet cells)
33
Q

What are bronchi + functions?

A

2 divisions of tracheae leading to 1 lung
Produce mucus -> traps first particles
Have CILIA move dirt mucus to throat
Large bronchi supported by cartilage

34
Q

What are bronchioles?

A

Branching subdivisions of bronchi
walls -> muscles lined with epithelial cells
Muscles allow constricting -> control flow of air in + out of alveoli

35
Q

What are alveoli?

A

Minute air sacs -> end of bronchioles
Between alveoli -> collagen + elastic fibres -> allows stretch when air filled
Lined with epithelium

36
Q

What is breathing?

A

Maintaining diffusion of gases across alveolar epithelium air moved in + out of lungs

37
Q

What is inspiration?

A

Breathing in -> Active process

38
Q

Describe the process of inspiration?

A

External intercostal muscle

39
Q

What is expiration?

A

Breathing out largely passive process (not reuire energy)

40
Q

Describe the process of expiration?

A

Internal intercoastal muscle

41
Q

What happens during normal breathing?

A

Recoil of elastic tissue in lungs -> main cause air forced out
Under Strenous conditions -> various muscle -> major part

42
Q

What is the role of alveoli in gas exchange?

A

Alveolus lined with eithelial cells
Around alveolus is network of pulmonary capilaries RBC flattened against thin capillary walla in order to squueze through
Capillaries walls -> single layer

43
Q

Why is the diffusion of gases between alveoli alveoli + blood rapid?

A 
Short diffusion pathway 
V.thin walls
V.large toal SA
Steep conc gradient (maintains)
More time for diffusion (RBC slowed)
44
Q

What is the definition of digestion system?

A

exchange surface through which food substances are absorbed

45
Q

What is an oesophagus?

A

Carries food mouth -> stomach

46
Q

What is the stomach?

A

Muscular sac, inner layer produces enzymes

47
Q

What is the stomachs function?

A

Store + digest (esp protein)

Has glands that produce enzymes -> digest proteins

48
Q

What is the ileum?

A 
Long muscular tube
Food further digested by enzymes
Inner walls folded into villi - increases SA
Surface further increased microvilli
Absorbs into bloodstream
49
Q

What is the large intestine?

A

Absorbs H2O -> from secretions of many digestive glands

50
Q

What are salivary glands?

A

Situated near mouth
Pass secretions via duct
Contain enzyme amylase hydrolyse starch

51
Q

What is the rectum?

A

Faeces stored -> periodically removed by anus

Final rection of intestines

52
Q

What is the pancreas?

A

Large gland situated below stomach
Produces secretion -> pancreatic juice
Protease hydrolyse protein lipase -> lipids, amylase -> starch

53
Q

Describe the physical breakdown journey of food?

A

Large food broken into smaller pieces by teeth

54
Q

Describe chemical digestion?

A

Hydrolyses large, insoluble molecules into smaller soluble ones -> by enzymes

55
Q

Describe what happens during carbohydrate digestion?

A

Saliva enters via salivary glands

56
Q

Describe what happens during lipid digestion?

A

Hydrolysed by enzyme : lipase

57
Q

Describe what happens during protein digestion?

A

large complex molecule

hydrolyse by enzymes peptidases

58
Q

What is an endopeptidase?

A

Hydrolyses peptide bonds -> AA central region of protein molecule -> form series of peptide molecules

59
Q

What is an exopeptidase?

A

Hysrolyses peptide bonds on terminal AA of peptide molecules formed endopeptidases -> release dipeptides + single AA

60
Q

What are dipeptidases?

A

Hydrolyses bond between 2AA of dipeptide membrane bound, part of CSM of EC lining ileum

61
Q

What are the adapted functions of the ileum?

A

Walla folded + possess villi -increases SA + rate of aborption
Thin
Lined with epithelial cells other sides -> sides network of blood capillaries

Villi situated at the interface between lumen (cavity) of intestines + blood other tissues in the body

62
Q

What properties of the ileum increase absorption?

A

digestion protein produces AA
Carbohydrates -> monosacharides, fructose, galactose
Absorbing methods -> diffusion + co-transport

AQA A-level Biology Year 1 (10 decks)

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