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AQA A level biology <33 > November mock prep- topic 3 > Flashcards

November mock prep- topic 3 Flashcards

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1
Q

what are the features of exchange surfaces?

A

large SA:V ratio which increases rate

very thin meaning there is a short diffusion pathway

selectively permeable to allow selected materials

movement of environmental medium to maintain diffusion gradient

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2
Q

why do single celled organisms have a large SA:V ratio?

A

They have a large SA:V ratio because they are small

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3
Q

what is the tracheae?

A

internal network of tubes supported by strengthened rings

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4
Q

what are tracheoles?

A

smaller dead end tubes which bring oxygen directly to respiring tissues

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5
Q

what are spiracles?

A

small holes on the outside of the insect which open and close by valves

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6
Q

how are gases exchanged in insects?

A

along the diffusion -

the concentration of oxygen drops near the end of the tracheoles which creates a diffusion gradient

the carbon dioxide produced in respiration creates a diffusion gradient in the opposite direction

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7
Q

outline the process of mass movement in insects?

A

the contraction of muscles squeezes the trachea
1) anaerobic respiration produces lactate which lowers the water potential
2) this causes water to move into the cells from the tracheoles
3) water in the tracheoles decreases in volume leading to air being drawn in

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8
Q

how is water loss limited in plants?

A

waxy cuticle
reduced SA:V
hairy leaves
leaves roll up

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9
Q

how is water loss limited in insects?

A

spiracles that open and close
small SA:V
waterproof covering

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10
Q

why do leaves have a short diffusion pathway?

A

there is no living cell far away from the external gas and diffusion occurs in the gas phase

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11
Q

what is the benefit of having a large surface area in leafs?

A

rapid diffusion

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12
Q

describe the structure of the human gas exchange system

A

nostril
trachea
bronchi
bronchioles
alveoli

lungs surrounded by ribs
internal and external intercostal muscles

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13
Q

outline the process of inspiration

A

internal intercostal relax
external intercostal contract
diaphragm flattens
volume of thorax increases
pressure in lungs decreases
atmospheric pressure greater
air drawn in

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14
Q

outline the process of expiration

A

internal intercostal contract
external intercostal relax
diaphragm relaxes
volume of thorax decreases
pressure in lungs increases
air forced out

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15
Q

how is pulmonary ventilation rate calculated?

A

tidal volume x breathing rate

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16
Q

how is the human gas exchange system adapted?

A

contain alveoli surrounded by lots of capillaries- increases diffusion
thin walls- short diffusion pathway
red blood cells slowed as they pass through and are pushed up against the walls

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17
Q

why is food firstly broken down mechanically?

A

to provide a large surface area for chemical digestion

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18
Q

what’s the function of bile salts in lipid digestion?

A

breaks lipids down into micelles(tiny droplets) meaning there is a large surface area for lipase to break down the lipid

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19
Q

what 4 different enzymes are used in the digestion of carbohydrates?

A

amylase
maltase
sucrase
lactase

20
Q

what do endopeptidases do?

A

break polypeptides into smaller chains

21
Q

what do exopeptidases do?

A

remove terminal amino acids

22
Q

how are carbs and proteins absorbed?

A

co transport and diffusion

23
Q

describe the process of the absorption of lipids

A

glycerol and 3 fatty acids in the epithelial cells are recombined by the endoplasmic reticulum

golgi apparatus form chylomicrons which are excreted by exocytosis

they enter the lacteals where they are passed into the blood system

24
Q

how do valves work?

A

controlled by pressure changes which prevents backflow of blood

25
Q

what is oxygen affinity?

A

how easy it is for oxygen to be taken up
high affinity- easy to be taken up, but harder to release
low affinity- hard to be taken up, but easy to be released

26
Q

why are affinities different?

A

slight difference in amino acid sequence
(tertiary/ quaternary structure)

27
Q

what is the difference between oxygen loading and offloading?

A

loading- oxygen binds
unloading- oxygen released

28
Q

what is the difference between oxygen loading and offloading?

A

loading- oxygen binds
unloading- oxygen released

29
Q

what does the oxygen bind to on the haemoglobin?

A

ferrous Fe 2+ ion

30
Q

describe the protein structure of haemoglobin

A

primary- sequence of amino acids in 4 polypeptides
secondary- each chain folds into an alpha helix
tertiary- each fold into a precise shape
quaternary- all 4 linked to form an almost spherical structure in which each polypeptide is associated with a haem group

31
Q

what are oxygen dissociation curves?

A

a curve that shows the relationship between the oxygen saturation of haemoglobin and the partial pressure of oxygen

32
Q

explain the shape of the oxygen dissociation curve

A

1) difficult for first oxygen to bind due to the shape of haemoglobin
2) binding of the first oxygen slightly changes the shape of the haemoglobin making it easier for the next two oxygen to bind
3) less likely for fourth oxygen to bind due to probability

33
Q

how can the position of the curve show you the affinity?

A

more to left- higher affinity
more to right- lower affinity

34
Q

what is the effect of carbon dioxide on affinity?

A

decreases the affinity for oxygen as the low pH causes the haemoglobin to change shape

35
Q

what are the main features of transport systems?

A

suitable medium to carry materials

form of mass transport

closed system of tubular vessels

mechanism for moving medium involving a pressure difference

36
Q

what happens during diastole?

A

blood enters right atrium
pressure increases until it is higher than that in the ventricles
atrioventricular valves open
ventricle walls relax
pressure decreases until lower than that in the pulmonary artery and aorta
semi lunar valves close

37
Q

what happens during atrial systole?

A

atrial walls contract
ventricle walls recoil
blood forced out

38
Q

what happens during ventricular systole?

A

walls of ventricles contract simultaneously
an increase in pressure causes the atrioventricular valves to shut, preventing backflow
pressure increases further
blood forced into vessels when pressure is higher than that in the pulmonary artery and aorta

39
Q

what is the equation to work out cardiac output?

A

heart rate x stroke volume

40
Q

what is tissue fluid?

A

means by which materials exchanged

41
Q

what is ultrafiltration?

A

hydrostatic pressure pushes tissue fluid out plasma
this is opposed by the hydrostatic pressure and lower water potential outside

42
Q

describe the movement of water through the stomata

A

more humid next to stomata
creates a water potential gradient from the stomata to the air
water diffuses out

43
Q

describe the movement of water through cells in leafs

A

evaporation in mesophyll cells lowers water potential
water enters through osmosis lowering water potential in neighbouring cells
take turns to take in water from neighbouring cells

44
Q

describe transpiration

A

cohesion tension theory-
water evaporates from mesophyll cells
water sticks together by hydrogen bonds
forms continuous column down xylem
transpiration pull
xylem under tension due to hydrostatic pressure

45
Q

describe the process of translocation

A

sucrose transported into companion cells by facilitated diffusion before being actively transported into spaces in cell wall
cotransported with hydrogen into drive tube elements
sucrose in phloem lowers water potential
water moves from xylem into the phloem increasing the water potential in the xylem
creates a high hydrostatic pressure at the top and a low one at the bottom of the phloem
sucrose and moves down and into sink cells by active transport
sucrose transported into other sink cells or into storage

AQA A level biology <33 (12 decks)

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