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A-Level Bio > Topic 3 > Flashcards

Topic 3 Flashcards

1
Q

larger SA:V and organism size correlation

A

smaller organism -> larger SA:V

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2
Q

Gas exchange in small organisms like amoeba

A

very large SA:V
small diffusion distance
exchange gases across surface

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3
Q

gas exchange in larger organisms

A

smaller SA:V ratio
higher metabolic needs, requiring efficient transport of waste out and reactants into cells
have adaptations for efficiency eg ……

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4
Q

Adaptations to increase SA:V

A

villi/microvilli for absorbing digested food
alveoli/bronchioles in GE
spiracles and tracheoles in GE
gill filaments and lamellar in GE
thin wide leaves in GE
many capillaries - capillary network

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5
Q

Breathing

A

ventilation
movement of air into and out of the lungs

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6
Q

gas exchange

A

diffusion of O2 in and CO2 out via alveoli

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7
Q

order of airflow out of human gas exchange system

A

alveoli
bronchioles
bronchi
trachea
mouth

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8
Q

EXTERNAL intercostal muscle contraction causes

A

inspiration

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9
Q

INTERNAL intercostal muscle contraction causes

A

expiration

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10
Q

inspiration effect on
ext IM
int IM
diaphragm
lung air pressure
thoracic volume
air movement

A

contract
relax
contracts down and flattens
initially drops lower than atmospheric pressure
increases
air moves in down pressure gradient

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11
Q

expiration effect on
ext IM
int IM
ribcage
diaphragm
lung air pressure
thoracic volume
air movement

A

relax
contract to pull the rib down and in
down and inwards
relaxes to move up and dome
initially greater than atmospheric pressure
decreases
air moves out down pressure gradient

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12
Q

pulmonary ventilation meaning and equation

A

total volume of air moved into lungs during 1 minute (dm3min-1)

PM = tidal volume(dm3) x ventilation rate(min-1)

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13
Q

human gas exchange occurs where

A

in alveoli between alveolar epithelium and blood

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14
Q

how are alveoli adapted to make diffusion more efficient?

A

thin walls to minimise diffusion distance

many alveoli

surrounded by network of capillaries to remove exchanged gases and therefore maintains a conc grad

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15
Q

how do insects prevent water loss

A

exoskeleton made of hard fibrous material to protect and lipid layer to prevent water loss

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16
Q

spiracles on insects

A

holes in the abdomen

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17
Q

3 methods of insect gas exchange

A
  1. GE by diffusion as O2 is used up and CO2 produced creating a conc gradient from tracheoles to the atmosphere
  2. mass transport, so insect contracts and relaxes abdominal muscles to move gases on mass
  3. anaerobic respiration (in flight) producing lactate, lowering cell wp and drawing water into cells from tracheoles. this decreases volume of water in tracheoles and more air from the atmosphere is drawn in
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18
Q

insect adaptations for efficient GE

A

large no of fine tracheoles for large SA
thin tracheole walls for short DD
short dist between spiracles and tracheoles for short DD
use of O2 and CO2 sets up steep diffusion gradients

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19
Q

3 insect adaptations preventing water loss

A

small SA:V where water can evaporate from
waterproof exoskeleton lipid layer
spiracles can open and close to reduce water loss

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20
Q

why do fish need a gas exchange system

A

waterproof
small SA:V

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21
Q

Ficks law

A

diffusion is proportional to:

(SAxΔconcentration)/length of diffusion path

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22
Q

fish gill anatomy

A

gills made up of gill filaments
each filament is covered in lamellae (perp. to filament)
large SA for GE

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23
Q

fish adaptations for efficient GE

A

many lamellae so large SA:V
short diffusion distance due to capillaries in each lamellae
countercurrent flow maximises diffusion gradient

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24
Q

why is countercurrent flow advantageous in fish?

A

ensures eqm not reached
diffusion gradient of O2 and CO2 is maintained across entire length of gill lamellae

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25
Q

How do plants reduce water loss? (xerophytes)

A

curled leaves trapping moisture
close stomata at night when no photosynthesis occurs
hairs trapping moisture
sunken stomata to trap moisture -> increases local humidity, decreases diffusion gradient
thicker cuticle reducing evaporation
longer root network to reach more water

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26
Q

what happens in digestion

A

large biological molecules hydrolysed to smaller molecules that can be absorbed across cell membranes

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27
Q

carbohydrate digestion

A

amylase produced in pancreas and salivary glands
hydrolyses polysacchs to disacch maltose
sucrase/lactase are membrane bound enzymes to turn the two disacchs to monosacchs

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28
Q

protein digestion

A

endopeptidases break peptide bonds between AAs in the middle of the ppt chain
exopeptidases break peptide bonds between AAs at the end of a ppt chain
dipeptidases break peptide bonds between 2 AAs

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29
Q

where does protein digestion occur?

A

stomach, duodenum, ileum

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30
Q

where does carb digestion occur?

A

mouth, duodenum, ileum

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31
Q

what are lipids digested by?

A

by lipase and bile salts
lipase hydrolyses the ester bonds in triglycerides forming monoglycerides and fatty acids
bile salts are produced in the liver and can emulsify lipids to form micelles, increasing SA for lipase to act on

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32
Q

where does lipid digestion occur?

A

duodenum
ileum

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33
Q

2 stages of lipid digestion

A

physical : emulsification and micelle formation
chemical : lipase

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34
Q

describe the 2 stages of lipid digestion

A

physical
lipids coated in bile salts to emulsify
many small lipid droplets provides large SA for faster lipase hydrolysis

chemical
lipase hydrolyses lipids into glycerol and fatty acids

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35
Q

micelles

A

vesicles formed of fatty acids, glycerol, monoglycerides and bile salts

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36
Q

absorption of lipids

A

micelles from digestion (by lipse and bile salts) diffuse across CSM as fatty acids are non polar
once in the cell, they reform triglycerides in the smooth endoplasmic reticulum and golgi apparatus

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37
Q

how are villi adapted for efficient absorption

A

microvilli for large SA
capillary network for steep conc grad
thin walls for short diffusion pathways

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38
Q

co transport of glucose/AA in ileum

A

epithelial cell to capillary:
AT of Na+ using ATP

ileum lumen to epithelial cell:
diffusion gradient of Na+
Na+ moves in with glucose/AA simultaneously via FD using symport

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39
Q

why is co transport needed in the ileum

A

more glucose/AAs are in the cells so they are being moved against the conc grad

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40
Q

haemoglobin is a _______ structure

A

quaternary

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41
Q

oxyhaemoglobin dissociation curve

A

oxygen is loaded in places with a high ppO2 eg alveoli
and unloaded in placed with low ppO2
eg respiring tissues

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42
Q

cooperative binding

A

when first oxygen binds to haemoglobin, it’s easier for further oxygens to bind due to haemoglobin’s change of shape when O2 first binds

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43
Q

Bohr effect

A

when high CO2 conc leads to the curve shifting RIGHT
O2 affinity DECREASES
due to slight change of shape jn haemoglobin

44
Q

ODC at alveoli

A

curve shifts left
increased affinity for oxygen
uptakes more oxygen

45
Q

ODC at respiring tissues

A

curve shifts RIGHT
DECREASED affinity for O2
unloads more O2

46
Q

closed circulatory system?

A

blood remains within blood vessels

47
Q

double circulatory system

A

blood passes through the heart 2x in each circuit

48
Q

why is a double circulatory system needed?

A

manages pressure of blood flow
low bp at lungs to prevent damage to capillaries in alveoli and reduces speed of blood flow for more time for GE
high bp to rest of body so it reaches all respiring cells in the body

49
Q

in clockwise order from right atria, name the blood vessels leaving and entering the heart and their origin/destination

A

aorta to rest of body
pulmonary vein from lungs

vena cava from body
pulmonary artery to lungs

50
Q

kidney blood vessels

A

renal artery in
renal vein out

51
Q

cardiac muscle properties

A

myogenic (contracts and relaxes without nervous/hormonal stimulation)
never fatigues (w constant glucose and oxygen supply)

52
Q

coronary arteries purpose

A

supply cardiac muscle w oxygenated blood

53
Q

where do coronary arteries branch off of

A

aorta

54
Q

what causes a myocardial infarction

A

blocking of coronary arteries
cardiac muscle doesn’t receive oxygen
cells die
leads to myocardial infarction

55
Q

right atrium and ventricle on diagram

A

blue, and on the left

56
Q

atrial walls adaptation

A

thinner muscular walls
don’t need to contract as hard as not pumping blood far away (only to ventricles)
elastic walls stretch when blood enters

57
Q

ventricular walla adaptation

A

thicker muscular walls to bring a larger force from contraction
high bp so blood flows longer distances eg to lungs and rest of body

58
Q

right ventricle adaptation

A

pumps blood to lungs
low pressure
due to thinner muscular walls
prevents damage to capillaries in lungs

59
Q

left ventricle adaptations

A

pumps blood to body
high pressure needed to reach all resp cells
thicker muscular wall needed compared to right ventricle
enables larger contractions for higher blood pressure

60
Q

veins

A

into heart

61
Q

artery

A

away from heart

62
Q

semi lunar valves location

A

in aorta and pulmonary artery

63
Q

av valves location and name of each one

A

between atria and ventricles
bicuspid = left
tricuspid = right

64
Q

valves job

A

prevent blood backflow
only open when pressure is higher behind the valve

65
Q

septum purpose

A

separates oxygenated and deoxygenated blood
maintains high O2 conc in oxygenated blood to maintain diffusion gradient to enable diffusion at respiring cells

66
Q

arteries muscle layer, elastic layer, wall thickness and valve presence

A

muscle layer: thicker than veins so that construction and dilation can occur to control blood volume
elastic layer: thicker than veins to maintain bp, and walla can stretch and recoil in response to the heart beat
wall thickness: thicker wall than veins to help prevent vessels bursting due to high pressure
valves: no

67
Q

veins muscle layer, elastic layer, wall thickness and valve presence

A

ml: relatively thin so it cannot control blood flow
el: thin as bp much lower
wt: thin as bp is much lower so lower risk of bursting. thinness also allows vessels to easily be flattened which helps blood flow back up to heart
v: yes

68
Q

capillaries have a narrow diameter to

A

slow blood flow
RBCs only just fit, and are squashed against walls, maximising diffusion

69
Q

arterioles muscle layer, elastic layer, wall thickness and valve presence

A

ml: thicker than in arteries to restrict blood flow into capillaries
el: thinner than arteries as lower bp
wt: thinner than arteries as pressure is slightly slower
v: no

70
Q

capillaries muscle layer, elastic layer, wall thickness and valve presence

A

ml: none
el: none
wt: 1 cell thick for short dd for exchange of materials between blood and cells
valves: no

71
Q

cardiac cycle stages

A

diastole
atrial systole
ventricular systole

72
Q

what happens in diastole?

A

atria + ventricular muslces are relaxed
blood enters atria via vena cava and pulmonary vein
blood flowing into atria increases pressure within atria

73
Q

what happens in atrial systole?

A

atria muscular walls contract
increases atrial pressure
forces AV valves to open and blood flow into ventricles
ventricular muscular walls are relaxed

74
Q

what happens in ventricular systole?

A

after a short delay, the ventricle muscular walls contract, increasing the pressure beyond that of the atria.
this causes AV valves to close and SL valves to open
blood is pushed out of the ventricles into the pulmonary arteries and aorta

75
Q

cardiac output =

A

heart rate(bpm) x stroke volume(dm3)

76
Q

define cardiac output

A

volume of blood leaving one ventricle in one minute

77
Q

tissue fluid definition

A

fluid containing water, glucose, AAs, FAs, ions, oxygen which bathes the tissues

78
Q

Tissue fluid formation through ultrafiltration

A

blood entering from arterioles has high hydrostatic pressure
water, glucose, ions, AAs, FAs forced out of capillaries

79
Q

what is forced out of capillaries in tissue fluid and what remains

A

out:
water molecules
dissolved minerals and salts
glucose
small proteins
AAs
FAs
oxygen

in:
RBCs
platelets
large proteins

80
Q

reabsorption of tissue fluid?

A

large molecules in capillaries cause lowered wp in them
towards venule end, hydrostatic pressure is lowered due to loss of liquid, but wp is very low
water reenters capillary by osmosis

81
Q

why is the lymphatic system needed?

A

not all liquid will be reabsorbed by osmosis
eqm will be reached
rest of tissue fluid is absorbed into the lymphatic system which eventually drains back into the bloodstream near the heart

82
Q

transpiration

A

loss of water vapour from the stomata by evaporation

83
Q

4 factors affecting transpiration

A

light
temp
humidity
wind

84
Q

light effect on transpiration

A

causes more stomata to open
larger SA for evaporation

85
Q

temp effect on transpiration

A

more heat
more EK
faster moving molecules
more evaporation

86
Q

humidity effect on transpiration

A

negative correlation
more water vapor in air will make wp outside leaf more +ve
this reduces the diffusion gradient

87
Q

wind effect on transpiration

A

more wind blows away humid air containing water vapor
maintaining diffusion gradient of gaseous water molecules

88
Q

cohesion tension theory purpose

A

allows water to move up a plant against gravity for long distances

89
Q

cohesion tension theory

A

cohesion
adhesion
root pressure

90
Q

cohesion

A

hydrogen bonds between water molecules
they stick together
they travel up the column as a continuous water column

91
Q

adhesion

A

water sticks (adheres) to xylem walls
the narrower the xylem, the bigger the impact of adhesion

92
Q

root pressure

A

as water moved into the roots by osmosis it increases the volume of liquid inside the root
this is root pressure
the increase in rp forces water above it upwards (positive pressure)

93
Q

movement of water up xylem

A
  1. wv evaporates out of leaf stomata
  2. lower pressure created here
  3. more is pulled up the xylem to replace it
  4. hydrogen bonds make them a cohesive column of water in the xylem
  5. water molecules adhere to xylem walls too
  6. as the water column is pulled up is creates tension so the xylem is pulled in to become narrower
94
Q

phloem tissue 2 key cells

A

sieve tube elements
companion cells

95
Q

sieve tube elements structure

A

living cells
no nucleus
few organelles

96
Q

companion cells purpose

A

provide ATP for AT of organic substances

97
Q

source cell example

A

leaf

98
Q

sink cell example

A

root

99
Q

Translocation 3 steps

A

How is sucrose transported from the source to the sieve tube element
Movement of sucrose within phloem’s sieve tube element
Transport of sucrose to sink

100
Q

How is sucrose transported from the source to the sieve tube element

A

photosynthesis occurs in leaves so high sucrose conc is there, so sucrose is actively transported into the sieve tube element using the companion cell.

101
Q

How does sucrose move within the phloem sieve tube element

A

increase of sucrose in the STE lowers it’s wp
water enters STE from surrounding xylem vessels via osmosis
increase in water volume in STE increases hydrostatic pressure causing the liquid to be forced towards the sink

102
Q

How is sucrose transported to the sink cells

A

sucrose used in respiration at the sink/stored as insoluble starch
more sucrose is actively transported into the sink cell so the wp decreases there
this causes osmosis from the STEs to the sink cells (and some to the xylem)
that also decreases water volume in the STEs, decreasing their hydrostatic pressure

103
Q

How do you explain the movement of soluble organic substances in plants?

A

They are due to the difference in hydrostatic pressure between the source and sink end of the STEs

104
Q

Tracer experiment

A

plants grown in radioactively labelled carbon dioxide
used in photosynthesis to create sugars with the RLCO2
thin slices of the stems are cut and placed on an xray film that turns black when exposed to radioactive material
the section of the stem containing sugars turns black, highlighting the phloem and showing sugars are transported by the phloem

105
Q

Ringing experiment

A

a ring of bark and phloem are peeled and removed from a tree trunk
the trunk swells above the removed section
analysis of the liquid in the swelling region shows that it contains sugar
when the phloem is removed, sugars can’t be transported and the phloem therefore transports sugars

A-Level Bio (9 decks)

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