exchange Flashcards

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1
Q

Equation to work out SA:V ratio

A

Surafe area/volume

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2
Q

What does a low SA:V ratio mean

A

A low SA:V ratio means that there are parts of an object that are a long way from the edge. Means there is a longer diffusion distance.

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3
Q

What happens to SA:V as size increases

A

As size increases, surface area:volume ratio decreases

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4
Q

What is an organisms metabolic rate

A

Metabolic rate is the amount of energy expended by that organism in a time period

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5
Q

What is the general rule for metabolism

A

The greater the mass of an organism, the higher the organisms metabolic rate. This is because organisms with high metabolic rate requires more efficient delivery of oxygen to cells as more respiration is needed

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6
Q

How to increase rate of exchange when it’s a big organism

A

Larger organisms come up with specialised surface area

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7
Q

Unicellular organisms

A

They have a large SA:V ratio. Diffusion distance is short to get from outside the cell to the centre. They can exchange materials directly with their environment. They lose water and heat very easily so cant live in very hot or cold climates.

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8
Q

Multicellular organisms

A

They have a small SA:V. Diffusion distance is large. Heat is maintained better so can survive more easily in cold climates. Some cells arent exposed to outside at all so need internal mass transport systems.

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9
Q

Adaptation for cold climate

A

Challenge- heat loss
Behavioural- small mammals with large SA:V. They may also hibernate in the coldest months.
Physical- adapted animals with have a streamlined, compacted body shape to give a smaller SA:V. May also have thick fur e.g. arctic foxes

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10
Q

Adaption for hot climate

A

Challenge- overheating
Behavioural- spending lots of time in the water. Nocturnal as to avoid hot daytime.
Physical- animals with a low SA:V often have larger ears to increase surface area

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11
Q

Adaption for dry climates

A

Challenge: water loss
Behavioural- may be nocturnal so most active in cooler temperatures
Physical- small animals with high SA:V have kidney structures to produce less urine

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12
Q

Structure of insects

A

Evolved to live on land and have microscopic air filled pipes. Trachae divides into tracheoles. Divides until they penetrate into individual body cells. Gases are directly exchanged between cells and the atmosphere- there is no need to transport them. Air enters the trachea through pores on the surface of the exoskeleton called spiracles. CO² and O² will diffuse in/out of spiracles down there concentration gradient for gases. Spiracles can be closed/not open all the time, this is to prevent water loss a d to keep the organism waterproof

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13
Q

Structure of fish

A

Each gill is made of lots of gill filaments which are attached to a bony arch which creates a large surface area for water or flow over. Gill filaments have tiny folds called lamellae which increase surface area. Lamellae have lots of blood capillaries and a thin layer of cells.

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14
Q

What is countercurrect flow

A

Countercurrent flow is where blood and water flow over and through the lamellae in opposite directions to each other. Blood flows next to water that has higher oxygen concentration, so diffusion happens along the full length of the lamellae. Blood absorbs more and more oxygen as it moves along. Even when blood is highly saturated there is still a concentration gradient so more oxygen can flow in

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15
Q

Adapted structure for fish

A

Thin walls for lamellae- shortens diffusion distance
Lots of gill filaments and lamellae- increases surface area
Countercurrent flow of blood to water- maintains concentration gradient
Large number of capillaries and lamellae- circulation constantly removes oxygenated blood to maintain steep concentration gradient
Ventilation by operculum- ensures fresh water always goes over gills to replace lost oxygen.

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16
Q

How does ventilation work in fish

A

The mouth opens, so the operculum shut. Water enters cavity due to a decrease in pressure. The mouth then closes which opens the operculum. This increases pressure which forces the water out of the gills.

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17
Q

Where does co² enter and oxygen leave

A

Happens in the stomata normally on the lower epidermis

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18
Q

What is right above the lower epidermis

A

The spongy mesophyll

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19
Q

Adaption of spongy mesophyll

A

Lots of air gaps which means there is more air space to allow diffusion through the gas phase and increase SA:V formexchnage into photosynthesising cells

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20
Q

What tissue is above the spongy mesophyll

A

The palisades mesophyll tissue

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21
Q

Adaptions for palisade mesophyll layer

A

It is more compact to increase light absorption by chlorophyll. High rate of photosynthesis which maintains a steep concentration gradient.

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22
Q

What layer is above the palisade mesophyll tissue

A

The upper epidermis

23
Q

Adaption of upper epidermis

A

Has few to no stomata which is topped with a waxy cuticle in order to limit water loss.

24
Q

What is the compensation point

A

At night a plants gas exchange reverses and begins a net absorption of oxygen and releases co². The point in the day when net co² uptake is 0 is the compensation point.

25
Q

How do guard cells work

A

ATP-powered proton pump transports hydrogen ions out of cells. The potassium ions diffuse into cells down electrochemical gradient. This lowers water potential inside the cell. Wated enters cell by osmosis. The turgid pressure in the cell increases. The thin wa,,s bend more so the cell curves and the stoma opens

26
Q

Where does gas exchange take place in mammals

A

In the lungs

27
Q

Structure of lungs

A

.air goes through the mouth and down the trachea. Trachea splits in half turning into bronchi, which branch of into bronchioles. These goe into the alveoli which are small air sacs

28
Q

Structure of aveoli

A

. Alveolar epithelium and capillaries are very things diffusion distance is very short
. Lots of alveoli which increases surface area
. Constant ventilation of air in and out of lungs- ensures concentration of oxygen in alveolus is higher nd concentration of co² is lower than blind and therefore maintains a steep concentration gradient.

29
Q

Process of Inhalation

A

Diaphragm contracts and moves down. External intercostal muscles contract and pull the ribcage up and out. Increases volume in thoracic cavity which reduces air pressure. Air rushes in due to there being a concentration gradient.

30
Q

Process of exhalation

A

Diaphragm relaxes and moves up. External intercostal muscles relax and move ribcage down and in. Decreases volume in thoracic cavity which increases the air pressure because there is less space. Air moved out of the trachea down the pressure gradient.

31
Q

what 2 measurements telling you about the lungs functioning

A

ventilation and tidal volume

32
Q

how to measure lung function

A

by using a spirometer and work out breathing rate, the tidal volume and ventilation from this alone.

33
Q

what is forced expiratory volume

A

the maximum volume of the air that can be breathed out in one second

34
Q

what is forced vital capacity

A

the maximum volume of air it is possible to breathe forcefully out of the lungs

35
Q

two types of lung disease

A

restrictive disease and obstructive disease

36
Q

what is restrictive lung disease

A

makes it hard to fully breathe in. severely reduces FVC but FEV is less impacted

37
Q

what is obstructive lung disease

A

makes it hard to breathe out as air ways are blocked. both FVC and FEV are both very low

38
Q

tuberculosis

A

cause- bacteria inhaled. the macrophage build up makes hard lumps in alveoli. eventually the infection will die and damage the alveoli
effect- alveoli have smaller SA. scar tissue is thicker. less elasticity.
tidal volume- decreased
ventilation rate- increased

39
Q

pulmonary fibrosis

A

cause- formation of scar tissue in the lungs after an infection or breathing in substances
effect- scar tissue is thicker. elasticity is reduced.
tidal volume- decreased
ventilation rate- increased

40
Q

asthma

A

cause- airways become inflamed due to an allergic reaction to inhaled substances
effect- reduces rate of gas exchange
FEV-severely reduced

41
Q

salivary gland and carbohydrates

A

amylase enzyme in saliva which breaks glycosidic bonds in starch to form maltose

42
Q

pancreas and carbohydrates

A

pancreatic amylase released into the small intestine which breaks glycosidic bond to hydrolyse starch to form maltose

43
Q

small intestine and carbohydrate

A

membrane bound disaccharidase into cell membrane of epithelial cells as it breaks glycosidic bonds to hydrolyse disaccharides

44
Q

how do the monosaccharides get into the cell

A

glucose and galactose- co transport with sodium
fructose- facilitated diffusion through channel protein

45
Q

digestion of proteins

A

peptidase breaks down proteins. hydrochloric acid in stomach creates optimum pH for enzyme pepsin which is secreted by cells which line the stomach. other peptidases are membrane-bound and found within cells that lined the ileum. the single amino acids are then absorbed into the bloodstream.

46
Q

three types of protease enzymes that breaks bonds

A

endopeptidases- inside hydrolyse peptide bonds within a large protein to create smaller polypeptide chain. creates more terminal ends for exopeptidases
exopeptidases- outside. hydrolyse terminal peptide bonds to remove individual amino acids and create smaller polypeptide chains
dipeptidase- a type of exopeptidase. these are often located on the membrane of epithelial cells lining the small intestine. the work specifically on dipeptides to hydrolyse the peptide bond holding them together. this creates two single amino acids which can then be transported through membrane into the epithelial cell

47
Q

what does a lipase reaction turn a triglyceride into

A

fatty acids and monoglycerides

48
Q

where are lipase

A

they are made in the pancreas and secreted into the small intestines

49
Q

where are bile salts

A

they are produced in the liver and stored in the gallbladder which releases them into the small intestine

50
Q

what does bile salts do

A

breaks down large fat globules by emulsifying them into small droplets. helps to speed up the action of lipase by increasing surface area.

51
Q

what happens once the lipid is broken down

A

the monoglycerides and the fatty acids stay attached to the bile salts and for micelles which help to absorb fat into the blood stream.

52
Q

absorption of amino acids

A

happens in the small intestine. the villi are folded thin and have a good blood supply. amino acids are absorbed by co transport binding to a sodium ion.

53
Q

absorption of lipids

A

micelles hit epithelial cells and breakdown allowing monoglycerides and fatty acids to diffuse across membrane because they are lipid soluble. transported to endoplasmic reticulum where they are resynthesised into triglycerides. inside Golgi, bind with cholesterol and protein to for chylomicrons. chylomicrons travel in a vesicle to the cell membrane and go through exocytosis into the lymphatic vessel as its too big to get into capillary.