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biolala > Adaptations for Gas Exchange > Flashcards

Adaptations for Gas Exchange Flashcards

1
Q

what happens as a result of a cell increasing in size?

A

diffusion pathway gets longer
slower diffusion
diffusion will not meet the cell’s needs such as supplying nutrients like oxygen and glucose and removing waste like carbon dioxide

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2
Q

define gas exchange

A

process of oxygen into cells/blood and removing carbon dioxide

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3
Q

define ventilation

A

process of bringing an exchange medium like air or water to and from an exchange surface

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4
Q

define respiration

A

hydrolysis of glucose to form ATP/phosphorylation of ADP

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5
Q

what must happen for an organism to become larger?

A

a number of cells must come together so it becomes multicellular

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6
Q

describe 5 factors of unicellular organisms such as amoebas

A

extremely large surface area to volume ratio
gas exchange occurs across the whole surface
permeable membrane allowing diffusion of gases
specialised gas exchange organs are not needed
diffusion is sufficient to meet the oxygen requirements of the organism

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7
Q

describe 3 factors of a flatworm which is a simple multicellular organism

A

this organism has evolved a flattened shape to overcome the problem of an increase in size
this increases their surface area to volume ratio so no cell in the body is far from the surface so there is no need for specialised gas exchange organs as it has a short diffusion pathway
they exchange gases directly with the environment by diffusion and diffusion across the permeable membrane is sufficient to meet the oxygen requirements of the organism

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8
Q

describe 6 factors of an earthworm which is a simple multicellular organism

A

developed a tubular shape and is restricted to damp environments
worms secrete mucus to keep the cells of the body surface moist allowing gases to dissolve and diffuse
elongated shape provides a large surface area to volume ratio compared with a compact organism of similar volume
they exchange gases directly with the environment by diffusion across the moist surface since blood vessels are close to the body surface so gases can diffuse in/out of the blood and then across the cells covering the body surface
blood circulates in the vessels maintaining a conc. gradient for diffusion of oxygen into the cells and carbon dioxide out
blood contains the respiratory pigment haemoglobin to carry oxygen to body cells

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9
Q

why do multicellular organisms require a specialised gas exchange surface? give 8 points

A

as the size of an organism increases its surface area to volume ratio decreases
diffusion across the body is insufficient to provide enough oxygen for organism to survive
larger organisms are more metabolically active so have a higher oxygen demand
diffusion pathway across body surface is too large and rate of diffusion is too slow
so larger multicellular organisms need a specialised gas exchange surface between the organism and its external environment
they are provided with a large area of gas exchange surfaces to increase surface area for diffusion
they also need a method of circulation to distribute the gases around the body
many animals have a toughened body surface so gave internal gas exchange surfaces like lungs

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10
Q

in order to achieve maximum rate of diffusion all respiratory surfaces must be: list 4 things

A

large surface area to volume ratio
thin
moist
permeable

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11
Q

what additional features increase the efficiency of gas exchange in organisms which possess a circulatory system and respiratory pigment?

A

extensive blood supply surrounding the exchange surface because a circulatory system helps to maintain conc. gradient increasing the rate of diffusion

respiratory pigments such as haemoglobin which increase the oxygen-carrying capacity of blood

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12
Q

why do insects need a good supply of oxygen for respiration?

A

since they fly which requires a lot of energy

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13
Q

why is an insects’ gas exchange system different to other animals?

A

they don’t use blood to transport gases

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14
Q

how does air go into the insect?

A

it diffuses into the insect through paired holes called spiracles running along each side of the body. these spiracles lead to a system of branched chitin-lined air tubes called trachea

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15
Q

the spiracles can open and close like valves. why is this important?

A

when its open it allows oxygen in for respiration but when closed it is to reduce water loss

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16
Q

how do insects ventilate during periods of activity?

A

at rest, simple diffusion of gases meets the oxygen needs of the insect, during flight movements of the abdomen ventilate the trachea with the aid of air sacs off the trachea

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17
Q

describe the gas exchange surface of insects

A

the trachea branch repeatedly until they end as very fine thin-walled tracheoles. oxygen diffuses directly from the ends of the tracheoles into the cells and carbon dioxide diffuses out of the cells into the tracheoles. the surface of the tracheoles is lined with chitin which keeps the airways open during body movements while allowing some flexibility

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18
Q

give 4 advantages of the tracheal system for gas exchange

A

oxygen is supplied directly to tissues
no respiratory pigment needed
oxygen diffuses faster in air than in blood
spiracles close to reduce water loss

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19
Q

what is the disadvantage of the insect tracheal system?

A

only efficient in smaller organisms and chitin is heavy so it would slow the insect down if it was too large

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20
Q

why are the gas exchange organs retained inside the body of all terrestrial organisms?

A

reduces water loss
reduces heat loss
protection by the ribs or exoskeleton in insects

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21
Q

what problems are caused by living in water?

A

less oxygen in water than air
rate of diffusion lower than water
water is more dense so doesn’t flow as easily

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22
Q

what two groups can fish be categorised in?

A

cartilaginous fish
bony fish

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23
Q

describe cartilaginous fish eg sharks

A

have a skeleton made entirely of cartilage
nearly all live in sea water
5 gill clefts behind the head on each side
water is taken in the mouth and is forced through the gill slits when the floor of the mouth is raised
gas exchange involves parallel flow: blood in the capillaries circulates in the same direction as water flowing over the gills

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24
Q

describe bony fish eg herring

A

have an internal skeleton made of bone
gills are covered with a flap called the operculum
live in freshwater and seawater
gas exchange involves counter-current flow : blood in the gill capillaries circulates in the opposite direction as water flowing over the gills
usually 4 gills on each side

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25
Q

how does water flow into, through and out of the fish?

A

water is taken in through the mouth, passes over the gills and is expelled via the operculum
movements of the buccal cavity floor and operculum allow a one-way current of water to flow through the gills for exchange of gases

26
Q

describe the structure of the gills of bony fish

A

along each gill arch there are many thin filaments and on these are the gill lamellae . therefore the gill filaments have a large surface area for gas exchange
blood circulates through the gill lamellae into the capillaries and carbon dioxide diffuses out into the water

27
Q

describe how countercurrent works

A

blood always meets water with a higher oxygen concentration
the gradient for diffusion of oxygen into the blood from the water is maintained over the whole length of the gill lamellae
oxygen diffuses into blood across the whole length of gill lamellae
counter-current flow is more efficient than parallel flow as it results in a higher blood oxygen saturation level

28
Q

describe how parallel flow works

A

water is taken into the mouth and blood flows through the gill capillaries in the same direction as the water
gas exchange is very efficient at first as there is a very high concentration gradient
about halfway along the gill lamellae, equilibrium is reached and diffusion of oxygen and carbon dioxide is no longer possible

29
Q

describe briefly the gas exchange in amphibian larvae

A

the larvae live in water so have gills for gas exchange
the adult amphibians are terrestrial so live on land

30
Q

describe briefly the gas exchange in adult amphibians

A

when inactive, diffusion happens across their moist skin
when active, it happens across lungs

31
Q

describe the lung structure of an amphibian

A

lungs have a simple structure with little folding of the gas exchange tissues

32
Q

give the names of structures in the human breathing system

give 14

A

larynx, cartilage, tracheae, left lung, bronchus, heart, diaphragm, alveoli, pleural membranes, ribs, pleural cavity, inner intercostal muscles, outer intercostal muscles, bronchiole

33
Q

why do rings of cartilage support the trachea, bronchi and bronchioles?

A

prevents them from collapsing during inspiration when the pressure is low

34
Q

what is the name of the airtight compartment of the body that encloses the lungs?

A

thorax

35
Q

what is the role of goblet cells?

A

produce and secrete mucus to trap microorganisms, cilia will then waft to move the mucus up and out of the trachea.

36
Q

why is there pleural fluid in the pleural cavity?

A

provides lubrication
prevents friction with other organs and helps lungs to stick with thorax and expand with it

37
Q

what is in each bronchiole?

A

hundreds of alveoli providing a large surface area to volume ratio

38
Q

describe briefly about alveolus

A

each alveolus is lined with a thin film of water, to allow gases to dissolve and diffuse, with lung surfactant which prevents watery lining from creating surface tension

39
Q

describe what happens to the alveoli due to emphysema lung tissue disease

A

alveoli air sacs broken down
drastically reduced gas exchange surface area, reducing surface area to volume ratio and the scarring thickens the walls of the alveoli reducing the efficiency of diffusion.

40
Q

describe the ventilation of the human lungs during inspiration and expiration

A

inspiration:
external intercostal muscles and ribs contracts and moves out and up
outer pleural membrane moves out and up with the ribcage
inner pleural membrane moves out and up with the outer pleural membrane as the pressure in the pleural cavity decreases
thorax increases in volume
diaphragm contracts (flattens)
alveoli increase in volume and lungs pulled out
pressure in alveoli decreases below atmospheric pressure

expiration:
external intercostal muscles and ribs relaxes and moves in and down
outer pleural membrane moves in and down
inner pleural membrane moves in and down
thorax decreases in volume
diaphragm relaxes (dome shape)
alveoli decrease in volume and lungs move in
pressure in alveoli increases above atmospheric pressure

41
Q

describe the pressure changes during inspiration

A

the diaphragm flattens and the rib cage expands pulling on the outer pleural membrane, which lowers the pressure in the pleural cavity
the inner pleural membrane pulls on the lungs which increases the volume of the lungs/alveoli
this in turn decreases the pressure in the alveoli
the pressure in the alveoli is below atmospheric pressure so air moves in

42
Q

what changes would you expect to see during strenuous exercise?

A

greater/faster pressure changes and in volume
faster inspiration/expiration/breathing

43
Q

why is the alveoli suitable as a gas exchange surface?

A

large surface area to volume ratio due to many alveoli
moist
short diffusion distance due to extensive capillary network and walls of alveoli and capillaries are one cell thick
maintenance of conc. gradient - circulation of blood/ventilation of air

44
Q

describe what is surfactant

A

a chemical substance covering the surface of alveoli, reduces surface tension, prevents alveoli from sticking together and collapsing when breathing out

45
Q

why is the cellular demand for oxygen in a mammal higher compared to a fish the same size?

A

mammals are warm-blooded and have to maintain their body temp.

46
Q

list 12 structures in the breathing system and their function

A

external intercostal muscles - when these contract, the ribs are pulled up and out increasing the volume of the thorax
bronchioles - bronchi branch into these smaller tubes
larynx - box-shaped structure above trachea containing vocal cords
alveoli - main site of gas exchange
bronchi - trachea splits into 2 of these
surfactant - prevents alveoli from sticking together and collapsing, reduces surface tension
trachea - tube held open by rings of C-shaped cartilage
ribs - bones moved by intercostal muscles and alter the size of the thorax
diaphragm - dome-shaped muscle relaxes and contracts altering the volume of the thorax
pleural cavity - contains pleural fluid which acts as a lubricant to reduce friction between lungs and inside wall of thorax during ventilation
epiglottis - flap of skin that stops food entering the trachea when swallowing
pleural fluid - acts as a lubricant providing friction-free movement against the inner wall of the thorax

47
Q

out of all organisms studied, which need haemoglobin?

A

mammal, amphibian, earthworm, fish

48
Q

where is the ventilation in the fish?

A

buccal floor movements

49
Q

which organism has water as their respiratory medium?

A

amoeba, flatworm, fish , amphibian (air also)

50
Q

what are the 4 adaptations of leaves to gas exchange?

A

flat/thin
air spaces in spongy mesophyll - means a lot of cell walls are in contact with air
mesophyll walls are wet due to transpiration
structural pores

51
Q

how do plants respire?

A

they generate ATP so they respire all the time
oxygen is required
when light available, plants carry out photosynthesis using chloroplasts, carbon dioxide is required

52
Q

how are plant leaves adapted for photosynthesis? give 7

A

large surface area to absorb as much light as possible

leaves can orientate themselves towards the sunlight

leaves are thin to allow light to penetrate lower layers

cuticle and epidermis are transparent to allow light to pass through the mesophyll below

palisade cells are elongated and densely packed together and contain many chloroplasts

chloroplasts can move and rotate within the mesophyll cells to maximise light absorption

intercellular air spaces allow carbon dioxide to diffuse into cells and oxygen and water vapour to diffuse away

53
Q

where in the leaf is the stomata found and what is their role?

A

lower epidermis
to allow co2 in

54
Q

how many guard cells surround each stoma?

A

2

55
Q

what is unusual about guard cells?

A

they are the only epidermal cells that contain chloroplasts
they have unevenly thickened inner cell wall

56
Q

what causes the stomata to open?

A

light makes potassium ions and water to enter guard cells causing a change in shape
or
potassium pump and entry of water causes stomata to open

57
Q

how does the structure of stomata help it to open/close?

A

inner cell wall is thick and the outer wall is thin so if guard cells become turgid the pore opens and if the guard cell becomes flaccid the pore closes

in some plants the inner cell wall is thin so the ends of the guard cells expand and stoma opens

58
Q

describe in detail the mechanism for stomatal opening

A

potassium ions are actively transported from the epidermal cells into the guard cells
stored starch, which is insoluble, in the guard cells is converted to malate, which is soluble, by enzymes in the cytoplasm
both above processes happen due to ATP
the water potential in the guard cells is lowered so water enters by osmosis
the guard cells become turgid and curve apart because the outer cell walls are thinner than the inner cell walls so they have more stretch.

59
Q

why are stomata open during the day and closed at night?

A

open - plants need co2 to diffuse into the leaf for photosynthesis

close - allows plants to reduce water loss

60
Q

what do chloroplasts provide as a result of photosynthesis?

A

glucose
energy
ATP
sugar

biolala (21 decks)

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