3.3 Organisms Exchange with their Environment Flashcards

1
Q

surface area of a cube, cuboid and cylinder

A

cube (ll) * 6 sides
cuboid 2(lw
lh*hw)
cylinder 2PiR + 2PiR~H

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2
Q

3 adaptations of the tracheal system of an insect

A

1- tracheoles branched to increase surface area
2 - tracheoles have thin walls to reduce diffusion pathway
3 - in stages of movement, fluid is forced out the ends to allow for rapid diffusion

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3
Q

3 adaptations of a xerophyte to prevent water loss

A

1 - sunken stomata to trap water vapour to reduce water potential gradient
2 - small/needle shaped to reduce surface area for water to be lost across
3 - waxy cuticle/waterproof which is impermeable to gases

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4
Q

why is the metabolic rate higher in smaller organisms

A

the larger the surface area to volume ratio, the more heat loss, the more respiration needed to produce the heat lost

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5
Q

how is the alveolar endothelium adapted

A

one cell thick epithelial layer to ensure short diffusion pathway
branched to increase surface area
very close to capillaries to ensure short diffusion distance and steep concentration gradient
moist lining so gases can easily dissolve across

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6
Q

how is the atria different to ventricles

A

ventricles have thicker muscular walls to contract with enough force to provide the necessary pressure

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7
Q

explain how air movement affects transpiration rate

A

a good airflow removes water vapour from the air so the concentration gradient between the leaf and air is maintained which increases water loss

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8
Q

explain how humidity affects transpiration rate

A

causes less transpiration because if air is saturated with water vapour, the concentration gradient is weaker so less water is lost

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9
Q

explain how light intensity affects transpiration rate

A

higher intensity causes more transpiration because the guard cells become turgid so the stomata open allowing water to be lost

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10
Q

explain how temperature affects the rate of transpiration

A

the higher the temperature, the more transpiration occurs as particles have more kinetic energy so diffusion occurs faster

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11
Q

define the hydrostatic pressure

A

the residual pressure from the heart beating which is created when blood is forced through the capillaries

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12
Q

define oncotic pressure

A

the movement of fluid out of the capillaries which causes the water potential of the capillaries to decrease

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13
Q

describe the process of tissue fluid formation

A

there is a high hydrostatic pressure at the arterial end of the capillary and the HSP inside is higher than that in the tissue fluid
this difference in pressure forces water and other small molecules out of the capillary to form tissue fluid
this causes the HSP in the capillary to decrease as water leaves it
the WP at the venue end is lower than the tissue fluid due to a loss of fluid and proteins remaining
some tissue fluid returns to the capillary from the venule end via osmosis
excess TF is drained into the lymphatic system

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14
Q

explain a closed, double circulatory system

A

blood is confined to the vessels and passes twice through the heart for each complete circuit of the body

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15
Q

simply, describe the journey of blood through the circulatory system

A

deoxygenated blood to the vena cava to the right atrium
out the right ventricle via the pulmonary artery to the lungs
oxygenated blood via the pulmonary vein from the lungs into the left atrium
out the left ventricle via the aorta to the body

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16
Q

define myocardial infarction

A

when the coronary arteries are blocked so an area of the heart gets no blood so no oxygen can be used for respiration and the cells begin to die

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17
Q

explain how the structure of an arteriole is related to its function

A

a tough fibrous outer layer resists pressure changes
a muscle layer which contracts to control and reduce blood flow
an elastic layer which recoils to maintain blood pressure
a thin endothelium which is smooth to reduce friction and thin for a short diffusion pathway

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18
Q

explain how the structure of an artery is related to its function

A

a relatively thick muscle layer which constricts and dilates to control blood flow and thus the blood pressure
a comparatively thick elastic layer which stretches and recoils to help maintain high pressure
a large thickness which resists the vessel from bursting from pressure
no valves because the high pressure prevents blood from flowing backwards

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19
Q

explain how the structure of a vein is related to its function

A

thin muscle layer because blood doesn’t flow to tissues so contraction/dilation isn’t necessary
thin elastic layer because they have a low blood pressure
small thickness because they have a low pressure
valves because the low pressure means blood might flow backwards

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20
Q

explain the process of the movement of water across the cells of a leaf

A

mesophyll cells lose water to the air spaces by evaporation
the cells now have a lower WP so water enters them by osmosis from neighbouring cells
this lowers their water potential which, in turn, draws in more water from neighbouring cells by osmosis

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21
Q

explain the process of transpiration

A

water evaporates from the mesophyll cells
due to cohesion, water molecules form hydrogen bonds between one another
due to adhesion, the water molecules form a continuous, unbroken stream down the xylem
more water is drawn up behind the stream as it evaporates
due to tension, the column of water is pulled up the xylem

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22
Q

explain how a xylem vessel is adapted to its function

A

made of dead cells so water can move through unaffected
lignification which supports and strengthens the structure
no end walls so water can move in an unbroken and continuous tube

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23
Q

what are bordered pits

A

cavities in the lignified walls for water to flow between vessels

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24
Q

define a source and a sink

A

a source is a site of production of sugars
a sink is where the sugars will be used or stored for future use

25
explain the mechanism of translocation
sucrose is made from the products of photosynthesis and diffuses down the CG by facilitated diffusion into the companion cells H+ ions are actively transported from companion cells into spaces within cell walls the ions then diffuse down the gradient into sieve tube elements the sieve tubes have a lower WP so water moves from the xylem into sieve tubes by osmosis, creating a higher hydrostatic pressure at the sink, sucrose is used so more is drawn in via active transport causing the hydrostatic pressure to decrease and increase at the source as a result, a mass flow of sucrose occurs down the hydrostatic pressure gradient at STEs.
26
what are companion cells responsible for
supporting sieve elements by carrying out respiration/metabolism
27
describe the structural differences between companion cells and sieve tube elements
companion cells have a dense cytoplasm with lots of mitochondria and large nuclei but sieve tubes have little cytoplasm, no nucleus and ribosomes
28
where are the atrioventricular valves and what is there function
between the left atrium and ventricle + between the right set they prevent back flow by closing when contraction of the ventricles means ventricular pressure exceeds atrial pressure this ensures that blood moves to the aorta and pulmonary artery instead of the atria
29
where are the semi lunar valves and what is their role
they are in the aorta and pulmonary artery they close to prevent back flow into ventricles when the pressure in vessels is higher than that in the ventricles this occurs when the elastic walls of the vessels recoil and their pressure increases and when the ventricular walls relax to decrease their pressure
30
define cardiac output
the volume of blood is pumped by one ventricle of the heart in one minute
31
define stroke volume
the volume of blood pumped out at each beat
32
how is the structure of the capillary related to its function
the walls consist mostly of the lining layer so there is a short diffusion pathway for a quick rate they are numerous and highly branched which increases the surface area for exchange narrow diameter so they can permeate tissues and ensure a short diffusion pathway to all cells narrow lumen so they are close to cells for a short DP there are spaces between the endothelial cells to allow white blood cells to escape in order to deal with infections
33
state the equation for cardiac output
CO = Heart Rate * Stroke Volume
34
explain the events in diastole
muscles in the heart relax atrioventricular valves open because the atrial pressure has increased blood therefore flows into ventricles the atria are filled with blood semi lunar valves remain shut as ventricular pressure is lower than the arteries
35
describe atrial systole
atria walls contract atrioventricular valves are open still this forces the remaining blood into the ventricles from the atria semilunar valves are shut
36
describe ventricular systole
ventricles contract av valves shut because the ventricular pressure has increased semi lunar valves then open and blood is forced into the arteries
37
describe the relationship between the position of the dissociation curve and oxygen affinity
the further the left the curve, the greater the affinity because oxygen was associated at lower partial pressures. the further the right the curve, the lower the affinity because oxygen was only associated at relatively high partial pressures.
38
explain the Bohr effect of carbon dioxide on haemoglobin
the higher the rate of respiration the more carbon dioxide is produced by tissues the large amount of carbon dioxide lowers the pH the lower the pH the greater the HmG shape change oxygen is thus more readily unloaded so there is more oxygen available for respiration
39
describe the structure of haemoglobin
proteins with a quaternary structure, each polypeptide chain is associated with a haem group that contains an Fe2+ ion which can combine with a single oxygen molecule
40
state the site of association and dissociation
associating in the lungs where hmg binds with oxygen dissociating in tissues where hmg releases oxygen
41
what does a high and low affinity mean
high affinity means easy association and that it’s harder to dissociate low affinity means easy dissociation and that it’s harder to associate
42
explain the sigmoid shape of the oxyhemoglobin dissociation curve
1- the gradient is shallow because at low partial pressures oxygen, little oxygen can bind. this is because the hmg shape makes it difficult for the first oxygen molecule to bind to a haem group 2- after the first binding, the quaternary structure/shape changes which makes it easier for other fe2+ ions to bind. this means it takes a smaller increase in partial pressure oxygen for the second oxygen to bind than the first. the gradient steepens. 3- after the third binding, due to probability it is harder for the 4th molecule to bind because it is less likely to find an unoccupied site. the gradient reduces and flattens.
43
describe the process of absorption of triglycerides
micelles come into contact with the epithelial cells lining the villi this causes the break down of micelles to release monoglycerides and fatty acids these are non polar so can easily diffuse across the cell surface membrane into epithelial cells
44
define emulsification
when large lipid globules are broken down into several small lipid globules
45
explain how hydrolysis of lipids occurs
lipase breaks down lipids via hydrolysis creating monoglycerides and fatty acids these attach with bile to form micelles which carry fatty acids and monoglycerides into the intestinal endothelium via endocytosis cholesterol is added across the molecule micelles release the acids and MGs so they diffuse across the membrane into the cell due to non-polarity
46
describe the 4 steps to carbohydrate digestion
1- salivary amylase hydrolyses starch in the mouth into maltose 2- this is swallowed into the stomach where acid denatures amylase and prevents any further hydrolysis of starch 3- once passed into the small intestine, pancreatic amylase continues hydrolysis of starch into maltose 4- when at the ileum, the epithelial lining produces maltase to hydrolyse maltose into alpha glucose
47
explain the adaptations of villi for their function
they increase surface area for diffusion very thin endothelial cells to reduce DP muscular so can mix contents to maintain a CG good supply of blood to maintain gradient microvilli further increase SA for diffusion
48
what does the smooth muscle in bronchi do
dilates when more air is needed and constrict when less air is needed
49
describe the features of the alveoli
numerous to increase SA thin walls to reduce diffusion pathway extensive capillary network to maintain a steep CG
50
what happens if guard cells become flaccid
stomata close so no more water can be lost through them
51
describe what happens to diffusion when an insect is anaerobically respiring
there is a quicker rate because the production of lactate lowers the WP in muscle cells so water at the trachiole ends is drawn into respiring muscle by osmosis. this allows for quicker diffusion of gases.
52
state the structure of a gill
there is a series of gills on each side each gill arch is attacked to two stacks of filaments there are rows of lamellae on the surface of each filament the lamellae surface has a single layer of flattened cells covering the network of capillaries
53
describe and explain the structure of leaves of dicotyledonous plants
they have a waterproof cuticle to reduce water loss the upper epidermis is full of tightly packed cells the palisade mesophyll has elongated cells with chloroplasts the spongy mesophyll provides air spaces for carbon dioxide to diffuse into cellls quickly stomata and guard cells control water loss and are thin for a short DP carbon dioxide is quickly used to maintain the CG
54
describe what happens when the guard cells are turgid
the stoma remain open to allow air to enter
55
describe the need for a specialised system of gas exchange
a supply of oxygen is needed for aerobic respiration to produce ATP for biochemical processes remove of carbon dioxide is necessary because accumulation alters the pH in cells
56
describe how the tracheal system of insects is specialised for their function
a spiracle which is often closed to prevent water loss trachea walls have rings of cartilage to prevent collapsing when breathing pressure changes as oxygen is used quickly by respiring tissues, a CG is maintained so more is drawn into the spiracles
57
describe how more active insects supply themselves with more oxygen
they close their spiracle and use muscles to create movement for ventilation which creates a mass flow of air into the trachea
58
describe and explain the method of using a potomètre
1- cut the plant shoot under water (to prevent air entering) 2- place the shoot in the tube and set up apparatus necessary 3- make sure the tube is airtight using vaseline to seal any gaps (if air enters it will affect readings) 4- dry the leaves of the shoot (moisture affects rate) 5- remove the capillary from the water beaker to allow a single air bubble then put it back 6- set up your environmental factor and allow the plant to adapt 7- record the starting location of the air bubble and leave for a time period 8- then record the end location of the bubble 9- change your investigation factor and reset the bubble by opening the tap, repeat
59
how would you provide the airflow, humidity, light intensity and temperature for the photometer experiment
a fan, spray water in a plastic bag and wrap around the plant, change the distance of the light source from the plant and use the room temperature