TOPIC 3A-EXCHANGE AND TRANSPORT SYSTEMS Flashcards
A) In all organisms what substances do they need to take in and excrete from the environment?
A)-cell’s organisms need to take O2 in (aerobic respiration) + nutrients
-they also need to excrete waste products like CO2 + urea
B) Outline the main factors that affect organisms with substance exchange with their environment
B)-most organisms need to stay at roughly same temp so heat needs to be exchanged too
-also how easy substance exchange occurs depends on the organism’s SA:V ratio.
A) EXAMPLE: A hippo can be represented by a block (2cm x 4cm x 4cm) and a mouse can be represented by a cube (1cm x 1cm x 1cm). Compare their S.A: V ratio.
A) HIPPO: volume= 2x4x4= 32cm3
- its S.A= 2x4x4=32cm2 (top + bottom surfaces of cube)
- -> + 4x2x4=32cm2 (4 sides of cube)
- ->total S.A= 64cm2
- ->so hippo SA: V is 64:32 –> 2:1
MOUSE: volume= 1x1x1= 1cm3
- it’s S.A: is 6x1x1=6cm2
- ->so mouse S.A: V ratio is 6:1
B) Therefore what does this comparison of SA:V ratio show?
B)-cube mouse’s S.A is 6 times it’s volume BUT cube hippo’s S.A is only twice it’s volume
–>so smaller animals have a bigger surface area compared to their volume.
A) What main substances do all organisms needs to supply every cell with and excrete?
A)-need to supply all cells with substances like glucose and oxygen (for respiration)
-also need to remove waste products from all cells toa avoid damaging itself.
B) Describe the exchange of substances in single-celled organisms
B)-the substances can diffuse quickly in or out of cell across cell-surface membrane
–>diffusion rate is quick due to small distances substances have to travel
C) Outline and briefly explain the main 2 reasons as to why diffusion of substances across the outer membrane in multicellular organisms is slow
C)1-some cells deep in the body–>means big distance between them and outside environment
2-large animals have low S.A:V ratio–>therefore difficult to exchange enough substances to supply large volume animal through relatively small outer surface.
D) Define the term “mass transport”
D)-an efficient system used to carry substances to an from their individual cells.
E) What is mass transport referred to in mammals?
F) Therefore, what do multicellular organisms need for substance exchange?
E)-normally refers to circulatory system which uses blood to carry glucose + oxygen around body
–>it also carries hormones/antibodies + waste like CO2
F)-need specialised exchange organs
-also need efficient exchange system to carry substances to and from inidividual cells–>mass transport.
G) Describe “mass transport” in plants
G)-involves transport of water and solutes in xylem and phloem.
A) How does heat generated from metabolic activity affect an organism and what is it influenced by?
A)-it means organism has to try and remain at it’s right temperature which is pretty heavily influences by an organisms size + shape.
B) Explain how the rate of heat loss from an organism depends on it’s S.A (effect of organism’s size)
B)-larger organisms (like hippo) have smaller S.A
- ->makes it harder for it to lose heat from body
- if organism small (e.g: mouse) its relative S.A large so heat lost easier
- ->mean smaller organisms need relatively high metabolic rate to generate enough heat to stay warm.
A) Briefly explain how a “compact” and “non-compact” shaped animal affects heat loss
A)-compact: have small S.A relative to volume –>minimising heat loss
- less compact (those that are “gangly”/with “sticking out bits”) have large S.A relative to volume
- ->this increases heat loss from their surface.
B) What affects an animal as to whether it’s compact or not?
B)-depends on temperature of animals environment.
C) Outline the body temperature and average outside body temperature of the following animals and how their shape affects their S.A:V ratio
C)1-ARCTIC FOX: body temp about 37 degrees C/average outside temp around 0 degrees C
–>small ears + round head to reduce SA:V + heat loss
2-AFRICAN BAT-EARED FOX: body temp 37 degrees C + average outside temp about 25 degrees C
–>big ears + pointier nose to increase S.A:V + heat loss
3-EUROPEAN FOX: body temp 37 degrees C/average outside temp 12 degrees C
–>is intermediate between the 2 foxes to match temp of it’s environment.
A) State and explain the following additional adaptations that animals also have for the following problems they experience in their environment:
1-High S.A:V animals tend to lose more water
2-To support high metabolic rates
3-samller mammals
4-Larger organism in hot regions trying to stay cool (e.g: elephants/hippos)
A)1-lose more water as it evaporates from their surface
–>some small desert animals have kidney structure adaptions so produce less urine to compensate
2-so small mammals living in cold regions need to eat lots of high energy foods like seeds/nuts
3-these may have thick fur layers/hibernate when weather gets v. cold
4-elephants developed large flat ears to increase their S.A so can lose heat more
-hippos spend much of day in water–>a behavioural adaptation to help them lose heat.
A) What 3 main features do most gas exchange surfaces have in common and so outline their overall effect
A)1-have large S.A
2-they’re thin (often 1 layer of epithelial cells)
–>this provides short diffusion pathway across exchange surface
3-organism also maintains steep concentration gradient of gases across exchange surface
-all of these features have overall effect of increasing diffusion rate.
B) How do single-celled organisms exchange substances with their environment and what features do they have to aid this process?
B)-they absorb and release gases by diffusion through their outer surface
- features: relatively large S.A + thin surface + short diffusion pathway (oxygen can’t take part in biochemical reactions as soon as diffuses out of cell)
- ->so no need for gas exchange system.
A) Why do fish have special adaptations to get enough oxygen?
A)-there is low concentration of oxygen in water than air
B) Describe how the gills of a fish are adapted to acquire the maximum amount of oxygen from the water (reference to diagram of gill)
B)1-each gill made of lots of thin plates–>gill filaments
–>these give large S.A for gas exchange
2-gill filaments covered in lots of tiny structures called lamellae
–>these increase S.A even more
-lamellae have lots blood capillaries + thin surface layer of cells to speed diffusion up
C) Explain the counter-current flow system in fish
C)-blood flow through lamellae in one direction while water flows over in opposite direction–>counter-current flow system
- ->this maintains concentration gradient between water and blood
- ->concentration of oxygen always higher in water than blood so max O2 diffuses from water in to blood.
A) Outline the structure used by insects in their body for gas exchange
A)-insects have microscopic air-filled pipes called trachea which used for gas exchange.
B) Step-by-step describe the gas exchange in insects from taking oxygen in and getting rid of CO2
B)-air moves into trachea via pores on surface called spiracles
- ->O2 travels down conc gradient towards cells
- ->trachea branch off in to smaller tracheoles that have thin permeable walls and go to individual cells
- ->this means O2 diffuses directly in to respiring cells (means insect’s circulatory system not transport O2)
- CO2 from cells moves down it’s own conc gradient towards spiracles to be released in to atmosphere
- insects use rhythmic abdominal movements to move air in and out of the spiracles.
A) Describe the involvement of the main two gases O2 and CO2 in plants
B) What is the main gas exchange surface in the leaf?
A)-plants need CO2 for photosynthesis which produces O2 as “waste” gas
–>they need O2 for respiration which produces CO2 as waste gas.
B)-it’s the surface of the mesophyll cells in the leaf.
C) Explain how this gas exchange surface is adapted for efficient gas exchange
D) What controls the opening and closing of stomata?
C)-well adapted as have large S.A
-mesophyll cells are inside leaf
–>gases move in + out through special pores in epidermis called stomata (singular=stomata)
-stomata can open to allow exchange of gases
–>and close if plant losing too much water
D)-guard cells.
A) What is the side effect of gas exchange in plants and insects?
B) Consequently how do plants and insects respond to this problem?
A)-tends to make them lose water–>sort of trade-off between the 2
B)-luckily plants + insects have evolved adaptations to minimise water loss without reducing gas exchange too much.
C) How are insects adapted to reduce water loss?
C)-they close their spiracles using muscles
- ->also have waterproof waxy cuticle all over their body
- ->and have tiny hairs around spiracles
- ->these 2 adaptations both reduce evaporation.
D) In appropriate detail explain how plants are adapted to reduce water loss during gas exchange
D)-plant’s stomata usually kept open during day to allow gaseous exchange
- ->water enters guard cells making them turgid which opens stomatal pore
- ->if plant starts to get dehydrated guard cells lose water and become flaccid which closes pore.
E) Describe “xerophytes”
E)-these are plants that are specially adapted fro life in warm, dry or windy habitats where water loss a problem.
F) Briefly explain the following adaptations of xerophytes:
1-Stomata sunken in pits 2-Layers of "hairs" on epidermis 3-Curled leaves with stomata inside 4-Reduced n. of stomata 5-Waxy, waterproof cuticles
F)1-these trap moist air–>reduces conc. gradient of water between leaf and air
–>reduces amount of water diffusing out of leaf and evaporating
2-again these too trap moist air round stomata
3-protecting them from wind (windy conditions increase diffusion + evaporation rate)
4-so there are fewer places for water to escape
5-these found on leaves and stems–>reduce evaporation.
A) When does VENTILATION and the GAS EXCHANGE SYSTEM come in to action in humans?
A)-comes in to action when humans need to get O2 into blood (for respiration) and get rid of CO2 (made by respiring cells)
B) Outline how the breathing system splits down further and further in humans when air is breathed in
B)1-as breathe in air enters trachea (windpipe)
- ->trachea splits to 2 bronchi–>1 bronchus leading to each lung
- ->each bronchus branches off into smaller tubes-bronchioles
- ->bronchioles end in small “air sacs” called alveolus
- ->gas exchanged here.
C) State the 3 parts of the gas exchange system that work together to move air in and out
C)-ribcage/intercostal muscles and diaphragm.
A) What does ventilation consist of?
B) What is ventilation controlled by?
A)-inspiration (breathing in) and expiration (breathing out).
B)-controlled by movements of diaphragm/internal and external intercostal muscles + ribcage.
C) Briefly explain the process of inspiration step-by-step
C)1-external intercostal + diaphragm muscles contract
2-this causes ribcage to move up + out and diaphragm flattens
–>increases thoracic cavity volume (space where lungs are)
3-as thoracic volume increases–>lung pressure decreases (to below atmospheric pressure)
4-air will always flow from high to low pressure area (i.e: down a pressure gradient)
–>so air flows down trachea into lungs
D) What type of process is “inspiration”?
D)-active process–> needs energy.
E) Describe step-by-step the process of “expiration”
F) Outline the type of process that normal expiration is
E)1-external intercostal + diaphragm muscles relax
2-ribcage moves down + in and diaphragm becomes curved again
3-thoracic volume decreases–>causes pressure to increase (to above atmospheric pressure)
4-air forced down pressure gradient and out of lungs F)-passive process–>not need energy
G) How does “forced expiration” work?
G)-during forced expiration external intercostal muscles relax AND internal intercostal muscles contract
- ->pulling ribcage further down + in
- ->during this time movement of the 2 sets of intercostal muscles said to be antagonistic (opposing).
A) Describe “alveoli”
B) What is each alveolus made from?
A)-lungs contain millions of these microscopic air sacs where gas exchange occurs
B)-each one made from single layer of thin, flat cells called alveolar epithelium.
A) Outline the effect of there being lots of alveoli in the lungs
B) What are the alveoli surrounded by?
A)-means there is big S.A for exchanging O2 and CO2
B)-surrounded by network of capillaries.
C) Describe the gas exchange of O2 and CO2 at the alveoli
C)-O2 diffuses out of alveoli across alveolar epithelium and capillary endothelium (type of epithelium that fomrs the capillary wall)
- ->and into haemoglobin in blood
- CO2 diffuses into alveoli from blood and breathed out.
D) Give a summary on the movement of air through the gas exchange system and in particular the diffusion of oxygen in to the blood capillaries
D)-O2 from air moves down trachea, bronchi and bronchioles into alveoli
- ->this movement happens down a pressure gradient
- ->once in alveoli O2 diffuses across alveolar epithelium, then capillary endothelium–>ends up in capillary itself
- ->this movement occurs down a diffusion gradient.
A) Describe how the following features of the alveoli speed up the rate of diffusion so that gas exchange can occur quickly:
1-thin exchange surface
2-large S.A
3-steep conc gradient
A)1-the alveolar epithelium only 1 cell thick
–>means diffusion pathway short (speeds diffusion up)
2-large n. of alveoli means means S.A large for gas exchange
3-steep conc gradient of O2 and CO2 between alveoli and capillaries–>increases diffusion rate
–>this constantly maintained by blood flow and ventilation.
A) What does “lung disease” affect?
B) How do doctors diagnose lung disease?
A)-affects both ventilation (breathing) and gas exchange in lungs–>how well lungs function
B)-by carrying out tests
C) Define and describe the following key terms:
1-Tidal Volume
2-Ventilation Rate
3-Forced Expiratory Volume (FEV1)
4-Forced Vital Capacity (FVC)
A)1-its the volume of air in each breath–>usually between 0.4 dm3-0.5dm3 for adults
2-is n. of breaths per min–>for healthy person it’s around 15 breaths
3-it is the maximum volume of air that can be breathed out in 1 sec
4-is the maximum volume of air possible to breathe out forcefully from lungs after v. deep breath.
D) With reference to the graph (example) show how tidal volume/ventilation rate and other breathing measures could be determined
D)-sharp peak shows deep breath
- ->peak then back down below 2 shows deep breath out
- tidal volume of normal breath shown between 2 dashed lines
PULMONARY TUBERCULOSIS (TB):
A) Describe how ones gaseous exchange surface is damaged when they become infected with tuberculosis bacteria
B) Consequently, what is the effect of the gaseous exchange surface becoming damaged?
A) -the immune system builds a wall around bacteria in lungs
–>this forms small + hard lumps known as tubercles
–>infected tissue within the tubercles dies and gaseous exchange surface damaged.
B)-tidal volume is decreased
C) What does TB also causes and what is the effect?
C)-tuberculosis causes fibrosis–>further reduces tidal volume
A) Describe the formation of fibrosis and what causes it
D)-fibrosis is formation of scar tissue in lungs
- ->could be due to infection OR exposure to substances like abestos/dust
- ->the scar tissue is thicker + less elastic than normal lung tissue.
B) Therefore, why is TIDAL VOLUME and FVC reduced as a result of fibrosis?
E)-means lungs less able to expand so unable to hold as much air as normal
- ->so tidal volume and FVC reduced
- ->i.e: smaller volume of air can be breathed out forcefully)
C) Why is there a reduction in the rate of gaseous exchange from fibrosis?
D) Outline the symptoms off fibrosis
C)-this is as diffusion is slower across a thicker scarred membrane
D)-shortness of breath/dry cough/chest pains/fatigue + weakness
E) Briefly explain why fibrosis sufferers have a faster ventilation rate than normal
E)-to get enough air into their lungs to oxygenate their blood.
A) Describe the lung diseases “asthma”
A)-its a respiratory condition where airways become inflamed + irritated
–>causes vary from case to case but usually due to allergic reaction to substances like pollen and dust
B) Explain what occurs during an “asthma attack” and how it leads to the serious reduction of FEV1
B)-from asthma attack smooth lining of broncholes contracts + lots of mucus produced
- ->causes constriction of airways so difficult for sufferer to breath properly
- ->air flow in + out of lungs severely reduced
- ->so less O2 enters alveoli and moves to blood
- ->reduced airflow means FEV1 seriously reduced
- ->i.e less air can be breathed out per second.
C) What is “emphysema” and what causes it?
C)-is lung disease caused by smoking OR long-term air pollution exposure
–>foreign particles in smoke (or air) become trapped in alveoli
D) Outline how emphysema affects elastin
D)-causes inflammation which attracts phagocytes to the area
–>phagocytes produce an enzyme that breaks elastin (protein found in alveoli cell walls) down
E) How does the loss of elastin cause problems?
E)-elastin is elastic–>helps alveoli return to their normal shape after inhaling/exhaling air
- ->loss of elastin means alveoli can’t recoil t expel air as well (remains trapped in alveoli)
- loss of elastin also leads to destruction of alveoli walls
- ->this reduces S.A of alveoli–>so rate of gaseous exchange decreases.
F) What are the symptoms of emphysema?
F)-shortness of breath + wheezing
–>people with emphysema have increased ventilation rate as they try to increase amount of air (with oxygen) reaching lungs.
A) How do all the diseases described above often make sufferers feel tired and weak?
A)-TB/fibrosis/asthma + emphysema all reduce gas exchange rate in alveoli
- ->less O2 able to diffuse into blood stream–>so body cells receive less O2–>so aerobic respiration rate reduced
- ->means less energy released
- ->so sufferers often feel tiered + weak.
A) What are “risk factors” in terms of diseases and outline an example
A)-all diseases have factors that increase one’s chance of getting the disease
- E.G: widely known if smoke then more likely to get lung cancer
- ->smoking is risk factor for lung cancer.
B) Describe what it means by “correlation” and how it’s normally misinterpreted
B)-it’s a link between 2 things
- normally misinterpreted that correlation is cause of disease BUT it isn’t
- ->E.G: smokers have increased chance of getting cancer but not necessarily mean smoking causes disease
- ->lot’s of other factors to consider.
EXAMPLE 1: Smoking and lung cancer
Study the 2 graphs in detail:
A) Describe the data shown
A)-graph on left shows that n. of adult males in GB who smoke decreased between 1990-2012
-graph on right shows that male lung cancer mortality (death) rate decreased between 1990-2012 in U.K.
B) From the data provided what conclusions may be drawn?
B)-there is correlation between n. of males who smoke and mortality rate for male lung cancer
- ->BUT can’t say one caused other as could be other reasons for trend like death from lung cancer may have decreased as less asbestos being used in homes
- ->not due to less smoking.
C) Outline the other points that needs to be considered when evaluating this data (in terms of this example)
C)-graph on right shows mortality (death) rates
- ->lung cancer cases rate may of been increasing BUT medical advances may mean more surviving
- ->so only mortality was decreasing.
D) You also need to evaluate the way in which scientific data has led to government restrictions on risk factor sources:
Medical studies in the 1950’s and ‘60’s documented the link between smoking and various forms of cancer, particularly lung cancer. What did this evidence prompt the government to do?
D)-prompted first voluntary agreement between government and tobacco companies in 1971
- ->it stated tobacco products + adverts should carry health warning label
- ->as of OCT 2008 picture health warnings made compulsory on all U.K cigarette boxes after studies suggested they more effective than written warnings alone.
EXAMPLE 2: AIR POLLUTION AND ASTHMA (with reference to attached graph)
A) State the information that the 2 graphs provide
A)-top graph shows n.of asthma cases per 100, 000 of population diagnosed in U.K 1996-2000
-bottom graph shows emissions (millions of tonnes) of sulfur dioxide (of air pollutant) from 1996-2000 in U.K.
B) Describe the data shown by the 2 graphs
B)-top graph shows that n.of new asthma cases in U.K fell from 1996-2000 at 87% to 62% per 100,000 people
-bottom graph: shows emissions of sulfur dioxide in U.K fell from 2 to 1.2 million tonnes from 1996-2000.
C) What conclusions may be drawn from the data?
C)1-link between n.of new asthma cases and SO2 emissions in U.K
- ->rate of new asthma cases fallen as SO2 emissions fallen
- ->can’t say one causes other as could be other reasons for trend
- ->E.G: n. of new asthma cases could be falling due to decrease in n. of people smoking
- can’t say asthma cases reduction linked to reduction in pollution (general) either as only SO2 levels studied.
D) When evaluating this data what other points would need to be considered?
D)-top graph shows new asthma cases
- ->rate of new cases may be decreasing but existing cases becoming more severe
- emissions were for whole of U.K but air pollution varies area to area–>E.G: cities tend to be more polluted
- asthma data doesn’t take any other factors into account that may increase risk of developing asthma
- ->E.G: allergies/smoking etc.
