Surface area and gas exchange (p1)

Question 1

surface area

Answer 1

total area of an organism that is exposed to the external environment

Question 2

volume

Answer 2

total internal volume (amount of space inside an organism)

Question 3

as the surface area _______ the surface area:volume ratio decrease.
This is because volume ________ more rapidly than the surface area as the size increases.

Answer 3

as the surface area increases the surface area:volume ratio decrease.
This is because volume increases more rapidly than the surface area as the size increases.

Question 4

single cell organisms have a ____ SA:V ratio which allows for exchange of substance via simple __________. large surface area allows for maximum absorption of nutrients and secretion of gases. small ______means diffusion distance to all organelles is short.

Answer 4

single cell organisms have a high SA:V ratio which allows for exchange of substance via simple diffusion. large surface area allows for maximum absorption of nutrients and secretion of gases. small volume means diffusion distance to all organelles is short.

Question 5

in ____ organism diffusion across the outer membrane is too slow because:
1.________ diffusion distance to cells and tissues in the organisms.
2.less ______ for absorption and secretion of substances.

Answer 5

in multicellular organism diffusion across the outer membrane is too slow because:
1.longer diffusion distance to cells and tissues in the organisms.
2.less surface area for absorption and secretion of substances.

Question 6

As an organism increase in size the SA:V ratio _______

Answer 6

As an organism increase in size the SA:V ratio decreases

Question 7

large___________ animals and plants evolved __________ to facilitate exchange of substances with environment. Have a large variety of specialised,cells, tissues,organs and systems.

Answer 7

large multicellular animals and plants evolved adaptations to facilitate exchange of substances with environment. Have a large variety of specialised,cells, tissues,organs and systems.

Question 8

rather than diffusion multicellualr organism use specialised exchange ________ to absorb and excrete substances.

Answer 8

rather than diffusion multicellualr organism use specialised exchange organs to absorb and excrete substances.

Question 9

exchange organ example

Answer 9

lungs

Question 10

mass transport

Answer 10

multicellular organisms need efficent systems to carry substances to and from indivdual cells e.g circulatory system.

Question 11

need for a specialised system for gas exchange

Answer 11

1. supply of oxygen-organisms require ATP for survival. Majority of ATP produced through aerobic respiration requring oxygen
2. removal of co2-is a waste product of aerobic respiration, if accumulates in tissues alters the pH.

Question 12

Gas exchange surface

Answer 12

gas exchange occurs over gas exchnage surface= a boundary between outside envrionment and internal environment. organisms need oxygen and co2 to diffuse across exchange surface as quick as possible.

Question 13

what do gas exchange surfaces have in common

Answer 13

-large surface area
-thin= short diffusion pathway across surface
-maintains a steep concentration gradients. (increases rate of diffusion)

Question 14

relationship between surface area to volume ratio and metabolic rate.

Answer 14

-the greater the mass of an organism, the higher the metabolic rate
-although metabolic rate increases with body mass the BMR per unit of body mass is higher in smaller animals than in larger animals
-Smaller animals have a greater SA:V ratio so they lose more heat, meaning they have to use up more energy to maintain their body temperature

Question 15

metabolic rate

Answer 15

energy expended by an organism within a given time

Question 16

basal metabolic rate (BMR)

Answer 16

metabolic rate when organism is at rest. BMR is significantly lower than when organism is moving

Question 17

how can metabolic rate be measured

Answer 17

oxygen consumption, co2 production, heat production

Question 18

body ______ and shape affects heat exchange as impacts surface area to volume ______.

Answer 18

body size and shape affects heat exchange as impacts surface area to volume ratio.

Question 19

Other behavioural and physiological adaptations other than size and shape animals may have

Answer 19

1- animals with high SA:V ratio tend to lose more water . some small desert animals hvae kidney structure adaptions to produce less urine tocompensate
2- to support high BMR small mammals in cold regions eat large amounts of high energy foods e.g seeds and nuts
3-larger organisms in hot regions e.g elphants and hippos fid it hard to keep cool due to relatively slow heat loss . Elphants hace large flat ears increas SA. hippos spend much of the day in water-bhevaioural adaptaion.

Question 20

Fish use a _______–_______ system for exchange

Answer 20

Fish use a counter current system for exchange

Question 21

There is a _______ concentration of oxygen in water than air. so fish have special _______ to get enough of it.

Answer 21

There is a lower concentration of oxygen in water than air. so fish have special adaptaions to get enough of it.

Question 22

structure of the gills

Answer 22

each gill is made out of thin plates called gill filaments, which give big surface area for of exchange gases
gill filaments are covered in lots of lamellae increasing surface area further.
lamellae have lots of blood cappilaries and thin surface layer to speed up diffusion

Question 23

counter current system in fish gills

Answer 23

1.blood flows though the lamellae in one direction water flows over in the opposite direction
2. this is called a coungter current system
3.maintains the concerntartion gradient between the water and the blood
4.concentraions of oxygen in water always higher than in blood,so as much oxygen as possible diffuses from the water to the blood.

Question 24

water containing _____ enters the fish through the mouth and passes out through the _______.

Answer 24

water containing oxygen enters the fish through the mouth and passes out through the gills

Question 25

how does the counter -current system maintain a concentration gradient

Answer 25

-water and blood flow opposite directions -so water with relatively high oxygen always flows next to blood with lower concerntartion

Question 26

Adaptations of gas exchange surfaces, shown by gas exchange: -across the body surface of a _______-celled organism -in the _______ system of an insect (tracheae, tracheoles and spiracles) -across the gills of fish (gill lamellae and filaments including the counter-______ principle) -by the _______ of dicotyledonous plants (mesophyll and stomata).

Answer 26

Adaptations of gas exchange surfaces, shown by gas exchange: -across the body surface of a single-celled organism -in the tracheal system of an insect (tracheae, tracheoles and spiracles) -across the gills of fish (gill lamellae and filaments including the counter-current principle) -by the leaves of dicotyledonous plants (mesophyll and stomata).

Question 27

Gas exchange in insects

Answer 27

-terrestrial insects have microscopic airfilled pipes that they used for gas exchange called tracheae -air moves into the tracheae through pores on the surface called spiracles. -oxygen travels down concentration gradient towards the cells -tracheae branch off smaller tracheoles which have thin permeable walls and go to individual cells, means oxygen diffuses directly to the respiraing cells (the insects circulatory system doesn't transport o2) -CO2 moves down concerntration gradients towards the spiracles , where it is released into the atmosphere -use rhythmic abdominal movements to move air in and out if the spiracles.

Question 28

how do insects control water loss

Answer 28

-if loosing to much water close spiracles using muscles to prevent all water loss. -have a water proof waxy cuticle over there bodies (exoskeleton) and tiny hairs around their spiraces which reduces water loss. - small surface area: volume ratio minismise area from which water is lost.

Question 29

what ways is the tracheal system in insects designed to allow gas exchange

Answer 29

-larger surface area of tracheoles and tracheae. -short diffusion pathway from spirical to tracheae to tracheoles. -concertrantion gradient between CO2 and oxygen allowing diffusion

Question 30

why are the end of the tracheoles filled with fluid ( insects)

Answer 30

-tracheal system contains a special fluid for carrying oxygen -sometimes water build up in the bottom of the tracheoles causing slow diffusion -to removes this lactic acid begins to build up (anaerobic repiration) this decreses the water potential , water then moves back into the cells. (osmosis)

Question 31

Spiracles (insects)

Answer 31

Tiny holes that let the air enter the body and prevent water loss. controlled by specialised muscles to be opened and closed. (are mostly closed to prevent water loss) used to pass air into the trachea

Question 32

trachea (insects)

Answer 32

Tube lined with chitin , branches into smaller tubes called tracheoles (contribute to large surface area)

Question 33

tracheoles (insects)

Answer 33

deliver oxygen to cells and tissues of the insect lined with a single layer of cells to reduce diffusion distance fluid filled ends

Question 34

chitin (insects)

Answer 34

inpermeable rings work to stop structure collapsing . Impermeable stop diffusion

Question 35

lactic acid- oxygen dissolved into this fluid when reaches indvidual cells through simple diffusion, ______is released from this proccess into the environment through the _________ (insects)

Answer 35

lactic acid- oxygen dissolved into this fluid when reaches indvidual cells through simple diffusion, CO2 is released from this proccess into the environment through the spiracles

Question 36

exoskeleton (insects)

Answer 36

all insects have an exoskeleton, with a waxy coating that is impermeable to gases

Question 37

how does gas exchange occur at respiring tissues ( insect)

Answer 37

-concentration gradient created as oxygen used by respiring tissues allowing o2 to diffuse through spiracles via diffusion (co2 produce by respiring tissues moves out)

Question 38

how does gas exchange occur at respiring tissues in very active flying insects

Answer 38

-active flying insects require more rapid intake of oxygen. so create a mass flow of air into the tracheal system by -closing the spiracles,using muscles to create a pumping movement for ventelation -during fligh the production of lactate in respiring tissues decreas water potentila of muscle cells -water in narrow end of tracheoles drawn into respiring cells by osmosis -this allows gases to diffuse more quickly

Question 39

limitations of insect tracheal system

Answer 39

relies on a short diffusion pathway so they are limited to how big they can become

Question 40

Gas exchange in dicotyledonous plants

Answer 40

-need carbon dioxide for photosynthesis,produce oxygen as a waste product -they need oxygen for respiration,which produces carbon dioxide as a waste product

Question 41

Structural and _________ compromises between the opposing needs for efficient gas exchange and the limitation loss shown by terrestrial _________and xerophytic plants

Answer 41

Structural and functional compromises between the opposing needs for efficient gas exchange and the limitation of water loss shown by terrestrial insects and xerophytic plants

Question 42

the main gas exchange surface is the surface of ______ cells in the leaf. they are well adapted-they have a large surface area Gases move in and out through special pores in the _______(mainly lower) called _______. They can open for gas exchange and close if loosing to much water._______ cells control the opening and closing of the stomata.

Answer 42

the main gas exchange surface is the surface of mesophyll cells in the leaf. they are well adapted-they have a large surface area Gases move in and out through special pores in the epidermis (mainly lower) called stomata. They can open for gas exchange and close if loosing to much water. Guard cells control the opening and closing of the stomata.

Question 43

upper epidermis

Answer 43

layer of tightly packed cells

Question 44

waxy cuticle

Answer 44

waterproof

Question 45

paliside mesophyll

Answer 45

layer of elongated cells with chloroplasts

Question 46

spongy mesophyll

Answer 46

-has an extensive network of air spaces -air spaces in spongy mesophyll layer to diffuse rapidly into cells

Question 47

lower epidermis

Answer 47

layer of tightly packed cells

Question 48

Guard cells

Answer 48

control opening and closing of the stomata

Question 49

stomata

Answer 49

-tiny pores usually on the underside of leaves -usually kept open during the day to allow gas exchange -each is surroinded by guard cells which open and close the stomatal pore -in this way control rate of gas exchange and water loss by evapouration-as stomata are closed at time water loss would be excessive

Question 50

mechanism of gas exchange in plants

Answer 50

-when guard cells are turgid (full of water) stomata remains open allow air to enter the leaf. -air spaces in spongy mesophyll layer to diffuse rapidly into cells -CO2 is used up quickly in photosynthesis by cells containing chloroplast -maintaing the concerntration gradient -there is no active vetinlation required as thinnes of plant tissues and presence of stomata create a short diffusion pathway

Question 51

how do guard cells control stomata open and close

Answer 51

-when guard cells are turgid (full of water) stomata remains open allow air to enter the leaf. -if plant become dehydrated the guard cells become flaccid and stomata shut

Question 52

some plants are specially adapted to warm,dry and windy habitats where water loss is a problem. these plants=xerophytes. Some adaptaions are:

Answer 52

-stomata sunk in pits to trap water vapour, reducing the concerntartion gradient of water between leaf and the air . reducing evapouration. -layer of hairs on the epidermis to trap water vapour around the stoma -curled leaves with stomata on the inside protecting them from wind (wind can increase evapouration) -reduced number of stomata so their are fewer places water can escape -thicker waxy waterproof cuticles on leaves and stem to reduce evaporation.

Question 53

why do humans need gas exchange?

Answer 53

-humans need to get oxygen into the blood for respiration -they need to remove carbon dioxide produce by respiring cells

Question 54

Ventilation and the exchange of gases in the lungs. The mechanism of breathing to include the role of the diaphragm and the _______ interaction between the external and internal _________ muscles in bringing about pressure changes in the thoracic cavity.

Answer 54

Ventilation and the exchange of gases in the lungs. The mechanism of breathing to include the role of the diaphragm and the antagonistic interaction between the external and internal intercostal muscles in bringing about pressure changes in the thoracic cavity.

Question 55

structure of the human gas exchange system

Answer 55

As you breathe in air enters the trachea. the trachea splits into two bronchi-one bronchus leading to each lung. Each bronchus branches off into smaller tubes called bronchioles. each bronchioles ends in small air sacs called alveoli. This where gas exchanged. the rib cage,intercostal muscles and diaphragm work together to move air in and out.

Question 56

what allows gas exchange in humans?

Answer 56

breathing /ventilation

Question 57

trachea (human)

Answer 57

aiway that leads from the mouth and nose to bronchi. is lined with mucus secreting goblet cells and cilia . the cilia sweep microorganisms and dust away from the lungs

Question 58

lungs

Answer 58

humans have two,both a centeral part of the respiratory system and is where gas exchange takes place

Question 59

bronchi

Answer 59

plural is bronchus . left and right bronchi are at the bottom of the trachea and are similar in structure but narrower.they lead to bronchioles

Question 60

bronchioles

Answer 60

narrow tubes (less than 1mm) carry air from bronchi to alveoli.as they are so narrow and they have no supporting cartillage they can collapse

Question 61

alveoli

Answer 61

main sight of gas exchange in the lungs.Tiny sacs with many structural adaptations to enable efficient gas exchange such as thin walls and a large sa:v ratio.

Question 62

capillary network (humans gas exchange)

Answer 62

extensive network of capillaries surronds the alevoli and are an exchange surface between lungs and blood. during gas exchange oxugen diffuses from the alveoli into the capillaries while co2 diffuses the other way and is exhaled.

Question 63

intercostal muscles

Answer 63

lie between ribs internal contract leading to expiration external contact leading to exhalation

Question 64

ventilation (humans)

Answer 64

consists of inhalation and exhalation, controlled by movement of diaphragm, internal and external intercostal muscles and the ribs.

Question 65

passage of air in humans

Answer 65

nose/mouth---> trachea------> bronchi-----> bronchioles-----> alveoli.

Question 66

inspiration

Answer 66

-external intercostal muscles contract causing ribcage to move up and out -diaphragm contracts cuasing it to flatten -this increases the volume of the thoracic cavity, causing the pressure inside to decrease below atmospheric pressure. -causing air to flow into the lungs -is an active process (requires energy)

Question 67

expiration at rest

Answer 67

-external intercostal muscles relax cuasing ribs to move down and back -diaphragm relaxes moving up into dome shape. -this decreases the volume of the thoracic cavity increasing the pressure forcing air out of the lungs. -passive

Question 68

expiration forced/exercising

Answer 68

-active process -during forced expiration external intercostal muscles relax internal contract pulling ribcage further down and in -during this time the movement of the 2 sets of intercostal muscles is antagonistic -abdominal muscles contact and push organs up against diaphragm increasing internal pressure forcing exhalation.

Question 69

alveoli structure

Answer 69

wall of each alveolus is one cell think, this is the alveloli eputhelium ( short diffusion pathway) walls of cappillaires are made from capillary endothelium (also 1 cell thick) walls of alevoli contain elastin , which is elastic and helps alveoli return (recoil) to their normal shape after inhaling or exhaling air has a layer of moisture

Question 70

The essential features of the alveolar _________ as a surface over which gas exchange takes place.

Answer 70

The essential features of the alveolar epithelium as a surface over which gas exchange takes place.

Question 71

movement of O2 and CO2 in human gas exchange system

Answer 71

-air contianing oxugen enters through nose/mouth and move down the trachea,bronchi and brinchioles into the alveoli. -this movemnt is down the pressure gradient -oxygen then diffuses (down the gradient) into the blood where it can then be transported around the body -CO2 moves along it pressure and concerntration gradient but in the opposite direction to o2 so it can be breathed out.

Question 72

Gas exchange in alveoli

Answer 72

oxygen diffuses out of the alveoli through the alveoli epithelium and capillary endothelium into heamoglobin in the blood. co2 diffuses into the alveoli from the blood

Question 73

Factors affecting rate of diffusion human gas exchnage

Answer 73

alevoli have feature that allow quick gas exchange thin excange surface-alveolar epithelium is only 1 cell thick providing a shirt diffusion pathway large surface area-millions of alveoli so large surface area for gas exchnage also a steep concerntration gradient of o2 and co2 between alveoli and capillaries increasing rate of diffusion this gradient is maintained by flow ofv blood and ventilation.

Question 74

how is concerntartion gradient maintained human gas exchange

Answer 74

-exchange of oxygen and carbon dioxide occurs between alveoli and capillaires - they are exchnaged ina process of diffusion -air in the alveoli contains a high concerntration of o2 and the oxygen diffuses from the alveoli into the blood capillaries before being carried away to the rest of the body for aerobic respiration. -bloof in the capillaries has a relatively low oxygen concerntration and high co2 concerntartion . co2 diffusies from the blood into the alveoli to be exhaled

Question 75

breathing rate (ventilation)

Answer 75

number of breaths / minute

Question 76

forced expiatory volume (FEV)

Answer 76

max volume of air that can be breathed out in a second

Question 77

forced vital capacity

Answer 77

maxiumum volume of air it is possible to breathe forcefully out the lungs after a deep breathe in

Question 78

tidal volume

Answer 78

volume of inspried air per breath at rest

Question 79

total lung capacity

Answer 79

total amount of air the lungs can hold

Question 80

lung diseases affect ________ and gas exchange

Answer 80

lung diseases affect ventilation and gas exchange

Question 81

Tuberculosis

Answer 81

-pulmonary tuberculosis (TB) is cause by bacteria -immune system cells build a wall around the bacteria forming small hard lumps called tubercles -infected tissue in the tubercles dies and gas exchange surface is damaged reducing tidal volume -reduced tidal volume=less air inhaled with each breath so have to breathe faster to take in enough oxygen -common symptoms=persistant cough,coughing up blood and muscus,shortness of breathe,chest pains and fatigue

Question 82

fibrosis

Answer 82

-scar tissue build up in lungs, may be due toinfection or exposure to substances such as asbestos or dust -scar tissue=thicker and less elastic than normal lung tissue -this means lungs ability to expand reduced meaning volume of air can hold reduced-reduce tidal volume and forced vital cpacity -rate of gas exchange reduced as diffusion is slower acroos thick scarred membrane -sympatoms faster ventilation to get enough oxygen, short breath,dry cough ,chest pain,fatigue and weakness

Question 83

asthma

Answer 83

-aiways become inflamed and irritated usually becausex of allergic reactions to substances like dust or pollen -during asthma attach smooth muscle of the bronchioles contracts and a large amount of mucus is produced, causing constriction on the airways making it diffucult to breathe -airflow in and out of lungs reduced so less oxygen enters alveoli and moves into the blood, FEV severly reduced symtoms wheezing tight test and shortness of breath in an attack symptoms can come on suddenly. can be relived by drugs often inhalers which cuase the muscles in the bronchioles to relax and open up the airways

Question 84

emphysema

Answer 84

-cuased by smoking or long term exposure to air pollution- foriegn particles becoem trapped in alveoli -cause inflammation attracting phagocytes to the area thye release the enzyme that breaks down the elastin in wall of alveoli -alveoli can't recoil to exhale air aswell so some air is trapped in alveoli -can cause destruction to alveoli walls decreasing surface area reducing the rate of gas exchnage -symptoms=shortness of breathe ,wheezing , increaed venitlation rate as they try and increase oxygen reaching hteir lungs

Question 85

lung cancer

Answer 85

-tumours devlop if mutations occur in oncogenes or tumour-suppressor genes of bronchiol epitheliol cells-causing uncontolled mitosis and a mass of cells in lumen of the airways -tomour becomes larger as has no methos of prgrammed cell death as it become larger it develops a blood supply (vascularisation) -tumour interfers with normal working of lungs e.g squeezing against blood velssels or cancer cells enetr lymphatic system which may develop an second tomour -symptoms,coughing up blood,persistant cough,coughing increased amount of muscus,bacl or shoulder pain ,wheezing,breathing difficulties,sudden wl.

Question 86

COPD (chronic obstructive pulmonary disease)

Answer 86

- range of lung based diseases such as chronic bronchitis or emphysema -cuased by goblet cells in ciliated epithelium becoming enlarged producing more mucus , this destorys cilia in trachea and prevents them from sweeping mucus away from lungs -mucus contains bacteria,dust and other microorganisms and block narrow bronchioles,causing coughing,scar tissue and infection. -infection attrats phagocytes to the lungs relasing elastase which damaged elasticity of alveolar walls -without enough elastin alveoli breakdown na may burst creating large air spaces in alveoli (reduced SA)and patients become wheezing and breathless as the diseas progresses may need a constanr supply of o2. symptoms shortness of breath, chronic/persistant cough,chest tighness,diffuculty breathing when excersisng or any physical activity.

Question 87

why would a person with lung disease feel tired and weak

Answer 87

-reduce the rate of gas exchnage -less oxygen diffuses into the blood, so body cells recive less oxugen and rate of aeribic respiration decreases -less energy is released causing them to feel tired and weak.

Question 88

risk factors of lung disease

Answer 88

smoking air pollution gentic makeup infection occupation