B3.1-Gas exchange

Question 1

gas exchange definition

Answer 1

The process by which these gases are exchanged between living organisms and their environment

Question 2

why large animals require a specialized gas exchange system

Answer 2

-larger organisms have a smaller SA:V ratio so outer surface of organism cant carry out rapid gas exchange
-specialized larger gas exchange is required
-example: alveoli in lungs, spongy mesophyll

Question 3

properties of gas exchange surfaces

Answer 3

-permeable membrane: allows gases to diffuse across freely
-large surface area: increases quantity of gas exchanged
-thin tissue layer: shorter distance of diffusion, one cell thick
-moist: surface is covered in moisture to allow gases dissolve and diffuse

Question 4

adaptations for maintaining conc gradient

Answer 4

-dense network of capillaries surrounding tissues involved in gas exchange
-continuous blood flow through capillaries surrounding tissues involved ingas exchange
-animals with lungs= ventilate lungs with air, bringing high conc of 02 to alveoli and removing co2
-animals with gills=water is moved through gills, high conc of 02

Question 5

adaptation of gills

Question 6

features of inspiration

Answer 6

-diaphragm contracts, flattens
-external intercostal muscles contract
-ribcages moves up and out
-increasing volume in thorax
-air flows in

Question 7

lung structure

Answer 7

-trachea (made of cartilage rings)
-bronchus
-bronchioles (ending in alveoli)
-diaphragm
-intercoastal muscles
-ribs

Question 8

features of exhalation

Answer 8

-diaphram returns to dome shape
-abdomen muscles contract
-intercostal muscles contact
-ribcage moves down and in
-decreasing volume in thorax
-pressure rises
-air flows out

Question 9

ventilation definition

Answer 9

movement of air in/out of the alveoli in the lungs facilitating gas exchange

Question 10

-how lungs are adapted for gas exchange

Answer 10

1)alveoli secretes surfactant: prevents alveoli walls for adhering, reduced surface tension and provides a moist surface area for gas exchange
2) alveoli provides large surface area
3)short distance for diffusion: alveoli one cell thick
4) alveoli surrounded by extensive capillary beds to create a conc gradient

Question 11

Features of inhalation

Answer 11

-air drawn in
-volume of thorax increases
-diaphragm contracts/flattens
-rib cage moves out
-external intercostal muscles contract
-pressure inside thorax decreases
-abdomen muscles contract

Question 12

Features of exhalation

Answer 12

• air forced out
  -volume of thorax decreases
  -pressure inside thorax increases
  -rib cage moves in
  -external intercostal muscles relax
  -diaphragm relaxes- turns back to dome shape
  -abdomen muscles contract

Question 13

spirometer

Answer 13

measures lung volume

Question 14

tidal volume

Answer 14

volume of air breathed in/out in typical cycle when at rest

Question 15

inspiratory reserve volume

Answer 15

the maximum volume of air that can be breathed in (measured from max point of tidal volume)

Question 16

expiratory reserve volume

Answer 16

max volume of air a person can breathe out (measured from min point of tidal volume)

Question 17

vital capacity

Answer 17

The sum of inspiratory volume plus tidal volume plus expiratory volume

Question 18

adaptations for gas exchange in leaves

Answer 18

1. waxy cuticle; wax lipid layer covers epidermis cells, reduced evaporation of water from leaf
2. guard cells; open and close to allow Co2 and O2 to pass through
   3.palisade mesophyll cells; packed upper region of cylindrical cells containing chloroplast, located to receive max sunlight
3. spongy mesophyll; loosely packed cells, air spaces for gas exchange
4. Veins located in central leaf provide access to all cell layers
   6.stomata; open and close guard cells

Question 19

factors affecting transpiration

Answer 19

1. increased light increases transpiration. Light stimulates guard cells to open -stomata- permits diffusion
2. increased temp increases transpiration. Water particles gain kinetic energy, so particles diffuse through stomata at quicker rate
3. increased winds speeds increases transpiration. Moves water vapor away from leaf when air flows part, reducing conc of water outside leaf.
4. humidity decreases transpiration. Conc of water outside leaf increases, decreases conc gradient.

Question 20

Partial pressure

Answer 20

Pressure exerted by a single gas when found in a mixture of gases

Question 21

Hemoglobin structure in relation to oxygen binding

Answer 21

iron atom in haem group binds with O2.
4 iron atoms means it has the capacity to transport 4, O2.
4 02= fully saturated

Question 22

Affinity

Answer 22

Attraction for more oxygen

Question 23

Cooperative binding

Answer 23

The binding of 1 O2 molecule to haemoglobin increasing its affinity for remaining oxygen.

Question 24

relationship with oxygen binding and affinity

Answer 24

when there is no oxygen bound=low affinity
1 oxygen binds- haemoglobin changes shape making the next oxygen binding easier

Question 25

allosetric binding of CO2 to haemoglobin

Answer 25

-haemoglobin can bind to CO2 whic changes its affinity for O2. This is called allosetery. -binding of Co2 results in increase of release of 02 molecules (bohr shift)

Question 26

structure of foetal haemoglobin

Answer 26

1. has a different structure; 2 alpha, 2 gamma chains 2. has higher affinity for 02

Question 27

mother to feotus transfer

Answer 27

-in placenta capilaries of mother and foetus come close. -foetal side of placenta is lower in 02 and higher in C02 -conc gradient between blood is aided by foetal haemoglobin greater affinty for 02

Question 28

Oxygen dissociation curve

Answer 28

shows the affect of the cooperative binding of 02 molecules (partial pressure against percentage haemoglobin saturation) Explanation; -low partial pressures of 02, haemoglobin has low affinity for 02, shown by slow initial increase -1 02 binds to haemoglobin causing a change which increases the affinity -rapid increase in 02 saturation as partial pressures of o2 increases, allowing additional 02 molecules to bind -high partial pressures- curve flattens and most haemoglobin is saturated

Question 29

oxygen association curve in relation to body

Answer 29

in lungs- high partial pressure of 02 in capillaries -haemoglobin becomes saturated with 02 as it has a high affinity due to high partial pressure -respiring tissues use 02, low partial pressure for 02 around tissues

Question 30

structure of 02 association graph in foetal and adult haemoglobin

Answer 30

foetal haemoglobin graph shifted to left as it has a stronger affinity meaning percentage saturation is higher at every partial pressure

Question 31

oxygen dissociation curve showing adult hemoglobin and CO2

Answer 31

- Co2 shifted to right