Gaseous Exchange Flashcards

1
Q

list the materials an organism will exchange with its environment (4)

A
  • respiratory gases
  • nutrients
  • excretory products
  • heat
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2
Q

what features make a good gas exchange surface? (3)

A
  • large surface area
  • high concentration gradient
  • short diffusion pathway
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3
Q

“for exchange to be efficient, the surface area must be ___________ compared to its volume”

A

large

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4
Q

what is the difference between the SA:VOL ratio of a smaller organism and the SA:VOL ratio of a larger organism?

A

smaller organism = larger SA:VOL ratio
larger organism = smaller SA:VOL ratio

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5
Q

state the advantage and the disadvantage of small organisms having a large SA:VOL ratio

A

advantage
it means having a faster diffusion rate

disadvantage
the animal will lose more heat

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6
Q

what do smaller organisms do to compensate for the extra loss of heat? (3)

A
  • they increase their metabolic activity through processes such as respiration
  • a by product of respiration/metabolism is heat
  • this allows smaller organisms to maintain body temperature.
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7
Q

more heat loss =

A

increased metabolic rate

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8
Q

less heat loss=

A

decreased metabolic rate

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9
Q

state the main disadvantage of large organisms having a small SA:VOL ratio

A

they will have a slower rate of diffusion

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10
Q

what have larger organisms evolved in order to counter their slower rate of diffusion?

A

specialised ‘exchange systems,’ such as the lungs and intestines, that do have a large SA:VOL ratio

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11
Q

what is the name of the gas exchange system in insects?

A

the tracheal system

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12
Q

how does the movement of oxygen into insects occur? (4)

A
  • oxygen enters through the spiracles and into the tracheae
  • spiracles close
  • oxygen diffuses through the tracheae into the tracheoles where gas exchange occurs
  • oxygen is delivered directly to respiring tissues
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13
Q

which exact structure in the insects is the site of gas exchange?

A

the tracheoles

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14
Q

what are the adaptations of the tracheal system (the tracheoles) for efficient gas exchange? (3)

A

highly branched, provide a large surface area for faster diffusion

abdominal pumping, maintains the concentration gradient for oxygen and carbon dioxide

walls are one-cell thick, short diffusion distance

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15
Q

what exactly is abdominal pumping? (2)

A
  • movement of the insect’s body by its muscles
  • increases pressure and so forces carbon dioxide out
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16
Q

insects must balance minimising water loss with efficient gas exchange

to limit water loss, insects may have: (3)

A

rigid exoskeleton
covered with a waterproof cuticle
impermeable so reduces water loss

spiracles close
to prevent water loss

small hairs around the spiracles
trap water
reduces the water potential gradient

17
Q

what is the name of the gas exchange organ in fish?

18
Q

how does the movement of oxygen into fish occur? (6)

A
  • water carrying oxygen moves in through the mouth
  • the gills have finger like projections called gill filaments
  • each filament has many lamellae
  • lamellae contain capillaries
  • most oxygen is removed and enters the capillaries
  • water containing little oxygen leaves through the gill opening
19
Q

which exact structure of the fish is the site of gas exchange?

20
Q

what are the adaptations of the gills for efficient gas exchange? (3)

A

many gill filaments that contain many lamellae
provide a large surface area for diffusion

countercurrent flow
maintains the diffusion gradient along the entire length of the gill lamellae

lamellae have a thin epithelium
short diffusion distance

21
Q

what exactly is countercurrent flow?

A

water with a high oxygen concentration and blood with a low oxygen concentration flow in opposite directions

22
Q

how does the movement of carbon dioxide into plants occur? (3)

A
  • carbon dioxide enters via the stomata, which are opened by guard cells
  • diffuses into the air spaces of the spongy mesophyll down a concentration gradient
  • palisade mesophyll cells have a lower conc. of carbon dioxide owing to photosynthesis, so it moves from the air spaces into these cells down a concentration gradient
23
Q

which exact structure of a plant is the gas exchange organ?

24
Q

what are the adaptations of the leaf for efficient gas exchange? (3)

A

flat
have a larger SA:VOL ratio

many stomata
allow air to move in and out of the leaf

air spaces in the spongy mesophyll
short diffusion pathway

25
**plants balance minimising water loss with efficient gas exchange** to limit water loss, plants contain three key features:
**guard cells close the stomata at night** because less CO2 is required at this time of day **waxy cuticle** **most stomata found in the lower epidermis**
26
what are **xerophytes**?
plants that live in dry/arid environments
27
what are the adaptation of xerophytes **to reduce water loss**? (4)
**thick waxy cuticles** increased diffusion distance **hairs, stomata in pits, rolled leaves** trap water vapour and decreases water potential gradient **spines** reduces the SA:VOL ratio **small leaves with reduced stomata** reduced transpiration
28
what have humans evolved in order to carry out efficient gas exchange?
lungs
29
how do the lungs help with gas exchange?
they provide a **larger SA:VOL ratio**, which enables a **faster rate of diffusion**
30
describe the pathway oxygen takes through the body in order to enter the lungs and blood stream
oral/nasal cavity trachea bronchi bronchioles alveoli
31
which **exact** structure of the lungs is the site of gas exchange?
the alveoli
32
what are the adaptations of the alveoli for gas exchange? (4)
**large surface area** **surrounded by a network of capillaries** ensures a large concentration gradient between the oxygen and carbon dioxide **alveolar epithelium is one cell thick** short diffusion distance **alveolar epithelium permeable to oxygen and carbon dioxide**
33
**mechanics of breathing**: *inhalation* (4)
- diaphragm contracts; flattens - external intercostal muscles contract; rib cage up and out - thoracic cavity: size increases, pressure decreases - air moves into the lungs down a pressure gradient
34
**mechanics of breathing**:*exhalation* (4)
- diaphragm relaxes; returns to its dome shape - external intercostal muscles relax, internal intercostal muscles contract; rib cage in and down - thoracic cavity: size decreases, pressure increases - air moves out of the lungs down a pressure gradient
35
how is **pulmonary ventilation** calculated?
pulmonary ventilation rate = tidal volume x breathing rate