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Biology > Surface area to Volume ratio and Gas Exchange Unit 3.1 > Flashcards

Surface area to Volume ratio and Gas Exchange Unit 3.1 Flashcards

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1
Q

What are properties of single celled organisms? (3 points)

A
  • Large surface area to volume ratio
  • Substances like O2 can diffuse directly in and out of organism
  • Size of cell is limited
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2
Q

Why do multicellular organisms need exchange organisms and transport systems? 3 points

A

Because diffusion across outer membrane is too slow because:

  • Some cells deep within the body so there is a large diffusion distance
  • Smaller SA:vol ratio so the rate of diffusion not fast enough to support needs
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3
Q

What is the trend in the size of an organism and the SA to volume ratio?

A

-The larger the organism the smaller the SA:volume ratio

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4
Q

How can surface area to volume ratio be increased? 2 points

A
  • A flattened shape

- Specialised exchange surfaces with large areas

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5
Q

How do smaller animals maintain there body temperature?

A
  • Due to larger SA:volume ratio smaller animals loose heat more easily
  • High metabolic rate to maintain body temperature -eg mammals and birds
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6
Q

What are two body shape adaptations to increase or decrease heat exchange?

A
  • Large ears - large SA to volume ratio more heat lost to surroundings - animal cools faster in hot climate
  • Small ears - small SA to volume ratio less heat lost to surroundings- animal keeps heat in cold climate
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7
Q

What is a physiological adaptation to lower heat loss in animals?

A

-Hibernation - lowers metabolic rate and body temp, less heat loss

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8
Q

What are 2 behavioural adaptations to increase or decrease heat exchange?

A

-Huddling- eg in penguins- smaller sa to vol ratio- less heat loss

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9
Q

What are 5 features of specialised gas exchange surfaces?

A
  • Large SA:VOL ratio
  • Very thin
  • Selectively permeable
  • movement of environmental medium (maintain concentration gradient
  • transport system
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10
Q

What is the equation for rate of diffusion?

A

rate of diffusion = surface area x concentration gradient / diffusion distance

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11
Q

How is SA:VOL ratio increased for mammals in gas exchange?

A

Many small alveoli which form branching bronchioles

many narrow capillaries

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12
Q

How is rate of diffusion maximised?

A
  • Large SA:VOL ratio
  • Short diffusion distance
  • high concentration gradient
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13
Q

How is diffusion distance for gas exchange in mammals decreased?

A

Capillaries embedded in alveolus wall

Walls of alveoli and capillaries one squamous epithelial cell thick

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14
Q

How is concentration gradient in animals increases to maximise gas exchange?

A

-low concentration of oxygen in blood pumped from heart
-circular system removes O2 brings CO2
-ventilation system removes CO2 brings O2
high conc gradient
O2 and Co2 diffuse from high to low conc gradient

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15
Q

Explain the mechanism that causes forced expiration.

A
  • internal intercostal muscles contract
  • external intercostal muscles relax
  • causes decrease in volume of chest
  • air is forced down a pressure gradient
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16
Q

Explain gas exchange in insect’s.

A
  • Respiration creates conc gradient
  • Rhythmic abdominal movements allow air to diffuse in through spiracle
  • Spiracles open and close -> oxygenated air can be stored in air sacks
  • Air travels through many narrow branched tracheoles which penetrate muscles tissue and lie alongside cells
  • CO2 diffuses out O2 diffuses in
17
Q

How does insect’s movement increase gas exchange

A
  • water in tracheoles
  • Movement
  • > anaerobic respiration produces lactic acid
  • > lowers water potential in cells
  • > water moves into cells by osmosis
  • > increased tracheole surface area for diffusion
18
Q

How is rate of diffusion maximised in insects?

A
  • Many narrow branched tracheoles
  • > increased SA:VOL ratio
  • tracheoles penetrate muscle tissue and lie along side cells
  • > decreased diffusion distance
  • Respiration
  • > increased conc grad
19
Q

How do insect’s limit water loss?

A

Insects have a small Sa:Vol ratio which means they could loose water easily, to limit this they have:

  • Impermeable cuticle made of chitin except on spiracles
  • Spiracles can open and close to prevent water loss in hot climate
20
Q

Explain Ventilation in fish

A
  • Valve closes, mouth open, Buccal chamber expands
  • > Pressure decrease
  • > water flows in through mouth
  • Mouth closes, Valve opens, Buccal chamber contract
  • > Pressure increased
  • > water forced over llamella gills and flows out through valve
21
Q

How do fish increase SA:VOL ratio to maximize gas exchange?

A
  • 4 pairs of gills
  • Each have many filaments
  • Each filament has many lamella
22
Q

How have fish adapted a short diffusion distance to maximize gas exchange?

A
  • Walls of lamallae and capillaries are one squamous epithelial cell thick
  • Walls of capillaries and lamallae close together
23
Q

Explain counter current flow

A
  • Water and blood flow in opposite directions
  • This creates a concentration gradient across the length of the Gill plate
  • Oxygen moves from high concentration in water is lower concentration in blood
  • Higher saturation of oxygen in blood than with parallel flow
24
Q

Explain gas exchange in leaves of a plant

A
  • Spongy mesophyll photosynthesise reducing conc CO2 and increasing conc O2 in air spaces in leaf
  • Creates concentration gradient
  • CO2 diffuses out O2 diffuses in to leaf
  • Occurs at bottom of leaf(lower temp less water loss)
25
Q

How do plants maximise gas exchange

A
  • Flat shape
  • > Increased SA:VOL ratio
  • Many small stomata
  • > Allow air movement in and out of leaf
  • Air spaces in leaf
  • > decrease diffusion distance between air and mesophyll
26
Q

How do plants limit water loss

A

-Stomata open and close to balance has exchange and water loss

27
Q

How do insects maintain a concentration gradient

A

-Rythmic abdominal movements to pump oxygen in/carbondioxide out

28
Q

What is the difference between trachea and tracheae

A

Trachea found in animals, tracheae found in insects

29
Q

How do we breathe in?

A

-Diaphragm muscle contracts and diaphragm flattens
-External intercostal muscles contract in ribcage pulled up
-Volume of thoracic cavity increase and pressure decreases to below atmospheric pressure
-Air moves into lungs down a pressure gradient

30
Q

How do we breathe out?

A

-Diaghragm muscle rexales and moves up
-External inetcostal muscles relax and ribcage moves down
-Causes the volume of the thoricic cavity to decrease and the pressure to increase above atmospheric pressure
-Air moves out of lungs down a pressure gradient

Biology (30 decks)

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