Adaptations for Gas exchange Flashcards

1
Q

What is surface area

A

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

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2
Q

What is the volume

A

The total internal volume of the organism

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3
Q

What happens as the size of an organism increases

A

Surface area to volume ratio decreases

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4
Q

Surface are and volume formula for a cube

A

Sa= length x length x 6
V=length^3

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5
Q

Surface area and volume formula cuboid

A

2 x (length x height + length x width + width x height)

Volume = length x height x width

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6
Q

Surface area and volume formula for cylinder

A

SA= circle + round bit

2pir^2 + 2pi x rh

Volume =

Pi x r^2 x h

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7
Q

What does the agar block practical measure

A

The effect of changing surface area to volume ratio on diffusion

By timing rate of diffusion through different sized cubes of agar

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8
Q

Method for agar cube practical

A

Coloured agar is made up and cut into cubes of 0.5 , 1, 2 (cm^3)

Calculate the surface area, volume and ratio between the two for each cube

Place cubes into boiling tubes containing a diffusion solution (HCl)

Same volume of HCL

Measure the time taken for the acid to completely change the colour of the indicator in the agar blocks.

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9
Q

why do small single celled organisms need a high sa :v ratio

A

allows for the exchange of substances by simple diffusion

LARGE SA: maximum absorbtion of nutrients and gases and secretion of waste products

SMALL VOLUME: small diffusion distance

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10
Q

how do large organisms get around having a small SA:V

A

large variety of specialised cells to facilitate the echange of substances between their environment

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11
Q

what two gases mean that a specialised system is used in large animals and why are they so important

A

oxygen - most organisms require ATP for biological procceses which is produced through aerobic respiration - requiring oxygen

Carbon Dioxide - waste product of aerobic respiration, alters PH of cells = bad. It must be removed by the specialised system

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12
Q

why is diffusion not viable for multicellular organisms

A

longer distance
oxygen takes too long to diffuse into the cells
organism dies

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13
Q

what is the metabolic rate of an organism

A

the amount of energy expended by that organism within a given period of time

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14
Q

what is the BMR

A

basal metabolic rate - the metabolic rate of an organism at rest

thus only energy required for functioning of vita;l organs

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15
Q

what is the relationship between metabolic rate and body mass

A

the greater the mass of an organism , the higher the rate

eg. a rhino will require more atp than a mouse

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16
Q

3 adaptations of gas exchange surface

A

Large surface area
Short diffusion distance
Concentration gradient

17
Q

Why is there a need for gas exchange systems in larger organisms

A

Oxygen cannot only diffuse by simple diffusion as the distance would be too long so diffusion takes too long and the diffusion would be too inefficient and the organism would die

18
Q

What do all insects have

A

Rigid exoskeleton with a waxy coating that is impermeable to gases

19
Q

What is a spiracle
And what does it do relating to gases and water

A

An opening in the exoskeleton of an insect which has valves

Allowing air to enter the insect and flow into the system of trachea - most of the time the spiracle is closed to reduce water loss

20
Q

What are trachae

A

Tubes which lead to the trachaeoles
They are reinforced to keep them open as the air pressure inside them fluctuates

21
Q

How is a concentration gradient maintained between tracheoles and muscle cells

A

Oxygen is constantly being used up in respiration - allowing more oxygen to move into the cell by diffusion

This also produces co2 in respiration meaning that it moves out of the cells down the conc gradient

22
Q

How do very active insects get a more rapid supply of oxygen

A

Create a mass flow of air by
Closing the spiracles, using muscles to create a pumping movement for ventilation.

The production of lactate from lactic acid in cells lowers the water potential of muscle cells
Water moves into the muscle
Allows gases to diffuse faster

23
Q

What contains more oxygen , air or water?

A

Air contains around 30x more oxygen than water

24
Q

How are fish adapted directly to extract oxygen from water

A

Series of gills on each side of the head
Each gill is attached to filament
Which is attached to lamellae
Lamellar consists of a single layer of flattened cells that cover a vast network of capillaries

25
Counter current mechanism for converting water to oxygen
Blood flow is in the opposite direction to the flow of water This ensures the concentration gradient is maintained along the whole length of the capillary The water with the lowest oxygen concentration is found adjacent to the most deoxygenated blood
26
Adaptations of a leaf to aid the uptake of carbon dioxide Give the mechanism of this
When guard cells are turgid the stoma is open allowing air into the leaf Air spaces within the spongy mesothelioma layer allows carbon dioxide to rapidly diffuse into cells Carbon dioxide is used in photosynthesis - thus maintaining the concentration gradient Short diffusion pathway with stoma
27
Structures in the leaf
Waterproof cuticle Upper epidermis - tightly packed cells Palisade mesophyll - elongated cells with chloroplasts Spongy mesophyll - layer of cells that contains an extensive network of air spaces Stomata - pores which allow air to enter Guard cells - control opening or closing of stomach Lower epidermis - tightly packed cells
28
What effect do adaptations that reduce water loss have on gas exchange
Negative affect on gas exchange
29
How do insects minimise water loss
Waterproof exoskeleton that prevents water loss Ability to close spiracles Hairs around spiracles - trap water - water potential outside insect on spiracle is high so water cannot leave cell from high to low wp
30
How do xerophytic plants minimise water loss
Few stomata Hair surrounding stomata Needle shaped leaves - reduced surface area Thickened waxy cuticle
31
Adaptations of cacti
Spines that cannot photosynthesise Thick cuticle Large stem - stores water Has both shallow and deep roots allowing it to access all available water
32
Adaptations of Mara grass
Leaves can roll up to limit exposure to wind Exposed surface has no stomata and thick cuticle Large number of hairs