6.1: Exchange between organisms + their environment Flashcards

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1
Q

Tissue fluid

A

The environment around the cells of multicellular organisms.

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2
Q

Examples of things that need to be exchanged between an organism and its environment

A

respiratory gases
nutrients
excretory products
heat

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3
Q

Passive exchange process

and examples

A

No metabolic energy is required

eg: diffusion and osmosis

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4
Q

Active exchange process

and example

A

Metabolic energy is required

eg: active transport

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5
Q

For exchange to be effective:

A

The exchange surface(s) of an organism must be large compared with its volume

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6
Q

As organisms become larger their volume…

A

increases at a larger rate than their SA

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7
Q

Organisms have evolved

1 or both of these features

A

A flattened shape so that no cell is ever far from the surface.
Specialised exchange surfaces with large SAs to increase the SA:V ratio.

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8
Q

Example of organisms with a flattened shape

2

A

flatworm or leaf

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9
Q

Examples of organisms with specialised exchange surfaces

2

A

lungs in mammals

gills in fish

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10
Q

When calculating the SA:V of cells assume…

A

The cells have uniform shape

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11
Q

Features of specialised exchange surfaces

5

A

A large SA:V ratio which increases with rate of exchange.
Very thin so short diffusion distance.
Selectively permeable allows selected materials to cross.
Movement of the environmental medium to maintain a diffusion gradient.
A transport system to ensure the movement of the internal medium

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12
Q

Diffusion equation

A

= SA x difference in conc. / length of diffusion pathway

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