6.1 Organisms and Exchange Flashcards

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1
Q

Name 4 substances organisms needs to exchange in their environment

A
  1. Oxygen for aerobic respiration
  2. Nutrients
  3. Waste products such as carbon dioxide and urea
  4. Heat to stay at the same temperature
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2
Q

How do single-celled organisms exchange substances?

A
  • diffuse directly into or out of the cells across the cell-surface area
  • quick diffusion rate = short distance substances have to travel
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3
Q

Why is diffusion across the membrane too slow in multicellular animals? (2 reasons)

A
  • some cells are deep within the body so there is a big distance between cells and outside environment
  • larger animals have a low SA:V = its difficult to exchange enough substances to supply a large volume of animal through a small surface area
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4
Q

How does the SIZE of an animal influence its heat exchange?

A
  • rate of heat loss is dependent on surface area of an animal
  • large volume = small surface area = harder to lose heat
  • small volume = large surface area = easy to lose heat
  • smaller organisms need a high metabolic rate in order to generate enough heat to stay warm
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5
Q

How does the SHAPE of an animal influence its heat exchange?

A
  • compact shape = small surface area to their volume = minimal heat loss
  • less compact shape = large surface area to volume = increases heat loss from their surface area
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