Parasites and mutualists
LO: To explain how the survival of
one organism may depend on the
presence of another species
thr...
You have two minutes in pairs to write down
what you think a parasite and a mutualist
is.

Hink: For the mutualist think a...
In most feeding relationships a predator kills
and eats a prey and then moves on to find
a more prey.
Parasites
Parasitism is a feeding relationship in which
two organisms live together with one
feeding off the other.

The o...
Headlice and fleas
Headlice and fleas are parasites. They bite
other animals (hosts) such as humans so
they can feed off t...
Tapeworms
Other parasites, such as the tapeworm, live
inside their hosts. Tapeworms live inside
vertebrate intestines. The...
Tapeworms absorb nutrients from the host’s
gut which can cause the host to lose
weight.
The worm can also grow large enoug...
Add the following point to your
handout:
The scolex- head of the
tapeworm
• The head has hooks and suckers to attach
it to the small intestine wall.
• It has no eyes.
• The flat body gives it a large surface area
for food absorption
• It has no circulatory system, intestines or
much of a ...
• The outside of the worm contain
substances that stop it being digested by
enzymes in the small intestine.
• Each segment contains male and female
reproductive organs so the worm can self
fertilise its eggs if other tapeworms are...
The world's longest parasite is the tapeworm
so the next question is 'What is the world's
longest tapeworm?'
The longest t...
European mistletoe
Believe it or not mistletoes is also a
parasiste.
It has leaves that can photosynthesise but
its roots grow into the veins of the host
tree and absorb water and mineral sal...
Mutualists
Some organisms live in close relationships
where both organisms benefit. This is
called mutualism.
What do you think is happening
here?
Oxpeckers
Oxpeckers have a mutualistic relationship
with large herbivores in Africa.
Both the oxpecker and the herbivore b...
Cleaner fish
Cleaner fish eat dead skin and parasites
from the skin of larger fish, such as
sharks.
You could say a fish pedicure is a
mutualistic behaviour!!- why?
Nitrogen –fixing bacteria
Some organisms live in mutualistic relationships
inside other organisms.
Bacteria that turn nitr...
What do the bacteria gain?
they are protected from the environment
They gain chemical substances from the
plant they use a...
You may remember these from the work on
deep sea volcanic vents in topic 1- what
are they?
They are giant tubeworms.
Chemosynthetic bacteria
Chemosynthetic bacteria are producers that
get their energy from chemical substances
and not from ...
The tubeworms gather
the chemical
substances that the
bacteria need for
chemosynthesis.

The tubeworms
feed on
substances ...
Questions
1. In the human-headlouse feeding relationship,
name
i) the parasite
ii) the host
2. Explain fully the differenc...
Plenary

‘What am I?’ game!
Write down on your mini
whiteboard what the
description is describing
I am an organism
that feeds off
another
I am a parasite!
I am the organism
that the parasite
feed off
I am the host!
I am the worm that
absorbs nutrients from
my host’s intestine
I am a tapeworm
I am the parasite that
takes blood from it’s
host
I am a flea or
headlouse
I am the relationship
where both
organisms benefit
I am mutualism
I am the bacteria
that helps legumes
to gain nitrates
I am nitrogen-fixing
bacteria
I am the bacteria in
tubeworms that allow
them feed on substances
I make
I am
chemosynthetic
bacteria
BWS Parasites and mutualists
BWS Parasites and mutualists
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BWS Parasites and mutualists

  1. 1. Parasites and mutualists LO: To explain how the survival of one organism may depend on the presence of another species through: a)parasitism b)mutualism
  2. 2. You have two minutes in pairs to write down what you think a parasite and a mutualist is. Hink: For the mutualist think about the word mutual!
  3. 3. In most feeding relationships a predator kills and eats a prey and then moves on to find a more prey.
  4. 4. Parasites Parasitism is a feeding relationship in which two organisms live together with one feeding off the other. The organism doing the feeding is a parasite and the organism it feeds on is its host. Parasites usually harm their host but do not kill it. Can you think why this is?
  5. 5. Headlice and fleas Headlice and fleas are parasites. They bite other animals (hosts) such as humans so they can feed off their blood.
  6. 6. Tapeworms Other parasites, such as the tapeworm, live inside their hosts. Tapeworms live inside vertebrate intestines. Their eggs leave the host in its faeces. Eggs swallowed by other animals hatch and grow inside their bodies.
  7. 7. Tapeworms absorb nutrients from the host’s gut which can cause the host to lose weight. The worm can also grow large enough to block the host’s intestines.
  8. 8. Add the following point to your handout:
  9. 9. The scolex- head of the tapeworm
  10. 10. • The head has hooks and suckers to attach it to the small intestine wall. • It has no eyes.
  11. 11. • The flat body gives it a large surface area for food absorption • It has no circulatory system, intestines or much of a nervous system.
  12. 12. • The outside of the worm contain substances that stop it being digested by enzymes in the small intestine.
  13. 13. • Each segment contains male and female reproductive organs so the worm can self fertilise its eggs if other tapeworms are not nearby.
  14. 14. The world's longest parasite is the tapeworm so the next question is 'What is the world's longest tapeworm?' The longest tapeworm ever removed from a human came out of Sally Mae Wallace on September 05, 1991. In all, doctors pulled 37 feet of tapeworm out of Sally Mae Wallace's body through her mouth. If you find all of this disgusting, be glad you're not a whale as tapeworms in whales can grow up to 120 feet long.
  15. 15. European mistletoe Believe it or not mistletoes is also a parasiste.
  16. 16. It has leaves that can photosynthesise but its roots grow into the veins of the host tree and absorb water and mineral salts.
  17. 17. Mutualists Some organisms live in close relationships where both organisms benefit. This is called mutualism.
  18. 18. What do you think is happening here?
  19. 19. Oxpeckers Oxpeckers have a mutualistic relationship with large herbivores in Africa. Both the oxpecker and the herbivore benefit from the relationship. The oxpecker eats parasitic insects that live on the skin of the herbivore.
  20. 20. Cleaner fish Cleaner fish eat dead skin and parasites from the skin of larger fish, such as sharks.
  21. 21. You could say a fish pedicure is a mutualistic behaviour!!- why?
  22. 22. Nitrogen –fixing bacteria Some organisms live in mutualistic relationships inside other organisms. Bacteria that turn nitrogen in the air into nitrogen compounds are called nitrogen-fixing bacteria. Some live inside the roots of legumes (plants like peas that produce pods).
  23. 23. What do the bacteria gain? they are protected from the environment They gain chemical substances from the plant they use as food. What do the legumes gain? It gets nitrogen compounds which it needs to grow well from the bacteria.
  24. 24. You may remember these from the work on deep sea volcanic vents in topic 1- what are they? They are giant tubeworms.
  25. 25. Chemosynthetic bacteria Chemosynthetic bacteria are producers that get their energy from chemical substances and not from light. There are chemosynthetic bacteria inside giant tube worms.
  26. 26. The tubeworms gather the chemical substances that the bacteria need for chemosynthesis. The tubeworms feed on substances made by the bacteria.
  27. 27. Questions 1. In the human-headlouse feeding relationship, name i) the parasite ii) the host 2. Explain fully the difference between parasitic relationships and mutualistic relationships. 3. The tubeworm-bacteria relationship is mutualistic. Explain why each organism needs the other. 4. With the mutualistic relationship of the nitrogenfixing bacteria and the legume what do both organisms gain?
  28. 28. Plenary ‘What am I?’ game! Write down on your mini whiteboard what the description is describing
  29. 29. I am an organism that feeds off another
  30. 30. I am a parasite!
  31. 31. I am the organism that the parasite feed off
  32. 32. I am the host!
  33. 33. I am the worm that absorbs nutrients from my host’s intestine
  34. 34. I am a tapeworm
  35. 35. I am the parasite that takes blood from it’s host
  36. 36. I am a flea or headlouse
  37. 37. I am the relationship where both organisms benefit
  38. 38. I am mutualism
  39. 39. I am the bacteria that helps legumes to gain nitrates
  40. 40. I am nitrogen-fixing bacteria
  41. 41. I am the bacteria in tubeworms that allow them feed on substances I make
  42. 42. I am chemosynthetic bacteria

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