Temperature's Effect on the Rate of Wiggle of a Maggot
I think that the rate of wriggle of the maggot will increase as the
temperature increases, up until the temperature reaches around 40°C
and the rate of wriggle will stay constant. As the temperature reaches
60°C the rate of wriggle will be almost zero.
The rate of wriggle will depend on the amount of chemical reactions
in the maggot. Most or all of these reactions depend on
enzymes. These are biological catalysts. Enzymes are large proteins
that speed up chemical reactions. In their globular structure, one or
more polypeptide chains twist and fold, bringing together a small
number of amino acids
to form the active site. This is the location on
the enzyme where the substrate binds and the reaction takes place.
Enzyme and substrate fail to bind if the shape is not an exact match.
This is often known as the lock and key theory as it is specific to
one and only one substrate. This ensures that the enzyme does not
participate in the wrong reaction. The enzyme itself is unaffected by
the reaction. When the products have been realized, the enzyme is
ready to bind with a new substrate. Temperature is one of the main
factors along with pH that affect the working of enzymes. An increase
in temperature would mean that the substrates were moving around
faster, and therefor, more collisions will occur with the correct
substrates. This is called the collision theory. This would involve a
faster rate of reaction. When this occurs in the maggot, if affects
the rate of respiration which is where the maggot gets a lot of its
energy from. The chemical and word equations for this reaction are
Oxygen + Glucose è Carbon + Water
602 + C6H12O6 è 6CO2 + 6H2O
If the temperature is too cold, the enzyme shape is altered slightly
and the reaction does not happen, as the substrate no longer fits in.
This does not have a long-term effect on it as if the enzyme is warmed
up; it will return to its original shape.
If it's too hot (say above about 38°C), the enzyme shape is again
altered and so the reactions once more do not happen. This is bad news
though as the higher temperatures actually permanently destroy the
enzyme. If boiled, for example, the enzyme would never go back to its
original shape. It would never work again.
The best temperature or "optimum" temperature is when the enzyme's
shape is the best to fit the substrate molecule. For warm-blooded
mammals like humans, this is our body temperature (37°C).
This is the shape of graph I am expecting:
The red represents the steady increase in enzyme activity as the
The blue represents the start of the denaturing of the enzymes
The green represents the total denaturing of the enzymes and the
stopping of the wriggling.
The X represents the optimum temperature.
The main object of my preliminary is to determine what 1 wriggle is
and to decide how often and over what range to take my measurements.
Results of preliminary:
From this I have decided that I am going to take the temperature for 1
minute and I will count as 1 wriggle a movement from side to side as
The main safety concern in this experiment comes from the hot water
used to heat us the maggot. To minimize the risks, avoid handling
anything containing the hot water.
· Place 1 maggot in a test tube with gauze in the bottom as shown on
· Insulate a beaker with tin foil
· Heat water up to required temperature and pour into beaker
· Place test tube into the beaker and the start timer
· After 30 seconds start counting the amount of wriggles
· After a further minute, stop timer and record the amount of wriggles
· Repeat for temperatures from 30°C - 60°C
· Repeat whole experiment twice
Diagram of apparatus
Record amount of wriggles in a minute every minute. Do this for 30°C,
35°C, 40°C, 45°C, 50°C, 55°C and 60°C. Repeat experiment twice and
calculate averages so as to reduce the effect of anomalous results.
· Test tube
· Tin foil
To make this a fair test I am going to leave the maggot in the test
tube and beaker for 30 seconds to climatize. This is to make sure that
the recorded results are for the correct temperatures. I also
insulated the beaker to try and keep the temperature constant
throughout the 90 seconds. If possible I will also do at the
experiments on the same day so that room temperature is the same and
the maggots I use will all be the same age.
I have made no changes to my original plan.
Analysis of Results
I can see from my graph that my prediction was correct in that the
rate of wriggle increases with the temperature. Then it stays at a
constant for approximately 10°C and by 60°C almost all wriggling had
stopped due to the denaturing of the enzymes. This is because when the
substrates become hotter, they move faster. This means that the
substrate collides with the enzyme more frequently and therefore more
reactions occur. At around 38°C the enzymes reach their optimum
temperature. At any temperature above this, the proteins in the
enzymes begin to change shape and denature. This means that the
substrate will no longer fit into the active site and the reaction
cannot be completed. If the reaction cannot be completed then
respiration will not take place and no energy can be converted and
therefore the maggot wriggles less and less until it finally stops.
The main problem I faced whilst doing this experiment was keeping the
water and the maggot at the correct temperature. Apart from this
problem which I did predict would happen and therefore I used
insulation, there were no other problems.
The most obvious anomalous result is for °C. This drop in rate of
wriggle did not fit the line of best fit I had drawn as the amount of
wriggles was less than it should have been at that temperature. This
may be for many reasons. Possibly because the maggot we used was
different to the rest, or the room temperature may have dropped and
therefore the temperature of the water and the maggot would have
dropped faster than it did for the rest of the experiments
Possible changes to plan
If I were to do this experiment again I would use a water bath instead
of a beaker full of water, as it is much more accurate in keeping the
temperature constant. I would also make sure all the experiments were
done on the same day so as to keep room temperature as stable as
possible. I would also use temperatures closer together between
35°C and 55°C so I could get an accurate curve on the top of the
I could have done this experiment many different ways - Including
timing how long it took to reach a certain amount of wriggles at
different temperatures, or counting wriggles every 10 seconds for a
minute. All of these would back up the work that I have done and the
conclusions I have come to.