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My hypothesis is that with an increase in temperature a Daphnia's heart rate willincrease.

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  • Essay length: 1132 words
  • Submitted: 21/10/2003
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GCSE Humans as Organisms

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HEFC BIOLOGICAL SCIENCE - UNIT 2 Joseph Colledge

ASSESSED PRACTICAL

VARIATION OF DAPHNIA HEART BEAT WITH TEMPERATURE

a) My hypothesis is that with an increase in temperature a Daphnia's heart rate will

increase, likewise with a reduction in temperature the heart rate will decrease. This is due to the Daphnia being an ectothermic organism, so its body heat is determined by its environment, namely that their body temperature is the same as the water they are floating in. Thereby having a direct effect on its metabolic rate.

b) A Daphnia was taken via a teat pipette from a beaker of room temperature water

(Measured at 20?C) and placed onto a cavity slide, this was then placed under a microscope. The heart was then located via the use of diagrams and confirmation sought by a person who had previously carried out the experiment. It was then decided that to get the most accurate results a group of 2 people would be most efficient, one person would be responsible for counting the beats per minute whilst the other would govern the time. It was also decided that as the heart was beating so

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