Investigating the Effect of Alcohol on Heartbeat of Daphnia
Daphnia are the organisms that are involved in this experiment to find
out what effect alcohol has on their heartbeat. It is easy to study
the effects of alcohol on the heart of Daphnia as the organ can be
easily seen through the transparent body of Daphnia. The number of
heartbeats may be counted before submersion in alcohol and after
submersion in alcohol to investigate the effect of alcohol.
Daphnia belong to the Phylum Arthropoda and are Branchiopoda which
belong to the class, Crustacea. Daphnia are invertebrates and also
have an exoskeleton, jointed appendages, a dorsal heart and open blood
The effect of alcohol on humans is that it slows down the heartbeat,
so it may be that alcohol will have the same effect on Daphnia. WHY???
However, it is possible that the heartbeat of Daphnia may not decrease
if submerged in alcohol. This is because Daphnia differ to humans in
many ways firstly Daphnia are invertebrates whereas humans are
vertebrates. Also, like most crustaceans Daphnia live in an aquatic
environment and so it could be possible that the heart of Daphnia may
be adapted differently to respond to ethanol.
Alcohol effects the transmission of the nerve pulses along neurones to
produce the affect that it does so on the heartbeat of Daphnia.
Alcohol interferes with the nervous system by slowing down the nerve
impulses that are sent down neurones from the brain. Alcohol does this
by binding with the receptor sites where normally certain
neurotransmitters may only bind with the receptor sites in the
membrane. This means that the nerve impulses consequently will slow
down and so also slowing down the heartbeat of the Daphnia.
From this background information I have found that alcohol does slow
down the heartbeat in humans. This can also be related to Daphnia in
the same way. Therefore I predict that as the concentration of alcohol
surrounding the Daphnia increases the greater the percentage decrease
The aim of the investigation was to find out the effect of alcohol on
the heart rate of Daphnia. My hypothesis was, as the concentration of
alcohol increases the lower the heartbeat of the Daphnia will fall. To
test my prediction I carried out 25 individual experiments which were
all carried out using the same procedure but varying the alcohol
concentration of the solution. To investigate how alcohol
concentration affects the heartbeat of Daphnia I recorded the
heartbeat of 25 Daphnia for a period of 7 minutes. This included 1
minute before submersion in alcohol, 3 minutes during submersion in
alcohol and 3 minutes after submersion in alcohol. I then found the
percentage decrease of the heartbeat of the Daphnia from the resting
heart rate. At the highest...