Dawid Biczysko
18019730
Science Level 3
Assignment 3.2
Introduction
In this assignment I will go through my pondweed experiment in
maximum detail explaining and evaluating the process. I will also present
a conclusion that uses proper scientific protocol and language. I will also
use scientific protocols to evaluate the outcomes of the investigation.
Aim: Our aim for this experiment is to find out how the distance of light
affects photosynthesis when it comes to plants for this test, we will be
using pondweed. We want to find out if the number of bubbles with
oxygen will increase or decrease as the light is further away from the
plant. This will give us the answer that we need in order to finish our
experiment. We want to see if the rate of photosynthesis will be affected
by the light intensity, this means we want to check if when the light is
further away from the plant, if the rate of photosynthesis will decrease
meaning it will generate less bubbles than if the light intensity was to be
higher meaning it should theoretically produce more bubbles due to
more light being able to engage with the plant, and due to the higher
light intensity that would occur. We do not want to include heat in this
experiment which is why we are using an Iodine vapour tank to protect
the pondweed from potential heat damage, and to stop large
temperatures affecting our results. Our Hypothesis is that, the rate of
photosynthesis will be affected by the light intensity as we know that
without the correct light source, intensity and heat, there will be no
photosynthesis that will be able to occur during the process of the
experiment and the photosynthesis and we believe that, the light will play
a big part in our experiment and will affect the pondweed in a way where
the less light it has, the fewer the bubbles it will produce meaning the
rate of photosynthesis will decrease over the long distance.
Apparatus: A lamp, pondweed, clicker, Iodine vapour tank, test tube,
paper clip and a clamp. The lamp will be used as the source of light
which we will be testing if the intensity will affect the rate of
photosynthesis. The pondweed will be our control variable which we
want to observe and check how the rate of photosynthesis reacts to the
intensity of the light. The clicker will be used to count the number of
bubbles generated by the pondweed throughout the experiment. The
Iodine vapour tank will protect the pondweed from the heat that the lamp
, Dawid Biczysko
18019730
Science Level 3
gives off to prevent affecting our results and damaging the plant itself.
Finally, the paper clip will hold the pondweed down to the bottom of the
test tube so that it does not float about and the clamp will hold the test
tube in place so that the light intensity is focused on the pondweed.
Safety Hazards: When it comes to this experiment, we must be careful
with the equipment as the lamp can be very dangerous. The light is very
strong and could permanently or periodically blind us. This means that
we should be careful to not look directly at the light as it could burn our
eyes and damage our vision. We must also be careful to not break any
glass when handling the test tube or the Iodine vapour tank. Broken
glass could mean that we could cut our skin, or get pieces of glass
shards in our hands, feet or even our face.
Hypothesis: My hypothesis / prediction is that the number of bubbles
will be higher the closer the light is to the pond weed / test tube. The
further the test tube is from the light, the less bubbles will be produced,
this is because I believe the rate of photosynthesis will decrease as the
light intensity decreases. In addition to this, we believe that as the light
intensity decreases the rate of photosynthesis will decline. We will not be
focusing on the temperature in our experiment, because we do not want
it to affect our results in any way, this experiment is to only find out how
the light intensity affects the pondweed and how it changes its rate on
photosynthesis. Temperatures could affect our results as they could give
us potentially inaccurate or very different results each time unless we
had a steady water temperature every time, we did the experiment. This
would be not possible as we are testing the light and as the light moves
further away from the pond weed, the temperature will decrease
depending on the distance and measurements used. At 10cm, we would
most likely get a higher temperature than we would if the light was 50cm
away from the plant.
Variables
Independent Variable – The distance that the light is away from the
pondweed
Dependent Variable – Number of bubbles produced every one minute
Control Variables – Source of light, pondweed, same area / room