CORE PRACTICALS

1.6: Investigate biological
specimens using
microscopes
including
magnification
calculations and
labelled scientific
drawings from
observations

This practical allows students to develop their skills in
using a light microscope, preparing slides, and
producing labelled scientific drawings. Students need
to be familiar with the set-up and use of a light
microscope, as well as to be able to identify structures
that they see. Magnification calculations will also be
required.

1.10
Investigate the effect
of pH on enzyme
activity

For this core practical students will investigate the
effect of pH, however other variables can also be
investigated to enhance practical work in this area.
This method uses amylase (in solutions of different
pH) to break down starch. The reaction can be
monitored by using iodine to test the presence of
starch in the solution with a continuous sampling
method. To maintain the temperature of the solution,
a Bunsen burner and water beaker must be used.

1.13B
Investigate the use
of chemical reagents
to identify starch,
reducing sugars,
proteins and fats

Carry out food tests shown below:
1. identify starch by using iodine solution
2. identify reducing sugars using Benedict's
solution (and a water bath)
3. identify protein using the Biuret test (adding
potassium hydroxide to a solution of the food,
followed by copper sulfate)
4. identify fats and oils (lipids) using the emulsion
test to show the formation of a precipitate

1.16 Investigate osmosis
in potatoes

A known mass of potato must be added to sucrose
solution, left for some time, and the final mass
recorded to obtain the percentage change in mass.
This investigation looks at the exchange of water
between the potato and solution and allows the
concentration of sucrose in the potato to be
determined. The practical provides an opportunity for
the appreciation of the need to control variables.

5.18B
Investigate the
effects of antiseptics,
antibiotics or plant
extracts on microbial
culture

This practical provides the opportunity for learners to
carry out aseptic techniques (Biology statement 5.17).
Petri dishes pre-poured with agar must be inoculated
with bacteria and discs of antiseptic/antibiotics/plant
extracts can be used to determine their effect on
bacterial growth.
Sterile aseptic technique must include the use of a
Bunsen burner.

6.5
Investigate the effect
of light intensity on
the rate of
photosynthesis

Algal balls (or similar) must be set up and placed at
varying distances from a light source to investigate
the effect of light intensity on the rate of
photosynthesis. The rate must be measured and
compared to the distance away from the light source

8.11
Investigate the rate
of respiration in
living organisms

Use of a simple respirometer to measure the effect of
temperature on the oxygen consumption of some
small organisms. A simple respirometer can be made
using a tube with soda lime, cotton wool and
organisms with a capillary tube to coloured liquid.
Students can then track the progress of the liquid up
the capillary tube over a set time. This experiment
must be carried out using a water bath set at different
temperatures. Safety and ethical considerations must
also be covered

9.5
Investigate the
relationship between
organisms and their
environment using
field-work
techniques, including
quadrats and belt
transects

This investigation involves the use of a belt transect
along a gradient (e.g. shaded area to an area with no
shade). It involves students thinking about how to
sample their chosen area, including the identification
and observation of plants/organisms.