• Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

Testing Starch in a (Variegated) Leaf - Lab Report

Extracts from this document...


Aim: To test various leaves for the presence of starch Hypothesis: After the iodine reagent is added, the green areas on the leaf, where starch is supposedly present, will turn to a blue-black colour - the positive test for starch. Method: 1. Obtain your leaf and cut a small sample of your leaf; 2. Immerse the leaf samples in hot water for 1-2 minutes (depending on the size of the leaf samples) 3. Remove the leaf samples from the hot water and keep them carefully to one side. 4. Half fill a boiling tube with alcohol and place the tube in hot water until bubbles start to form in the alcohol. 5. Place the leaf samples in the hot alcohol for about 5 minutes. 6. ...read more.


Repeat experiment 11. Write observations 12. Draw conclusions Safety Procedures: * Handle the hot water bath with care * The alcohol is highly flammable; handle the test tube with care * Keep all flammable items away from the experiment. * Small samples were taken of the experiment, so that the experiment could be replicated (repeated). * The leaf was placed in hot water to remove the waxy covering (the cuticle), and to break the cell membranes, and stopping all chemical processes. * Since chlorophyll dissolves in alcohol (solvent), the alcohol is first heated as it works best at higher temperatures. * The leaf samples were placed in the hot alcohol so they could be decolourised. ...read more.


Conclusion: From the experiment, we can now conclude that the starch and chlorophyll was present in the same place. When the chlorophyll uses sunlight to produce glucose (as well as other products), the glucose is converted into starch for storage of sugars. This starch was present in the places of the chlorophyll, the green pigment. Also we can conclude that starch is only present when chlorophyll is present. Evaluation: The leaf was boiled to break the cell membranes, and to stop chemical processes. Although there may not have been sufficient time for this to happen, and thus the cell membranes may have just been partially broken. All of the chlorophyll from the leaf sample may not have dissolved in the alcohol, the solvent. A small amount may have remained in the leaf sample. - Rohan M ...read more.

The above preview is unformatted text

This student written piece of work is one of many that can be found in our GCSE Green Plants as Organisms section.

Found what you're looking for?

  • Start learning 29% faster today
  • 150,000+ documents available
  • Just £6.99 a month

Here's what a teacher thought of this essay

3 star(s)

This report on the starch test on leaves adequately describes the method and likely outcome of the test for green leaves grown in the light.

GCSE exam questions very rarely ask for this method but focus on investigations where the plant has been denied one factor required for photosynthesis. The writer does mention that a positive result was achieved only for the green areas of the leaf and the essay would have benefited from a discussion of variegation in plants where leaves have both green and white areas.

The writer's method is a little vague in places and would be difficult to repeat since exact details of size and temperature are omitted.

3 stars

Marked by teacher Ross Robertson 26/04/2013

Not the one? Search for your essay title...
  • Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

See related essaysSee related essays

Related GCSE Green Plants as Organisms essays

  1. Marked by a teacher

    Biology lab - transpiration

    5 star(s)

    Sclerenchyma are elongated cells that make up fibers. They have thick secondary walls and the protoplasts often die as they grow older. They are used for support and are found in vascular tissue. Collenchyma cells are living at maturity and have a thickened secondary wall.

  2. Marked by a teacher

    Year 11 Module B4 Revision notes. Plants, photosythesis, biomass and the carbon cycle.

    4 star(s)

    The contents of the cell push against the cell wall â this is called turgor pressure. Turgor pressure helps to support the plant tissues. If there is no water in the soil a plant starts to wilt. The cells start to lose water and they lose their turgor pressure.

  1. Marked by a teacher

    Investigate which surface of a leaf loses more water by transpiration.

    3 star(s)

    WEIGHT AFTER V. WEIGHT AFTER 24 HOURS TOTAL WEIGHT LOSS % WEIGHT LOSS SURFACE AREA LEAF 1(topside) 0.70 g 0.85 g 0.54 g 0.31 g 44.3 17.14 cm sq LEAF 2(underside) 0.64 g 0.84 g 0.76 g 0.08 g 12.5 15.66 cm sq LEAF 3(both)

  2. GCSE Biology - Photosynthesis Coursework

    Here, it was in fact at a light intensity of around 950 when it seems that another factor such as temperature or carbon dioxide concentration has become a limiting factor. In my main experiment therefore, it will not be necessary to take readings above this point.

  1. Testing a leaf for starch experiment

    Conclusion: From the experiment we can now conclude starch and chlorophyll were present in the same place. The green leaf which contained chlorophyll tested positive for starch while the yellow leaf containing no chlorophyll tested negative for starch. Discussion: Photosynthesis is the process whereby chlorophyll uses sunlight to produce glucose which is then converted to starch.

  2. photosynthesis lab report

    Remove the glass pieces. 5 Put control #1 in a dark cabinet 6 Put set up#2 under a 25 watt lamp 10cm from the plant 7 Put set up #3 under a 60 watt lamp 10cm from the plant 8 Wait for the result until next day 9 Next day,

  1. Determine the water potential of potato tuber cell with the varying affect of solute ...

    and remember to bung the tubes. Then record the mass of the paper on its own, now that you have the total mass, and the mass of the paper calculate the mass of the potato by itself (total - paper = ).

  2. Investigation into the relationship between the density of fresh water shrimps in fleet brook ...

    planktonic foodstuffs, oxygen, space for shelter).4 Dissolved oxygen and temperature. The solubility of oxygen from air, at normal atmospheric pressure, in pure fresh water is related to the temperature of the water by the equation: Cs = 475÷(33.5 + t )

  • Over 160,000 pieces
    of student written work
  • Annotated by
    experienced teachers
  • Ideas and feedback to
    improve your own work