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

The activity of enzymes.

Extracts from this document...


Experiment 25 DISCUSSION Grasshopper is recommended as a source of enzyme because it is relatively hygenic, cheap and is available in all seasons in Hong Kong. Short-homed grasshoppers have been used in this experiment. The species which have been'chosen are Ciastdmarzm manwratis and chondracris rosea. More conspicuous results could be obtained with the latter. These grasshoppers die easily in captivity making rearing difficult. But it is possible to keep them alive overnight by refrigeration and they can recover their activities on exposure to warm sunlight. Enzyme obtained from grasshoppers which have been frozen for one week are found to work although the guts have shrunken. As an alternative, locusts may also be used for this experiment because they are taxonomically the same as the grasshoppers mentioned above and have similar anatomy and physiology. In that case, the difficulty of rearing would not apply. ...read more.


In carrying out the iodine test for starch, it is advisable to use a very dilute solution Of 12-KI . 0. 5 CM3 of the stock solution (prepared by dissolving 1 g 12 and 2 g KI in 100 cm3 of distilled water) should be added to 10 CM3 of distilled water prior to use. Do not fill up the cavities of the spot plates with the dilute iodine solution all at the same time because the brown colour gradually fades. Iodine solution should be added to the plate row by row. If a Pasteur pipette is used, two drops of 12-KI solution should be added to each cavity. The above experiments have been tried out by about 200 teachers in a workshop for teachers conducted by the authors and the majority found that the activity of enzymes was in the following order: Protease M>F>H Arnylase Invertase M > H > F (F = fore-gut, M = mid-gut, H = hind-gut) ...read more.


indicates the presence of arnylase and invertase in the gut because arnylase hydrolyses starch to maltose (reducing sugar) and invertase hydrolyses sucrose to fructose and glucose (both are reducing sugars) which can be detected by Benediet's test. (2) 'Gut extract + distilled water' acts as control to indicate the presence of endogenous reducing sugar for comparison. (3) Removing adhering structures and content of the gut reduces the possibility of other sources of enzymes contributing to the arnylase activity. (4) It is possible that some of the reducing sugars detected from the test may be the action of maltase on maltose, which is converted to glucose. (5) The purpose of setting up boiled gut extract as one of the control is to show that the reaction proceeds only in the presence of active proteins. (6) The grasshopper is a herbivore so that anrylase and invertase are normally present in its gut for the digestion of plant materials, but not cellulose. ...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 Life Processes & Cells section.

Found what you're looking for?

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

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