Igcse2010 fernando enzymes
- 1. Enzymes Mainly based on the exercises from http://www.biology-resources.com/biology-questions.html IGCSE Revision Questions http://biodeluna.wordpress.com
- 2. Recommended resources to study enzymes. http://www.clickbiology.com/igcse-biology-revision-video-enzymes/ http://www.clickbiology.com/igcse-enzyme-ppt-presentation/
- 3. What is an enzyme?
- 4. What is an enzyme? A protein which acts as a catalyst , which speeds up the rate of reaction.
- 5. What is an enzyme? A protein which acts as a catalyst , which speeds up the rate of reaction. A substance that speeds up reactions without changing the produced substances
- 6. Guess the word... Reactions that build up molecules Reactions that break down molecules Combination of anabolic and catabolic reactions The molecule(s) the enzyme works on Molecule(s) produced by enzymes
- 7. Anabolic reactions: Reactions that build up molecules Reactions that break down molecules Combination of anabolic and catabolic reactions The molecule(s) the enzyme works on Molecule(s) produced by enzymes
- 8. Anabolic reactions: Catabolic reactions: Reactions that build up molecules Reactions that break down molecules Combination of anabolic and catabolic reactions The molecule(s) the enzyme works on Molecule(s) produced by enzymes
- 9. Anabolic reactions: Catabolic reactions: Metabolism: Reactions that build up molecules Reactions that break down molecules Combination of anabolic and catabolic reactions The molecule(s) the enzyme works on Molecule(s) produced by enzymes
- 10. Anabolic reactions: Catabolic reactions: Metabolism: Substrate: Reactions that build up molecules Reactions that break down molecules Combination of anabolic and catabolic reactions The molecule(s) the enzyme works on Molecule(s) produced by enzymes
- 11. Anabolic reactions: Catabolic reactions: Metabolism: Substrate: Product: Reactions that build up molecules Reactions that break down molecules Combination of anabolic and catabolic reactions The molecule(s) the enzyme works on Molecule(s) produced by enzymes
- 12. Enzymes will usually react with only one substance. This can be explained by the 'lock and key' theory. If this theory is correct, which of the following substances, represented by P, Q, R and S would be acted on by enzyme A? http://www.epc.org/mediafiles/lock--key.jpg
- 13. Enzymes will usually react with only one substance. This can be explained by the 'lock and key' theory. If this theory is correct, which of the following substances, represented by P, Q, R and S would be acted on by enzyme A? http://www.epc.org/mediafiles/lock--key.jpg
- 14. Write the formula for glucose.
- 15. Write the formula for glucose. C 6 H 12 O 6
- 16. Name the chemical elements present in a protein
- 17. Name the chemical elements present in a protein All proteins are composed of sub-units called amino acids. Proteins contain the elements carbon, hydrogen, oxygen, nitrogen and sulphur.
- 18. A protein-digesting enzyme when mixed with starch solution would ... (a) have no action (c) produce glucose (b) produce amino acids (d) digest the starch?
- 19. A protein-digesting enzyme when mixed with starch solution would ... (a) have no action (c) produce glucose (b) produce amino acids (d) digest the starch? no effect on starch .
- 20. What does the enzyme catalase do?
- 21. What does the enzyme catalase do? Catalase speeds up the breakdown of hydrogen peroxide to water and oxygen.
- 22. Which of the following are the building blocks of catalase? monosaccharides nucleic acids vitamins amino acids
- 23. Which of the following are the building blocks of catalase? monosaccharides nucleic acids vitamins amino acids
- 24. Factors which affect enzyme activity
- 25. Factors which affect enzyme activity Volume and concentration of substrate Volume and concentration of enzyme pH , there is an optimum pH, above or below this results in denaturation Temperature , there is an optimum temperature. In body 37 C is optimum Low temperature slows down enzymes High temperature permanantly denatures enzymes http://www.crampuppy.com/1/IGCSE/biology/digestion.shtml
- 26. An experiment is conducted to find the effect of temperature on an enzyme- controlled reaction. Which of the following graphs is most likely to illustrate the results rate of reaction
- 27. A student's account of an experiment reads as follows: I placed some diastase powder (a starch-digesting enzyme) in some starch solution in a test- tube. By taking samples from the tube and testing them with iodine, I found that the starch gradually disappeared. I repeated the experiment but added a few cubic centimetres of dilute sodium carbonate (an alkali) to the starch solution before adding the diastase. The starch took longer to disappear. I concluded that diastase had an optimum pH of 7 (neutral). Criticise (a) the student's experimental design (as judged by the report), (b) the student' s interpretation of the results.
- 28. In any enzyme experiment you should control variables as: pH (controlled adding buffers) Temperature
- 29. In an experiment to investigate the influence of temperature on the rate of reaction of a mylase on a starch solution, the following results were obtained: Plot these results on a graph, with temperature on the horizontal axis. (a) Between 20º C and 35º C, what is the effect of temperature on the rate of reaction? (b) What appears to be the optimum temperature for the reaction between salivary amylase andstarch? (c) Why do you think the reaction starts to slow down above 44º C? (d) Why do you think the reaction stops completely above 50° C? 25 17 11 7 4.5 4 3 6.5 12.5 no change even after 30 min 20 25 28 31 33 37 44 47 50 55 Reaction time before iodine gave negative results/min Temperature ° C
- 30. In an experiment to investigate the influence of temperature on the rate of reaction of a mylase on a starch solution, the following results were obtained: Plot these results on a graph, with temperature on the horizontal axis. (a) Between 20º C and 35º C, what is the effect of temperature on the rate of reaction? (b) What appears to be the optimum temperature for the reaction between salivary amylase andstarch? (c) Why do you think the reaction starts to slow down above 44º C? (d) Why do you think the reaction stops completely above 50° C? REMEMBER : Test for starch: Iodine turns from brown to black 25 17 11 7 4.5 4 3 6.5 12.5 no change even after 30 min 20 25 28 31 33 37 44 47 50 55 Reaction time before iodine gave negative results/min Temperature ° C
- 31. What enzymes do you know taking part in digestion? answers
- 32. What enzymes do you know taking part in digestion? Salivary glands make amylase Glands in stomach (Gastric Glands) make Pepsin (Protease) Pancreas make amylase, lipase , trypsin (Protease) http://www.crampuppy.com/1/IGCSE/biology/digestion.shtml And what do they do?
- 33. Enzymes in digestion Salivary glands make amylase Glands in stomach (Gastric Glands) make Pepsin (Protease) Pancreas make amylase, lipase , trypsin (Protease) Amylase breaks down starch into maltose Protease (pepsin, trypsin) breaks down protein into polypeptides Lipase breaks down fat into glycerol and free fatty acids http://www.crampuppy.com/1/IGCSE/biology/digestion.shtml
- 34. Enzymes keywords enzyme active site substrate product denature temperature pH optimum catalase amylase trypsin pepsin pectinase lactase protease catalyst catalyse protein FROM: http://www.clickbiology.com/igcse-biology-revision-video-enzymes/
- 35. Concepts of biology- Using the Core Learning Goals: Science http://mdk12.org/instruction/clg/biology/goal3.html