| State the name of an enzyme that digests proteins | protease/ pepsin/ trypsin |
| State the type of biological molecule that catalyses reactions such as the conversion of glycogen to glucose. | enzymes |
| Suggest why the temperature of baby food must be controlled when the enzymes are added. | high temperatures denature enzymes / AW ;
low temperatures result in low energy / fewer collisions / slower reactions
/ AW ;
enzymes work best / most efficient at optimum temperature ; |
| State one other condition that must also be controlled to optimise enzyme activity. | pH ;
enzyme concentration ;
substrate concentration ; |
| A student used a respirometer to investigate the effect of temperature on the rate of respiration
of germinating seeds.
Predict the results of this investigation and explain your prediction | prediction
as temperature increases the respiration rate will increase ; ora
and then decrease ;
explanation:
there will be an optimum temperature (at a particular temperature) for
seed germination ;
ref to (respiratory / germination) enzymes ;
at high temperatures enzymes denature / described ;
at low temperatures not enough (kinetic) energy for, effective
collisions / biochemical reactions / respiration / digestion ; ora
AVP ; |
| State the names of A to D in Fig. 1.1. | A substrate ;
B active site ;
C enzyme-substrate complex ;
D product(s) ; |
| State two factors other than pH that would affect enzyme activity | 1 temperature ;
2 surface area of substrate ;
3 concentration / volume / amount / number, of enzyme (solution) ;
4 concentration / volume / amount, of (named) substrate (solution) ;
5 type of enzyme ;
6 type of substrate ; |
| Describe the effect of increasing pH on the activity of the protease in quinoa seeds. | 1 increases and decreases ;
2 peaks at / optimum, at pH 4.0 / 0.55 (au) ;
3 no activity beyond pH 6.5 ;
4 curve is symmetrical / AW ;
5 any data quote, e.g. activity is 0.55 (au) at pH 4.0 ; |
| Explain the activity of protease at pH 4.0 and at pH 7.0. | 1 pH 4 is the optimum (pH) ;
2 pH 7 enzyme is denatured ;
3 enzyme / protein / active site, has changed shape at pH 7;
4 shape of active site is complementary to substrate (4) / not (7) ;
5 enzyme-substrate complexes form (4) / not (7) ;
6 (most) effective collisions (between enzyme and substrate) (4) / none (7) ; |
| Enzymes have a specific three dimensional shape.
Explain why the shape of an enzyme is important. | correct ref to active site ;
enzyme must be complementary shape to, substrate / alcohol ;
to make enzyme – substrate complex / to allow substrate to bind to enzyme ;
ref to only fits one substrate / specific to one substrate ; |
| Explain why an increase in temperature causes an increase in enzyme activity | increased kinetic energy ;
molecules move faster ;
increased frequency of collisions ;
increased number of successful collisions ; |
| State one factor, other than temperature, that affects enzyme activity | pH ; |
| The biologist ensured all the cubes of cooked egg white were exactly the same size.
Suggest why | ref. to surface area;
affecting enzyme / enzyme activity;
allows comparison;
make experiment valid;
controlled variable; |
| Temperature must be controlled in this experiment.
Describe how temperature could be controlled. | water-bath / in a beaker of water/ incubator;
insulate test-tube;
allow solutions to equilibrate to temperature (before
experiment);
use a thermometer to check the temperature (is constant); |
| Predict the optimum pH for trypsin | (pH) 8
± 1; |
| Enzymes, such as proteases, are important in digestion.
Describe in detail how enzymes function, using other digestive enzymes as examples. | enzymes are protein; enzymes can be reused/ are unchanged in the reaction;
enzymes are specific; (enzymes are)catalysts / speeds up reaction;
lowers the energy needed for the reaction; successful collisions /enzyme-substrate complex /ESC; active site;
(enzyme and substrate) fit together;
complementary shape;
(digestive enzymes perform) chemical digestion
/ hydrolysis / catabolic reactions;
break down, large /insoluble, molecules into, small / soluble,
molecules;
amylase converts starch to sugars /maltose;
lipase converts lipid/fats, to fatty acids and glycerol;
maltase converts maltose to simple sugars /glucose;
ref to pH;
ref to denaturation; |
| Protein digestion begins in the stomach of the human alimentary canal and is completed in the small intestine.
Describe in detail how enzymes function to digest protein in the alimentary canal. | 1 enzymes are, biological / protein, catalysts / speed up
reactions; 2 ref to specificity; 3 active site;
4 substrate/ protein, fits into /AW, enzyme / active site; 5 ref to, complementary shape of molecules; 6 enzyme-substrate complex /ESC;
7 enzymes, lower energy needed for reaction;
8 enzymes are, unchanged (at end of reaction)/reused;
9 (enzymes) carry out, chemical digestion / hydrolysis / catabolic reactions;
10 break down, large /insoluble, molecules into,
small(er)/ soluble, molecules; 11 protein broken down to,
polypeptides /peptides /amino acids; 12 pepsin, active in stomach;
13 trypsin, active in, small intestine /duodenum / ileum;
ref. to conditions in alimentary canal
14 low pH/ pH 1–3 /(hydrochloric) acid, in stomach;
15 high pH/ alkaline /neutral / non-acidic / pH 7–9, in, small intestine / duodenum / ileum; 16 ref. to denaturation;
17 temperature is 37 °C; 18 ref. to successful collisions; |
| Pectinase is an enzyme used in the production of fruit juice.
(a) Describe in detail how enzymes function, using pectinase as an example | 1 enzymes are proteins;2 enzymes can be reused/ are unchanged in a
reaction;3 enzymes are specific;4 (enzymes are) catalyst / speeds up reaction;
5 lowers (activation) energy needed for the reaction;6 successful collisions;
7 enzyme-substrate complex /ESC; 8 active site; 9 (enzyme and substrate) complementary shape /AW;
10 ref. to optimum, temperature / pH;
11 too much heat results in denatured enzymes;
12 too little kinetic energy / heat, less (successful)
reactions;
13 incorrect pH results in denatured enzymes;
14 (substrate) is pectin / cell wall;
15 results / product, is clear juice;
16 mass / cheaper/ more (volume)/ yield, juice
production; |
| Some students compared how effective biological and non-biological washing powders are at
removing stains at temperatures between 10°C and 60°C.
• Pieces of stained cloth were washed using two different washing powders.
• The degree of stain removal was measured by using a light meter to record the
percentage of light reflected from the cloth.
• A light meter gave a value of 100% when the cloth was completely clean.
• Any stain left on the cloth reduced the percentage of light reflected.
Compare the effectiveness of the two washing powders at removing stains.
Use the information in Fig. 2.1 in your answer. | biological washing powder is more effective, at lower temperatures / between 10 °C and 40 °C / 10 °C and 43 °C ;
comparative data quote for the difference at a stated temperature ;
biological washing powder removes all stain between 30 °C and 40 °C ;
non-biological removes all stain only at 60 °C ;
effectiveness is similar, at high temperatures / between 50 and 60 °C ;
same trend, below 30 °C / at low temperatures / from 50 °C ;
idea of effectiveness of biological washing powder decreases between 40 °C and 44 °C, no such decrease for nonbiological washing powder ; |
| The students suggested that the enzymes in the biological washing powder were denatured at high temperatures.
Explain why enzyme molecules do not function when they are denatured. | active site changes shape ;
substrate no longer fits into, enzyme / active site ;
no enzyme-substrate complex / no successful collisions ; |
| State the name of the group of molecules that are made of proteins and act as catalysts. | enzymes |
