Meiosis with Crossing Over

Cloning in animal (Mammal e.g.: Dolly- 1997)

FORMAT OF ANSWERING QUESTION 2 OF PAPER 3

Paper 3 Question 2

Aspect	2003-2009(Marks)	2010-11
Problem statement	3	3
Objective of investigation	-	-
Hypothesis	3	3
Variables	-	3
List of apparatus and materials	3	3
Technique used	1	-
Experimental procedure	3	3
Presentation of data	1	2
Conclusion	-	-
Format of report	3	-
Total Marks	17	17

1. PROBLEM STATEMENT	Tip : In question form relating the manipulated variable (MV) and the responding variable (RV). (Must have question mark) Eg: What is the effect of (MV) on the (RV)?
2. HYPOTHESIS	Tip: A statement stating the relationship between MV and RV. Eg : The higher the MV, the higher /lower the RV
3. VARIABLES	Tip : Manipulated variable - this variable is being changed in this experiment. Responding v - this is being measured in this experiment. Fixed/Constant v - these are factors being kept constant throughout the experiment.
4. LIST OF MATERIAL AND APPARATUS	Tip : Material : Things that can only be used only once; eg, solutions. Apparatus : Things that can be reused again and again. Eg: beakers, test tube.
5. EXPERIMENTAL PROCEDURE	Tip : 1. Steps where you describe how apparatusand materials are handled (Setup of the expt). 2. Steps where you describe how the controlled/fixed variable is maintained. 3. Steps where you describe how the manipulated variable is altered. 4. Steps where you describe how the responding variable is measured and the instrument to be used. 5. Precautions.
6. PRESENTATION OF DATA	Tip : In table form with titles and units. (The experiment has not been carried out yet, so the results are not yet available).

Where does cell division occur?

Hair, skin, and fingernails are replaced constantly by cell division at a rapid rate throughout our lives. But, brain and nerve cells in the central nervous system do not divide at all after we are a few months old.

Subsequently, if the brain and nerve cells are destroyed later, the loss is usually permanent, as in the case of paraplegics.

Liver cells usually do not reproduce after an individual has finished growing and are not replaced except when there is an injury.

Red blood cells are also somewhat of an exception. While they are being constantly produced in our bone marrow, the specialized cells from which they come do not have nuclei nor do the red blood cells themselves.

Answer to Bioscore pg 78-79/ Hands on pg 42

2. Plan an experiment to study the effect of enzyme concentration on the activity of an enzyme.

Objective	To study the effects of enzyme concentration on the activity of salivary amylase.
Problem Statement	What are the effects of enzyme concentration on the activity of salivary amylase?
Hypothesis	The higher the enzyme concentration, the higher the rate of reaction until it reaches a maximum rate.
Variables	Manipulated: Enzyme concentration Responding: Time taken for the complete hydrolysis of starch//Rate of reaction //Activity of enzyme Fixed : Substrate concentration// temperature// pH
Materials & Apparatus	Materials :1% starch suspension, 0.2%, 0.4%, 0.6%, 0.8%, 1.0%, 1.2% amylase, iodine solution and distilled water. Apparatus : 5 ml syringe, 1 ml syringe, test tubes, glass rod, stopwatch, white tile with grooves, measuring cylinders and dropper.
Technique	Measure and record the time taken for the complete hydrolysis of starch using a stopwatch. // Calculate the rate of reaction using the formula : (1/time taken for the complete hydrolysis of starch).
Procedure	1. 6 test tubes were labelled as A, B, C, D, E and F and put in a water bath at 37oC. A : 1.0 ml 0.2% amylase B : 1.0 ml 0.4% amylase C : 1.0 ml 0.6% amylase D : 1.0 ml 0.8% amylase E : 1.0 ml 1.0% amylase F : 1.0 ml 1.2% amylase 2. Each test tube was filled with different volumes of amylase as given above. 3. A few drops of iodine were dropped separately on the grooves of a white tile. 4. 4 ml of 1% starch suspension was poured into test tube A. 5. The stopwatch was started. A small amount of mixture was added to the drop of iodine on the white tile immediately. 6. The colour change in iodine was observed. 7. The iodine test was carried out at an interval of 30 seconds until there was no more change in iodine colour (colour remained yellow). 8. The time taken when the colour of iodine remained yellow was recorded. 9. Steps 4-8 were repeated for test tubes B, C, D, E and F. 10. All observations were recorded. 11. A graph of rate of reaction (1/time) against enzyme concentration was plotted.
Results	Concentration of amylase (%) Time taken for the complete hydrolysis of starch (minutes) Rate of reaction (1/time) (min-1) 0.2 0.4 0.6 0.8 1.0 1.2
Conclusion	Hypothesis is accepted. The higher the enzyme concentration, the higher the rate of reaction until it reaches a maximum rate.

Procedure for page 34 (Hands-on)

Procedure:
1. 6 test tubes were labelled as A, B, C, D, E and F and put in a water bath at 37oC.
2. Each test tube was filled with different volumes of saliva and distilled water as given.
3. A few drops of iodine were dropped separately on the grooves of a white tile.
4. 4 ml of starch solution was poured into test tube A.
5. The stopwatch was started. A small amount of mixture was added to the drop of iodine on the white tile immediately.
6. The colour change in iodine was observed.
7. The iodine test was carried out at an interval of 30 seconds until there was no more change in iodine colour (colour remained yellow).
8. The time taken when the colour of iodine remained yellow was recorded.
9. Steps 4-8 were repeated for test tubes B, C, D, E and F.
10. All observations were recorded.
11. A graph of rate of reaction (1/time) against enzyme concentration was plotted.

Answer to Written Practical Question (Hands on Pg 40)

1a)

Set	Time taken (min)
A	20
B	10
C	3
D	6
E	30

b)(i) Observation 1-The time taken for complete hydrolysis of starch in set C/at 37oC is 3 minutes.
Observation 2-The time taken for complete hydrolysis of starch in set E/at 50oC is 30 minutes.
(ii) Inference 1 -The time taken for complete hydrolysis of starch in set C is fastest because 37oC is the optimum temperature for enzyme activity.
Inference 1 - The time taken for complete hydrolysis of starch in set E is the slowest because at too high temperature, that is 50oC, enzyme are denatured.

c)

Variable	Method to handle the variable
Manipulated variable Temperature	5 sets of apparatus using water baths of different temperatures, 15oC, 25oC, 37oC, 45oC and 50oC are set up.
Responding variable Time taken taken for complete hydrolysis of starch	Measure and record the taken for complete hydrolysis of starch using a stopwatch
Fixed variable pH// enzyme concentration// substrate concentration	Fix the pH to be the neutral throughout the experiment Fix 1ml of saliva throughout the experiment Fix 5 ml of starch throughout the experiment

d) The higher the temperature, the higher the rate of enzyme reaction until an optimum temperature is reached.
e)

Temperature (oC)	Time taken for hydrolysis of starch (minutes)	Rate of reaction (min -1)
15	20	0.05
25	10	0.10
37	3	0.33
45	6	0.17
50	30	0.03

f) An increase in temperature will also increase the rate of reaction until the optimum temperature of 37oC is reached. The rate of reaction decreases after 37oC.
g)An enzyme/amylase hydrolyses starch into a product that make the iodine solution remains unchanged/yellow, and the rate of reaction is affected by temperature.
h)The rate of reaction will be zero because all enzymes are denatured at high temperature of 70oC.