9 POTCHEFSTROOM HIGH SCHOOL FOR BOYS PRATICAL 1 LIFE SCIENCE GRADE 10 Name: _____________________________ Date: _____________________________ Total: 35 Duration: 60 Minutes Learners mark out of 35 Learner’s percentage Weighting of SBA task SKILL ASSESSED Skills for practical work Description Question number Follow Instructions Give Instructions Adhere to safety rules Handle Apparatus Knowledge of apparatus Improvising apparatus Handling chemicals/apparatus correctly Work safely and take precautions Make observations Make drawings Measuring (proportions/ratios, scale) Describing objects/processes Grouping/Classifying materials Observing results/features Comparisons Record Data Tables Graphs Drawings Descriptions Measure Reading scales
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POTCHEFSTROOM HIGH SCHOOL FOR BOYS PRATICAL 1 LIFE SCIENCE
GRADE 10
Name: _____________________________
Date: _____________________________
Total: 35
Duration: 60 Minutes
Learners mark out of 35
Learner’s percentage
Weighting of SBA task
SKILL ASSESSED
Skills for practical work Description Question numberFollow Instructions Give Instructions
Adhere to safety rules
Handle Apparatus Knowledge of apparatus
Improvising apparatus
Handling chemicals/apparatus correctly
Work safely and take precautions
Make observations Make drawings
Measuring (proportions/ratios, scale)
Describing objects/processes
Grouping/Classifying materials
Observing results/features
Comparisons
Record Data Tables
Graphs
Drawings
Descriptions
Measure Reading scales
Scaling
Measuring out quantities
Estimations
Making valid measurements
Supply correct Units
Interpret Converting information
Apply knowledge
Analyse data
Make deductions
Design/plan investigation
1
KNOWLEDGE AREA
Tissues, Cells and Molecular Studies
Structure, Control and Processes
Environmental Studies Diversity change and continuity
SPECIFIC OUTCOMES
Knowledge Practical skills Society and Science
Required percentage : 20 % 60 % 20 %
Actual percentage: 23 % 54 % 23 %
TOPIC: ORGANIC MOLECULES: ENZYMES
INSTRUCTIONS
1. Use black/blue ink or black ball-point pen. No pencil answers except for drawings.
2. Answer ALL the questions.
3. Write neatly and legibly
4. All drawings should be done in pencil and labelled in blue or black ink.
5. Draw diagrams or flow charts only when requested to do so.
6. The diagrams in this question paper may not necessarily be drawn to scale.
7. Non-programmable calculators, protractors and compasses may be used.
LEARNER DECLARATION
I confirm that this work was conducted under supervision in class by myself. I confirm that this work is my own.
Signature of learner: Date:
2
QUESTION 1.1:
Study the following experiment and answer the questions that follow:
Learners conducted an investigation to determine the effect of an enzyme called pectinase on apple juice production. Pectinases hydrolyses pectin, which is a component of the cell wall. It is useful because pectin is the jelly-like matrix which helps
cement plant cells together and in which other cell wall components, such as cellulose fibrils, are embedded. Therefore, pectinase enzymes are commonly used in processes involving the degradation of plant materials, such as speeding up the
extraction of fruit juice from fruit, including apples.
Experimental set –up:
The learners weighed out 50g of apple pulp in a 100 cm3 beaker and added 2 cm3 pectinase to this pulp. They mixed the pulp for 10 seconds using a glass rod and left it standing then for 5 minutes. The learners then used a filter funnel as shown in the diagram to pour the mixture into a measuring cylinder. They used a timer to track the total volume of apple juice in the measuring cylinder every 5 minutes for the next 30 minutes. The results were recorded in the table below.
Time (minutes) Volume of apple juice (cm3)
0 2.5
5 6
10 12
15 17.5
20 18
25 18
30 18
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1.3.1 Formulate a hypothesis for this investigation.
The presence of enzymes in food is very common. The use of enzymes in food processing is of the greatest impacts of biotechnology. Enzymes are involved in product development and in the development and enhancing of organoleptic characteristics (aroma, flavour and colour).
There are mainly two groups of enzymes which are used in fruit juice industries namely pectinases and amylases.
Pectinases were of the first enzymes to be used and commercially applied in the processing of juices and wines. Currently these enzymes account for approximately 20% of the worldwide enzyme market and are naturally produced by plants, fungi, yeast and bacteria. Apple juice clarification is affected by pH, temperature, enzyme contact time with the pulp and enzyme concentration. Overall the time required to obtain clarification is inversely proportional to the concentration of the enzymes used at a constant temperature in the range of 5 – 50°C, with treatment time of 2 – 16h. ,
1.2.3 What type of organic molecule is the substrate mentioned in 1.2.2?