Life Sciences Grade 12 IEB Paper 3 2016 Memo

Downloaded from hlayiso.com NATIONAL SENIOR CERTIFICATE EXAMINATION NOVEMBER 2016 LIFE SCIENCES: PAPER III MARKING GUIDELINES Time: 1½ hours 50 marks These marking guidelines are prepared for use by examiners and sub-examiners, all of whom are required to attend a standardisation meeting to ensure that the guidelines are consistently interpreted and applied in the marking of candidates' scripts. The IEB will not enter into any discussions or correspondence about any marking guidelines. It is acknowledged that there may be different views about some matters of emphasis or detail in the guidelines. It is also recognised that, without the benefit of attendance at a standardisation meeting, there may be different interpretations of the application of the marking guidelines. IEB Copyright © 2016 PLEASE TURN OVER

Downloaded from hlayiso.com NATIONAL SENIOR CERTIFICATE: LIFE SCIENCES: PAPER III – MARKING GUIDELINES Page 2 of 5 9. Table to show the colour of a variety of solutions/liquids when indicators (A and B) or Biuret are added. Test tube Colour (when indicators are added) A Light blue B Purple to lilac C Slight tinge of purple/lilac in a very 'milky' mixture D Light blue Layout of table (neat and in columns and rows) with both correct column headings (Descriptions of colour blue for A and D) (and more purple/lilac in B than in C). 10. Sediment/solid/ precipitate in test tube D with blue layer on the top. A, B and C – unchanged. (check what is written in the table) 11. A and D do not contain protein. B and C do contain protein (refer back to table). 12. (Contents of the test tube/various liquids or different solutions) added to the test tubes. 13. Presence or absence of protein/colour change (only 1 mark) 14. Test tube Protein in the test tube (%) A 0 B 5 (30/6) C 30 D 0 NOTE: Both A and D recorded 0 No units (%) in the body of the table 15. 15.1 More protein in C as it is pure milk. We have shown in A that there is no protein in water and B is diluted milk so less protein than in C. (C most and B less). This question asks where you expect to have more protein present. 15.2 No. The colour in B is more purple/lilac than in C as there is less milk (with particles in) to blur/obscure the indicator and colour change. 16. The colour/shade of purple/lilac would be in between what was observed in test tubes B and C. OR In between B and C. Lighter than B but darker than C. 17. Measured length or width of PB (… mm/length of scale bar in mm) × 15 µm = ... µm method may differ to calculate (or (3 fits in × 15 = between 42–48 µm) IEB Copyright © 2016 PLEASE TURN OVER

Downloaded from hlayiso.com NATIONAL SENIOR CERTIFICATE: LIFE SCIENCES: PAPER III – MARKING GUIDELINES Page 3 of 5 18. Heading: (bar graph to show) the protein content in (gram/100 cal of) different foods. 12 11 10 9 8 Protein content g/100 cal 7 6 5 4 3 2 1 0 Tofu Soybeans Quinoa Lentils Complete heading Bar graph Spaces between bars equal Label y-axis (protein content in gram/100 cal) Scale on y-axis correct Names of foods on x-axis/key Accuracy (maximum 3 if do a line graph) Histogram only 4/6 IEB Copyright © 2016 PLEASE TURN OVER

Downloaded from hlayiso.com NATIONAL SENIOR CERTIFICATE: LIFE SCIENCES: PAPER III – MARKING GUIDELINES Page 4 of 5 PART 2 EXPERIMENTAL DESIGN 19.1 Rennet added to milk will cause the milk to coagulate. Statement THE DESIGN MUST SPEAK TO THE HYPOTHESIS 19.2 To investigate whether milk in the presence of Rennet will coagulate and form lumps. OR To determine if adding Rennet will cause the milk to coagulate and form lumps. 19.3 (1) Take two identical test tubes. (2) Mark one test tube A and the other B. (3) Using a 10 ml syringe add 30 ml of milk to both A and B. (4) Add 4 drops of lemon juice to both test tubes A and B. (5) Into A add 4 drops of Rennet. (One test tube has Rennet and the other test tube no Rennet.) THIS IS A CRUCIAL POINT THAT NEEDS TO BE IN THE DESIGN. (6) Take a 250 ml beaker and to it add 200 ml water that is at a temperature of 70 oC (water bath). (7) Place both test tubes in the water bath for 10 minutes/set time. (8) Remove the test tubes from the water bath and tilt to the side to observe for small lumps/coagulation. (9) Record your observations in a table. (10) Repeat the investigation to verify your findings. IEB Copyright © 2016 PLEASE TURN OVER

Downloaded from hlayiso.com NATIONAL SENIOR CERTIFICATE: LIFE SCIENCES: PAPER III – MARKING GUIDELINES Page 5 of 5 Use the attached rubric for assessment for Question 1.3. Method Rubric Criteria 5 4 3 2 1 0 L Layout – appearance Layout meets criteria Layout is untidy and of method below: hard to read. neat and tidy and OR bulleted/numbered. Method is not formatted correctly with bullet points or numbers. A Aim – Method relates Method clearly tests an Method relates to the Method does not relate to prescribed aim that relates to the prescribed aim given, to the prescribed aim or experiment. prescribed experiment but is a little confusing achieve the desired and achieves the and does not achieve result. Method given is required result. the required result. the same as the given experiment. M Method – This needs All 5 criteria given An original experiment An original experiment An original experiment An original experiment None of the 5 criteria to be appropriate and below are met: provided. provided. provided. provided. are met. relevant to the aim, 1. An original OR clearly logical and experiment Plus 3 of 5 criteria are Plus 2 of 5 criteria are Plus 1 of 5 criteria is Method a copy of the sequential. If apparatus provided. met. met. met. original, given is given in the 2. Equipment is experiment. examination paper, the appropriate and method should resemble used correctly. the one given in the 3. Measuring of marking guidelines. solutions, reagents and marking of equipment are explained and this assists in the control of variables. 4. Instructions are scientifically valid and ordered. 5. Instructions are complete to produce measurable results that are recorded. Total: 50 marks IEB Copyright © 2016