NATIONAL SENIOR CERTIFICATE GRADE 10

Transcription

1 NATIONAL SENIOR CERTIFICATE GRADE 0 LIFE SCIENCES P3 (PRACTICAL) EXEMPLAR 202 MARKS: 60 TIME: hour This question paper consists of 4 pages.

2 Life Sciences/P3 (Practical) 2 DBE/202 NSC Grade 0 Exemplar QUESTION : OBSERVATION AND DRAWING SKILLS 20 MINUTES NOTE TO TEACHER Give learners the following items: microscope, onion (with epidermis removed), slide, cover slip, dropper and a small beaker of water. Make a wet mount slide of the onion epidermis. Your teacher will assess the preparation of your slide. (6).2 Set up your microscope and then observe your slide under the microscope. Your teacher will assess the way in which you set up the microscope. (5).3 Draw and label TWO cells of your specimen as seen under the microscope. (7) [8] QUESTION 2: CONDUCTING A PRACTICAL/INTERPRETING DATA 5 MINUTES NOTE TO TEACHER Give learners the following items: unknown sample (white powder you may choose whether it should contain starch or not), boiled water in a beaker, a small test tube, iodine solution, Benedict's solution/fehlings A and B, Biuret solution/millon's reagent, water and a dropper 2. Test the unknown sample for the presence of starch. Write down whether it contains starch or not. Your teacher will assess the way in which you conducted the test. (5) 2.2 Study the table below which shows the results of certain tests on FIVE different food types: A, B, C, D and E. NAME OF TEST AND COLOUR CHANGE FOOD TYPE Benedict's/ Fehling's test Iodine test Biuret/ Millon's test A Orange Yellow Pale blue/white B Blue Black Pale blue/white C Orange Yellow Purple/Brick-red D Blue Black Purple/Brick-red E Orange Black Purple/Brick-red 2.2. Which food type (A, B, C, D or E) contains the following: (a) (b) (c) (d) Only starch Only glucose Only protein and glucose Starch, glucose and protein

3 Life Sciences/P3 (Practical) 3 DBE/202 NSC Grade 0 Exemplar Rice contains starch and protein, but no glucose. Which food type (A, B, C, D or E) is probably rice? [5] QUESTION 3: DRAWING A GRAPH/INTERPRETING DATA 5 MINUTES NOTE TO TEACHER Set up the apparatus as shown in the diagram below. leafy shoot cotton wool test tube with water Apparatus used to investigate water loss from a leafy shoot The apparatus above was set up to investigate water loss from a leafy shoot. The total mass of the apparatus at the beginning of the investigation was 50 g. The apparatus was then weighed at 0-minute intervals over the next 50 minutes. After 50 minutes, the apparatus was taken outdoors and weighed every 0 minutes for another 50 minutes. The table below shows the decrease in mass of the apparatus over time in relation to the original mass of 50 g. INSIDE OUTSIDE Time (minutes) Decrease in mass (g) Plot a line graph of these results. (7)

4 Life Sciences/P3 (Practical) 4 DBE/202 NSC Grade 0 Exemplar 3.2 Name TWO environmental factors that could have caused the greater decrease in mass after 50 minutes. 3.3 State ONE way in which the reliability of the results could have been improved. () 3.4 Calculate the mass of the apparatus after 80 minutes. Show your working. [2] QUESTION 4: HEART DISSECTION 0 MINUTES NOTE TO TEACHER Dissect a sheep's/pig's heart to show its longitudinal section. Insert pins with flags/labels (A, B, C, D, E) on it as follows: A Aorta B (Left) ventricle (label should read Chamber B) C Pericardium D Tendon E (Right) atrium (label should read Chamber E) F (Right) ventricle (label should read Chamber F) Study the dissected heart with the labels and then answer the questions below. 4. Label parts A, B, C, D and E. (5) 4.2 State ONE function for each of parts A, D and E. (3) 4.3 Explain why the part labelled B has thicker muscular walls than the chamber labelled F. (3) 4.4 Explain the following: Why are vessels found on the surface of the heart? Why does blood not move back into the atria when the ventricles contract? [5] TOTAL: 60

5 NATIONAL SENIOR CERTIFICATE GRADE 0 LIFE SCIENCES P3 (PRACTICAL) EXEMPLAR 202 MEMORANDUM MARKS: 60 This memorandum consists of 4 pages.

6 Life Sciences/P3 (Practical) 2 DBE/202 NSC Grade 0 Exemplar Memorandum QUESTION. Use the following checklist to assess the making of the wet mount. CRITERIA DESCRIPTION MARK Condition of slide Is it free of dirt? Thinness/Amount of specimen Is it thin enough/spread out for light to pass through? Mountant Was the correct amount of water used not too little or too much? Cover slip Is there a cover slip? Cover slip lowered at an angle of 45 degrees? Presence of air No air bubbles under the cover slip bubbles under cover slip TOTAL 6.2 Use the following checklist to determine whether the microscope is set up correctly. CRITERIA DESCRIPTION MARK The mirror Is the correct mirror used? Is it adjusted to allow light to pass through onto the specimen? The condenser Is it adjusted correctly to focus the light source onto the specimen? The diaphragm Is it adjusted to regulate the amount of light reaching the specimen? Focus Is the specimen in clear focus? TOTAL 5.3 Use the following checklist to assess the drawing from the specimen. CRITERIA DESCRIPTION MARK Correct representation Does the drawing look like that which is under the microscope, i.e. are the shape, size, proportion and position of all parts correct? Caption Is there a suitable caption? Labels Are all visible parts correctly labelled? Are all the labels one below the other? Magnification/scale Is this indicated in the caption of the drawing? Rules for biological drawings The pencil lines of the drawing are neat and continuous. There is no crossing over of label lines. TOTAL 7 [8]

7 Life Sciences P3 (Practical) 3 DBE/202 NSC Grade 0 Exemplar Memorandum QUESTION 2 2. Use the following checklist to assess the candidate's procedure. DESCRIPTION MARK Mixed powder with water in test tube Selected iodine solution as reagent Used dropper to put in a few drops of iodine solution Boiled water NOT used Recorded that white powder contained starch and turned black/did not contain starch and remained yellow TOTAL (a) (b) (c) (d) B A C E QUESTION D [5] 3. Graph showing the decrease in mass of the apparatus inside and outside the classroom Inside Outside Decrease in mass (g) Time (minutes)

8 Life Sciences/P3 (Practical) 4 DBE/202 NSC Grade 0 Exemplar Memorandum Allocation of marks for drawing of graph: Correct type of graph/ All plotted points joined Title of graph Correct label for X-axis, including correct units and appropriate scale for X-axis Correct label for Y-axis, including correct units and appropriate scale for Y-axis Plotting of points for graph 3: Plotted all points correctly 2: Plotted 6 0 of the points correctly : Plotted 5 of the points correctly 0: No points plotted correctly If the wrong type of graph is drawn, marks will be lost for correct type of graph. (7) 3.2 High light intensity High temperature Increased wind Low humidity (Any TWO) 3.3 Repeat the investigation several times () 3.4 Mass of apparatus after 80 minutes: (50 24) = 26 g [2] QUESTION 4 4. A Aorta B Ventricle C Pericardium D Tendon E Atrium (5) 4.2 A Transports oxygenated blood from the heart to arteries of the body. D Attached to the valves and muscles; prevents the valves from being forced inside out. E Chamber that receives blood from the veins (3) 4.3 The left ventricle has to be able to produce a much greater force to push blood all around the body. The right ventricle has to push blood only to the lungs which are very close to the heart. (Any THREE) (3) Heart muscles are active living cells that require O 2 and food and have CO 2 and metabolic wastes removed The atrio-ventricular valves /bicuspid and tricuspid valves close ensuring that blood is pushed into the aorta and pulmonary arteries and not back to the atria. (Any TWO) [5] TOTAL: 60