Practical skills (generic) Banker

1. (a) A student records the time taken for a colour change in a results table. Which column heading is set out correctly?A time (seconds)B time / sC time takenD s / time [1]

Four students measured the length of the same dried bean seedling root. Their results were: 4.6 cm, 4.8 cm, 7.9 cm, 4.5 cm.

1. (a) Identify the anomalous result. [1]
2. (b) Calculate the mean, leaving out the anomalous result. Give your answer to 1 decimal place. [2]
3. (c) State why the anomalous result should not be included in the mean. [1]

Pondweed bubbles at different lamp distances:distance / cm | 10 | 20 | 30 | 40 | 50bubbles per minute | 64 | 35 | 20 | 13 | 8

1. (a) State the dependent variable shown in the table. [1]
2. (b) Describe the relationship shown by the results. [2]
3. (c) Suggest a suitable scale for the y-axis if the grid is 10 large squares high. [1]

1. (a) Which type of graph should be drawn to show the number of students in a class with each blood group (A, B, AB, O)?A line graph with points joinedB bar chart with separate barsC histogram with touching barsD scatter graph with a line of best fit [1]

A student timed how long it took for starch to be digested by amylase at different temperatures. Results: 10 °C took 240 s; 20 °C took 130 s; 30 °C took 70 s; 40 °C took 55 s; 50 °C took 180 s.

1. (a) Draw a results table for these data with suitable headings. Describe what your table must include. [2]
2. (b) Calculate the rate of reaction at 30 °C using rate = 1000 ÷ time. Give your answer to 1 decimal place and state the unit. [2]
3. (c) State which variable goes on the x-axis of a graph of these results. [1]

A piece of potato had a mass of 48 g. After 30 minutes in a concentrated salt solution its mass was 36 g.

1. (a) Calculate the percentage change in mass of the potato piece. Give a negative sign for a decrease. [2]
2. (b) Explain why percentage change is used rather than the change in mass when comparing pieces. [1]

1. (a) The student wrote '20 °C' in each cell of the temperature column and '5 min' in each cell of the time column. Explain how the table should be improved. [2]
2. (b) The student recorded times as 32, 41.5, 38 and 40.25 s. Suggest how these should be recorded. [1]
3. (c) State where the independent variable should be placed in a results table. [1]

Volume of oxygen collected from yeast and hydrogen peroxide:time / min | 0 | 5 | 10 | 15 | 20volume / cm³ | 0 | 12 | 22 | 30 | 36

1. (a) Assuming a straight line between the two nearest readings, estimate the volume of gas collected at 12 minutes. [2]
2. (b) Describe the shape of the graph that these results would give. [2]
3. (c) Calculate the mean rate of gas production over the first 10 minutes. [1]
4. (d) State two rules for plotting a line graph of these results. [2]

Height of a radish seedling:day | 1 | 2 | 3 | 4 | 5height / cm | 2.0 | 3.5 | 5.5 | 8.0 | 11.0

1. (a) Calculate the mean growth rate in cm per day between day 1 and day 5. [2]
2. (b) State whether the growth rate is constant. Use the data to explain. [2]
3. (c) Explain why a line of best fit through the origin would be wrong for these data. [1]

1. (a) Which feature should a biological drawing have?A shading to show the darker areasB clear, continuous outlines drawn with a sharp pencilC label lines with arrowheadsD a small drawing in one corner of the space [1]

1. (a) State four rules the student should follow when making a drawing of a hibiscus leaf. [4]

1. (a) State what should be written below a drawing to show its size compared with the real specimen. [1]
2. (b) Give two rules for drawing label lines. [2]
3. (c) Explain why a drawing should use most of the space provided. [1]

A student draws a guava leaf. Line AB is drawn on the drawing from the tip of the leaf to the base of the blade and is 126 mm. The same distance on the real leaf is 84 mm.

1. (a) Calculate the magnification of the drawing. [2]
2. (b) Describe how the student should draw the veins on the leaf. [1]
3. (c) State why it is important that the line used to measure the drawing is drawn in the same place as on the real leaf. [1]

A student's drawing of a flower is 25 mm tall in a space 120 mm tall. The petals are drawn with many short sketchy lines, the centre of the flower is shaded dark, and label lines have arrowheads and cross each other.

1. (a) Give three faults in the student's drawing. [3]
2. (b) Explain why biological drawings are not shaded. [1]

A student looked at stained onion epidermis with a light microscope and was asked to draw three adjacent cells.

1. (a) Suggest why the student drew only a few cells rather than the whole field of view. [1]
2. (b) State two structures the student should draw and label in an onion epidermal cell seen with a light microscope. [2]
3. (c) Explain why the cell walls should be drawn as double lines between neighbouring cells. [1]

A student is asked to draw a soaked broad bean seed, split open to show the inside.

1. (a) The seed is 16 mm long. The student wants the drawing to be 80 mm long. Calculate the magnification needed. Give your answer to 1 decimal place. [2]
2. (b) Describe how the student should label the seed coat on the drawing. [2]
3. (c) Suggest why the student should look at the real specimen rather than copying a diagram from a book. [1]

A student makes a drawing of a preserved housefly.

1. (a) Describe how the student should make sure the proportions in the drawing are correct. [2]
2. (b) The housefly is 7 mm long. The student's drawing is 105 mm long. Calculate the magnification. [2]
3. (c) Suggest one piece of apparatus to help observe the fine details of the housefly. [1]

1. (a) State two safety precautions when heating test-tubes of food solution with Benedict's solution. [2]
2. (b) State the apparatus used to keep the test-tubes at 80 °C and how to check the temperature. [2]

1. (a) Name the apparatus you would use to measure each of the following: (i) the mass of a leaf (ii) the length of a root (iii) the temperature of a water bath (iv) the time for a colour change. [4]
2. (b) State the unit you would use for (i) and (ii). [1]

1. (a) Which apparatus is most suitable for measuring exactly 2.5 cm³ of enzyme solution?A 100 cm³ beakerB 50 cm³ measuring cylinderC 5 cm³ syringeD 250 cm³ conical flask [1]

1. (a) Explain how to read the volume in a measuring cylinder accurately. [2]
2. (b) A measuring cylinder has graduations every 2 cm³. The liquid lies halfway between the 36 and 38 cm³ marks. State the reading. [1]
3. (c) Suggest why a stop-clock reading to 0.01 s does not make reaction timing more accurate than one reading to 1 s when a person starts and stops it. [1]

1. (a) Describe how the student could make three solutions of sucrose of concentration 0.5, 0.25 and 0.1 mol/dm³ from a 1.0 mol/dm³ stock, each of total volume 20 cm³. Give the volumes of stock and water for each. [3]
2. (b) State why the student should use a different syringe for the stock solution and the water. [1]

Three students measured the same plant shoot: 12.4 cm, 12.6 cm, 12.5 cm.

1. (a) Calculate the range of the three readings. [1]
2. (b) The ruler used had a zero error: the zero mark was 0.3 cm from the end used. All readings were 0.3 cm too large. State the name for this type of error and give the corrected mean. [2]
3. (c) Explain why repeating the measurement would not remove this error. [1]

A student timed how long it took for pieces of apple, cut by hand with a knife, to turn brown in air on the bench. She judged the end point by eye.

1. (a) Suggest two sources of error in this method. [2]
2. (b) For each error, suggest an improvement. [2]

1. (a) A student repeats an experiment three times and gets very similar results each time. What does this show?A the results are accurateB the results are repeatable / reliableC there are no systematic errorsD the hypothesis is proved [1]

A student investigated the effect of temperature on the number of leaf discs floating in sodium hydrogencarbonate solution under a lamp. She used one tube at each of 20 °C and 40 °C, cutting discs from different leaves with scissors.

1. (a) Explain why the student's method may give unreliable results. [2]
2. (b) Suggest three improvements to the method. [3]

1. (a) A student investigates how the concentration of salt solution affects the change in length of potato strips. What is the independent variable?A the change in length of the stripsB the concentration of salt solutionC the temperature of the solutionsD the starting length of the strips [1]

A student set up three tubes: A — yeast + sugar solution; B — yeast + water; C — boiled yeast + sugar solution. She counted bubbles of gas from each tube for 5 minutes at 30 °C.

1. (a) Suggest why the student included tube C with boiled yeast. [2]
2. (b) State one variable that must be the same in all tubes. [1]
3. (c) Write a hypothesis for this investigation. [1]

A student tests four fruit drinks sold in a Lahore market to compare their reducing sugar content using Benedict's solution.

1. (a) Identify (i) the independent variable (ii) the dependent variable. [2]
2. (b) State two variables that should be kept the same. [2]
3. (c) Describe a suitable control for this investigation. [1]

1. (a) Plan an investigation to find the effect of pH on the time taken for amylase to digest starch. Include the independent, dependent and controlled variables, how you would take measurements and how you would make results reliable. [6]