Unit 6 Biology Past Paper PDF

Safety of photosynthesis with light intensity: Allergies from the plant or broken glass might cut someone (1/1) Preliminary of photosynthesis with light intensity: Find a suitable method to measure the volume of gas being released Over a suitable time period Find a suitable range for light inte...

Safety of photosynthesis with light intensity: Allergies from the plant or broken glass might cut someone (1/1) Preliminary of photosynthesis with light intensity: Find a suitable method to measure the volume of gas being released Over a suitable time period Find a suitable range for light intensity (3/3) Method of photosynthesis with light intensity: The dependent variable is the number of oxygen released per unit time. (1/1) The control variable is temperature by placing the beaker in a thermostatically controlled water bath, and pH using a buffer. (4/4) Use a 5 different distances from 10-30 cm of lamp from the beaker. (1/1) First, place a piece of pondweed, approximately 10 cm long, in a large beaker of water. Remove any bubbles by running your finger and thumb over the surface of the pondweed under water. Then cover half of the beaker with aluminium foil, so light only can enter from the either side of the beaker. Add a half spatula of sodium hydrogen carbonate to the beaker of water, the sodium hydrogen carbonate is used to provide excess carbon dioxide and leave it for 5 minutes. (1/1) Next, position the lamp 10 cm away from the beaker, and allow the plant to acclimatise. (1/1) Then fill the capillary tubbing of Photosynth meter with water. After that, place the funnel end of the tubbing in the beaker of water, then place the pondweed cut end in top of the funnel opening. Place a paper clip to help weight it in the correct position. As the bubbles of oxygen begin to form and pass into the capillary tubbing, start the stop clock. After 10 minutes, use the syringe to draw any oxygen produced into the capillary tubbing. (1/1) Use the syringe to refill the capillary tubbing then begin recording again. (1/1) Then find the rate using this equation number of bubbles/time. (1/1) Lastly, repeat the experiment for the other distances and find the mean and standard deviation. (1/1) (10/10) Limitations of photosynthesis with light intensity: Difficult to control temperature. Possible errors when measuring the volume of gas released. Surface area can't be controlled. (3/3) Preliminary of observing grasshoppers: Find a method to identify the species. Find a suitable sampling method. Find the time the grasshopper are most active. (3/3) Method of observing grasshoppers: The dependent variable is the number of grasshoppers per unit area. (1/1) The control variable is pH and temperature, to control this variable is the use slope of rode and gravel area. (2/2) Draw a large grid over the maps 2/3 of the area is being sampled. Assign the numerical scale to the grid, creating a coordinate grid. (1/1) Use a random number generator to generate 20 coordinates for the first area, this is where the quadrats are placed. Place the quadrat at the coordinates, and count the number of grasshoppers. If the box of the quadrat is more than half-filled then count it as a full square, then calculate the percentage of full boxes counted. Record the abundance in a table. (1/1) Repeat for one sample area. (1/1) Repeat the whole investigation at different times of the year. (1/1) Population density= number of grasshoppers/area. (1/1) (8/8) Limitations of observing grasshoppers: Difficult to control ph. Difficult to identify the species. Difficult to see the species move. (3/3) Method of calcium concentration on brine shrimp: The dependent variable is the number of brine shrimp hatched per unit time. (1/1) The control variable is temperature and pH, and control them using a thermostatically controlled water bath and a buffer. (1/1) Use five different concentrations of the calcium ions and label the beaker with the different concentrations. (1/1) Then create a salt solution by adding 2grams of salt with 100 cm\^3 of DE chlorinated water and add the calcium concentration. Use a stirring rod to make sure the contents have been mixed properly. Then slightly damp a piece of graph paper, and carefully sprinkle the brine shrimp eggs, and use a magnifying glass to count 40 eggs. Then use a scissor to cut the graph paper around the eggs. After that, place the eggs in the salt solution, and the graph paper facing down. The eggs will fall down after 2 minutes. Repeat for every concentration and calculate mean. (1/1) Place the beaker in an incubator. Next, make another salt solution by adding 2 grams of salt in the 100cm\^3 DE chlorinated water, and stir. This is used to count the number of eggs hatched. Then place a light source next to the beaker, and place the eggs into the beaker that is used for counting. Use a pipette to count the number of brine shrimp swimming towards the light source. Record the number of brine shrimp hatched in a table. Repeat the counting for 2 further days. (1/1) (5/5) Preliminary of fresh pineapple juice affecting the growth rate of bacteria: Find a method to extract pineapple juice. Find a method to pH for growth of bacteria. Find a suitable way to count bacteria. (3/3) Method of fresh pineapple juice affecting the growth rate of bacteria: The dependent variable is the number of bacteria in 24 hours. (1/1) The control variable is pH and temperature, to control the pH we must use a buffer, and to control temperature we must use an incubator. (2/2) First, we must use aseptic techniques such as disinfecting the table, and working near a Bunsen burner, also sterilising the equipment being used, and using an upward flame. (1/1) Then find a suitable range of concentration of pineapple juice e.g. from 0.5%-1.5% To extract the pineapple juice, we need to use a pestle and mortar to crush the pineapple. (1/1) Use a 500 cm\^3 of a conical flask filled 0.5% of pineapple solution. This should be constantly stirring using a magnetic stirrer. After that, add 1.25g of yeast and swirl to mix, and place a cotton wool as a stopper. And then incubate at room temperature. Fill a cuvette with distilled water to calibrate the colorimeter and set it to absorbance. Mix the yeast suspension, and use a pipette to measure 3 cm\^3 into a new cuvette, and place the cuvette into the colorimeter on absorbance. (1/1) Find the growth rate by dividing the number of bacteria by hour. (1/1) Repeat the experiment for different concentration of pineapple juice, and take a new sample of the yeast suspension every 20-30 minutes for 2 hours. (1/1) (Use of nutrient broth) with and without pineapple juice. Repeats for each set up Preliminary of yeast respiring: Find a suitable redox indicator. Find a suitable range of TTC. (3/3) Method of yeast respiring: The dependent variable is time of TTC to change colour. (1/1) The control variables are the pH and concentration of TTC, to control pH we will use a buffer. (2/2) Use a range of temperature from 10-30C. (1/1) Set up a water bath at 30C, and add 10cm\^3 of yeast suspension into a test tube using a pipette, and add the test tube into the water bath. (1/1) Add 1cm\^3 of TTC into a new test tube, and leave it in the water bath for 5 minutes to reach 30C. Then add the TTC to the yeast suspension, and place the test tube into the water bath, and start the stop clock. (1/1) Then stop the stop clock when the colour becomes red. To find the rate divide 1 by the time the colour changes to read. (1/1) Repeat for other temperatures. (1/1) Repeat the whole investigation and calculate mean and standard deviation. (8/8) Limitations of yeast respiring: Difficult to see end point. Difficult to prevent contamination of yeast culture. (2/2) (8/8) Limitations of fresh pineapple juice affecting the growth rate of bacteria: Difficult to count bacteria because it is uneven. Light may affect growth rate. Factors related to colorimeter use. (3/3) Preliminary of antibacterial compounds that reduce bacterial growth: Find a suitable method to measure clear zone of inhibition. Find a suitable method to control ph. Find a suitable mass of leaves. (3/3) Method of antibacterial compounds that reduce bacterial growth: The dependent variable is the zone of inhibition. (1/1) The control variable is the temperature and pH, to control temperature we must use an incubator for 48 hours, and to control pH we must use a buffer. (2/2) First thing we must do is aseptic technique such as disinfecting the table, and working near a Bunsen burner, also sterilising the equipment being used, and using an upward flame. (1/1) Use a range of masses of the leaves e.g. from 2-4 grams Use a pestle and mortar to add water and the leaves and crush them then add alcohol, the place the discs, so the discs would be soaked into the solution. (1/1) Place an inoculate into to the bacteria and swipe it onto the agar, then place the discs onto the agar. (1/1) Then place tape on either side, so the bacteria could respire aerobically. Invert the petri dish and incubate it at 25C for 48 hours. (1/1) Measure the zone of inhibition using a ruler, and use the area of the circle. (1/1) Repeat for different masses. Repeat the whole investigation and calculate mean. (1/1) (9/9) Limitations of antibacterial compounds that reduce bacterial growth: Difficult to measure distances. Contamination might occur. (2/2) Preliminary of mung beans and their RQ: Find a suitable age of mung beans. Find a suitable pH for respiration. Find a suitable method to measure gas volume. (3/3) Method of mung beans and their RQ: The dependent variable is the distance moved by meniscus. (1/1) The control variables are the pH and the temperature, to control the pH we will use a buffer and to control the temperature we will use a thermostatically controlled water bath. (2/2) Use seedlings with different ages. (1/1) Measure 5g of soda lime using a mass balance, then wrap it with muslin and place it in a test tube. And make another test tube without soda lime. (1/1) On top of it place a gauze. Then sterilize the seeds to prevent contamination, and weigh the seeds using a mass balance, next place it in a test tube, and replace the bung. (1/1) Carefully using a pipette place the coloured liquid into the tube, furthest away from the spirometer. Record the initial distance and final. (1/1) Record the distance every minute for 5 minutes. (1/1) Calculate RQ by dividing CO2 released by O2 consumed. (1/1) Repeat the investigation for other ages. Repeat the whole investigation and find the mean and standard deviation. test tube with capillary tube / gas syringe the apparatus must be able to work how to find the volume of oxygen used reading gas syringe (8/8) Limitations of mung beans and their RQ: Seedlings may change from aerobic to anaerobic respiration. Difficult to measure distance. (2/2) Preliminary of gibberellin solution: