Practicals Flashcards
Investigate how the rate of photosynthesis is dependent on light intensity- 6 marker
I would Add water to a beaker, and add sodium hydrogen carbonate which provides carbon dioxide.
I would add a piece of pondweed plant to the beaker ( make sure that I cut the end of the pondweed plant which ensures that the xylem tubes are open so there will be er oxygen and water movement: oxygen bubbles escape more easily, so I’ll be able to see the bubbles clearly.) make sure that the cut end is facing upwards.
Place an inverted funnel on the pondweed plant and add a test tube on top of the funnel to count the oxygen bubbles being produced.
Place a lamp at a fixed distance of 30cm (acts as light energy)
Start a stopwatch and count the number of OB being produced in 60 seconds.
Repeat this process for 3 times and calculate an average result.
Place the lamp at a closer distance (10cm) and count the number of OB being produced in 60 seconds, I would realize that the amount of OB increased since the light intensity increased so there will be a faster rate of photosynthesis.
Make a table and record the results of distance vs the amount of OB produced, then I would plot the results in a graph.
What is the independent variable, DV and CV of the photosynthesis practical? How to improve accuracy and reliability for this study?
IV- what you change. (Distance)
DV- what you measure. (amount of oxygen bubbles produced)
CV- what you keep the same. (Volume of water, concentration of sodium hydrogen carbonate, etc)
You can improve accuracy by using a gas syringe instead of counting the OB ( which can measure the volume of gas in a chemical reaction) for precise results
Repeat the experiment at different distances ( 10cm, 20, 30)and calculate an average.
Control the temperature by using a water bath to ensure the temperature is steady.
Investigate the effect of exercise on heart rate ( make a practical procedure) 6 marker-
Measure student A resting heart rate by using 2 fingers ( middle and index finger) and pressing gently on your wrist or on your neck. And record on a table your resting heart rate.
I would make student A Perform an exercise; jogging for 4 minutes
Immediately after measure their heart rate for 1 minute by using a heart monitor and record the number of heart beats in 60 seconds on the table.
Rest for 3 minutes and measure your heart rate again after recovery and record it by writing it down on the table.
Repeat this process again with student B, to ensure a wide range of results. Repeat 3 times to ensure accuracy.
Calculate the average heart rate for each stage (resting, immediately after exercise, and during recovery).
Compare the results of your heart rate before exercise and after exercise and plot a graph of heart rate vs exercise based on your results.
What is the IV, DV, CV In this investigation?
IV- the amount of exercise being done
DV- heart rate
CV- same type of exercise, the food intake of the students prior to the investigation, method of measuring the heart rate, the temperature of the environment, etc.
Why is an LED lamp used instead of a normal lamp? Why is an LED lamp used for the experiment?
In an LED lamp, we can keep the temperature constant since light is being released without too much heat, so only light is affecting photosynthesis, which makes it a fair test, since in a normal lamp as light intensity increases, heat increases. Which is not a fair test since we don’t know what affected the rate of photosynthesis.
Led lamp is used since it prevents the denaturing of enzymes in the plant, and helps maintain the water temperature stable.
What are we using the scalpel for in the Osmosis Practical?
To make sure we cut even pieces of potato, all of them should be the same size, length and width. to ensure the surface area is the same for osmosis, because if it wasn’t it wouldn’t be a fair test.
What does a positive/ negative answer indicate whilst you’re calculating the percentage change in mass for the potato cylinders in the osmosis practical?
Positive answer- indicates that the potato gained mass/ water ( water molecules move in)
Negative answer- shows that the potato lost water ( water moves out of the potato)
How to calculate percentage change?
Final - Initial divided by initial x 100
What does the point where the line crosses 0% mean? For the osmosis practical?
That’s the isotonic concentration, in which there is no net movement of water.
Why use % change instead of just mass change?
Because it standardizes results of different sized potato’s.
As sucrose concentration increases, the percentage change decreases, why?
The water molecules move out the potato, causing the overall mass to decrease.
What is the risk assessment for the osmosis practical-
When using the scalpel, cut away from your fingers.
Use a cutting board.
How does using more concentrations of sucrose relate to accuracy?
The more variety of concentrations you use, the more reliable and accurate the graph is.
Why does the frequency of breathing increase whilst exercising?
The muscles are working harder and aerboically respiring since there needs to be oxygen being delivered to the muscles and carbon dioxide to be removed to keep up with the high energy demand the body requires, if the body cannot meet the energy demand then the muscles will anaerobically respire which produces lactic acid.
What are some variables from the students from the exercise investigation that have to be controlled to be able to ensure a fair test?
Students should be similar size, same fitness level, same gender, age
Investigate the effect of exercise on breathing-
Why does exercise increase heart rate?
So that glucose is delivered to the muscles
