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Calculate the mean number of starch grains in potato cells P, Q and R - Edexcel - GCSE Biology Combined Science - Question 6 - 2020 - Paper 1
Question 6
Calculate the mean number of starch grains in potato cells P, Q and R. Which structures are found in plant cells but are not found in animal cells? A cell membrane... show full transcript
Worked Solution & Example Answer:Calculate the mean number of starch grains in potato cells P, Q and R - Edexcel - GCSE Biology Combined Science - Question 6 - 2020 - Paper 1
Step 1
Calculate the mean number of starch grains in potato cells P, Q and R
Answer
To calculate the mean number of starch grains, sum the starch grains from the potato cells P, Q, and R, and divide by the total number of cells analyzed. If we denote the number of starch grains in each cell as:
- P = 6
- Q = 8
- R = 4
The mean is calculated as follows:
ext{Mean} = rac{P + Q + R}{3} = rac{6 + 8 + 4}{3} = 6
Thus, the mean number of starch grains is 6.
Step 2
Which structures are found in plant cells but are not found in animal cells?
Answer
The correct answer is D: cell wall, chloroplast, large vacuole. These structures are distinctive features of plant cells. The cell wall provides structural support, chloroplasts are involved in photosynthesis, and the large vacuole plays a role in storage and maintaining turgor pressure.
Step 3
Calculate the percentage difference in the mean length of starch grains in potato 2 at 5 weeks and in potato 3 at 10 weeks.
Answer
To calculate the percentage difference, use the formula:
ext{Percentage Difference} = rac{| ext{Value 1} - ext{Value 2}|}{ ext{Average of Value 1 and Value 2}} imes 100
Assuming the mean length of starch grains in potato 2 at 5 weeks is 50 and in potato 3 at 10 weeks is 30:
Calculating: ext{Percentage Difference} = rac{|50 - 30|}{(50 + 30)/2} imes 100 = rac{20}{40} imes 100 = 50\%
Step 4
State why the potatoes need glucose.
Answer
Potatoes require glucose as it serves as a primary energy source for cellular respiration. Glucose is essential for producing ATP, which powers various metabolic processes in the plant. Additionally, glucose contributes to the synthesis of other carbohydrates and is vital for growth and development.
Step 5
Devise a plan to investigate the effect of light intensity on the rate of photosynthesis.
Answer
To investigate the effect of light intensity on the rate of photosynthesis, follow these steps:
- Setup: Utilize a water plant, such as Elodea, placed in a controlled environment with a light source.
- Vary Light Intensity: Use a dimmer or adjustable lamp to change the distance from the plant to control light intensity.
- Measure Photosynthesis Rate: Record the number of oxygen bubbles produced as a measure of the photosynthesis rate over a fixed time interval.
- Control Variables: Maintain constant temperature, carbon dioxide concentration, and water availability to ensure that only light intensity is varied.
- Repeat: Conduct multiple trials at each light intensity to improve reliability and average the results.
- Data Analysis: Plot results to visualize the relationship between light intensity and the rate of photosynthesis.