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Bacteria grown in a liquid medium is called a bacterial culture - Edexcel - GCSE Biology - Question 7 - 2020 - Paper 1
Question 7
Bacteria grown in a liquid medium is called a bacterial culture. As the number of bacteria increases the bacterial culture becomes opaque. This is because light is a... show full transcript
Worked Solution & Example Answer:Bacteria grown in a liquid medium is called a bacterial culture - Edexcel - GCSE Biology - Question 7 - 2020 - Paper 1
Step 1
Give two aseptic techniques the scientist should use when taking samples from the bacterial culture.
Answer
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Sterilize the instruments used for sampling, such as pipettes or surgical scissors, by using an autoclave or flame.
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Use gloves or disinfectant wipes to clean the surface of the culture container before and after taking the sample to prevent contamination.
Step 2
Calculate the time taken for the amount of light being absorbed by the bacterial sample to double from 0.5 to 1.0 arbitrary units.
Answer
According to Figure 8, the light absorption reaches 0.5 at around 20 minutes and 1.0 at around 60 minutes.
To calculate the time taken for the light absorption to double, we find the difference:
60 minutes - 20 minutes = 40 minutes.
Therefore, it takes 40 minutes for the light absorbed to double from 0.5 to 1.0.
Step 3
Step 4
Step 5
Discuss the advantages and disadvantages of growing crop plants that produce a toxin that can kill insects.
Answer
Advantages
- Less damage to crops: The toxin specifically targets pests, reducing the damage done to the plants.
- Increased yield/more food: Healthier plants can produce a higher yield due to less pest damage, contributing to food security.
- More profit: Farmers may enjoy higher profits due to reduced losses from pests.
- Less use of chemical insecticides: Reducing reliance on synthetic pesticides can lead to lower environmental impact.
Disadvantages
- Insects develop resistance to the toxin: Over time, pests may evolve to become resistant, reducing the effectiveness of the toxin.
- Higher production costs: Growing genetically modified plants may require more investment in biotechnological processes and initial setup.
- Risk of cross fertilization: There is a potential risk of genetically modified crops cross-breeding with non-GM plants, leading to unintended consequences.
- Detrimental impact on the food web in the area: Non-target organisms may be affected, disrupting the existing ecosystem balance.
- Public perception and reliance on seed companies: Some consumers might have reservations about GM crops, and there could be dependence on a few large companies for seeds.