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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
- Flame sterilization of the sampling tool (e.g., inoculating loop) to eliminate any contaminants.
- Working near a Bunsen burner to create an updraft that minimizes airborne 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
From Figure 8, the light absorption increases from 0.5 arbitrary units at approximately 40 minutes to 1.0 arbitrary units at around 80 minutes. Therefore, the time taken for the amount of light absorbed to double is:
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 insects that harm plants, reducing crop loss.
- Increased yield: By controlling pest populations, more food can be produced.
- More profit: Higher yields lead to increased profits for farmers.
- Less use of chemicals: Farmers may rely less on chemical insecticides, which can be harmful to the environment.
Disadvantages:
- Insects develop resistance: Over time, some pests may develop resistance to the toxin, necessitating new approaches.
- Cost of production: Plants may be more expensive to produce initially due to the genetic engineering process.
- Impact on non-target organisms: The toxin might affect beneficial insects, leading to ecological imbalances.
- Dependence on seed companies: Farmers may become reliant on specific genetically modified seeds and the companies that produce them.