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The UK driving test requires a person to be able to read a number plate at a distance of 20.5 metres - Edexcel - GCSE Biology - Question 10 - 2020 - Paper 1
Question 10
The UK driving test requires a person to be able to read a number plate at a distance of 20.5 metres. Some people are short-sighted so cannot read the number plate ... show full transcript
Worked Solution & Example Answer:The UK driving test requires a person to be able to read a number plate at a distance of 20.5 metres - Edexcel - GCSE Biology - Question 10 - 2020 - Paper 1
Step 1
Explain how a diverging lens corrects short-sightedness.
Answer
A diverging lens helps to correct short-sightedness by allowing light rays to diverge before they reach the eye. This alters the focal point of the light so that it is projected onto the retina rather than in front of it. This adjustment enables short-sighted individuals to focus on distant objects clearly.
Step 2
What is the number of men who are colour blind in the city?
Answer
First, calculate the number of men in the city: 51% of 2,000,000 is 1,020,000 men. Since 1 in 12 men are colour blind, the number of colour blind men is calculated as follows:
ext{Number of colour blind men} = rac{1,020,000}{12} = 85,000
Therefore, the answer is B 85,000.
Step 3
Explain why more men than women are colour blind.
Answer
More men than women are colour blind because the gene responsible for colour blindness is located on the X chromosome. Men have one X chromosome, so if they inherit the recessive allele for colour blindness, they will express the trait. In contrast, women have two X chromosomes, meaning they would need to inherit the recessive allele on both chromosomes to be colour blind. This makes it less common for women to be affected.
Step 4
Explain the probability of the baby boy being colour blind.
Answer
The father is colour blind and has the genotype X^(c)Y (where X^(c) represents the X chromosome with the allele for colour blindness). The mother, who does not have the allele, has the genotype XX. The possible offspring combinations for a baby boy (XY) are:
- From the father: X^(c)Y
- From the mother: XY (the mother contributes an X)
Thus, the only possibility for their son is X^(c)Y, meaning he will be colour blind. Therefore, the probability of the baby boy being colour blind is 100%.
Step 5
Explain how a change in the DNA sequence of a gene can result in the production of a different protein.
Answer
A change in the DNA sequence of a gene alters the sequence of mRNA during transcription. This alteration can lead to a different amino acid sequence in the resultant polypeptide chain. For example, if the change leads to the substitution of one amino acid for another, it can affect how the protein folds and its overall shape. A change in shape can impact the protein's function, leading to a different physiological outcome.