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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 aids short-sighted individuals by ensuring that light rays diverge before entering the eye. This alteration allows the light to focus correctly on the retina rather than in front of it, enabling the person to see distant objects clearly.
Step 2
What is the number of men who are colour blind in the city?
Answer
To determine the number of men who are colour blind in the city, we first calculate the total number of men:
Number of men = 2,000,000 * 0.51 = 1,020,000
Since approximately 1 in 12 men are colour blind, the number of colour blind men:
Number of colour blind men = 1,020,000 / 12 = 85,000.
Thus, the answer is B) 85,000.
Step 3
Explain why more men than women are colour blind.
Answer
Colour blindness is predominantly linked to the X chromosome. Since men have one X chromosome (XY), if they inherit the recessive allele for colour blindness, they will be colour blind. Women, having two X chromosomes (XX), require two copies of the recessive allele to express colour blindness, hence making it less common in females.
Step 4
Explain the probability of the baby boy being colour blind.
Answer
The mother does not carry the allele for colour blindness and the father is colour blind. The father can only pass on the Y chromosome to his son, ensuring that the son will not inherit his X chromosome. Since the mother has two normal X chromosomes, the baby boy will inherit a normal X from her, making the probability of him being colour blind 0%.
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 can alter the sequence of mRNA produced during transcription. This affects the order of codons in the mRNA, leading to the incorporation of a different amino acid during translation. Consequently, the final polypeptide produced may have an altered shape or function, resulting in a protein that does not perform its intended role effectively. For instance, the protein formed in cone cells of the retina may fail to interact correctly with light, causing colour blindness.