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a) The earlobes of an individual are detached or attached - Edexcel - GCSE Biology - Question 1 - 2012 - Paper 1

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a) The earlobes of an individual are detached or attached. This is determined by the alleles inherited from their parents. An individual with attached earlobes must... show full transcript

Worked Solution & Example Answer:a) The earlobes of an individual are detached or attached - Edexcel - GCSE Biology - Question 1 - 2012 - Paper 1

Step 1

State the genetic term used to describe an individual with the genotype ee for attached earlobes.

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Answer

The genetic term used to describe an individual with the genotype ee for attached earlobes is 'homozygous recessive.' This means that the individual has two identical recessive alleles.

Step 2

Draw a Punnett square to show the inheritance of the alleles.

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Answer

To illustrate the inheritance of alleles, we create a Punnett square:

   | E  | e  
---|----|----
 e | Ee | ee |
 e | Ee | ee |

This demonstrates the potential offspring genotypes.

In this case, there are two Ee (heterozygous) and two ee (homozygous recessive) offspring genotypes.

Step 3

Determine the probability of obtaining an offspring with attached earlobes.

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Answer

The probability of obtaining an offspring with attached earlobes (genotype ee) is 2 out of 4, or 50%. This can also be expressed as:

  • 1/2
  • 0.50
  • 50%
  • 1:1 or 2:2

Any of these representations is acceptable.

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