4 (a) Figure 5 shows how alcohol consumption increases the risk of developing liver cancer - Edexcel - GCSE Biology Combined Science - Question 4 - 2021 - Paper 1

Cancer development in the liver generally occurs through a series of mutations that accumulate over time. Here’s an overview:

1. Mutations occur in DNA: These genetic changes can arise from environmental factors, such as exposure to carcinogens like alcohol, leading to alterations in normal cellular functions.

2. Uncontrolled Cell Division: The mutated cells begin to divide uncontrollably, leading to a rapid increase in cell numbers.

3. Tumor Formation: As these abnormal cells continue to proliferate, they form a mass or tumor, subsequently disrupting normal liver function and potentially leading to malignant cancer.

1. Wear gloves: This prevents exposure to bloodborne pathogens during the procedure.

2. Use a sterile needle: Ensuring that a new and sterile needle is used helps to avoid infections.

The genotype of female Z is heterozygous (Hh).

Explanation:

• Female Z has one allele for the dominant trait (H) and one for the recessive trait (h). This means that offspring who inherit her dominant allele will not exhibit haemochromatosis, while those inheriting the recessive allele may develop the condition if paired with another recessive allele from the other parent.