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Cancer is caused by changes in cells - OCR Gateway - GCSE Biology - Question 19 - 2021 - Paper 1

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Cancer is caused by changes in cells. (a) Describe the effects that cancer has on cells. (b) Cells usually become cancerous due to damage to their DNA.... show full transcript

Worked Solution & Example Answer:Cancer is caused by changes in cells - OCR Gateway - GCSE Biology - Question 19 - 2021 - Paper 1

Step 1

Describe the effects that cancer has on cells.

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Answer

Cancer affects cells in several ways:

  1. Uncontrolled Growth: Cancer cells proliferate uncontrollably, leading to an increase in cell numbers and a lump or mass called a tumor.

  2. Invasion of Surrounding Tissues: Cancer cells can invade nearby tissues and organs, disrupting their normal structures and functions.

  3. Metastasis: Cancer cells can spread to distant parts of the body through the bloodstream or lymphatic system, leading to secondary tumors in organs such as the lungs, liver, or bones.

  4. Altered Cell Function: Cancer cells often lose the ability to perform the functions of normal cells, affecting physiological processes in the body.

Step 2

Calculate how many females in the UK could develop breast cancer due to a mutation in the BRCA gene.

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Answer

To calculate how many females in the UK could develop breast cancer due to a mutation in the BRCA gene:

  1. Calculate the number of females with a mutation in the BRCA gene:

    The total number of females is 3×1073 \times 10^7.

    The fraction of females with a mutation is given as 1 in 400, so:

    Number with mutation=3×107400=7.5×104\text{Number with mutation} = \frac{3 \times 10^7}{400} = 7.5 \times 10^4.

  2. Calculate the number likely to develop breast cancer:

    Given that 60% of women with this mutation are likely to develop breast cancer:

    Number likely to develop=0.6×7.5×104=4.5×104\text{Number likely to develop} = 0.6 \times 7.5 \times 10^4 = 4.5 \times 10^4.

  3. Therefore, the answer in standard form is:

    4.5×1044.5 \times 10^4.

Step 3

Explain why operating to remove this tumour could produce side effects.

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Answer

Operating to remove a brain tumour can produce side effects for several reasons:

  1. Proximity to Critical Structures: The brain is a vital organ containing many critical structures, including neurons that control bodily functions. Surgery may inadvertently damage these structures, leading to side effects.

  2. Swelling and Inflammation: Post-surgery inflammation can cause swelling in the brain, which might lead to increased pressure and various neurological complications.

  3. Neurological Deficits: Depending on the tumor's location, removal might result in changes in cognitive function, movement, speech, or sensory perception, leading to long-term or permanent deficits.

In summary, one possible side effect could be neurological deficits resulting from damage to surrounding brain tissue.

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