CHAPTER 10 – HUMAN HEALTH


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TEST TUBE


1. Haemophilia is an inherited human condition caused by a mutation in a single gene. Haemophiliacs are unable to clot blood effectively. Examine the pattern of inheritance for haemophilia in the pedigree chart shown in Fig. 10.2 and answer the questions that follow:


1 2 3 8 : Fig. 10.2


a. Square 1 and circle 2 represent a male and a female. How many offspring did these parents produce?


b. Person 4 is a male haemophiliac. Are any of his offspring haemophiliacs? Explain your answer.


c. Some non-haemophiliacs may be carriers of the disease. What evidence is there to suggest that person 7 is a carrier?


2. Research one other inherited condition: • What is it called? • What change to a gene or chromosome causes it? • Is it caused by a dominant gene or recessive gene? • What effect does this mutation have on a person’s health?


Environmental factors


Cancer is not an inherited disease, but gene mutations that increase the risk of developing some cancers (e.g. breast cancer) can be passed from parents to offspring. Some cancers become more common as people age, such as prostate cancer in males and ovarian cancer in females. Cancer-causing mutations can also happen due to environmental factors. For example:


• Smokers are at greater risk than non-smokers of developing lung cancer.


: Fig. 10.3 Exposure to UV rays can cause skin cancer


• Exposure to the Sun (or sunbeds) increases the risk of skin cancer, as UV rays in sunlight damage the DNA of skin cells.


? TEST TUBE


3. a. Research one of the following treatments for cancer: • radiotherapy • chemotherapy


b. How does this treatment work to slow cell division?


4. Suggest two lifestyle behaviours that could reduce a person’s risk of developing cancers caused by environmental factors.


Elements of Science 93 4 5 6 7


Male, not haemophiliac Male, haemophiliac Female, not haemophiliac Female, haemophiliac


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