Try it on paper first. A hint, the key idea and the worked solution are here when you need them.
A tumour grows from one cell, and the number of cells doubles each time. About cells weigh g.
Normal cells stop dividing when they touch, which is contact inhibition. A malignant tumour invades and spreads by metastasis, and a benign tumour does not. After doublings, a tumour that grew from one cell has cells. Carcinogens may be physical, chemical or biological.
Have you tried it?
Work it out on paper first. It is fine to get stuck or make a mistake: that is how we learn. When you are ready, go through the solution one step at a time, and check each step against your own.
Given. Start: cell. About cells weigh g.
Plan. Use for the cells, and divide by for the mass.
Step 1. Ten doublings. cells.
Step 2. Twenty doublings. cells.
Step 3. Thirty doublings. cells. The mass is g, which is g to one decimal place.
Answer: ; ; g.
Check. Each doublings multiply the number by about , as .
Watch out. Real tumours do not double at a steady rate for ever. Many cells die, and growth slows down.
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