Answer and Explanation:
Humans are one of the most powerful biotic factors. Human activities have had great influence on the distribution of other organisms. The use of aerosols and industrial chemicals like chlorofluorocarbons which are residual and persistent can cause depletion of the ozone layer. This results in harmful radiations from the sun reaching the earth's surface.
Excessive production of CO2 by the industries and removal of vegetation like the trees results in the accumulation of CO2 in the lower atmosphere. This causes the greenhouse effect which results in global warming.
Radioactive emission from nuclear reactors, mine and radioactive wastes causes cancer, mutations and even death.
Answer:
4
If the beaker was not cleaned, starch could have been in it.
the answers are 1,4,5 hope it helps
