Explain why, at point X, carbon dioxide is neither taken up nor given out by the tomato plants. (1)

This is an controlled experiment because he is only changing the amount of carbon dioxide in the air. Since he is only changing one variable at a time and comparing it to a natural, unaltered tomatoe area, his experiment is controlled.

Explanation:

The definition of a controlled experiment is a test where the person conducting the test only changes one variable at a time in order to isolate the results. An experiment where all subjects involved in the experiment are treated exactly the same except for one deviation is an example of a control experiment.

lunar landing mission. apollo 11 was the first manned mission to land on the moon. the first steps by humans on another planetary body were taken by neil armstrong and buzz aldrin on july 20, 1969. the astronauts also returned to earth the first samples from another planetary body.

explanation:

affects the water bodies: excessive use of fertilizers causes eutrophication. the fertilizers which are used on plants affect the quality of land on which it is used, further causing erosion of soil. the fertilizers used on plants contain harmful chemical fumes which affect the environment.