Question

a student finds a puddle of water in a garden and takes a sample. he wants to perform an experiment to determine if there are living things in the water. how could he collect data that would provide evidence of living things? a. determine the amount of oxygen and carbon dioxide present in the water b. measure the weight of the sample over several days to see if the weight increases c. observe the water closely to look for particles that are large enough to be seen d. examine the sample under a microscope to see if cells are present

Explanation:

To determine if there are living things in the water sample, the key characteristic of living things is the presence of cells (all living organisms are made of cells). Option A measures gas levels, which doesn't directly indicate life. Option B measures weight change, which could be due to non - living factors like evaporation or sediment accumulation. Option C observes large particles, but non - living particles can also be large. Option D examines the sample under a microscope to check for cells, which is a direct way to identify the presence of living organisms as cells are the basic unit of life.

Answer:

D. examine the sample under a microscope to see if cells are present