What of the following organisms is located only in the 3rd trophic level of the soil food chain?
a. bacteria
b. fungi
c. protozoa
d. nematodes

The correct answer is option - c. protozoa.

Explanation:

Amoeba and other protozoans are located at the third trophic level of the soil food chain. Nematodes are generally present in the second trophic level but sometimes in the third trophic level also.

Bacteria and fungi have a place in the second trophic level in the soil food chain. Amoeba engulfs bacteria for nutrition.

Thus, the correct answer is option- c. protozoa.

a physical change is being made.

in the year 2850, humans successfully colonized mars. the martian modules that were constructed could hold only a small population of people. it is now a century later, and the population on mars has grown to 600 people. of the current mars population, 45 people express the recessive phenotype for phenylketon- uria (pku) syndrome (pp genotype).

explanation: