In a Hypothetical Situation, a Bacterium Lives on the Surface

question 20

Multiple Choice

In a hypothetical situation, a bacterium lives on the surface of a leaf, where it obtains nutrition from the leaf's nonliving, waxy covering while inhibiting the growth of other microbes that are plant pathogens. If this bacterium gains access to the inside of a leaf, however, it causes a fatal disease in the plant. Once the plant dies, the bacterium and its offspring decompose the plant. What is the correct sequence of ecological roles played by the bacterium in the situation described here? Use only those that apply.
1) nutrient recycler
2) mutualist
3) commensal
4) parasite
5) primary producer

• A) 1, 3, 4
• B) 2, 3, 4
• C) 2, 4, 1
• D) 1, 2, 5
• E) 1, 2, 3

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Definitions:

Hardy Weinberg Principle

A principle that describes how allele and genotype frequencies in a population remain constant from generation to generation in the absence of evolutionary influences.

Antigens

Substances that are recognized by the immune system and can provoke an immune response, typically proteins or polysaccharides found on pathogens.

Dominant Allele

An allele that expresses its phenotype even in the presence of another (recessive) allele.

Hardy-Weinberg Equilibrium

A principle stating that genetic variation in a population will remain constant from one generation to the next in the absence of disturbing factors.