In an ecosystem, a sudden decrease in the number of bacteria in the soil would most likely result in

Bacteria in the soil, are responsible for the process of nitrogen fixation. It aids in the conversion of atmospheric nitrogen into nitrogen-containing compounds (like ammonia) that can be used by plants. If there will be a sudden decrease in the number of bacteria in the soil there will be lesser nitrogen supply for plants and organism, air and water which comprise our ecosystem.

answer: a. a gene that causes a specific trait.

that scientist would be robert hooke