In an experiment to determine the percentage of humus and water in a soil sample, the following results were obtained
Weight of the evaporating basin alone = 80.5g
Weight of basin and soil = 101.5g
Weight after drying the soil in the oven = 99.0g
Weight of basin and roasted soil = 95.5g
The percentage of humus in the soil sample is

An example of a filter -feeding animal is

The interaction of a community of organisms with its abiotic environment constitutes