The ecological efficiency at each trophic level of a particular ecosystem is 20%. if the green plants of the ecosystem capture 100 units of energy, about units of energy will be available to support herbivores, and about units of energy will be available to support carnivores.

one person pulls 90n one way and the other has 100n pulling the other way.

so the net force = 90 - 100 = -10n,

or the ans can be 10n if the picture shows -90n and 100n instead.

myth. it was once thought that animals, including cats and dogs, could only see in black and white. however, scientists have proven this to be a myth. in all animals, including humans, the perception of colour is determined by the presence of cells in the eye called cone photoreceptors.