The following diagram shows part of a river into which sewage was dumped. Some of the effects of adding sewage to the river are shown in graph.
a) At which point in the river are decomposers most active?
b) What happens to the oxygen level of river at that particular point?

heat a spark and oxygen

humans are now responsible for causing changes in the environment that hurt animals and plant species. we take up more space on earth for our homes and cities. we pollute habitats. human activity often changes or destroys the habitats that plants and animals need to survive.

the dna molecules have a negative charge because of the phosphate groups in their sugar-phosphate backbone, so they start moving through the matrix of the gel towards the positive pole. power is turned on and dna fragments migrate through gel (towards the positive electrode).

explanation:

i believe it is c: genes for body color and wing size are inherited separately from each parent.