Which cell structure contains the cell's genetic material and controls many of its activities?
a
nucleus
b
cell envelope
c
cytoplasm
d
organelle

Suggest why placing wheels under a heavy box reduces the neccessary force required to push it along at a constant speed.

Amarine ecologist has constructed the conceptual model shown in the diagram. what predictions can be made from using this model? where the tertiary consumers get their energy how often primary producers are able to reproduce when bacteria and fungi initiate the process of decomposition whether other secondary consumers are present

Ascientific idea becomes valid when it is what?