Secondary since plants/animals already lived there, but got killed/driven out of the area they lived/thrived in/on.
They reproduce over the years making it less frog to survive
Answer:
in science Observation is essential in science. Scientists use observation to
collect and record data, which enables them to construct and
then test hypotheses and theories . Scientists observe in many
ways – with their own senses or with tools such as microscopes,
scanners or transmitters to extend their vision or hearing
Answer:
you are correct sir. It is a controlled experiment
Explanation:
