Answer:
Here is some background information...
Explanation:
Leeuwenhoek (1633-1723) used melted glass balls to form lenses for apparently crude simple microscopes that nevertheless magnified up to 275 times! Modern tests have concluded that he could have achieved a resolution of two micrometres.
C.specialized cells
such as choanocyes which grab food when filter feeding
Answer:
In animal field studies, why do scientists usually try to work without making the animals aware that the humans are present? It is necessary to observe the animals without disturbing them. When a controlled experiment is not possible, why do scientists try to identify as many relevant variables as possible?
