Why can influenza viruses reinfect a person even after memory cells have produced immunity?

Two atoms have the same number of protons but a different number of neutrons. these atoms are: A. electrons B. radiation C. molecules D. isotypes

Millions of years ago a freshwater lake existed between which two continents

What type of cell division is used to replace old cell?

You cut your arm accidentally and shortly after, you notice the area around the cut is turning red and feeling hot. which response is it? a) barrier response b) fever c) inflammatory response d) immune response

Succession occurs when environmental factors affecting an ecosystem change. True or False

What human activity would have the most significant effect on the temperature of the earth? A) deforestation B) producing smog C) producing CFCs D) burning fossil fuels

Which resource is sometimes unpredictable in terms of energy production?

How many strands does a DNA molecule have?

The nucleus of an atom always contains one or more?

Why is it important for nitrogen to be recycled in an ecosystem?