Which does not contribute to genetic variation?
A. chromosome number
B. crossing
over
C. meiosis
D. random mating

What is the answer for the complicated molecules that make up living things usually contain carbon. why is carbon so important in these molecules?

Witch type of microscope is used to view very small cell components like proteins and dna?

Below, the levels of organization in a multicellular organism are shown from least to most complex. which level of organization can be described as several different types of tissues working together to perform a common task?