Why did Meselson and Stahl choose to grow E. coli in broths of nitrogen isotopes? A. The bacteria's phosphate groups would be replaced by the nitrogen.
B. The nitrogen would be incorporated into deoxyribose.
C. The nitrogen would influence bonding between base pairs.
D. The nitrogen would be incorporated into the DNA nucleotides.

Ablastocyst is a group of cells that forms after a human egg is fertilized. the blastocyst consists of two types of cells. some of these cells will become the placenta. what do the other cells develop into?

Dna. we have heard that we are a product of our dna. but where is it? how do we "get" our dna? it is passed to us, from our parents, but in what form? several vocabulary words associated with inheritance are used interchangeably and sometimes, incorrectly. let's see if you can clear this up for someone just learning about inheritance and cell structure.

Science which of the following is an example of a cyclic behavior that is seasonal? i think the answer is d, i just need to double check : ). a. running from predators. b. searching for water. c. hunting at night. d. migrating for warmth. ***