Answer:
double helix
Explanation:
Together, a base, sugar, and phosphate are called a nucleotide. Nucleotides are arranged in two long strands that form a spiral called a double helix
2 and 3 are too similar to distinguish because they both are saying it's been back up on several different accounts but 3 seems like a more solid answer go with 3
Each chromosome contains one molecule.
The Circuit-Level involves the spinal cord.
There are 4 thing that need to happen for natural selection to occur:
1) reproduction
2)heredity
3)variation in fitness or organisms
4)variation in individual characters of the population.
