What intermolecular force is responsible for holding the two strands of a dna double helix together?

An enzyme lowers the energy of activation. what does that mean?

How does the molecular clock work? a. it analyzes the brain functionality of two different species.b. it examines and compares the physical characteristics of two different species.c. it illustrates relationships between two different species.d. it compares the number of mutations that exist in the dna of two different species.

Which is a genetic engineering advancement directly related to a career in biotechnology? 1) improving solar energy collection 2) transporting textiles at higher rates 3)creating crop foods that resist insect pests 4)repairing historical sites with quality materials