Which statement describes an example of gene therapy?

a. a virus is used to transfer human dna into a bacterial cell.

b. a defective gene is replaced with a normal gene.

c. dna banding patterns are used to identify an individual.

d. the genes for a certain desirable trait are identified.

B. A defective gene is replaced with a normal gene.

a covalent bond, specfically triple bond

the nitrogen cycle provides nitrogen to the ecosystem from the atmosphere, ground and oceans. nitrogen is an important component of complex molecules such as amino acids and nucleotides, which lead to the creation of proteins and dna, the building blocks of all life. plants absorb nitrogen in the form of ammonium, nitrate ion and, on rare occasions, as amino acids. animals receive nitrogen necessary for biological processes from feeding on living or dead organic matter.