Why does adenine only pair with thymine in dna? why does cytosine only pair with guanine?

Adenine,Thymine,Guanine,Cytosine are nitrogenous base pairs of DNA

Explanation:

Due to base pairing rule Adenine binds with thymine and guanine binds with Cytosine.1 purine+1 pyrimidine. The imidazole ring of purine attaches with pyrimidine ring.Two purines never fit between the two strands of DNA.Therefore hydrogen bond (H-bond) connects these two bases by means of N1 and amino acid. These bases make up a nucleic acid.Adenine binds with thymine with 2 (H-bonds) and similarly guanine binds with cytosine with 3 (H-bonds). This binding follows the Erwin Chargaff's Rule

increase soil erosion                                             reduce soil erosion

cattle grazing                                                         hydroseeding

deforestation                                                         contour plowing

                                                                                planting vegetation

plant roots basically hold the top soil

together and stop soil erosion because

in such situation top soil is not removed

during flood but cattle grazing causes

soil erosion because cattle consume the

grasses and herbs and top soil is exposed.

same situation occurs because of

deforestation, the trees and plants are cut

down to expose top soil which causes soil

erosion

acceleration= v2-v1/t so 8m/s-3m/s / 3s =to 8/3 or

2.67 m/s^2

hope i

-lavira: )