Fish live completely in water, amphibians partly in water and land while reptiles live on land. Fish and reptiles have scales while amphibians have smooth skin. Fish breath through gills, amphibians through gills and lungs while reptiles through lungs. They are generally classified as vertebrates.
The basic repeating unit of nucleic acids are known as nucleotides
Carbon and hydrogen.
The simplest group of organic molecules are the alkanes which have only these 2 elements. Eg methane, CH4.
Cause now afays climate changes very fast and more technologies hot advanced