Atrain is to cars as a molecule of dna is to

Genes

Explanation:

The cars are the part of the train. This means that the genes are the part of the DNA.

The genes are the small components of the DNA. The functional unit of DNA are genes.

These genes are responsible for the characters that is transferred by DNA from one generation to another generation.

It can be said that the genes are the functional unit of DNA as Cars are the functional unit of train.

humans are now responsible for causing changes in the environment that hurt animals and plant species. we take up more space on earth for our homes and cities. we pollute habitats. human activity often changes or destroys the habitats that plants and animals need to survive.