Complete the paragraph below by writing the most appropriate word in each of the spaces. A ..................................................... includes a long molecule of DNA that is divided into sections called genes. Genes may be copied and passed on to the next generation. Each gene may have two or more alternative forms called ..................................................... . One of these forms may be ..................................................... and the other recessive. A change in the structure of a gene or in the number of chromosomes is called a ..................................................... . Chemicals and ..................................................... may increase the rate at which these changes take place.

1. (a)Complete the paragraph below by writing the most appropriate word in each of the spaces. A ..................................................... includes a long molecule of DNA that is divided into sections called genes. Genes may be copied and passed on to the next generation. Each gene may have two or more alternative forms called ..................................................... . One of these forms may be ..................................................... and the other recessive. A change in the structure of a gene or in the number of chromosomes is called a ..................................................... . Chemicals and ..................................................... may increase the rate at which these changes take place.[5]