What are
principle basis on classification

Classification is a systematic ordering of the object of research, in this case, ecosystems at the earth's surface or, in other words: landscape units as 'holons'. As for general principles of classification, we can learn a lot from the best-known classification, the taxonomical classification of species.

Explanation:

c) 50% there are four chromosomes. after crossing over, 2 of the four have been changed. that means any gamete has a 2 in 4 chance or 50% chance of receiving the mutated chromosome.