Answer:
Dosage and form in which the chemical is present are the factors that determine the level of harm of chemical on the environment.
Explanation:
Dosage usually mean amount of chemical. Some chemicals cause harm to the environment in a very low amount and some chemicals damage the environment when the amount is too high, these chemicals are not considered as toxic. Form of chemicals also affects its toxicity. Some chemicals are harmful in one state and beneficial in another state.
Answer:
The mentioned characteristics of variability are witnessed because of the phenomenon known as X chromosome inactivation in heterozygous females. As females possess two X chromosomes, they actually should not possess any color blindness.
The phenomenon of X-chromosome inactivation takes place in a random manner at the time of embryo development. During this only one X chromosome is inactivated. If the chromosome comprising the defective gene is inactivated, the individual will possess normal vision.
If the chromosome comprising the usual gene gets inactivated than the individual will be color blind. In the given case of female, X inactivation took place in one eye. The inactivation of normal alleles has taken place and thus she possesses normal vision with one eye and is color blind in the other eye.
