Abiotic changes have the ability to dictate biotic ones. This can be caused by humans. For example: an abiotic thing can be an element like water. If the water in a lake gets poisoned by chemical compounds, this is an abiotic change. However, since the lake is now poisoned it’ll likely harm or even kill fish, bacteria, algae, and any other wildlife living within the lake. It doesn’t stop there though, without the lake surrounding animals won’t have clean water to drink, they can now die from either the poisoning, dehydration, or starvation if they lived off of the aquatic life from the lake.
An independent variable is the only variable that is changed while the rest is kept the same. In this setup, the doctor is using different creams on the same patient with the same skin condition so the independent variable is the skin cream and not the skin condition.
