Answer:
C. 444 Ma
Explanation:
The first plants that managed to colonize the land appeared around 470 million years ago, while the first arthropods on land appear i the fossil records around 450 million years ago, so we can say that around the period of 444 million years ago they were well established on land. The first arthropods that started to have terrestrial life were almost identical to those in water, with only minor changes that enabled them to breathe and move more easily. The first plants on land were non-vascular plants. They were small as they initially didn't had deep and well established roots.
Microtubules originate on the centre of the cell taking the positive end to the periphery of the cell, while the negative end remains turned to the centre of the cell. The melanosomes move along these microtubules using motor proteins desiganted kinesins and dyneins. The kinesins are responsible for moving the melanosomes to the positive end of the microtubule (periphery of the cell) generating dark-colored cells, whereas dyneins move the melanosomes to the negative end of the microtubule (centre of the cell) generating light-colored cells.
Smog is an abiotic factor affecting a biotic factor(s).
This is because smog isn't a living organism so it is abiotic while humans are multicellular organisms so therefore, they are biotic factors.
Smog has a negative effect on many biotic factors.
