Questions: 1. How is a cell membrane like the plastic bag in the experiment?
2. Define diffusion.
3. List two reasons why molecules will not diffuse into cells.

Explanation:

1. cell membranes are partialy permeable, only allowing passage to some certain molecules.

2. diffusion is the movement of molecules across partially permeable membrane down concentration gradient.

3. the molecules are too big to pass through partially permeable membrane. the concentration of the molecule might be higher in the cell than in the solution/surroundings.

it depends on how much it could carry.

the oldest known insects are believed to live around 400 millions ago as suggested by the fossil records.   some plants having woody stems also evolved during this time.

after the evolution of insects the first four legged species or the tetrapods evolved in shallow freshwater habitats from the intermediate species approximately 397 million years ago. the tetrapods went on conquering the land giving rise to amphibians, reptiles, mammals and birds.

the major split in tetrapods first occurred 340 million years ago branching off from amphibians.

363 million years ago when the carboniferous period began the insects started roaming on land and taking flights, following which the four limbed tetrapods adapted in the terrestrial habitat.