The student is trying to see which substance (disinfectant 1, 2, 3, or the distilled water) can disinfect the most.
You would expect an earthworm to have no exoskeleton because as you see it is very flexible and soft. Organisms with such have body parts that are divided and an earthworm do not have any visible parts on them also having an exoskeleton would not allow an organism to move like an earthworm does.
"Lactose intolerance" means that your stomach has an extremely hard time digesting lactose, found in dairy products such as milk. For the second part of the question, can you tell me if you mean adapting to resist against lactose or the development of lactose from a long time ago.
Answer:
There are approximately five main climate types on Earth:
Tropical.
Dry.
Temperate.
Continental.
Polar.
