Which is a limitation of comparative investigations?

They give results that are usually not repeatable by other scientists.
They might show variable relationships that are not actually cause and effect.
They can usually only be conducted in labs instead of in natural environments.
They are usually inexpensive, but they do not provide new information

What heat is removed how does a gas become a liquid

Chlorophyll is found in plant leaves and absorbs light from the sun to enable plants to perform photosynthesis. magnesium is an important component of chlorophyll. the concentration of magnesium ions is higher in the root-hair cells of plants than in the soil. which mechanism of ion uptake would best enable a plant to produce a steady supply of chlorophyll? osmosis diffusion passive transport active transport

Nasa scientists must work together to make sure that everything is correct and accounted for when launching a shuttle. besides a physicist, what other type of scientist would be in making sure that the shuttle has the appropriate type and amount of fuel to reach its destination?