Green algae lack the vascular tissues, that is they do not have phloem or xylem for transporting water and nutrients throughout their bodies. They have a thalloid that means they do not have a body divided into root stem and leaves. The thalloid body helps in absorbing nutrients from surroundings.
The land-based plants have xylem and phloem (vascular tissues) to transport water, nutrients, and minerals throughout the body.
The variable that researchers manipulate is the independent variable.
The reason for this is because in experiments different manipulations are often introduced. The sole purpose of these manipulations is to see whether they will affect our independent variable and if they will change its value.
