There are many different types of scientific investigations. which of the following forms requires the identification and control of variables?
a.
model-building
b.
observational field studies
c.
collection of specimens
d.
laboratory experiments

The gene that causes sickle-cell disease is present in a higher percentage of residents of sub-saharan africa than among those of african descent living in the united states. even though this gene causes sickle-cell disease, it also provides some protection from malaria, a serious disease that is widespread in sub-saharan africa but absent in the united states. discuss an evolutionary process that could account for the different percentages of the sickle-cell gene among residents of the two regions.

You have 2 plants of the same type and same size, same amount of leaves. one of them is put inside the house and the other one is put in the balcony. you water them saturday, one plant with 200 ml and the other with 400 ml of water. which one of your plants need less water? explain.

What is the name of the type of cell division that occurs in the prokaryotic cell cycle