Because if we're simultaneously moving/manipulating two different variables it can be very hard to determine why one variable is changing and why the other is changing. While this can be done with more complicated experimental designs, it usually is the case that scientists will only manipulate one variable and not two different ones.
Answer:
D-Vacuole
Explanation:
The vacuole performs many functions such as storing water, nutrients,and wastes and it also plays a major role in the structure of the plant
IV: 4 types of nail polish
DV: brand of nail polish that lasts the longest
Control: nails
Constant: bottom coat and top coat
Experimental Group: Nail polish
Hypothesis: The types of nail polish would eventually chip away after a week .
Answer:
The stem cells was discovered by Ernest McCulloch and James Till in 1981. Studies conducted for stem cells can be used for bone marrow transplantation and to treat various diseases.
Explanation:
Stem cell are the cells that has the ability to differentiate into different cells of the body. In 1978 human cord blood discovered as stem cell. The stem cell research come to known in 1981.
Ernest McCulloch and James Till discovered the stem cell research while working on the mice bone marrow. He found that the different blood cells were formed by the single class of cells.
Experiments on mice and other animals have been conducted to study the stem cells so far. The study of stem cell is useful to cure the genetic defects, Cancer and other harmful diseases.
