Answer: A. Chemical signal
Explanation:
Chemical signal is the type of communication which coordinates actions between neighboring cells
.
This ability originated in single cells organisms and was essential for the evolution of multicellular organisms because after a cell receives a message, it is transferred across the plasma membrane and changes are brought about within the cell in response to this message.
The first, second, and fourth statements are correct.
<h2><u>Answer:</u></h2>
Fossil: is preserved pre historic life form present under ground at high pressure for a long time.Animal die and burried under layers of sediments.
It provides evidence about the history of life on earth. It also shows different groups of organisms, including species,that have changed over time. Because the formation of any fossil depends upon the precise combination of conditions.
As the world changes, plants and animals change with time . From fossils we compare organisms of modern time with ancient , the species we see today are very different from species that lived in the past. Thus, the fossil record can be used to show that organisms changed to meet new condition.
Answer:
Option C, Plant A
Explanation:
Control group within an experiment is the substance/organism or subject which shall enact as a base for comparison of impact of experiment created on the dependent variables.
Here, the impact of fertilizer is to be studied on plant. Thus, plant set up is dependent variable and amount of fertilizer is an independent variable. Out of all plants one plants is getting 0 amount of fertilizer hence this plant can be used for comparison with other plants which receives the fertilizers.
