Answer:
That is administered and controlled
Step-by-step explanation:
A variable is the condition or a product that may vary without the influence of any investigator. Such variables can be found abundantly in our daily lives, ranging from air to sunlight. Controlling such variables ensures the limitation of their influence on the outcome of an experiment. In connection to this experiment, the variables that are controlled are the mineral content in the water, the amount of bacteria food, the amount of light and the the constant temperature of 20 degrees C.
If not administered or these variables controlled, the experiment would not clearly explain the impact of caffeine on the heart beat of the water fleas as other variables may have influenced it. Thus variables are controlled to study the singular impact of any agent or effect.
The evidence supporting the idea that modern birds and reptiles share a common ancestor is that feathers are a derived characteristic that first evolved in reptiles. Feathers represent an evolutionary derived trait.
In evolutionary biology, an autapomorphy is a distinctive phenotypic trait referred to as a derived trait, which is unique to a particular group/taxon.
The derived traits are phenotypic features that arise during the evolution of a particular taxonomic group.
These traits (derived traits) differ from the phenotypic trait of the ancestor of the group.
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Treehouses are built on the stem and the three branches, which do not grow in length, only in width. Trees grow in length only in the area of the buds, which are located at the ends of branches.
Maybe it is easier to understand this if you imagine that you put a small house replica on the palm of your hand and that your fingers are constantly growing from their tips. So, the house on your palm would not move, only your fingers, (the analogy to the three top buds) would become longer.
Darwinism is a theory of biological evolution developed by the English naturalist Charles Darwin (1809–1882) and others, stating that all species of organisms arise and develop through the natural selection of small, inherited variations that increase the individual's ability to compete, survive, and reproduce.
Answer;
-Gap junctions
Explanation;
-Gap junctions are a specialized intercellular connection between a multitude of animal cell-types. they are organized collections of protein channels in cell membranes that allows ions and small molecules to pass between adjacent cells.
-Gap junctions allow the exchange of ions, second messengers, and small metabolites between adjacent cells and are formed by two unrelated protein families, the pannexins and connexins.
