Answer:
The correct option is A. they evolved from land mammals.
Explanation:
Evolution can be described as a process through which organisms in a species change over a period of time due to the natural selection of the environment. Those organisms that have many similarities in their functions or structures are considered closer to one another and have the same common ancestors.
The properties mentioned in the question about cetaceans resembles the properties of land mammals. For example, cetaceans lack gills and breathe air. Land mammals also do not have gills and need to respire for living. The cetaceans have fin bones which are similar to the limb bones in the land mammals. Hence, these observations show that cetaceas have evolved from land mammals.
This reaction is called a condensation reaction. It is also known as a dehydration reaction.
When three fatty acids become attached to a glycerol molecule, a triglyceride is formed. The fatty acids become attached to the glycerol through a condensation reaction named so because 3 water molecules are formed from the 3 OH groups from the fatty acid chains and 3 H atoms from the glycerol.
The bond formed between the fatty acid chain and the glycerol is called an ester linkage.
Answer:
D) Even a slight reproductive advantage will eventually lead to the elimination of the less well adapted of two competing species.
Explanation:
The competitive exclusion describes relationship between two species that compete for the limiting sources, and cannot coexist. It is enough for one species to have slightly advantage to be dominant over the other. As a consequence, other species (the weaker one) will be extincted (shift to a different ecological niche).
