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.
 
        
             
        
        
        
The greatest issue facing
society that results from the development of new applications of cell
technology is that it can make the arteries narrower especially for patients
with heart diseases. Although cell technology has been revealed as an ideal
cure for heart related diseases.
 
        
                    
             
        
        
        
Answer:
Answer: Homozygous
Explanation:
An organism in which the two copies of the gene are identical that is, have the same allele is called homozygous for that gene.
 
        
             
        
        
        
<span>Molecular scientists can read the DNA code and compare the DNA of different organisms. This concept is ude in molecular clocks to determine the Moleular Phylogenies. It is letter B. Hereditary molecular differences are being analyzed in phylogeny which is mainly from the DNA sequence in order to acquire information on the evolutionary relationships of an organism.</span>
        
                    
             
        
        
        
Answer:
Carbon binds to oxygen, hydrogen, and nitrogen covalently to form the many molecules important for cellular function. Carbon has four electrons in its outermost shell and can form four bonds. Carbon and hydrogen can form hydrocarbon chains or rings