Answer:
<h2>
A
</h2>
Explanation:
1. A channel between two adjacent cells in known as an intercellular cleft.
2. And through these channels many molecules  can easily pass between cells.
3. Importance of Intercellular clefts:
i) It is very important in transportation of fluids and small solutes.  
ii) It contains gap junctions, tight junctions, desmosomes, and adheren proteins and these junctions help in regulate cell communication by signal transduction, surface receptors, or a chemogradient.
 
        
                    
             
        
        
        
Two examples of organisms who do not reproduce sexually are:
1. Yeast
2. Hydra
 
        
             
        
        
        
The products and reactants of each cycle are connected. reactants of photosynthesis (6O2 and C6H12O6) are recycled as products in cellular respiration which produces 6H2O 6CO2 and energy to fuel photosynthesis
        
             
        
        
        
The correct answer is D. The theory of natural selection provided a better explanation of the processes that were being observed by the scientists.They observed that the related species birds found on one island were slightly different from that of the other, and certain portions earth, have the species, which were not found anywhere else.  
        
             
        
        
        
Heterozygous parents would have the genotype Rr. In a punnett square, this would show a result of 25% homozygous dominant (RR) offspring, 25% homozygous recessive (rr) offspring, and 50% heterozygous (Rr) offspring.
(I attempted to simulate a punnett square with the text)
    <u>  </u><u>R         r    
</u><u />R| RR  |  Rr
<u></u>r | Rr   |   rr<u>
</u>