Answer:
Parasitism 
Explanation:
Parasitism is the form of mutual relationship between two organisms which occurs in such a way that one organism always get benefit and the other always gets harm. The one getting harm may or may not be killed due to it.
There are many common parasitic relationships we see in eco system.For example, when a tick sucks blood out of a dog. it is causing harm to dog by decreasing the content of blood however getting benefit for itself since blood is its food and the nutrients present in blood are source of energy for tick.
Similarly, Malaria is caused in human by a parasite called plasmodium. It enters into the blood and causes a disease called Malaria which can even lead to the death of affected individual,the parasite itself stays healthy and gets benefit.
Hope it help!
 
        
             
        
        
        
A,b I think should be the answer
        
                    
             
        
        
        
ANSWER:⇒ cork 
People struggled to believe that some of Hooke's images were real because they were so strange and remarkable! Hooke noticed tiny boxlike spaces in cork under his microscope, which he depicted and characterized as cells. Plant cells have been discovered by him!
        
                    
             
        
        
        
<span>Nitrogen and phosphorous are the most prevalent aquatic pollution and contribute heavily to the excessive growth of algae in aquatic environments called algae blooms. The nitrogen from the fertilizers is found in molecules called nitrates which are compounds of both oxygen and nitrogen. Phosphorous helps algae to absorb carbon dioxide. So when the phosphorous levels are high the algae absorbs more carbon dioxide, which allows for faster photosynthesis and faster glucose production which leads to faster growth. Although algae need both nitrogen and phosphorous to grow, when the levels are too high the algae grows faster than the ecosystem can sustain leading to oxygen deprivation for the other aquatic organisms.</span>
        
             
        
        
        
Answer:
True, the model had to change as new information came to light. 
After the invention of new instruments, it enable us to do more research and verify old theories. 
Dalton atomic theory states that matter is composed of very small particles called atoms which is indivisible. Indivisible means cannot be broken down into simpler substances. But Rutherford performed an experiment and concluded that atom is divisible into proton, electron and neutron. Electron is present in the shell while proton and neutron are present inside the nucleus of an atom.