ecosystem:
Living and Nonliving Things in the Ecosystem. Ecosystems -- biological communities -- include living organisms like animals, plants, insects and bacteria, as well as nonliving components like rocks, soil, water and sunlight.
 
        
                    
             
        
        
        
The answer is A. a light wave
C and D both need water as a medium and sound needs air to vibrate in order to travel. light, on the other hand, does not need a medium
        
                    
             
        
        
        
<span>A. Redwood trees
 K-selected species are living organisms that are usually larger than those in the r-selected species</span>
        
                    
             
        
        
        
Answer:b; exocytosis
Explanation: leukocytes are amoeboid white blood cells, which are involved in immune response .such response included combating foreign bodies like micro organisms which invade the body.they do this by engulfing the micro organisms and digesting them.
Phagocytosis, pinocytosis, receptor mediated endocytosis are the ways in which the cells engulfs the Invaders.
In endocytosis,the membrane of the cell traps the organism by forming an invagination.it then encloses the micro organism and digests it. 
 
        
             
        
        
        
Heat from the sun makes it through near the Antarctic (where the hole is) is melting the ice and not allowing some key species to feed. seals don't have ice to come up for air through like normal so polar bears starve. loss of land means less food for a lot of species because the hunting grounds is closing and there is no room to expand.