Answer:
the concentrations of salt water because its being controlled by the scientists.
Explanation: the iv= between the control and expariment.
dv= data or out come
constant+ not changed at all
 
        
                    
             
        
        
        
Answer: D). Primary species have large numbers of offsprings, and climax communities contain species that have small numbers of offsprings. 
An ecological succession is a process of gradual changes occurs in a biological community with respect to changes in the non-living abiotic factors  (water, air and sunlight) and with respect to time until the ecosystem attains stability. Primary or pioneer species are the species which invade the previously barren and primitive landmass for their survival. These species make the environment suitable for the growth of other species. These grow and develop in the initial stages of succession. These species are simple organisms which reproduce asexually and produces large number of offsprings. Examples are lichen and moss. Lichen grows on the surface of rocks and acids released by them causes withering of rocks into soil which facilitate the growth of mosses and other plants. Climax community develops in an ecosystem after replacing many previously inhabiting species. Climax community develops in the end of the ecological succession. It contains species which are highly complex and uses sexual reproduction for the production of offsprings which are less in number as compared to those produced by pioneer species by asexual reproduction.   
 
        
                    
             
        
        
        
<span>The glacial sediment is known as glacial till.
 Glacial till is derived from entrainment and erosion of material by the moving ice of the glacier.
 It is being deposited a distance down -ice to form ground moraines, medical, lateral, and terminal. Glacial till is divided into primary deposits which are rewarded by fluvial transport. 
The large rock which is transported by a glacier is called moraines. Moraines are formed from debris which is previously carried along by a glacier and consists of rounded particles which range in size from the large boulders.
 Moraines are of different types, for example, ground moraines, lateral moraines, and recessional moraine.</span>
        
                    
             
        
        
        
The genotype of a normal male zygote is XY, with the X chromosome (sex chromosome) coming from the mother and Y from the father.