<span>A mature sporophyte produces spores by meiosis, a process which reduces the number of chromosomes to half, from 2n to n. Because meiosis is a key step in the alternation of generations, it is likely that meiosis has a fundamental adaptive function. The nature of this function is still unresolved (see Meiosis), but the two main ideas are that meiosis is adaptive because it facilitates repair of DNA damages and/or that it generates genetic variation.
The haploid spores germinate and grow into a haploid gametophyte. At maturity, the gametophyte produces gametes by mitosis, which does not alter the number of chromosomes. Two gametes (originating from different organisms of the same species or from the same organism) fuse to produce a zygote, which develops into a diploid sporophyte.</span>
        
             
        
        
        
Answer:
The oceans are present on the 70 percent of the world but only 5 percent of the total oceans are explored yet.
There are many reasons of this problem but the most important is the hydrostatic pressure.
Hydrostatic pressure can be described as the pressure or weight exerted by the water on the object.
With every increase in 10 meters the pressure increase by 6.47kg (14.27lbs) each square inch of surface. 
Due to extreme pressure, oxygen level in the cells of body fluctuates and person becomes unstable and can become unconscious.
 
        
             
        
        
        
A characteristic of carbon is that it is highly reactive and can form unstable bonds with any available atom. 
        
             
        
        
        
Answer:
Some of the hydrogen bonds with other elements, but most of it remains free hydrogen. Both hydrogen and helium are light elements, so they will tend to evaporate into space over time. ... But the gravity of Earth isn't strong enough, so Earth's early atmosphere of helium and free hydrogen evaporated into space.
Explanation: