Answer: A semi-permeable membrane is that which only allows certain
                substances to pass through.
 
        
                    
             
        
        
        
Dr. Alvarez is doing research on the subfield of psychology called the behavioral neuroscience. Scientists from the field study the biological foundation of human behavioral characteristics. These scientists are trying to find out what physiological processes and anatomical structures are involved in certain aspects of human behavior.
        
             
        
        
        
 
Well, we have a book to write on this topic but imma explain it briefly plus simply. 
- Global warming emphasizes the environment with rising temperatures, water shortages, increased fire threats, droughts, weeds and pest attacks, severe storm damage and salt attacks, to name just a few.(In simple words) 
Now, we'd go briefly and discuss some common affects briefly :
- Hotter days - The climate is getting more and more warmer and year 2015 was the hottest year ever record throughout the history. The Earth's temperature had already warmed by 1°C which is really dangerous. 
- Rising sea levels - Rising sea levels due to climate change is the biggest problem causing natural calamities. Increased ocean temperatures are melting glaciers and ice caps all over the world. Melted ice increases the volume of water in our oceans. Warmer temperatures also result in the expansion of the water's mass, which causes sea levels to rise, threatening islands and coastal cities.
- More frequent and intense extreme weather - Extreme weather events like bushfires, cyclones, droughts and floods are becoming more common and more aggressive as a result of global warming. 
Hope it helps <3
 
 
        
             
        
        
        
The crossing over is a process that is essential to human genetic diversity. During the crossing over parts of the homologous chromosomes ( two chromosomes identical by structure, but different in origin, one inherited from the mother and one from the father) randomly exchange parts of their sequences.
If the crossing-over didn't exist, this would greatly decrease the genetic diversity, because the chromosomes would always bee passed o the next generations unchanged.