Diatoms have cell walls composed of silicon dioxide.
A. silicon dioxide.
        
                    
             
        
        
        
Answer:
I would say overpopulation
Thus because when they are trying to navigate through jungles, they are destorying whats in their path, without realizing. There are so many of the elephants it just keeps happening over and over like a cycle.
 
        
             
        
        
        
Answer:
Plant cells have cell walls, constructed outside the cell membrane and composed of cellulose, hemicelluloses, and pectin, a cell membrane similar to that of the animal cell, a large central vacuole, a water-filled volume enclosed by a membrane known as the tonoplast, they contain plastids, the most notable being chloroplasts, which contain the green-colored pigment chlorophyll that converts the energy of sunlight into chemical energy, and then all the other organelles of the animal cell (mitochondria, endoplasmic reticulum, nucleus and nucleolus, golgi apparatus, etc.)
 
        
             
        
        
        
Answer:
The frequency will be  35/36
Explanation:
An AAaa tetraploid plant will only produce a gamete which will be Aa, but during a self crossing a progeny with genotype AAaa will be produced and this will happen at a frequency of 35/36 and this simply means that the progenies produced during the self crossing  will all have a dominant phenotype
 
        
             
        
        
        
Answer: The mesosphere starts at 31 miles (50 km) and extends to 53 miles (85 km) high. The top of the mesosphere, called the mesopause, is the coldest part of Earth's atmosphere, with temperatures averaging about minus 130 degrees F (minus 90 C). This layer is hard to study
Explanation: hope this helps please give brainliest!