Answer:
Observers ahead of the wave observe an apparent increase in wave frequency  
Explanation:
This is the Doppler Effect. The frequency of a wave increases when the source approaches the observer and decreases as the source recedes.
B, C, and D are wrong. Observers behind the source notice a decrease in frequency.
 
        
             
        
        
        
Eukaryotic cells have a membrane-bound nucleus, whereas prokaryotic cells do not. In eukaryotes, the nucleus is just one of numerous membrane-bound organelles. Prokaryotes, on the other hand, lack organelles that are attached to the membrane.
        
                    
             
        
        
        
Fossil fuels release carbon dioxide gas when they burn which adds to the greenhouse effect and increases global warming. Of the three fossil fuels, for a given amount of energy released, coal produces the most carbon dioxide and natural gas produces the least.
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Answer:
Yes the cell will re-aggregate
Explanation:
Cells from tissue B are isolated and dissociated, then treated with the antibodies raised against cell type A membrane proteins. Will cells from tissue By aggregate.
Aggregation permits a cell-cell contact present in a tissue, this enhances the function and behavior if the cells. 
 
        
                    
             
        
        
        
Asexual reproduction is a form of reproduction in which the number of chromosomes or the fusion of gametes is not altered. 
Being genetically identical to the parent is advantageous for organisms when the environment changes fast, and reproduction is needed.
A gamete (a reproductive cell with one set of chromosomes, like an egg or sperm) combines with another to form a zygote, eventually developing into an organism of cells with two sets of chromosomes. Sexual reproduction is a type of reproduction that involves this complex life cycle (diploid).
The advantages of sexual reproduction are numerous. Several instances include:
more genetic variation
immunity against contagious diseases
fewer genetic diseases
Evolutionary fitness has increased
Learn more about Sexual reproduction here:
brainly.com/question/815744
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