Crossing over contributes to genetic variation by exchanging chromosomal segments between non-sister chromatids of homologous chromosomes.
What is crossing over?
- Crossing over is the exchange and recombination of genetic components between the homologous chromosomes.
- This occurs in the pachytene stage of the meiosis-1 of the meiotic division.
- Crossing over occurs with the help of an enzyme and the enzyme responsible for crossing over is called Recombinase.
Thus, crossing over contributes to genetic variation by exchanging chromosomal segments between non-sister chromatids of the homologous chromosomes.
Learn more about crossing over: brainly.com/question/927405
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Every year the farmer was taking care of his ice field, keep it clean and clear of all the unnecessary shrubs and then reuse the debris to fertile the soil again and then grow rice again. But since he fell sick, there is no one to take care of his rice field which will leads to the growth of unnecessary plants and weeds in it.
There will grow wild plants and shrubs which will contaminate the rice field.
 
        
             
        
        
        
Answer:
 I'm not sure exactly what your supposed to do but a,b and c are all correct but d is false.
 
        
             
        
        
        
The biomolecules contain l<span>arge, complex molecules.</span>