Answer:
Chromosome condenses 
Pairing up to form tetrad
Crossing over 
Lining up on metaphase plate
Homologous chromosome separate 
Explanation:
Condensation of chromosomes occurs in prophase I phase. Pairing up to form tetrad occur during prophase I. Crossing over occurs during prophase I of meiosis cell division. Chromosomes line up along the metaphase plate in the stage of Metaphase. Centromeres break down and homologous chromosomes separate in anaphase I phase of meiosis.
 
        
             
        
        
        
Answer:
Waste disposal
Why? Contributes to the greenhouse effect and causes pollution
Solution: If you bring your lunch to school, package it in reusable containers instead of disposable ones. Carry food in reusable plastic or cloth bags, and bring drinks in a thermos instead of disposable bottles or cartons. 
Solution: Compost leftover food
Hope this helps
 
        
             
        
        
        
I think the answer is genotype
        
                    
             
        
        
        
Answer:
The skin is very important for the functioning of the nervous system, this is because, it serves as the sensory organ, which transmit the sense of touch to the brain for interpretation. The skin acts as the receptors of stimuli that are coming from outside of the body. For instance, if one mistakenly touch an hot pot with a bare hand, one will quickly remove the hand immediately. This is because the skin was able to sense the touch of hotness and send the information to the brain for the correct interpretation of the stimuli. Therefore, without the skin, the functioning of the nervous system will be impaired.  
 
        
             
        
        
        
Explanation:
los seres vivos pueden considerarse sistemas abiertos porque cada ser vivo es un sistema complejo constituido por un conjunto de subsistemas que interactúan y funcionan por un objetivo en común, la conservación y la continuidad de la vida.