Answer:
The correct answer will be option- synaptonemal complex.
Explanation:
The tetrad arrangement of the genetic material in an organism is mediated by a highly conserved structure known as the synaptonemal complex.  The synaptonemal complex is formed during the prophase I of the meiosis I which attaches the chromatin of the homologous chromosomes.
The synaptonemal complex is a proteinaceous structure which is formed by the two lateral ladders like elements with a central portion composed of the central element. The chromatin gets attached to the lateral elements while the central a portion bridge space between the two ladders thus help in the formation of the tetrad.
Thus, option- synaptonemal complex is the correct answer.
 
        
             
        
        
        
Answer:
Porifera—gastrovascular cavity, coelomate.
Explanation:
Sponges do not contain digestive system but obtain nutrients through the diffusion process. Porifera is the most commonly asymmetrical in nature but can also have radial symmetry. Porifera has no coelom. 
Lacking a true digestive system, they depend on the intracellular digestive processes of their choanocytes for their energy intake. Gas exchange, circulation, and excretion occur by diffusion between the water and the cells.
 
        
             
        
        
        
Answer:
Hey there!
A population increase follows a period of scarcity.
With more people, the food and water resources get scarce, and isn't always enough for everyone.
Let me know if this helps :)
 
        
                    
             
        
        
        
Answer:
Both statements are true
Explanation:
Many small tree saplings are competing for sunlight on the forest floor because tree saplings in forest floors are often deprived of adequate light as a result of the shade created by bigger trees in the forest. <em>Hence, the saplings jostle for light in order to effectively carry out light-requiring physiological activities such as photosynthesis and chlorophyll synthesis.</em>
The West Nile virus a virus that <em>generally affects the central nervous systems of birds - the primary host. It is transmitted from one bird to another through contact and by a vector - the mosquito</em>. The virus is also capable of being contracted by humans where it causes fatal neurological disorders.
 
        
             
        
        
        
Because they are made mostly or partly out of gas.