Answer:
Blood-brain barrier.
Explanation:
Blood brain barrier may be defined as the barrier between the blood capillaries and the component of the brain tissue. This blood brain barrier provide protection against the pathogens present in the blood.
The blood-brain barrier uses tight junctions that prevent the entry of microbes in the underlying tissue. The tight junctions allows only the entry of some selected particles and prevent the entry of other particles.
Thus, the correct option is (3).
 
        
             
        
        
        
1) Colonial organisms require large areas with resources to sustain the entire colony, just as colonial people do. They are unable to grow in places that are sufficient to sustain a small number of organisms and if their population becomes to large, the colony collapses on itself. This is all visible in people as well.
2) Colonial organisms have greater safety due to their large numbers; however, unlike individual organisms, they are unable to sustain themselves with a smaller number of resources and migrating from one area to another is also more difficult for them.
3) A multicellular organism is more mobile and able to perform more functions in a better manner; however, this also leads to greater energy requirements than that of a single celled organism.<span />
        
                    
             
        
        
        
The <u>Coast Guard</u> works with the Environmental Protection Agency to enforce marine biology regulations along the coast and in the Great Lakes channels.
Answer: Option A
<u>Explanation:</u>
The Environmental Protection Agency (EPA) takes initiative to instill certain regulations to maintain the Ocean and its resources with the help of coastal guards and NGO’s. The Ocean coast is polluted due to various avoidable and unavoidable pollutants like oil leakage, industries letting in their waste, ship wrecks etc.
President Richard Nixon was the one who created this EPA. The EPA takes utmost care by educating the people of the necessity to maintain the coast in a disciplined attitude so as to have a pollution free oceanic coast which would in turn not adhere into the relevant working stream. Avoiding litter is the main rule that has been imposed.
 
        
                    
             
        
        
        
Answer:
Earth formed around 4.54 billion years ago, approximately one-third the age of the universe, by accretion from the solar nebula. Volcanic outgassing probably created the primordial atmosphere and then the ocean, but the early atmosphere contained almost no oxygen.
Explanation:
 
        
             
        
        
        
Mutations can lead to missing or malformed proteins, and that can lead to disease. ... Some mutations happen during cell division, when DNA gets duplicated. Still other mutations are caused when DNA gets damaged by environmental factors, including UV radiation, chemicals, and viruses. Few mutations are bad for you.