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).
Answer:
There are four main stages in the water cycle. They are evaporation, condensation, precipitation and collection. Let's look at each of these stages. Evaporation: This is when warmth from the sun causes water from oceans, lakes, streams, ice and soils to rise into the air and turn into water vapour (gas).
Explanation:
It's quoted...
"Approximately 4.5 billion years ago, gravity pulled a cloud of dust and gas together to form our solar system. While scientists aren't certain of the exact nature of the process, observations of young stellar systems combined with computer simulations have allowed them to develop three models of what could have happened so many years ago"