They have two pairs of main nerve cords organized around a number of paired ganglia. while they don't have a "true brain"-- they have somewhat of a nervous system, composed of the two, or three pairs of nerve cords contained in the visceral mass.
Answer:
C.. A hypothesis is a possible, testable explanation for a scientific question
Answer:
The peptide:MHC class II complex can be recognized by antigen-specific armed ... Some microbial antigens can activate B cells directly in the absence of T-cell help. ... 9-1. The humoral immune response is initiated when B cells that bind antigen ... cells presenting these internal peptides can then activate the B cell to make . Explanation:
Answer:
While Earth is only the fifth largest planet in the solar system, it is the only world in our solar system with liquid water on the surface. Just slightly larger than nearby Venus, Earth is the biggest of the four planets closest to the Sun, all of which are made of rock and metal.
Explanation:
Gravitropism or geotropism which is a growth response to gravity
a growth response to light is called phototropism
