Which statement describes the second line of defense?

(a) The second line of defense includes biological and chemical barriers.
(b) The skin is the major organ of the second line of defense.
(c) The second line of defense keeps most pathogens out of the body.
(d) The second line of defense is encountered by pathogens that enter the body.

Which statement about dna replication is true? a. eukaryotes only have one circular chromosome that unwinds at multiple locations. b. eukaryotes can only replicate one segment of a chromosome at a time. c. prokaryotes can only replicate their single circular chromosome in the nucleus. d. prokaryotes only have one origin of replication to initiate replication.

This is so important ugh its 25 points

Why did adult crab numbers decline in he ecosystem, even though sea stars were still available?