Answer:
The correct answer is The cells do not have proper receptor.
Explanation:
During paracrine signaling a signaling molecules are generated from one cell.The generated signaling molecule then binds to the receptor of neighboring cell to carry specific signal from donor cell to the acceptor cell.
But the signaling molecules will not bind to the cell that is producing it because that producing cell do not contain proper receptor to bind that signaling molecule.
The binding of signaling molecule to the receptor of its producing cell occur during autocrine signaling.
Answer:
Identifying the fossil is the first step. We have already identified this fossil as a clamshell. We know clam are from the sea, but if you didn't, you could conclude this from knowing where you found the fossil (likely near the beach). Discovering where it is can also lead you to a conclusion on it's arrival as a fossil, perhaps washed up on shore or buried by an animal.
Explanation:
Phylogenetic species concept (PSC) The concept of a species as an irreducible group whose members are descended from a common ancestor and who all possess a combination of certain defining, or derived, traits (see apomorphy). ... "phylogenetic species concept." A Dictionary of Biology. .
Or
The biological species concept has its limitations (although it works well for many organisms and has been very influential in the growth ofevolutionary theory). ... In thisexample, Ensatina salamander lineages A and B are separate species.Each has a common ancestor that individuals of other species do not.
I hope that this helps you out