47. Allopatric populations of two different Darwin's finches show similar beak morphology. However, there are signs of character displacement in sympatric populations of these two species. What does "character displacement" mean? What is the most likely driving force for character displacement?

46. What is the evolved biological function of the CRISPR/Cas system in bacteria? How does the CRISPR/Cas system work in gene editing? 

(2) Which community has a higher level of diversity?

40. Pavlov demonstrated that if he always rang a bell just feeding a dog, the dog would eventually salivate when the bell sounded. This is an example of (A)associative learning (B) imprinting (C)fixed action pattern (D) problem solving

39. In vertebrate photoreceptor cells, which of the following responses occurs when light stimulation is present? (A)The photoreceptor becomes depolarized. (B) The photoreceptor cell releases the neurotransmitter glutamate. (C)The G-protein signaling activity of opsin is shut down in the photoreceptor cell. (D) The cGMP-gated sodium channel on the plasma membrane of the photoreceptor cell closes.

38. Inhibitory postsynaptic potential refers to to (A)depolarizing graded potential； K+ (B) hyperpolarizing graded potential； K+ in a postsynaptic cell, which is caused by increased permeability (C)depolarizing graded potential； Na* (D) hyperpolarizing graded potential； Na*