The protein Sonic Hedgehog (SHH) plays a role in specifying the identity of digits (such as fingers and toes) in mammals. Several digits arise directly from cells that both express and respond to secreted SHH. What type of signaling would this be considered?
A. synaptic
B. paracrine
C. autocrine
D. direct contact
E. endocrine
Answer: C
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In poultry, the genes for rose comb (R) and pea comb
(P) produce walnut whenever they occur together (R__ P__); single-combed individuals have the homozygous condition for both genes (rr pp). (a) Give the F1 and F2 phenotypic results of a cross of a pure-breeding rose comb (RR pp) with a pure-breeding pea comb (rr PP). (b) Give the phenotypic results of a cross of Rr Pp x rr Pp. (c) Give the phenotypic results of a cross of RR Pp x rr Pp. (d) Give the phenotypic results of a cross of Rr pp x rr Pp. (e) Give the phenotypic results of a cross of Rr Pp x rr pp. What will be an ideal response?
Trends in the evolution of animals includes
a. cephalization. b. the development of types of symmetry. c. variation in coelomic cavities. d. the development of segments. e. all of these.
How do plants control water uptake
What will be an ideal response?
E. coli 0157:H7 characteristics include all the following except
A. it only causes occupational illness in people who work with animals. B. it is transmitted by ingestion of contaminated, undercooked food, especially hamburger. C. it causes a bloody diarrhea. D. it is reservoir is cattle intestines. E. some cases go on to hemolytic uremic syndrome (HUS) with possible kidney failure.