Following statements are regarding to anterior-posterior polarity in planaria.

A. The anterior expression of Notum functions to antagonize the posteriorly produced Wnt, leading to head specification.

B. Regulation of the balance between Wnt and Notum signals may underlie not only head-tail specification but also regulation of organ size.

C. In addition, there appears to be an anterior-to-posterior gradient of Erk signaling that functions as a positive inducer of tail specification.

D. Wnt signaling achieves its repression of head regeneration by inhibiting Erk. Therefore, only in those more anterior regions lacking Wnt (due to Notum’s repression of Wnt) can Erk induce head regeneration.

Which of the following statements are incorrect?

#Question id: 5756

#Unit 8. Inheritance Biology

Type of mutation caused by an addition or deletion of a base in a polypeptide-encoding part of a gene

#Question id: 5757

#Unit 8. Inheritance Biology

A new E. coli mutant was tested for auxotrophy. The mutant grows on:

minimal medium (M) + arginine (A) + proline (P)

M + P + histidine (H)

M + A + H + P

but not on M or on M + A + H. The mutant requires

#Question id: 5758

#Unit 8. Inheritance Biology

#Question id: 5760

#Unit 8. Inheritance Biology

The fluctuation test of Luria and Delbruck (studying resistance to bacteriophge T1 infection) established that

#Question id: 5761

#Unit 8. Inheritance Biology

E. coli cells were spread on an agar plate, producing 1000 colonies.  The colonies are replica plated on two agar plates containing the antibiotic kanamycin and one agar plate without antibiotics.  All of the colonies are able to grow on the agar plate without antibiotic but only 4 colonies are able to grow on each of the agar plates containing kanamycin.  You notice that the four colonies that grew on each of the kanamycin containing plates are in the exact same position.  This demonstrates

#Question id: 5762

#Unit 8. Inheritance Biology

An individual cell homozygous for a mutant allele of the gene for a human enzyme contains no detectable activity for that enzyme. The mutation is best described as