In this problem we will explore some of the many ways that mutations in two different genes can interact to produce different Mendelian ratios. Consider a hypothetical insect species that has red eyes. Imagine mutations in two different unlinked genes that can, in certain combinations, block the formation of red eye pigment yielding mutants with white eyes. In principle, there are two different possible arrangements for two biochemical steps responsible for the formation of red eye pigment. The two genes might act in series such that a mutation in either gene would block the formation of red pigment. Alternatively, the two genes could act in parallel such that mutations in both genes would be required to block the formation of red pigment.

Further complexity arises from the possibility that mutations in either gene that lead to a block in enzymatic activity could be either dominant or recessive. If the crosses is made between a wild type insect with red eyes and a true breeding white eyed strain with mutations in both genes. Such considerations yield the Pathways in parallel with recessive mutations in both genes, determine the phenotype of the F1 progeny and the expected phenotypic ratio of red to white eyed insects in the F2.

#Question id: 11849

#Unit 6. System Physiology – Plant

According to chemiosmotic model for polar auxin transport, auxin _____A_______is driven by the______B________ across the plasma membrane, while auxin ___C_____is driven by the_________D_________

#Question id: 11848

#Unit 6. System Physiology – Plant

Polar transport is specific for active auxins, such as

#Question id: 11847

#Unit 6. System Physiology – Plant

On the basis of isotopic labeling and metabolite identification, oxidative pathways are more likely to be involved in the controlled degradation of IAA by____

Statement-I ___IAA is oxidized without decarboxylation to OxIAA

Statement-II___ IAA-aspartate conjugate is oxidized first to the intermediate dioxindole-3-acetylaspartate, and then to OxIAA

#Question id: 11846

#Unit 6. System Physiology – Plant

In maize  orange pericarp (orp) mutant is

#Question id: 11845

#Unit 6. System Physiology – Plant

IAA Is synthesized from__

#Question id: 11844

#Unit 6. System Physiology – Plant

The following statements are made to describe the biosynthetic pathway of IAA;

a)  IPA pathway involves a deamination reaction to form IPA, followed by a decarboxylation reaction to form indole-3-acetaldehyde (IAld) and then oxidized to IAA by a specific dehydrogenase

b) IAN pathway is similar to the IPA pathway, except that the order of the deamination and decarboxylation reactions is reversed, and different enzymes are involved

c) IAM pathway  involves the two enzymes  tryptophan monooxygenase and IAM hydrolase

d) In the IAN pathway, tryptophan is first converted to indole-3-acetaldoxime and then to indole-3-acetonitrile. The enzyme that converts IAN to IAA is called nitrilase

Which of the following is the correct  statements  of about the biosynthesis of  IAA?