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 series with dominant 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: 10353

#Unit 6. System Physiology – Plant

Aminotransferases are found in multiple organelles such as cytoplasm, chloroplasts, mitochondria, glyoxysomes, and peroxisomes, these aminotransferases one of its organelles may have a significant role in amino acid biosynthesis such as;

#Question id: 10354

#Unit 6. System Physiology – Plant

One of the enzyme that are involve in the ammonium assimilation is Asparagine synthetase (AS), some statements given below about AS such as,

a) This enzyme that catalyzes this reaction, is found in the cytosol of leaves and roots and in nitrogen-fixing nodules

b) High levels of light and carbohydrate inhibit the expression of genes coding for AS and the activity of the enzyme

c) Conditions of ample energy stimulate AS, thus they favor nitrogen assimilation into glutamine and glutamate

d) Energy-limited conditions inhibit GS and GOGAT, stimulate AS, and thus favor nitrogen assimilation into asparagine, a compound that is rich in nitrogen and sufficiently stable for long-distance transport or long term storage

Which of the following statements about AS is correct?

#Question id: 10355

#Unit 6. System Physiology – Plant

The conversion of ammonium to amino acids requires two enzymes such as GS and GOGAT,

a) High levels of light and carbohydrate—conditions that stimulate plastid GS and Fd-GOGAT

b) Conditions of ample energy inhibit GS and GOGAT

c) The stimulation of GS and GOGAT, they favor nitrogen assimilation into glutamine and glutamate, compounds that are rich in carbon and participate in the synthesis of new plant materials

d) In energy-limited conditions inhibit GS and GOGAT

Which of the following statements about GS and GOGAT is correct?

#Question id: 10356

#Unit 6. System Physiology – Plant

Why the GS  and GOGAT is activated in light and while the AS is inhibited?

#Question id: 10357

#Unit 6. System Physiology – Plant

Why the glutamine and glutamate will not be transported while  asparagine will prefer to be transported?

#Question id: 10358

#Unit 6. System Physiology – Plant

Which of the following essential micronutrients is associated with nitrate reductase enzyme found in higher plants?