Sox9 is an autosomal gene involved in several developmental processes, most notably bone formation. In the gonadal rudiments, Sox9 induces testis formation. Expression of the Sox9 gene is specifically upregulated by the combined expression of Sry and Sf1 proteins in Sertoli cell precursors. Thus, Sry may act merely as a “switch” operating during a very short time to activate Sox9, and the Sox9 protein may initiate the conserved evolutionary pathway to testis formation. Following statements are regarding to the functions of Sox9.

A. It appears to be able to activate its own promoter, thereby allowing it to be transcribed for long periods of time.

B. It activates the ability of β-catenin to induce ovary formation, either directly or indirectly.

C. It binds to cis-regulatory regions of numerous genes necessary for testis production.

D. Sox9 binds to the promoter site on the gene for anti-Müllerian hormone, providing a critical link in the pathway toward a male phenotype.

E. Sox9 inhibits the expression of the gene encoding Fgf9, a paracrine factor.

Which of the following statements are correct?

#Question id: 3265

#Unit 11. Evolution and Behavior

If the curve shifts to the left or to the right, there is no gene flow, and the population size consequently increases over successive generations, then which of these is (are) probably occurring?

#Question id: 3266

#Unit 11. Evolution and Behavior

One species mates at the season when daylight is increasing from 13 hours to 13 hours, 15 minutes; another species mates at the season when daylight is increasing from 14 hours to 14 hours, 15 minutes. The isolating mechanism is

#Question id: 3267

#Unit 11. Evolution and Behavior

In a typical Mendelian population, individuals carrying gene ‘a’ in homozygous condition suffer from phenylketonurea. Those with A in homozygous condition are normal. Others, who are heterozygotic with Aa, are carriers. If the frequency of ‘a’ in a population is 0.20, what is the percentage of normal individual in the population?

#Question id: 3268

#Unit 11. Evolution and Behavior

A population of insects is in Hardy-Weinberg equilibrium for a gene with alleles A = orange and a = yellow eyes. There are 91% orange and 9% yellow individuals in the population. If the fitness of the yellow phenotype suddenly drops to zero, what will be the allele frequency in the next generation?

#Question id: 3269

#Unit 11. Evolution and Behavior

Two plant species live in the same biome but on different continents. Although the two species are not at all closely related, they may appear quite similar as a result of

#Question id: 3270

#Unit 11. Evolution and Behavior

Heterozygote advantage should be most closely linked to which of the following?