Genes that control coat color in mammals represent some of the best early examples of genes with multiple alleles exhibiting different phenotypes. A classic example is the C gene in hamsters. Three of the known alleles of this gene are C, c^a and c^k. Each supplies a different amount of black pigment to the coat hair. The phenotypes of three different homozygous strains are as follows.

would mate the true-breeding  c^a c^a  hamsters to the true-breeding c^k c^k  hamsters to produce heterozygous  c^a and c^k  F1 progeny. Crosses and their interpretation that would have allowed geneticists to come to the conclusion that c^a and c^k were likely to be alleles of the same using the concept that alleles of the same gene will be tightly linked. What will be the ratio of F2 hamster;

#Question id: 5142

#Unit 5. Developmental Biology

The D set of blastomeres is the “organizer” of snail embryos. Experiments have demonstrated that the non-diffusible polar lobe [cortical] cytoplasm that is localized to the D blastomere is extremely important in normal molluscan development.  Which of the following is incorrect?

#Question id: 5143

#Unit 5. Developmental Biology

Select the correct sequence of events in photoreceptor induction in drosophila.

A. Morphogenetic furrows moves across eye disc

B. Eyeless gene expression

C. R8 photoreceptor cells develop

D. R7 photoreceptor cells develop

#Question id: 5144

#Unit 5. Developmental Biology

Following statements regarding to noncanonical wnt pathways.

A. The planar cell polarity, or PCP, pathway functions to regulate the actin and microtubule cytoskeleton, thus influencing cell shape, and often results in bipolar protrusive behaviors necessary for a cell to migrate.

B. Wnts (such as Wnt5a and Wnt11) can activate Disheveled by binding to a different receptor (Frizzled paired with Ror instead of Lrp5), and this Ror receptor complex phosphorylates Disheveled in a way that allows it to interact with Rho GTPases.

C. Wnt/PCP signaling through cytoskeleton control can direct cells to divide in the different plane ( forming upper and lower tissue compartments) and to move within that different plane.

D. the Wnt/calcium pathway leads to the release of calcium stored within cells, and this released calcium acts as an important secondary messenger to activates a phospholipase (PLC) whose enzyme activities release a compound that in turn releases calcium ions from the cytosol.

Which of the following is incorrect?

#Question id: 5145

#Unit 5. Developmental Biology

Doris Taylor’s research group used detergents to remove all the cells from a cadaveric rat heart, which left behind the natural extracellular matrix. Proteins such as fibronectin, collagen, and laminin held together the rest of the extracellular matrix and maintained the intricate shape of the heart. The researchers then infused this extracellular matrix scaffold with cardiomyocyte progenitor cells. Surprisingly, these cells differentiated and organized into a functionally contracting “recellularized” heart. The behavior of extracellular matrix scaffold can promote the differentiation and rebuilding of a beating heart is analogous to which of the interactions?

#Question id: 5146

#Unit 5. Developmental Biology

Choose the correct match.

#Question id: 5147

#Unit 5. Developmental Biology

What is the dissimilarity amongst "fate" and "specification"?