A  plant species arrives at  an  island  for the first time, where it  is  exposed to  a  new set of  pollinators.  Over the course of 20 generations, the characteristics of its flowers change. The figures above show the frequency distribution of petal length in the original colonizing population (Figure 1) and 20 generations later (Figure 2). Which of these explanations is consistent with the observed change in petal length?

#Question id: 1535

#Unit 4. Cell Communication and Cell Signaling

Following statements are regarding to cancer stem cell (CSCs).

a. A representative subpopulation of cancer cells with peculiar molecular aspects that resemble some of those typical of normal stem cells.

b. These cells are capable of replenishing the repertoire of identical cancer cells.

c. These cells cannot create heterogeneous progeny that differentiate into more mature cells.

d. These cells show extraordinary proliferative potential.

e. These cells show excessive programmed cell death.

Which of the following combination is correct?

#Question id: 1534

#Unit 4. Cell Communication and Cell Signaling

Cadherin proteins help animal cells stick (adhere) to each other. Choose which statement about cadherin in cancer cells that are metastasizing (spreading) throughout a patient's body is most likely correct.

#Question id: 1533

#Unit 4. Cell Communication and Cell Signaling

Why might using retroviral vectors for gene therapy increase the patient's risk of developing cancer?

#Question id: 1532

#Unit 4. Cell Communication and Cell Signaling

For a particular microarray assay (DNA chip), cDNA has been made from the mRNAs of a dozen patients' breast tumor biopsies. Which of the following types of evidence will researchers be looking for in order to determine if the cells are cancerous?

#Question id: 1530

#Unit 4. Cell Communication and Cell Signaling

What are the differences and similarities between the transforming genes of retroviruses and those of DNA tumor viruses?

#Question id: 1529

#Unit 4. Cell Communication and Cell Signaling

Which of the following statements are true regarding to gain-of-function and loss-of-function mutations with respect to cancer.