Following statements are regarding to convergent extension of the dorsal mesoderm in xenopus.

A. For convergent extension the first force is a polarized cell cohesion wherein the involuted mesodermal cells intercalate and the second force is differential cell cohesion.

B. The intercalations of mesodermal cells, both mediolaterally and radially, are stabilized by the planar cell polarity (PCP) pathway that is initiated by Wnts independent of β-catenin signaling.

C. The intercalations of mesodermal cells, are stabilized by the planar cell polarity (PCP) pathway that is initiated by Wnts dependent of β-catenin signaling.

D. Another factor regulating convergent extension is calcium influx from environment.

E. Ca2+ is released from intracellular stores and is required for convergent extension.

Which of the following combination is correct?

TLS Online TPP Program

#Question id: 12467

#Unit 10. Ecological Principles

Review the formula for effective population size. Imagine a population of 1,000 small rodents. Of these, 300 are breeding females, 300 are breeding males, and 400 are nonbreeding  juveniles.  What is the effective  population size?

TLS Online TPP Program

#Question id: 12468

#Unit 10. Ecological Principles

If the sex ratio in a population is significantly different from 50:50, then which of the following will always be true? 

TLS Online TPP Program

#Question id: 12469

#Unit 10. Ecological Principles

A population of strictly monogamous swans consists of 40 males and 10 females. What is the effective population size (ne) for this population?

TLS Online TPP Program

#Question id: 12470

#Unit 10. Ecological Principles

An ecologist recorded 12 white-tailed deer, Odocoileus virginianus, per square mile in one woodlot and 20 per square mile on another woodlot. What was the ecologist comparing?

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#Question id: 12471

#Unit 10. Ecological Principles

To measure the population density of monarch butterflies occupying a particular park, 100 butterflies are captured, marked with a small dot on a wing, and then released. The next day, another 100 butterflies are captured, including the recapture of 20 marked butterflies. One would estimate the population to be

TLS Online TPP Program

#Question id: 12472

#Unit 10. Ecological Principles

During the spring, you are studying the mice that live  in  a  field  near your home. There are lots  of  mice in  this field, but you realize that you rarely observe any reproductive females. This most likely indicates