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?

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#Question id: 12229

#Unit 10. Ecological Principles

Community ecologists would consider which of the following to be most significant in understanding the structure of an ecological community?

TLS Online TPP Program

#Question id: 12230

#Unit 10. Ecological Principles

Historically, most ecological research on the community has focused on which of the following? 

TLS Online TPP Program

#Question id: 12231

#Unit 10. Ecological Principles

Which of the following studies would a community ecologist undertake to learn about competitive interactions? 

TLS Online TPP Program

#Question id: 12232

#Unit 10. Ecological Principles

White-breasted nuthatches and Downy woodpeckers both eat insects that hide in the furrows of bark in hardwood trees. The Downy woodpecker searches for insects by hunting from the bottom of the tree trunk to the top, while the White-breasted nuthatch searches from the top of the trunk down. These hunting behaviours best illustrate which of the following ecological concepts?

TLS Online TPP Program

#Question id: 12233

#Unit 10. Ecological Principles

Monarch butterflies are protected from birds and other predators but the cardiac glycosides they incorporate into their tissues are from eating milkweed when they were in their caterpillar stage of development. The wings of a different species of butterfly, the Viceroy, look nearly identical to the Monarch so predators that have learned not to eat the bad-tasting Monarch avoid Viceroys as well. This example best describes

TLS Online TPP Program

#Question id: 12234

#Unit 10. Ecological Principles

All of the following have been used by plants to avoid being eaten except