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TLS Online TPP Program

#Question id: 7240

Given below are the list of some organism (column A) and determination of their dorsal-ventral axis (column B)

S.No.

Organism

(Column A)

S.No

Determination of dorsal ventral axis

(Column B)

A.

Chick

i.

sperm entry point and cortical rotation

lead to specification of dorsal side opposite the

point of sperm entry

B.

Zebrafish

ii.

initial symmetry-breaking event unknown.

Localization of maternal Ndr1 and nuclear b -catenin species dorsal side and position of organizer

C.

Xenopus

iii.

interaction between inner cell mass

and trophectoderm

D

Mouse

iv.

posterior marginal zone specifies ventral end

of dorso-ventral axis

 Choose the correct option:

#Unit 5. Developmental Biology
  1. A-iv, B-ii, C-i, D-iii
  2. A-ii, B-i, C-iii, D-iv
  3. A-i, B-ii, C-iii, D-iv
  4. A-iv, B-iii, C-I, D-ii
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TLS Online TPP Program

#Question id: 12339

#Unit 10. Ecological Principles

If a species is a keystone predator, then its removal from a community should
TLS Online TPP Program

#Question id: 12340

#Unit 10. Ecological Principles

Keystone species are thought to have profound effects on the structure and composition of ecological communities because they
TLS Online TPP Program

#Question id: 12341

#Unit 10. Ecological Principles

The figure shows population growth trajectories over time (as indicated by the arrows) of two stored-grain beetle  species  when  grown  together  under  constant  conditions.  Three  experiments  were  performed  that  differed only in the initial densities of the two species. Which of the following is the best interpretation of the experimental results?
TLS Online TPP Program

#Question id: 12342

#Unit 10. Ecological Principles

Which of the following is a biological attribute that would most likely allow a species to become cosmopolitan in distribution?
TLS Online TPP Program

#Question id: 12343

#Unit 10. Ecological Principles

Hybrids between some related species of plants are sterile because the parent plants had different chromosome numbers. Occasionally the chromosome number of such a hybrid  plant doubles spontaneously. Which of the following best describes the descendants of those plants with the double chromosome number?
TLS Online TPP Program

#Question id: 12344

#Unit 10. Ecological Principles

The concept of punctuated equilibrium refers to