CSIR NET 2023 | Life Science: Developmental Biology | 05 June

In elauata (elu) mutant of Arabidopsis, shoot apical meristem (SAM) size as well as expression of wuschel (wus) are increased whereas SAM size is reduced in wus mutant plants. With this information, choose the correct statement which best describes the function of wus and elu genes

Which of the following are correct about morphogenetic movements?

A) movement of an individual cell with respect to other cells in the embryo is termed migration

B) movement of a cell from the surface of an embryo into its interior is termed ingression

C) movement of a cell from the interior of an embryo to the external surface is termed egression

D) spreading of a sheet of cells is termed involution

Differentiated cells express the genes and proteins characteristic of their final identity in the adult, and that identity can be altered only under special circumstances. How does the concept of differentiation, as described here, differ from the concept of determination?

Following statements were made regarding vulval development in Caenorhabditis elegans:

1) The six vulval precursor cells (VPCs) are influenced by the anchor cell to form an equivalence group.

2) In the loss of function lin-12 mutants, both cells become uterine whereas, in gain of function mutants, both become anchor cell.

3) If the anchor cell is destroyed early in development, all six VPCs divide once and contribute towards the formation of hypodermal cells.

4) The anchor cell/ventral uterine precursor decision is due to Notch-Delta mediated mechanism of restricting adjacent cell fates.

5) The paracrine factor secreted by the anchor cell directly activates the Notch-delta pathway.

Which one of the following options represents a combination of correct statements?

Given below are a few statements regarding the role of Disheveled (Dsh) and β-catenin (β-cat) in the development of sea urchin.

1) Dsh is localized in the vegetal cortex of the oocyte before fertilization and in the region of the 16-cell embryo about to become the micromeres.

2) Dsh is localized in the cytosol of the oocyte during oogenesis and in the micromere forming blastomeres of a 16- cell embryo.

3) β-cat accumulates predominantly in the micromeres and somewhat in the veg tier cells.

4) Treatment of embryos with lithium chloride does not allow the accumulation of β-cat in the nuclei of all blastula cells, and the animal cells thus become specified as endoderm and mesoderm.

5) When β-cat is prevented from entering the nucleus, the embryo develops as a ciliated ectodermal ball.

Which one of the following options represents a combination of correct statements?