Testosterone is an example of a chemical signal that affects the very cells that synthesize it, the neighboring cells in the testis, along with distant cells outside the gonads. Thus, testosterone is an example of ________.

 I) an autocrine signal

 II) a paracrine signal

 III) an endocrine signal

#Question id: 5130

#Unit 5. Developmental Biology

Regulation by gradients of paracrine factor concentration was elegantly demonstrated by the specification of different mesodermal cell types in the frog Xenopus laevis by activin, a paracrine factor of the TGF-beta family. Which of the following observations are correct from this graph?

#Question id: 5131

#Unit 5. Developmental Biology

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?

#Question id: 5132

#Unit 5. Developmental Biology

Upon secretion of wnt, When Wnt attaches to the Frizzled receptor on a responding cell, the cell secretes Notum, a hydrolase that associates with glypican and then cleaves off Wnt’s attached lipids in a process of deacylation or delipidation. This process:

#Question id: 5133

#Unit 5. Developmental Biology

Identify the correct ligands in both receptor serine kinase pathway.

#Question id: 5134

#Unit 5. Developmental Biology

Match the following cleavage patterns with the species in which they occur.

        Species                                           Cleavage Pattern

      A. Flatworm                                       i. Meroblastic discoidal

      B. Frog                                               ii. Meroblastic superficial

      C. Birds                                              iii. Holoblastic displaced radial

      D. Insect                                              iv. Holoblastic spiral

#Question id: 5135

#Unit 5. Developmental Biology

In xenopus, result of tissue transplantation during early and late gastrulae

(A) Cells of early newt gastrula exhibit conditional development.

(B) Cells of early newt gastrula exhibit autonomous development

(C) Cells of late newt gastrula exhibit conditional development.

(D) Cells of late gastrula exhibit autonomous development.

The correct inferences are: