Aquatic ecosystems that are most readily damaged by acid are those that lack an important buffer that dissolves into the runoff after a precipitation event. What is this buffer?

#Question id: 7214

#Unit 5. Developmental Biology

The anterior posterior compartment of each segment of drosophila is defined by wingless and engrailed genes. The following statements are given towards explaining their regulation:

A.cells secreting Hedgehog protein activate wingless expression in their neighbors, and the Wingless protein signal, which is received by the cells that secreted Hedgehog, serves to maintain hedgehog (hh) expression.

B.Engrailed protein also acts in an autocrine fashion, maintaining its own expression.

C.The cells expressing engrailed can bind wingless protein because they contain Frizzled, which is the Drosophila membrane receptor protein for Wingless.

D.Binding of Wingless to Frizzled activates the hedgehog signal transduction pathway, resulting in the continued expression of engrailed.

Which of the following option has all the incorrect statements?

#Question id: 7215

#Unit 5. Developmental Biology

Limb bud initiation could have either initiation factors genomes Listed below are some limb bud initiation (Column A), their lateral plate mesoderm (Column B).

#Question id: 7216

#Unit 5. Developmental Biology

Following statements are about Specification of cell fate by the Dorsal protein. Which of the following statement is correct?

#Question id: 7217

#Unit 5. Developmental Biology

Following statements regarding to the metamorphic changes of frog development.

A. The metamorphic changes are brought about by the secretion of the hormone thyroxine (T4) into the blood by the thyroid gland

B. the conversion of T4 into the more active hormone tri-iodothyronine (T3) by the target tissues

C. the degradation of T3 in the target tissues

D. by the deiodinases enzymes T3 converted into T4 in target tissues.

Which of the following options are correct?

#Question id: 7218

#Unit 5. Developmental Biology

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?

#Question id: 7219

#Unit 5. Developmental Biology

Following statements are regarding to the role of the Disheveled and β-catenin proteins in specifying the cells of the sea urchin embryo.

A. During normal development, β-catenin accumulates predominantly in the micromeres and somewhat less in the veg2 tier cells.

B. In embryos treated with lithium chloride, β-catenin accumulates in the nuclei of all blastula cells and the cells of the animal pole become specified as ectoderm.

C. When β-catenin is prevented from entering the nuclei (i.e., it remains in the cytoplasm), the vegetal cell fates are not specified, and the entire embryo develops as a ciliated ectodermal ball.

D. When β-catenin is prevented from entering the nuclei (i.e., it remains in the cytoplasm), the vegetal cell fates are specified, and the entire embryo specified as endoderm and mesoderm .

Which of the following statements are true?