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?

#Question id: 11400

#Unit 9. Evolution & Diversity of Life Forms

What is the primary ecological role of prokaryotes?

#Question id: 11401

#Unit 9. Evolution & Diversity of Life Forms

In a hypothetical situation, a bacterium lives on the surface of a leaf, where it obtains nutrition from the leafʹs nonliving, waxy covering, while inhibiting the growth of

other microbes that are plant pathogens. If this bacterium gains access to the inside of a leaf, it causes a fatal disease in the plant. Once the plant dies, the bacterium

and its offspring decompose the plant. What is the correct sequence of ecological roles played by the bacterium in the situation described here? Use only those that

apply.

1.  nutrient recycler          2.  mutualist            3.  commensal              4.  parasite          5.  primary producer

#Question id: 11402

#Unit 9. Evolution & Diversity of Life Forms

How can prokaryotes be considered to be more successful on Earth than humans?

#Question id: 11499

#Unit 9. Evolution & Diversity of Life Forms

Biologists have long been aware that the defunct kingdom Protista is paraphyletic. Which of these statements is both true and consistent with this conclusion?

#Question id: 11500

#Unit 9. Evolution & Diversity of Life Forms

The strongest evidence for the endosymbiotic origin of eukaryotic organelles is the similarity between extant prokaryotes and which of the following?

#Question id: 11501

#Unit 9. Evolution & Diversity of Life Forms

According to the endosymbiotic theory of the origin of eukaryotic cells, how did mitochondria originate?