In drosophila, the dorso-ventral axis of the embryo becomes divided into four regions early in embryogenesis.

A. The ventral mesoderm, which will form muscles and other internal connective tissues

B. The amnioserosa, which gives rise to an extra-embryonic membrane on the dorsal side of the embryo

C. The dorsal ectoderm, which gives rise to larval epidermis

D. The ventral ectoderm or neuroectoderm, which gives rise to the larval nervous system and epidermis

What is the correct sequence of these regions from ventral to dorsal?

#Question id: 11392

#Unit 9. Diversity of Life Forms

Modes of obtaining nutrients, used by at least some bacteria, include all of the following except

#Question id: 11393

#Unit 9. Diversity of Life Forms

Given that the enzymes that catalyze nitrogen fixation are inhibited by oxygen, what are two ʺstrategiesʺ that nitrogen-fixing prokaryotes might use to protect these enzymes from oxygen?

1.  couple them with photosystem II (the photosystem that splits water molecules)

2.  package them in membranes that are impermeable to all gases

3.  be obligate anaerobes

4.  be strict aerobes

5.  package these enzymes in specialized cells or compartments that inhibit oxygen entry

#Question id: 11394

#Unit 9. Diversity of Life Forms

Foods can be preserved in many ways by slowing or preventing bacterial growth. Which of these methods would not generally inhibit bacterial growth?

#Question id: 11395

#Unit 9. Diversity of Life Forms

Mitochondria are thought to be the descendants of certain alpha -proteobacteria. They are, however, no longer able to lead independent lives because most

genes originally present on their chromosome have moved to the nuclear genome. Which phenomenon accounts for the movement of these genes?

#Question id: 11396

#Unit 9. Diversity of Life Forms

Carl Woese and collaborators identified two major branches of prokaryotic evolution. What was the basis for dividing prokaryotes into two domains?

#Question id: 11397

#Unit 9. Diversity of Life Forms

Which statement about the domain Archaea is false?