Following statements are regarding to PAR proteins and the establishment of polarity during early development in nematodes.

A. The internal cytoplasm contains PAR-3, PAR-6, and PKC-3, and the cortical cytoplasm contains PAR-2 and PAR-1.

B. PAR-3 and PAR-6, interacting with the protein kinase PKC-3 are uniformly distributed in the cortical cytoplasm. PKC-3 restricts PAR-1 and PAR-2 to the internal cytoplasm by phosphorylating them.

C. Once PAR-1 is in the cortical cytoplasm, it phosphorylates PAR-3, causing PAR-3 (and its binding partner, PKC-3) to leave the cortex.

D. During first cleavage, the metaphase plate is closer to the posterior, and the fertilized egg is divided into two cells, one having the anterior PARs (PAR-1 and PAR-2) and one having the posterior PARs (PAR-3 and PAR-6).

Which of the following statements are correct?

#Question id: 8718

#Unit 9. Diversity of Life Forms

Which of the following would, if it had acted upon a gene, prevent this gene from acting as a reliable molecular clock?

#Question id: 8720

#Unit 9. Diversity of Life Forms

The question refers to the following table, which compares the percent sequence homology of four different parts (two introns and two exons) of a gene that is found in five different eukaryotic species. Each part is numbered to indicate its distance from the promoter (for example, Intron I is the one closest to the promoter). The data reported for species A were obtained by comparing DNA from one member of species A to another member of species A.

Which of these four gene parts should allow the construction of the most accurate phylogenetic tree, assuming that this is the only part of the gene that has acted as a reliable molecular clock?

#Question id: 8721

#Unit 9. Diversity of Life Forms

Based on cladistics, which eukaryotic kingdom is polyphyletic and, therefore, unacceptable?

#Question id: 8773

#Unit 9. Diversity of Life Forms

Which eukaryotic kingdom includes members that are the result of endosymbioses that included an ancient aerobic bacterium and an ancient cyanobacterium?

#Question id: 8774

#Unit 9. Diversity of Life Forms

A large proportion of archaeans are extremophiles, so called because they inhabit extreme environments with high acidity, salinity, and/or temperature. Such environments are thought to have been much more common on primitive Earth. Thus, modern extremophiles survive only in places that their ancestors became adapted to long ago. Which of the following is, consequently, a valid statement about modern extremophiles, assuming that their habitats have remained relatively unchanged?

#Question id: 8775

#Unit 9. Diversity of Life Forms

Use the following information to answer the question. Paulinella chromatophora is one of the few cercozoans that is autotrophic, carrying out aerobic photosynthesis with its two elongated "chromatophores." The chromatophores are contained within vesicles of the host cell, and each is derived from a cyanobacterium, though not the same type of cyanobacterium that gave rise to the chloroplasts of algae and plants. A crucial photosynthetic gene of the cyanobacterium that gave rise to the chromatophore is called psaE. This gene is present in the nuclear genome of the cercozoan, but is not in the genome of the chromatophore. This is evidence of ________.