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: 9051

#Unit 9. Diversity of Life Forms

What would happen to the seasons if Earth were tilted 35 degrees off its orbital plane instead of the usual 23.5 degrees?

#Question id: 31091

#Unit 4. Cell Communication and Cell Signaling

#Question id: 23126

#Unit 2. Cellular Organization

#Question id: 2977

#Unit 2. Cellular Organization

The mitotic exit network that localizes to spindle pole bodies and whose activity is regulated by spindle position belongs to the family of signaling pathways known as the Hippo pathway in metazoans. Following statements are-

A. The conserved core of the Hippo signaling pathways consists of the Hippo protein kinase, which activates the Lats-Mob1 kinase.

B. The kinases are organized by a scaffolding molecule that, at least in budding and fission yeasts, targets the kinase cascade to centrosomes.

C. As in many kinase signaling cascades, a GTPase controls the activity of the mitotic exit network and the septation initiation network.

D. In metazoans, activation of the Hippo pathway leads to tissue overgrowth because the transcriptional activator TAZ (known as YAP in the mouse) constitutively promotes the expression of growth- and proliferation-promoting genes.

Which of the following statements are incorrect?

#Question id: 2943

#Unit 2. Cellular Organization

Which of the following is NOT a mechanism by which G1/S cyclin-CDKs ensure progression through the cell cycle?