#Question id: 12409
#Unit 6. System Physiology – Plant
#Question id: 20542
#Unit 12. Applied Biology
#Question id: 19184
#Unit 13. Methods in Biology
#Question id: 5686
#Unit 5. Developmental Biology
Following statements are regarding to double fertilization in angiosperms.
A. One sperm cell fuses with the egg cell to produce the zygote that will develop into the new embryonic plant.
B. The second sperm cell fuses with the usually binucleate central cell, giving rise to the
endosperm, the tissue that nourishes the developing embryo. This second event is not “true” fertilization in the sense of male and female gametes undergoing fusion.
C. The second sperm cell fuses with the usually binucleate central cell, giving rise to the
endosperm, the tissue that nourishes the developing embryo. This second event is “true” fertilization in the sense of male and female gametes undergoing fusion.
D. During fertilization in angiosperm, when the sperm cells are released, the egg undergoes a flux of Ca2+. Then, chemicals released from the egg appear to make the sperm competent for cell fusion.
Which of the following statements are true?
#Question id: 2578
#Unit 2. Cellular Organization
Following statements are regarding to proteins which involve actin filament assembly.
A. To nucleate the assembly of branched actin, Arp2/3 needs to be activated by interacting with a nucleation promoting factor (NPF), in addition to associating with the side of a pre-existing actin filament.
B. The NPF WASp is inactive due to an intramolecular interaction that masks the WCA domain.
C. Two NPFs each bind an actin subunit at their WH2 domains, and together, they activate the Arp2/3 complex through its interaction with their connector and acidic domains.
D. The NPF WASp is activated by a coincidence detection mechanism by which intramolecular interaction in WASp is relieved, allowing the W domain to bind actin and the acidic A domain to activate the Arp2/3 complex.
Which of the following statements represents regulation of the Arp2/3 complex by NPF?