#Question id: 23185
#Unit 13. Methods in Biology
#Question id: 15887
#Unit 12. Applied Biology
#Question id: 28162
#Unit 13. Methods in Biology
Which of the following method for the purification of plant DNA, which forms an insoluble complex with nucleic acids.
#Question id: 13143
#Unit 10. Ecological Principles
The Norway rat (Rattus Norvegicus), a widespread pest, was controlled for about a decade by the anticoagulant warfarin. This chemical substance, placed in food pellets, is absorbed by the intestinal tract and inhibits the clotting of blood. After a population decline for about 10 years, rat populations increased and stabilized. In one European population, as illustrated in the graph below, the percentage of rats resistant to warfarin has remained fairly stable over a number of years.
Resistance to warfarin is governed by a dominant autosomal gene, R. More than 15 percent of the resistant animals are heterozygous at this locus (Rr). The table below indicates the response to warfarin and relative reproductive fitness of individuals that are homozygous or heterozygous for the dominant gene (R). The RR individuals have a 20-fold increase in vitamin K requirement over individuals.
#Question id: 5672
#Unit 5. Developmental Biology
Following statements are regarding to recognition of sperm by mammalian zona pellucida.
A. Sperm that have undergone the acrosome reaction bind directly to zona protein ZP2 and begin making a channel toward the oocyte.
B. Sperm with an intact acrosome bind to ZP2; they undergo the acrosome reaction on the zona pellucida and then transfer their binding to ZP3.
C. When a sperm reaches the oocyte and fuses with it, the cortical granules release proteins that digest portions of ZP2 and ZP3, making them nonfunctional and prevent polyspermy.
D. When a sperm reaches the oocyte and fuses with it, the cortical granules release proteins that digest ZP3 only, not ZP2 because ZP2 involve in the process of slow block to polyspermy.
Which of the above statements are correct?