Answer:
Amount of DNA in a diploid G2 nucleus after S phase has already undergone DNA replication hence the amount of DNA in a diploid nucleus in G1 would be 200 ng. As the organism is diploid, 200 ng of DNA would be carried on 14 chromosomes.
Answer:
Helper T cells are arguably the most important cells in adaptive immunity, as they are required for almost all adaptive immune responses. They not only help activate B cells to secrete antibodies and macrophages to destroy ingested microbes, but they also help activate cytotoxic T cells to kill infected target cells.
Explanation:
Helper T cells become activated when they are presented with peptide antigens by MHC class II molecules, which are expressed on the surface of antigen-presenting cells (APCs). Once activated, they divide rapidly and secrete cytokines that regulate or assist the immune response.
B because they are prokaryotes but cannot be classified as animals, plants, or fungi.
Answer:
B) speciation.
Explanation:
The Galapagos island is known for the different varieties of finches (species of birds) which could be distinguished on the basis of different beak shapes and size.
This is the result of the selection pressure which led to the divergence of the species on the island through a mechanism called adaptive radiation.
Since the adaptive radiation leads to the formation of different species on the same island, the process of formation species is known as the speciation.
Thus, speciation is the correct answer.
More than one third of North American bird species can be found in wetlands. Wetlands may contains fresh or salt water or both. Biodiversity and nutrient levels are high; many plants and organisms filter out waste materials. Birds like geese, ducks, herons, warbies, and egrets, to name a few, use wetlands for nesting and feeding.
