Select the statements about the k-t boundary that are true. select all that apply. select all that apply. the k-t boundary is a thin layer of clay found only in gubbio, italy. the k-t boundary in zumaia, spain is sharp--representing an abrupt change in the marine ecosystem. the k-t boundary separates rock layers of the cretaceous period from those of the tertiary period. the k-t boundary dates to 65 million years ago (when the dinosaurs disappeared).

Juan and carol were studying invertebrates in biology. they knew that segmented or earth worms preferred a dark, moist habitat. during this lab, they would be investigating the responses of organisms called planaria or dugesia tigrina. these were simple flatworms that still had a one-way digestive system and a very simple nervous system. juan and carol placed the planaria in a petri dish containing cool, distilled water that was partially covered with black paper. they shined a light on the dish. next, they removed the paper and placed a small amount of chicken liver at one end of the dish. they added a few large salt crystals to the water. finally, they added drops of hot water to the cool water in the petri dish. their results can be seen in the data table. according to their experiment, all but one conclusion is valid.

14) whenever diploid populations are in hardy-weinberg equilibrium at a particular locus a) the allele's frequency should not change from one generation to the next, but its representation in homozygous and heterozygous genotypes may change. b) natural selection, gene flow, and genetic drift are acting equally to change an allele's frequency. c) this means that, at this locus, two alleles are present in equal proportions. d) the population itself is not evolving, but individuals within the population may be evolving.

Which of the following initial observations would more directly lead to this research study? a) ginko biloba is cost effective and also possesses heart-protective, antioxidant, anti-inflammatory properties. b) metformin is an effective treatment of patients with t2d, but shows side effects that complicate the disease state. c) over the past several years, the cost of treating t2d within the united states has increased dramatically. d) many plants contain molecules that improve the health and quality of life of patients with a variety of diseases like t2d. e) t2d affects millions of individuals in the usa and worldwide many of who could benefit from improved therapies.