Ahaploid yeast strain that is deficient in its ability to make arginine, is crossed to a different haploid yeast strain also unable to produce arginine. the resulting diploid, f1 strain is able to make its own arginine. what is the best explanation?

a. each deficient haploid strain possessed a mutant allele, but not in the same gene, thus the diploid had 1 functional copy of each gene
b. the defective arginine biosynthetic enzymes, made from the mutant genes, were able to interact and make arginine
c. a crossing over event with one of the yeast strains gave a functional allele of the arginine biosynthesis gene

Which would happen if more forests were cut down? a. the nitrogen cycle would be stopped b. nitrogen would be fixed by bacteria more quickly c. the amount of co2 in the atmosphere would increase d. fossil fuels would build up in the soil c the amount of co2 in the atmosphere would increase

Two students are working together on an experiment that measures the effect of different liquid fertilizers on the thickness of plants’ stems. which is most likely to result in the greatest amount of error in their scientific experiment? a.one student measures the plant stem widths by using calipers. the other student measures the widths of the same plant stems again by using a different pair of calipers. b.one student measures the plant stem widths by using calipers. the other student types the measurements as they are taken into a computer spreadsheet. c.one student weighs liquids for the experiment by using a calibrated scale. the other student weighs liquids for the experiment by using a different calibrated scale.

19. a cell is viewed under a microscope and is found to have two nuclear envelopes and spindles that appear to be breaking apart. which phase of mitosis is the cell most likely in? a. metaphase b. prophase c. telophase d. anaphase