Gastrulation in sea urchins, Drosophila, and Xenopus all begin with a change in cell shape, in which the apical surface of an epithelial sheet contracts. This process is called:

#Question id: 17672

#XL - S Microbiology

#Question id: 11410

#XL - R Botany

Biodiversity hot spots, those areas with the greatest number of endemic species. Which of the following criteria to qualify as a hot spot region?

A. It must contain at least 1,500 species of vascular plants as endemics

B. It must have lost at least 70% of its original habitat

C. It must contain at least 500 species of bird species

D- It must contain high numbers of species

#Question id: 19577

#XL - P Chemistry

#Question id: 10769

#XL - T Zoology

#Question id: 5298

#XL - S Microbiology

Four E. coli strains of genotype a+ b− are labeled 1, 2, 3, and 4. Four strains of genotype a− b+ are labeled 5, 6, 7, and 8. The two genotypes are mixed in all possible combinations and (after incubation) are plated to determine the frequency of a+ b+ recombinants. The following results are obtained, where M = many recombinants, L = low numbers of recombinants, and 0 = no recombinants. On the basis of these results, assign a sex type (either Hfr, F+, or F−) to each strain