#Question id: 13131
#Unit 10. Ecological Principles
Biologists performed an experiment with flies to examine the effects of population size on the maintenance of genetic variation and on egg-to-adult survival. From a large source population, they randomly assigned eggs to three experimental populations of size N, equal to 20, 60, and0100. For later generations, they collected N eggs from each population and moved them into identical vials that co0ntained f2re0sh me4d0ium. Th6e0y coun8te0d the number of adult flies that emerged and used tissue samples from the adults for genetic analyses. Genetic variation was measured by scoring alleles at several polymorphic loci and expressed as the average number of alleles at those loci. The results are summarized in Figure 1 and Figure 2 below.
The numbers of adult flies that emerged from the three populations in the first generation are closest to which of the following?
#Question id: 2531
#Unit 2. Cellular Organization
The specific linkages between sugar rings, including the specific carbons that are linked together and the configuration of the linkage, are important for the properties of the polysaccharide;
I) Amylose a)β(1,3)-linkages
II) Cellulose b) β (1,4)-linkages
III) Callose c) α(1,4)-linked
d) α (1,3)-linkages
Which of the following linkage combination is correct linkages of the polysaccharides?
#Question id: 5284
#Unit 8. Inheritance Biology
DNA from a strain of Bacillus subtilis with genotype a+b+ c+d+ e+ is used to transform a strain with genotype a - b- c- d- e-. Pairs of genes are checked for co-transformation and the following results are obtained:
Pair of co-transform genes as follow
D-E, E-C, C-B, A-D
On the basis of these results, what is the order of the genes on the bacterial chromosome?
#Question id: 1580
#Unit 4. Cell Communication and Cell Signaling
Advantages of Toxoid (inactivated exotoxin) can be
#Question id: 2883
#Unit 2. Cellular Organization
Which, if any, of the following statements is incorrect?
I. In X-chromosome inactivation, the inactivated X chromosome is epigenetically silenced by a transcript, the XIST RNA, that is produced from the active X chromosome.
II. The XIST RNA works by coating most of the X chromosome that is to be inactivated and then recruiting Polycomb proteins to condense the chromosome.
III. The inactivated X chromosome carries the kinds of histone modification that are typical of heterochromatin.
IV. The pattern of X-chromosome inactivation is made randomly but once it has been established the same pattern of X-inactivation is propagated through all mitotic and meiotic cell divisions.