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TLS Online TPP Program

#Question id: 10708

Which of the following statements is a likely explanation for why invasive species take over communities into which they have been introduced?

#Unit 10. Ecological Principles

Invasive species are less efficient than native species in competing for the limited resources of the environment.
Invasive species are not held in check by the predators and agents of disease that have always been in place for native species.
Invasive species have a higher reproductive potential than native species.
Invasive species come from geographically isolated regions, so when they are introduced to regions where there is more competition, they thrive

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TLS Online TPP Program

#Question id: 13143

#Unit 10. Ecological Principles

The Norway rat (Rattus Norvegicus), a widespread pest, was controlled for about a decade by the anticoagulant warfarin. This chemical substance, placed in food pellets, is absorbed by the intestinal tract and inhibits the clotting of blood. After a population decline for about 10 years, rat populations increased and stabilized. In one European population, as illustrated in the graph below, the percentage of rats resistant to warfarin has remained fairly stable over a number of years.

Resistance to warfarin is governed by a dominant autosomal gene, R. More than 15 percent of the resistant animals are heterozygous at this locus (Rr). The table below indicates the response to warfarin and relative reproductive fitness of individuals that are homozygous or heterozygous for the dominant gene (R). The RR individuals have a 20-fold increase in vitamin K requirement over individuals.

Fitness is a measure of the reproductive success of a particular genotype. The highest fitness is 1.00.

In a population where warfarin is no longer applied, the expectation is that the

TLS Online TPP Program

#Question id: 13144

#Unit 8. Inheritance Biology

Shell coiling of the snail Limnaea peregra(genetic maternal effect) the shell coils (s+s+) which is termed dextral coiling, while some snails exhibiting sinistral coiling (ss). The allele for dextral (s +) is dominant over the allele for sinistral (s). If a male homozygous for dextral alleles (s+s+) is crossed with a female homozygous for sinistral alleles (ss) all of the F1 are heterozygous (s+s) and have a sinistral shell. If these F1 snails are self-fertilized, what is the phenotype of the F2 snail?

TLS Online TPP Program

#Question id: 13145

#Unit 8. Inheritance Biology

We can construct a genetic map by considering the recombination frequencies for each pair of genes. The recombination frequency between a and b is 50%, a and c is 50%, and b and c is 20%. What will be the correct prediction about this statements;

a) Recombination frequency between genes a and b and gene a and c is expected with independent assortment

b) The genes a and b and gene a and c may either be on different chromosomes or be very far apart on the same chromosome; so we will place them in different linkage groups