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03:38Norway rats have 42 chromosomes in their diploid cells. If such a cell enters meiosis, how many chromosomes and double-helical molecules of DNA will be present in each daughter cell at the end of meiosis II?
a. 21 chromosomes and 21 double-helical DNA molecules
b. 21 chromosomes and 42 double-helical DNA molecules
c. 42 chromosomes and 42 double-helical DNA molecules
d. 42 chromosomes and 84 double-helical DNA molecules
Triploid (3n) watermelons, which are seedless, are produced by crossing a tetraploid (4n) strain with a diploid (2n) plant. Explain why this mating produces a triploid individual.
A species of rotifer, a small freshwater invertebrate, lost the ability to reproduce sexually millions of years ago. A remarkable feature of its life cycle is the ability to withstand dry conditions. When the rotifer's environment dries out, so does the rotifer, and it can be blown to a new area. Rotifers that land in water will rehydrate and resume an active life. A major pathogen of these rotifers is a species of fungus that cannot survive drying. Some scientists hypothesize that drying rids the rotifers of this pathogen. Design an experimental study to test this hypothesis.
A species of rotifer, a small freshwater invertebrate, lost the ability to reproduce sexually millions of years ago. A remarkable feature of its life cycle is the ability to withstand dry conditions. When the rotifer's environment dries out, so does the rotifer, and it can be blown to a new area. Rotifers that land in water will rehydrate and resume an active life. A major pathogen of these rotifers is a species of fungus that cannot survive drying. Some scientists hypothesize that drying rids the rotifers of this pathogen. Why might the ability to withstand drying reduce any potential advantage of sexual reproduction in this rotifer species?
Select True or False for each statement.
T/FLinked genes are always inherited together.
T/FGenetic map distances measure the number of nucleotides between a pair of genes.
T/FThe farther apart genes are on a chromosome, the more likely there is to be a crossover between these genes during meiosis.
T/FCrossing over occurs between genes on different homologs of a homologous chromosome pair.
