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Ch. 13 - Meiosis
Freeman - Biological Science 7th Edition
Freeman7th EditionBiological ScienceISBN: 9783584863285Not the one you use?Change textbook
Chapter 13, Problem 10a

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.

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1
Define the hypothesis clearly: The hypothesis is that drying rids the rotifers of the fungal pathogen.
Identify the variables: The independent variable is the drying process, and the dependent variable is the presence of the fungal pathogen in rotifers.
Design the experimental groups: Create two groups of rotifers. Group A will be subjected to drying and rehydration, while Group B will remain in a consistently wet environment.
Determine the method of pathogen detection: Use a reliable method to detect the presence of the fungal pathogen in both groups before and after the drying process.
Analyze the results: Compare the presence of the fungal pathogen in both groups after the experiment. If Group A shows a significant reduction in the pathogen compared to Group B, it supports the hypothesis.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Asexual Reproduction

Asexual reproduction is a mode of reproduction where offspring are produced by a single organism without the involvement of gametes. This process results in offspring that are genetically identical to the parent, allowing for rapid population growth. In the case of rotifers, asexual reproduction has enabled them to survive and adapt over millions of years despite losing sexual reproduction capabilities.
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Desiccation Tolerance

Desiccation tolerance refers to an organism's ability to survive extreme drying conditions. Rotifers exhibit this trait by entering a dormant state when their environment dries out, allowing them to be transported to new locations by wind. Upon rehydration, they resume normal activity, which is crucial for their survival and dispersal in fluctuating environments.
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Pathogen Survival and Transmission

Pathogen survival and transmission involve the ability of a pathogen to persist and spread within a host population. In this context, the fungal pathogen affecting rotifers cannot survive desiccation, suggesting that drying may eliminate the pathogen from rotifer populations. Understanding this relationship is key to testing the hypothesis that desiccation helps rotifers rid themselves of the pathogen.
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Related Practice
Textbook Question
Norway 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 moleculesb. 21 chromosomes and 42 double-helical DNA moleculesc. 42 chromosomes and 42 double-helical DNA moleculesd. 42 chromosomes and 84 double-helical DNA molecules
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Textbook Question

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.

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Textbook Question

Meiosis results in independent assortment of maternal and paternal chromosomes. If 2n=6 for a given organism, and there is no crossing over, what is the chance that a gamete produced by this diploid organism will receive only paternal chromosomes?

a. 0

b. 1/16

c. 1/8

d. 1/3

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Textbook Question

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?

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Textbook Question

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.

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