Textbook Question
Propose an experiment to test the hypothesis that cells from only one region of a frog blastula form the ectoderm. What results from this experiment would support this hypothesis?
Ch. 47 - Animal Reproduction and Development
Freeman8th EditionBiological ScienceISBN: 9780138276263
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Table of contents
- Ch. 1 - Biology: The Study of Life13
- Ch. 2 - Water and Carbon: The Chemical Basis of Life14
- Ch.3 - Protein Structure and Function10
- Ch.4 - Nucleic Acids and the RNA World10
- Ch. 5 - An Introduction to Carbohydrates10
- Ch. 6 - Lipids, Membranes, and the First Cells11
- Ch. 7 - Inside the Cell10
- Ch. 8 - Energy and Enzymes: An Introduction to Metabolism10
- Ch. 9 - Cellular Respiration and Fermentation11
- Ch. 10 - Photosynthesis12
- Ch. 11 - Cell-Cell Interactions12
- Ch. 12 - The Cell Cycle8
- Ch. 13 - Meiosis12
- Ch. 14 - Mendel and the Gene23
- Ch. 15 - DNA and the Gene: Synthesis and Repair15
- Ch. 16 - How Genes Work16
- Ch. 17 - Transcription, RNA Processing, and Translation16
- Ch. 18 - Control of Gene Expression in Bacteria16
- Ch. 19 - Control of Gene Expression in Eukaryotes12
- Ch. 20 - The Molecular Revolution: Biotechnology, Genomics, and New Frontiers15
- Ch. 21 - Genes, Development, and Evolution12
- Ch. 22 - Evolution by Natural Selection16
- Ch. 23 - Evolutionary Processes13
- Ch. 24 - Speciation15
- Ch. 25 - Phylogenies and the History of Life13
- Ch. 26 - Bacteria and Archaea15
- Ch. 27 - Diversification of Eukaryotes16
- Ch. 28 - Green Algae and Land Plants16
- Ch. 29 - Fungi18
- Ch. 30 - An Introduction to Animals9
- Ch. 31 - Protostome Animals15
- Ch. 32 - Deuterostome Animals17
- Ch. 33 - Viruses16
- Ch. 34 - Plant Form and Function16
- Ch. 35 - Water and Sugar Transport in Plants16
- Ch. 36 - Plant Nutrition13
- Ch. 37 - Plant Sensory Systems, Signals, and Responses16
- Ch. 38 - Flowering Plant Reproduction and Development16
- Ch. 39 - Animal Form and Function17
- Ch. 40 - Water and Electrolyte Balance in Animals16
- Ch. 41 - Animal Nutrition16
- Ch. 42 - Gas Exchange and Circulation16
- Ch. 43 - Animal Nervous Systems16
- Ch. 44 - Animal Sensory Systems16
- Ch. 45 - Animal Movement11
- Ch. 46 - Chemical Signals in Animals16
- Ch. 47 - Animal Reproduction and Development16
- Ch. 48 - The Immune System in Animals16
- Ch. 49 - An Introduction to Ecology15
- Ch. 50 - Behavioral Ecology16
- Ch. 51 - Population Ecology16
- Ch. 52 - Community Ecology20
- Ch. 53 - Ecosystems and Global Ecology17
- Ch. 54 - Biodiversity and Conservation Ecology18
Chapter 47, Problem 6
Summarize the experimental evidence that Daphnia require three cues to trigger sexual reproduction. Discuss what these cues indicate about the environment.
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Identify the three cues necessary for Daphnia to trigger sexual reproduction: changes in photoperiod, population density, and food availability.
Explain how changes in photoperiod serve as a cue: Shorter days signal the approach of unfavorable conditions, prompting Daphnia to reproduce sexually to produce resting eggs that can survive harsh conditions.
Discuss the role of population density: High population density indicates limited resources, triggering sexual reproduction to produce more resilient offspring through genetic recombination.
Analyze the impact of food availability: A decrease in food availability signals deteriorating environmental conditions, encouraging sexual reproduction to ensure survival through genetically diverse diapausing eggs.
Summarize the environmental implications: These cues help Daphnia detect changes in their environment that could threaten their survival, prompting them to switch to a reproductive strategy that enhances the chances of their offspring's survival through adverse conditions.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Daphnia Reproduction
Daphnia, commonly known as water fleas, exhibit both asexual and sexual reproduction. Under favorable environmental conditions, they reproduce asexually through parthenogenesis, producing clones. However, when conditions become stressful, such as changes in temperature or food availability, Daphnia switch to sexual reproduction, which increases genetic diversity and resilience in fluctuating environments.
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Environmental Cues
Daphnia rely on specific environmental cues to trigger sexual reproduction. These cues typically include changes in population density, the presence of predators, and variations in resource availability. Each cue signals a shift in environmental conditions, prompting Daphnia to adapt their reproductive strategy to ensure survival and optimize offspring success.
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Adaptive Significance
The requirement for multiple cues to trigger sexual reproduction in Daphnia highlights the adaptive significance of their reproductive strategies. By integrating various environmental signals, Daphnia can better assess the overall health of their habitat. This multi-cue approach allows them to time sexual reproduction for when conditions are most favorable for the survival of their offspring, thereby enhancing their evolutionary fitness.
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Related Practice
Textbook Question
True or false: The corpus luteum is retained upon implantation due to the presence of the hormone human chorionic gonadotropin (hCG).
Textbook Question
Give examples of negative and positive feedback in hormonal control of the human menstrual cycle. Why can a high estradiol level be considered a 'readiness' signal from a follicle?
Textbook Question
Many frogs and mice are similar in size, yet a frog egg is vastly larger than a mouse egg. Propose a plausible explanation for this difference in the egg size.
Textbook Question
Which of the following statements regarding animal development is/are correct? Select True or False for each statement.
T/FThe neural tube forms after organogenesis is complete
T/FThe blastocyst is formed during cleavage
T/FDuring cleavage, the zygote divides rapidly without growth, forming a mass of cells
T/FAnimals have two germ layers
Textbook Question
How do spermatogenesis and oogenesis in humans differ with respect to numbers of cells produced, gamete size, and timing of the second meiotic division?