Textbook Question
What two major lineages make up the living Amniota?
Ch. 32 - Deuterostome Animals
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 32, Problem 6
Compare amniotic eggs to placentas.
Verified step by step guidance1
Identify the primary function: Both amniotic eggs and placentas serve the purpose of nurturing and protecting the developing embryo. However, they are found in different groups of animals and have distinct structures and functions.
Describe amniotic eggs: Amniotic eggs are found in reptiles, birds, and some mammals like monotremes. They have several layers including a hard or leathery shell that provides protection, and membranes that store waste and facilitate gas exchange.
Explain placentas: Placentas are found in most mammals. They are organs formed in the uterus during pregnancy that provide oxygen and nutrients to the growing fetus through the umbilical cord, while also removing waste products.
Compare development environments: Amniotic eggs develop externally, where the embryo grows inside the egg outside the mother's body. In contrast, development in species with placentas occurs internally, with the fetus developing inside the uterus connected to the mother.
Discuss evolutionary significance: The development of amniotic eggs allowed for reproduction away from water bodies, facilitating the colonization of diverse terrestrial environments. The evolution of the placenta allowed for more direct nurturing of the young, leading to longer gestation periods and more developed offspring at birth.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Amniotic Eggs
Amniotic eggs are a type of egg that contains a protective amniotic membrane, allowing for the development of embryos in a terrestrial environment. This adaptation is crucial for reptiles, birds, and some mammals, as it prevents desiccation and provides a stable environment for growth. The egg contains various membranes and fluids that support the embryo, facilitating gas exchange and nutrient absorption.
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Vertebrates
Placentas
Placentas are specialized organs that develop in the uterus of eutherian (placental) mammals, facilitating nutrient and gas exchange between the mother and the developing fetus. The placenta allows for a more direct and efficient transfer of oxygen and nutrients, while also removing waste products. This structure supports longer gestation periods and more complex development compared to amniotic eggs.
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Reproductive Strategies
Reproductive strategies refer to the various methods organisms use to reproduce and ensure the survival of their offspring. Amniotic eggs represent an oviparous strategy, where eggs are laid and develop outside the mother's body, while placentas exemplify viviparous reproduction, where the young develop inside the mother. These strategies reflect adaptations to different environmental pressures and life history traits.
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Related Practice
Textbook Question
Most species of hominins are known only from Africa. Which species have been found in other parts of the world as well?
a. early Homo—H. habilis and H. ergaster
b. H. erectus, H. neanderthalensis, and H. floresiensis
c. Australopithecus afarensis
Textbook Question
Which statement is true about endothermy in mammals and birds?
a. They both inherited this trait from a common ancestor.
b. Birds are more closely related to mammals than to reptiles.
c. Endothermy arose independently in these two lineages.
d. Birds are reptiles and all reptiles are ectothermic.
Textbook Question
Draw a phylogeny of major populations of modern humans that would reject the out-of-Africa hypothesis.
Textbook Question
Consider the evolution of protostomes and deuterostomes (this chapter):
Compare adaptations in protostomes and deuterostomes for living on land.
Recall that changes in the expression patterns of tool-kit genes in arthropods such as insects enabled a dramatic diversification of their segmented appendages and bodies.
Design an experiment to test whether this concept applies to vertebrates.