Podcast
Questions and Answers
All animals are ______.
All animals are ______.
multicellular
Animals are classified as ______ because they cannot synthesize all organic molecules from inorganic chemicals.
Animals are classified as ______ because they cannot synthesize all organic molecules from inorganic chemicals.
heterotrophs
Most animals have an internal ______ where digestion takes place.
Most animals have an internal ______ where digestion takes place.
gut
Muscle tissue is ______ to animals and is key for movement.
Muscle tissue is ______ to animals and is key for movement.
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Animal monophyly is supported by evidence from ______ and morphology.
Animal monophyly is supported by evidence from ______ and morphology.
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The body plans of animals can be characterized by their axis of ______.
The body plans of animals can be characterized by their axis of ______.
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Invertebrates include groups like sponges, cnidarians, and ______.
Invertebrates include groups like sponges, cnidarians, and ______.
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The major organ systems in vertebrates evolved in groups like tetrapods and ______.
The major organ systems in vertebrates evolved in groups like tetrapods and ______.
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The stages of food processing include ingestion, digestion, absorption, and ______.
The stages of food processing include ingestion, digestion, absorption, and ______.
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Gills, trachea, and vertebrate lungs are different types of ______ systems.
Gills, trachea, and vertebrate lungs are different types of ______ systems.
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The human excretory system model includes glomerular filtration and tubular ______.
The human excretory system model includes glomerular filtration and tubular ______.
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Neurons transmit signals through action potentials and the ______ pump.
Neurons transmit signals through action potentials and the ______ pump.
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Different modes of reproduction include asexual reproduction and ______ reproduction.
Different modes of reproduction include asexual reproduction and ______ reproduction.
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Animals share surprisingly few ______ features across species.
Animals share surprisingly few ______ features across species.
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A common set of extracellular matrix molecules includes ______ and proteoglycans.
A common set of extracellular matrix molecules includes ______ and proteoglycans.
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The common ancestor of animals was probably a colonial flagellated ______.
The common ancestor of animals was probably a colonial flagellated ______.
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In protostomes, the mouth arises from the ______.
In protostomes, the mouth arises from the ______.
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The process of ______ involves the formation and migration of germ layers.
The process of ______ involves the formation and migration of germ layers.
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The three germ layers are formed during ______.
The three germ layers are formed during ______.
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The first cell divisions of a zygote are known as ______.
The first cell divisions of a zygote are known as ______.
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Coordination among groups of cells improves through specific regulatory and ______ molecules.
Coordination among groups of cells improves through specific regulatory and ______ molecules.
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The endoderm is essential for the development of the body's __________ systems.
The endoderm is essential for the development of the body's __________ systems.
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Sponges belong to the phylum __________.
Sponges belong to the phylum __________.
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The choanoderm is the inner layer of cells that lines the internal __________ of the sponge.
The choanoderm is the inner layer of cells that lines the internal __________ of the sponge.
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The __________ is the outermost layer of cells that covers the exterior surface of the sponge.
The __________ is the outermost layer of cells that covers the exterior surface of the sponge.
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Animals that have no plane of symmetry are said to be __________.
Animals that have no plane of symmetry are said to be __________.
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Most animals exhibit some kind of __________, which can be classified along various planes.
Most animals exhibit some kind of __________, which can be classified along various planes.
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The general structure and arrangement of an animal's organ systems is referred to as its __________.
The general structure and arrangement of an animal's organ systems is referred to as its __________.
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Although sponges have specialized cells, they do not possess distinct __________ cell layers.
Although sponges have specialized cells, they do not possess distinct __________ cell layers.
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Gastrulation transforms a single-layered blastula into a multilayered structure with the formation of three primary germ layers: the ectoderm, mesoderm, and ______.
Gastrulation transforms a single-layered blastula into a multilayered structure with the formation of three primary germ layers: the ectoderm, mesoderm, and ______.
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Embryos of ______ animals have two cell layers: an outer ectoderm and an inner endoderm.
Embryos of ______ animals have two cell layers: an outer ectoderm and an inner endoderm.
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Triploblastic animals have three distinct cell layers: ectoderm, endoderm, and ______.
Triploblastic animals have three distinct cell layers: ectoderm, endoderm, and ______.
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______ are responsible for the development of the various structures and systems in the adult organism.
______ are responsible for the development of the various structures and systems in the adult organism.
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The ectoderm gives rise to structures such as skin, hair, nails, and the ______ system.
The ectoderm gives rise to structures such as skin, hair, nails, and the ______ system.
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The mesoderm is responsible for the development of many internal structures, including ______, bone, and the circulatory system.
The mesoderm is responsible for the development of many internal structures, including ______, bone, and the circulatory system.
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The endoderm gives rise to the innermost layers of ______ and internal organs.
The endoderm gives rise to the innermost layers of ______ and internal organs.
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Some biologists consider sponges to be ______ due to their lack of differentiated tissue types.
Some biologists consider sponges to be ______ due to their lack of differentiated tissue types.
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Placozoans are structurally very simple animals with only a few distinct __________.
Placozoans are structurally very simple animals with only a few distinct __________.
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Ctenophores, also known as __________, lack most of the Hox genes found in other eumetazoans.
Ctenophores, also known as __________, lack most of the Hox genes found in other eumetazoans.
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Ctenophores have a radially symmetrical, __________ body plan.
Ctenophores have a radially symmetrical, __________ body plan.
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The two cell layers in ctenophores are separated by an inert, gelatinous extracellular matrix called __________.
The two cell layers in ctenophores are separated by an inert, gelatinous extracellular matrix called __________.
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Cnidarians are specialized __________ that use toxins in their nematocysts to capture prey.
Cnidarians are specialized __________ that use toxins in their nematocysts to capture prey.
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Cnidarians possess simple nerve nets that help in integrating their body __________.
Cnidarians possess simple nerve nets that help in integrating their body __________.
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Many corals and anemones gain additional nutrition from __________ endosymbionts that live in their tissues.
Many corals and anemones gain additional nutrition from __________ endosymbionts that live in their tissues.
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Cnidarians, like ctenophores, are largely made up of inert __________.
Cnidarians, like ctenophores, are largely made up of inert __________.
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Study Notes
Origin and Diversification of Animals
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Animals display a wide range of body plans, differing in symmetry, body cavities, segmentation, and cephalization.
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Invertebrates encompass various groups, including sponges, cnidarians, lophotrochozoans, ecdysozoans, echinoderms, and hemichordates, each exhibiting unique origins and evolutionary paths regarding organ development.
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Vertebrates feature diverse evolutionary lineages, from tetrapods to amniotes, mammals, and ultimately humans. This section also includes discussion of the evolution of major organ systems within these groups.
Animal Nutrition
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Essential nutrients are critical for proper animal function.
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Food processing involves stages, including ingestion, digestion, absorption, and assimilation.
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Invertebrates and vertebrates demonstrate variation in their digestive systems.
Circulation and Gas Exchange
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Respiratory and circulatory systems are integrated.
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Respiratory pigments facilitate oxygen transport. Different respiratory systems (gills, trachea, vertebrate lungs) are described and compared.
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Vertebrate circulation includes the heart's anatomy, the ECG, the cardiac cycle, and the regulation of cardiac output, blood pressure, gas transport, and blood pH.
Osmoregulation and Excretion
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Osmoregulation maintains water and ion balance. This includes discussions about osmoregulators and osmoconformers in different environments.
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Human excretory systems act as a model for studying processes like glomerular filtration, tubular reabsorption, secretion, counter-current mechanisms, and regulation by hormones.
Nervous System, Sensory, and Motor Mechanisms
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Neuron structure and function are key topics, including action potentials, sodium-potassium pump function, and calcium pump function.
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The nervous system's role in transmission at the synapse and neurotransmitters are discussed.
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Sensory systems, such as the eye (retinal components, photoreceptors) and ear (cochlea, basilar membrane), are detailed.
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Detailed coverage of muscle contraction and relaxation mechanisms is provided, including energetics associated with the process.
Endocrine System
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An overview of the endocrine system, including how hormones act as chemical coordinators, is provided.
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The neuro-endocrine system is described.
Reproduction
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Various reproductive modes, including asexual reproduction, parthenogenesis, and aspects of sexual reproduction, are explored.
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Mammalian reproduction is studied as a model of sexual reproduction.
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The section includes discussions of the reproductive physiology of males and females, fertilization, pregnancy, childbirth, and special topics like AIDS and contraception.
What Characteristics Distinguish Animals?
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Multicellularity is a key animal characteristic differentiating them from bacteria, archaea, and most protists.
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Animal life cycles follow complex patterns of development from unicellular zygotes into multicellular organisms.
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Heterotrophic metabolism is a distinguishing feature. Animals obtain nutrients from their environment or with symbiotic aid.
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Internal digestion allows digestion within the animal's internal gut.
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Movement is a defining characteristic for the vast majority of animals. It is crucial for locating/procuring food.
How Do We Know Animals Are Monophyletic?
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Some animals don't move throughout their life cycle, while other plants and fungi have limited movement. The presence of a gut is also variable among animals.
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Multiple factors consolidate the idea that animals are monophyletic, encompassing all organisms in a single clade.
Animal Monophyly
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The most compelling evidence that animals share a common ancestor arises from phylogenetic data analyses of gene sequences.
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Morphology also helps determine the evolutionary relationship between various animal groups.
Surprisingly Few Shared Morphologic Features
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Unique cell junctions (tight, desmosome, and gap) distinguish animals.
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Extracellular matrix molecules (collagen, proteoglycans) are a common feature in all animal groups.
Common Ancestor of Animals
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The common ancestor of animals is likely a colonial flagellated protist similar to existing colonial choanoflagellates.
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Cells in this ancestral organism likely began to exhibit specialization related to different functions, leading to multicellularity.
Common Ancestor of Animals
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Coordination among cell groups in the common ancestor would likely have improved through specific regulatory and signaling molecules.
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The evolution of these molecules guided differentiation and cell migration in developing embryos leading to more complex organisms.
A Few Basic Developmental Patterns
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Differences in embryonic development patterns were historically used to classify animal groups.
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Analyses of gene sequencing data are increasingly important in differentiating and understanding animal phylogeny.
Cleavage
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The initial cell divisions of a zygote are referred to as cleavage (Radial and Spiral divisions).
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In general, the number of cells in the embryo doubles during cleavage.
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Different cleavage patterns exist among animals.
Gastrulation Stages
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Protostomes and deuterostomes are differentiated based on the development of the mouth and anus.
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Gastrulation is characterized by the formation and migration of germ layers—ectoderm, mesoderm, and endoderm—crucial for subsequent development into complex multicellular organisms.
Germ Layers
- Distinct germ layers form early in development, differentiating into numerous organs.
- Ectoderm gives rise to the skin, hair, nervous system, etc.
- Mesoderm gives rise to the circulatory system, muscle, and excretory organs.
- Endoderm gives rise to the digestive and respiratory systems and related organs.
Sponges
- Sponges lack true germ layers and are relatively simple multicellular organisms, exhibiting two primary cell layers (pinacoderm and choanoderm).
Animal Body Plans
- Animal body plans vary, yet they can often be categorized based on four key features: symmetry, body cavity structure, segmentation, and external appendages.
Symmetry
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Most animals are symmetrical, meaning they can be divided into similar halves along a plane or multiple planes.
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Asymmetry is seen in some early animal lineages such as Placozoans and sponges.
Sponges, Placozoans, Ctenophores, and Cnidarians
- These animal phyla have unique evolutionary characteristics, that were historically less detailed than other groups. Further work is ongoing to determine the evolutionary relationship between these groups.
Cnidarians
- Cnidarians are carnivores, possessing unique specialized cells with stinging nematocytes, enabling them to capture prey.
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Description
Explore the fascinating evolution of animals, from invertebrates to vertebrates. This quiz covers key concepts including animal body plans, nutrition, and the integrated systems of circulation and gas exchange. Test your knowledge on how these systems have developed across different species.
