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Questions and Answers
Which characteristic distinguishes animals from other eukaryotes?
Which characteristic distinguishes animals from other eukaryotes?
What is a unique property of cholesterol in relation to animals?
What is a unique property of cholesterol in relation to animals?
Which mode of reproduction is typically associated with animals?
Which mode of reproduction is typically associated with animals?
What role do homeotic genes play in animal development?
What role do homeotic genes play in animal development?
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Which characteristic describes the feeding style of the Elysia chlorotica?
Which characteristic describes the feeding style of the Elysia chlorotica?
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What is a key characteristic that differentiates animals from non-animal organisms?
What is a key characteristic that differentiates animals from non-animal organisms?
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Which protein is specifically mentioned as playing a role in cell-to-cell attachment in animals?
Which protein is specifically mentioned as playing a role in cell-to-cell attachment in animals?
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What does the absence of a cell wall in animals lead to regarding cell structure?
What does the absence of a cell wall in animals lead to regarding cell structure?
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What stage must animals go through during their development?
What stage must animals go through during their development?
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In the context of multicellularity, what crucial evolutionary development is necessary for animal cells?
In the context of multicellularity, what crucial evolutionary development is necessary for animal cells?
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Flashcards
Animal Characteristics
Animal Characteristics
Animals are multicellular eukaryotes that obtain their energy by consuming other organisms (heterotrophs).
Animal Origin
Animal Origin
The earliest direct evidence of animals dates back approximately 560 million years ago, appearing as multicellular, soft-bodied eukaryotes.
Heterotroph
Heterotroph
An organism that obtains energy by consuming other organisms.
Multicellular Eukaryote
Multicellular Eukaryote
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Animal exceptions
Animal exceptions
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Cell Adhesion
Cell Adhesion
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Cell Signaling
Cell Signaling
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Choanoflagellates
Choanoflagellates
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Cadherins
Cadherins
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CCD (Cytoplasmic Cadherin Domain)
CCD (Cytoplasmic Cadherin Domain)
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Study Notes
Topic 12: The Evolution of Animals I
- Animals are eukaryotes, multicellular, and heterotrophic (except some exceptions)
- They are able to reproduce sexually, and some can reproduce asexually
- They are capable of movement
- They have cells organized into tissues
- They undergo development through a blastula stage
- They lack cell walls, relying on extracellular matrix proteins (e.g., collagen) for structure and cohesion
Learning Outcomes
- List and define characteristics shared by all animals
- Explain how genetic data determines animal phylogeny
- Identify various modes of asexual reproduction in animals
- Justify the benefits of bilateral symmetry
- Explain how homeotic genes affect animal body plans
- Define key developmental terms (protostomes, deuterostomes)
- Illustrate differences in embryonic development between protostomes and deuterostomes
- Calculate, compare, and explain the consequences of different surface-to-volume ratios
- Define the modes of thermoregulation
- Determine the modes of thermoregulation from graphical data
- Explain adaptations to physical/physiological challenges faced on land
- Explain animal reproduction types (sexual, asexual: budding, fragmentation, parthenogenesis)
12.1 – Characteristics of Animals
- Animals are multicellular, eukaryotic organisms
- Animals are heterotrophic, meaning they obtain energy and nutrients by consuming other organisms
- Animals are capable of movement
- Animals exhibit a wide range of body plans and symmetries
12.2 – Body Plans, Embryogenesis, and Development
- Body Plans: Animals exhibit radial or bilateral symmetry
- Radial symmetry has a central axis with similar parts radiating outward (e.g., jellyfish)
- Bilateral symmetry has distinct left and right sides with anterior and posterior ends (e.g., humans)
- Hox genes: These regulatory genes control the placement and spatial organization of body parts during embryonic development, impacting morphology.
- Larval/Metamorphic stages: Some animals have distinct larval stages that undergo metamorphosis into adult forms (e.g., tadpole to frog).
- Embryogenesis:
- Cleavage: Cell divisions without growth in the early embryo
- Spiral/Radial cleavage: Different patterns of cell division relative to the embryo's axis
- Determinate/Indeterminate cleavage: The fate of each cell determined early, or able to differentiate into various cell types later.
- Gastrulation: Formation of three germ layers (ectoderm, mesoderm, endoderm) from the blastula. These layers give rise to various body tissues and organs.
- Protostomes vs Deuterostomes: Protostomes usually develop the mouth first from the blastopore, while Deuterostomes develop the anus first (blastopore forms the anus).
12.3 – Challenges and Adaptations
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Animals face challenges like temperature, humidity, solute concentration, gas partial pressure, and resource availability, leading to various adaptations for survival.
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Convergent evolution: Similar adaptations in different animal groups that live in similar environments
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Thermoregulation: Mechanisms to maintain a stable internal body temperature (homeotherms)
- Endotherms use internal metabolic processes to generate heat
- Ectotherms regulate body temperature through external sources
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Osmoregulation: Regulation of water and solute balance within an animal's body (especially important in aquatic environments)
- Animals in high-salt environments adapt by retaining ions and producing highly concentrated urine.
- Animals living in wet environments will prevent water loss through adaptations like sweat glands
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Surface-to-volume ratio: Affects heat conservation and metabolic activity. Surface area to volume ratio decreases as animals grow thus affecting heat loss / gain.
Reproduction
- All animals reproduce sexually
- Asexual reproduction also occurs (budding, fragmentation, parthenogenesis)
Tissues and Cell Specialization
- Sponges possess specialized cells (choanocytes, amoebocytes)
- These specialized cells and cellular interactions are crucial for developing tissues
- Simple organization in Porifera (sponges)
- Advanced organization in other lineages (tissues and organs)
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