Podcast
Questions and Answers
Which phylum is characterized by having radial symmetry and includes organisms like jellyfish and sea anemones?
Which phylum is characterized by having radial symmetry and includes organisms like jellyfish and sea anemones?
- Platyhelminthes
- Cnidaria (correct)
- Porifera
- Echinodermata
An animal exhibiting spiral cleavage during embryonic development most likely belongs to which group?
An animal exhibiting spiral cleavage during embryonic development most likely belongs to which group?
- Deuterostomes
- Protostomes (correct)
- Echinoderms
- Porifera
Which of the following describes an animal with a true coelom?
Which of the following describes an animal with a true coelom?
- A fluid-filled cavity not lined with mesodermal tissue.
- A fluid-filled cavity fully lined by mesodermal tissue. (correct)
- A solid body structure with no internal cavity.
- No fluid-filled cavity between the body wall and organs.
If the blastopore of an embryo develops into the anus, the animal is classified as a:
If the blastopore of an embryo develops into the anus, the animal is classified as a:
Which germ layer is responsible for the development of the nervous system and skin?
Which germ layer is responsible for the development of the nervous system and skin?
Which of the following phyla exhibits metamerism, or true segmentation?
Which of the following phyla exhibits metamerism, or true segmentation?
An organism with a heart that pumps circulatory fluid through vessels that then empty into sinuses bathing the tissues has what kind of circulatory system?
An organism with a heart that pumps circulatory fluid through vessels that then empty into sinuses bathing the tissues has what kind of circulatory system?
Which phylum includes organisms that are characterized by being acoelomate?
Which phylum includes organisms that are characterized by being acoelomate?
The mesoderm germ layer typically gives rise to which of the following systems in animals?
The mesoderm germ layer typically gives rise to which of the following systems in animals?
Which of the following phyla is characterized by having a pseudocoelom?
Which of the following phyla is characterized by having a pseudocoelom?
What type of symmetry is typically found in animals that exhibit cephalization?
What type of symmetry is typically found in animals that exhibit cephalization?
Which phylum contains organisms that are characterized as being asymmetrical?
Which phylum contains organisms that are characterized as being asymmetrical?
Considering the fate of the blastopore, which developmental pattern is associated with greater developmental flexibility and capacity for identical twin formation?
Considering the fate of the blastopore, which developmental pattern is associated with greater developmental flexibility and capacity for identical twin formation?
An unknown organism is discovered. Upon dissection, it’s found to have a fluid-filled body cavity only partially lined with mesoderm. How should it be classified?
An unknown organism is discovered. Upon dissection, it’s found to have a fluid-filled body cavity only partially lined with mesoderm. How should it be classified?
Which of the following animals possesses an open circulatory system?
Which of the following animals possesses an open circulatory system?
Imagine a novel marine organism is discovered. It displays radial cleavage and the blastopore becomes its mouth. This organism would be categorized as a:
Imagine a novel marine organism is discovered. It displays radial cleavage and the blastopore becomes its mouth. This organism would be categorized as a:
In an organism with true segmentation (metamerism), which of the following is likely to be observed?
In an organism with true segmentation (metamerism), which of the following is likely to be observed?
An animal embryo is developing, and the mesoderm layer fails to form. What systems will be directly affected by this failure?
An animal embryo is developing, and the mesoderm layer fails to form. What systems will be directly affected by this failure?
An animal exhibits bilateral symmetry. Which of the following is also likely to be present?
An animal exhibits bilateral symmetry. Which of the following is also likely to be present?
If you are studying an organism and observe that its blood is contained within vessels throughout its body, what type of circulatory system does it possess?
If you are studying an organism and observe that its blood is contained within vessels throughout its body, what type of circulatory system does it possess?
Flashcards
Phylum Porifera
Phylum Porifera
Sponges
Phylum Cnidaria
Phylum Cnidaria
Jellyfish, sea anemones, coral
Phylum Platyhelminthes
Phylum Platyhelminthes
Flatworms
Phylum Nematoda
Phylum Nematoda
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Phylum Mollusca
Phylum Mollusca
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Phylum Annelida
Phylum Annelida
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Phylum Arthropoda
Phylum Arthropoda
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Phylum Echinodermata
Phylum Echinodermata
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Egg cleavage
Egg cleavage
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What is the blastopore?
What is the blastopore?
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Protostome
Protostome
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Deuterostome
Deuterostome
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Endoderm
Endoderm
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Ectoderm
Ectoderm
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Mesoderm
Mesoderm
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Coelomate
Coelomate
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Acoelomate
Acoelomate
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Pseudocoelomate
Pseudocoelomate
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Segmentation
Segmentation
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Radial symmetry
Radial symmetry
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Study Notes
- Phyla are groupings of animals.
Phyla names
- Porifera (sponges)
- Cnidaria (jellyfish, sea anemones, coral)
- Platyhelminthes (flatworms)
- Nematoda (roundworms)
- Mollusca (snails, bivalves, octopi, squid)
- Annelida (segmented worms)
- Arthropoda (insects, arthropods, crustaceans)
- Echinodermata (starfish, sand dollars, sea urchins, sea cucumbers)
Egg Cleavage
- The fertilized egg, or zygote, undergoes cell divisions.
- At the 8 cell stage, cleavage is either radial or spiral.
- Radial cleavage: Four cells are stacked directly on top of another set of four cells.
- Spiral cleavage: Four cells are offset on top of another set of four by 45 degrees.
Fate of the Blastopore
- During cell cleavage, a hollow ball of cells called the blastula is formed.
- The gastrula forms when an indentation develops in the side of the blastula.
- This indentation is known as the blastopore.
- Protostome: The blastopore forms the mouth.
- Deuterostome: The blastopore forms the anus.
Germ Layers
- During embryological development, two initial cell layers form.
- Endoderm: The inner layer, from which the digestive system develops.
- Ectoderm: The outer layer, from which the skin and nervous system develop.
- Mesoderm: The third inner layer, from which the muscular, skeletal, and circulatory systems develop.
Body Cavity/Coelom
- Coelomate: A true body cavity is a fluid-filled space between the body wall and organs that is fully lined by tissues from the mesoderm.
- Acoelomate: There is no fluid-filled space between the body wall and organs.
- Pseudocoelomate: A fluid-filled space exists, but it is not fully lined by mesodermal tissue.
Segmentation
- Segmentation, or metamerism, is where features of an animal's body are divided into repeating units.
- True segmentation processes metamerism within the deep tissues of the body.
Body Symmetry
- Symmetry refers to how the body parts of an animal are arranged around an axis or across a plane.
- Radial symmetry: Repeating body parts are organized around a central axis.
- Bilateral symmetry: Body parts repeat across a plane.
- Asymmetrical: Lacking body symmetry.
Open vs. Closed Circulatory Systems
- Animals with closed circulatory systems have a heart that sends circulatory fluid through the body via blood vessels.
- Animals with open circulatory systems have a heart, but circulatory fluid leaves vessels and directly bathes the tissues of the organism.
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