XI_Zoology _ New Chap-07 STRUCTURAL ORGANISATION IN ANIMALS (Assertion and Reason Statements)
XI_ZOOLOGY_NEW_CHAPTER-04: ANIMAL KINGDOM_ A&R TEST ITEMS
# Correct Assertion Correct Reason
4.1 Basis of Classification; 4.1.1 Levels of Organisation
Different levels of cellular organization exist in the These levels vary from cellular aggregation to formation of
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Animalia. specialized organ systems with distinct functions.
Animal classification is based on fundamental Features such as cell arrangement, body symmetry, coelom
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features shared among various species. nature, and physiological systems.
Coelenterates exhibit tissue-level organization in their Cells with similar functions form tissues, showcasing higher
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cellular arrangement. complexity.
Higher phyla like Platyhelminthes display organ-level Organs specialized for distinct functions form a higher level of
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organization. structural organization.
Animals like Annelids, Arthropods, Molluscs, Organs associate to create functional systems, each serving
5 Echinoderms, and Chordates display organ system- specific physiological functions.
level organization.
Different animal groups exhibit varying complexities For instance, digestive systems vary from incomplete to
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in their organ systems. complete systems.
Animal groups display differences in circulatory These variations include open and closed types of circulatory
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system types. systems.
Animal classification based on common features: cell These features serve as the basis for systematic classification
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arrangement, body symmetry, etc. and differentiation among species.
4.1.2 Symmetry; 4.1.3 Dipioblastic and Triploblastic Organisation
Animals categorized based on symmetry. Sponges exhibit asymmetry; radial symmetry in Coelenterates,
9 ctenophores, and echinoderms; bilateral symmetry in annelids,
arthropods, etc.
Diploblastic animals defined by two embryonic layers Coelenterates are examples of diploblastic animals; mesoglea
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(ectoderm, endoderm) and mesoglea. lies between ectoderm and endoderm.
Triploblastic animals possess a third germinal layer, Animals from Platyhelminthes to Chordates exhibit triploblastic
11 mesoderm, in addition to ectoderm and endoderm. organization; mesoderm exists between ectoderm and
endoderm.
4.1.4 Coelom
Presence of a body cavity is crucial in classification. The body cavity, termed coelom when lined by mesoderm,
12 categorizes animals into coelomates (e.g., annelids, molluscs,
arthropods, echinoderms, hemichordates, and chordates).
Animals with a body cavity not entirely lined by Pseudocoelomates, like aschelminthes, have a body cavity with
13 mesoderm are categorized as pseudocoelomates. mesoderm present in scattered pouches between ectoderm and
endoderm.
Animals lacking a body cavity are classified as Acoelomates, such as platyhelminthes, lack a body cavity
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acoelomates. altogether.
4.1.5 Segmentation; 4.1.6 Notochord
Some animals exhibit body segmentation with Earthworms demonstrate metameric segmentation, known as
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repeated organs in segments. metamerism.
The presence of a notochord defines animals as Chordates form a mesodermally derived rod-like structure
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chordates or non-chordates. known as a notochord during embryonic development.
Animals lacking the notochord structure are classified Non-chordates, from porifera to echinoderms, do not form the
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as non-chordates. notochord structure during embryonic development.
4.2 CLASSIFICATION OF ANIMALS; 4.2.1 Phylum Porifera
The broad classification of Animalia is structured This classification presents different levels of organization,
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based on common fundamental features. symmetry, and body cavity types.
Kingdom Animalia comprises multicellular organisms. It includes levels of organization such as cellular, tissue/organ,
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and organ system levels.
Symmetry and body cavity are crucial features in They categorize animals into distinct groups like acoelomates,
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animal classification. pseudocoelomates, and coelomates.
Animals are classified based on the presence or Acoelomates lack a body cavity, Pseudocoelomates possess a
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absence of body cavities and their distinct types. false body cavity, and Coelomates have a true body cavity.
Symmetry in animals varies from mostly asymmetrical This symmetry pattern is observed among different phyla
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to bilateral. within the Kingdom Animalia.
Pseudocoelomates possess a false body cavity. Platyhelminthes have a body cavity not entirely lined by
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mesoderm.
Phylum Porifera, known as sponges, exhibits specific Sponges are mostly marine, asymmetrical, possess cellular
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characteristic features. organization, and utilize a water transport system.
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, XI_Zoology _ New Chap-07 STRUCTURAL ORGANISATION IN ANIMALS (Assertion and Reason Statements)
XI_ZOOLOGY_NEW_CHAPTER-04: ANIMAL KINGDOM_ A&R TEST ITEMS
# Correct Assertion Correct Reason
Sponges exhibit a water transport system. Water enters through ostia, travels through canals, enabling
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feeding, respiration, and waste elimination.
Sponges exhibit unique digestive and reproductive Their digestion is intracellular, and they reproduce both
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mechanisms. asexually and sexually.
Sponges possess a unique system of digestion and Digestion is intracellular, and the body is supported by spicules
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support. or spongin fibers in sponges.
Sponges have an intracellular digestion system. Digestion occurs within the cells rather than in a separate
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internal cavity.
Sponges exhibit indirect development with a distinct Fertilization is internal, leading to larval stages morphologically
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larval stage. different from adult sponges.
Classification as Acoelomates based on absence of Acoelomates like Porifera have no body cavity, and thus, they
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body cavity. are grouped in this classification.
Phylum Porifera characterized as primitive These organisms demonstrate cellular level organization, as
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multicellular animals. well as asymmetry and absence of a true body cavity.
Choanocytes line the spongocoel and canals in These cells play a role in the process of water transport and
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Porifera. feeding.
Water transport in sponges serves various The pathway helps in food gathering, respiratory exchange, and
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physiological functions. waste removal within these organisms.
Sponges reproduce both sexually and asexually. Reproduction occurs via fragmentation (asexual) and the
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formation of gametes (sexual).
35 Fertilization is internal in Porifera. Fertilization happens within the organism's body.
Sponges have hermaphroditic reproductive systems. Both eggs and sperms are produced by the same individual
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sponge.
4.2.2 Phylum - Coelenterata (Cnidaria)
Cnidarians possess cnidoblasts (cnidocytes) containing These cnidoblasts are used for anchorage, defense, and prey
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stinging nematocysts. capture.
Cnidarians exhibit two basic body forms: polyp Examples of polyps include Hydra and Adamsia, while Aurelia
38 (sessile and cylindrical) and medusa (umbrella-shaped and jellyfish are medusae.
and free-swimming).
Some cnidarians exhibit alternation of generation In these cnidarians, polyps produce medusae asexually, while
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(Metagenesis). medusae form polyps sexually (e.g., Obelia).
Examples of Cnidaria include Physalia, Adamsia, Physalia and Adamsia exhibit the polyp form, while Pennatula,
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Pennatula, Gorgonia, and Meandrina. Gorgonia, and Meandrina exhibit the medusa form.
Cnidarians exhibit tissue-level organization and are They possess a central gastrovascular cavity with a single
41 diploblastic. opening, perform both extracellular and intracellular digestion,
and some have calcium carbonate skeletons.
4.2.3 Phylum Ctenophora
Ctenophores possess eight external rows of ciliated These comb plates generate water currents for swimming,
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comb plates. enabling efficient locomotion in marine environments.
Ctenophores exhibit digestion that is both This dual digestive process allows them to break down food
43 extracellular and intracellular. particles outside their cells and within specialized internal
compartments, maximizing nutrient absorption.
Ctenophores reproduce only by sexual means with Fertilization occurs outside the body, followed by indirect
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external fertilization. development through larval stages.
Bioluminescence is well-marked in ctenophores. This ability to emit light might play roles in communication,
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attracting prey, or defense.
Ctenophores lack separate sexes and are considered They reproduce sexually with external fertilization and indirect
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hermaphrodites. development.
4.2.4 Phylum Platyhelminthes
Phylum Platyhelminthes have dorso-ventrally This flattened shape facilitates movement in narrow spaces
47 flattened bodies, hence are called flatworms. within their host organisms and contributes to their adaptation
to parasitic environments.
Phylum Platyhelminthes are mostly endoparasites Parasitic forms possess diverse tools for nutrient acquisition:
48 found in animals including human beings. hooks and suckers for attachment and direct absorption, and
even surface absorption in some species.
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