Chapter 10
Animalia
Section I: Multiple Choice Questions
Section 1: Multiple Choice Questions (MCQs)
1. Answer: B) Heterotrophs
2. Answer: C) Porifera
3. Answer: B) Nematode
4. Answer: A) Have shelled eggs
5. Answer: C) Ray-finned
6. Answer: A) Blastopore is associated with the anus
7. Answer: A) Sponges
8. Answer: D) All of the above
9. Answer: A) A spiny ribbon of tissues used for feeding in snails
10. Answer: C) Mantle
11. Answer: C) Arthropoda
12. Answer: D) Tracheal system
13. Answer: A) Function as a circulatory system that distributes nutrients to the
body cells
14. Answer: B) Nematoda - Roundworms, pseudocoelomate
15. Answer: D) An amniotic egg
16. Answer: B) Lay eggs
This concludes the MCQs for Section 1. Let me know when you'd like me to move
on to the short questions
Section II: Short Questions
1. Write distinct features of animals.
Animals are multicellular, eukaryotic organisms characterized by the absence of
cell walls, which allows flexibility and movement. They are heterotrophic, relying
on other organisms for food, and they exhibit diverse forms of locomotion.
Additionally, most animals have specialized tissues and organ systems, such as the
nervous and circulatory systems, enabling them to respond to stimuli and maintain
homeostasis.
2. Describe the body layers of sponges.
Sponges have two primary layers: the outer layer (pinacoderm), which consists of
flat cells (pinacocytes), and the inner layer (choanoderm), which contains
specialized cells called choanocytes responsible for water circulation and food
capture. Between these layers is a jelly-like matrix called mesohyl, which contains
amoebocytes that perform various functions like nutrient transport and
reproduction.
3. What are nematocysts?
Nematocysts are specialized stinging structures found in cnidarians like jellyfish
and hydras. These microscopic capsules contain coiled, thread-like tubes filled
with venom. Upon contact, the nematocyst ejects its thread to inject toxins into
prey or predators, aiding in defense and prey capture.
4. Give three features of platyhelminthes for parasitic mode of life.
Platyhelminthes (flatworms) have adaptations for parasitic life, such as a reduced
digestive system, relying on their hosts for nutrients. They have hooks and
suckers for attachment to host tissues. Additionally, their reproductive systems
are highly developed, enabling the production of a large number of eggs to
increase survival chances.
5. Give three distinguishing features of Aschelminthes.
Aschelminthes, or roundworms, possess a pseudocoelom that acts as a hydrostatic
skeleton. They have a complete digestive tract with a mouth and anus.
Additionally, their body is covered by a tough, non-cellular cuticle, which provides
protection and helps in maintaining shape.
6. How does locomotion take place in annelids?
Locomotion in annelids occurs through the coordinated contraction and relaxation
of circular and longitudinal muscles. Their segmented body is equipped with
bristle-like structures called setae, which grip the surface, enabling movement.
The hydrostatic skeleton provides further support for efficient locomotion.
7. Write five salient features of phylum Arthropoda.
Arthropods have segmented bodies divided into the head, thorax, and abdomen.
They possess a chitinous exoskeleton for protection and support. Their jointed
appendages allow diverse movements. They exhibit a well-developed nervous
system with sensory organs. Finally, they undergo metamorphosis during
development.
8. List any four harmful roles of insects.
Insects can act as vectors for diseases like malaria and dengue. They destroy
crops by feeding on plants, causing economic losses. Some insects infest stored
food, reducing its quality and usability. Additionally, certain species like termites
damage wooden structures and furniture.
9. List the similarities between echinoderms and chordates.
Echinoderms and chordates are both deuterostomes, with their embryonic
development showing radial cleavage and the anus forming from the blastopore.
Both possess an internal skeleton made of calcium-based structures. Additionally,
they share bilateral symmetry during their larval stages.
10. What does the term amphibian mean? Why are amphibians not considered a
very successful group of vertebrates?
The term "amphibian" means "double life," referring to their ability to live both
in water and on land. Amphibians are not highly successful vertebrates because
they depend on moist environments for survival and reproduction, making them
vulnerable to habitat changes and desiccation.
11. Describe the ways in which amphibians are adapted to life on land and why
they are still restricted to a watery or moist environment.
Amphibians are adapted to life on land through features like lungs for breathing
air, limbs for locomotion, and skin that can absorb oxygen. However, their skin
lacks a protective waterproof layer, making them prone to dehydration.
Additionally, amphibians rely on water bodies for reproduction as their eggs lack
protective shells and require moisture to develop.
12. List the adaptations that distinguish reptiles from amphibians and help them
adapt to life in dry terrestrial environments.
Reptiles have a scaly, keratinized skin that reduces water loss, and their eggs are
amniotic, allowing development in dry conditions. They possess efficient lungs for
breathing air and a more developed circulatory system, providing better oxygen
supply. These adaptations make reptiles well-suited to arid and terrestrial
habitats.
13. Give an example of ectothermic and endothermic animals.
Ectothermic animals, like reptiles (e.g., lizards), depend on external heat sources
to regulate their body temperature. Endothermic animals, such as mammals (e.g.,
humans), generate heat internally through metabolic processes, maintaining a
constant body temperature.
14. Name two phyla of animals that are radially symmetrical and two that are
bilaterally symmetrical.
Radially symmetrical animals belong to phyla Cnidaria (e.g., jellyfish) and
Echinodermata (e.g., starfish). Bilaterally symmetrical animals include phyla
Arthropoda (e.g., insects) and Chordata (e.g., mammals).
15. List the vertebrate classes in which we find each of the following:
A two-chambered heart: Found in fishes like sharks (Chondrichthyes).
The amniotic egg: Found in reptiles (e.g., lizards) and birds (e.g., chickens).
A four-chambered heart: Found in mammals (e.g., humans) and birds (e.g.,
pigeons).
Lungs supplemented by air sacs: Found in birds (e.g., ducks).
Placenta: Found in mammals (e.g., humans).
16. Write three main differences between Prototheria, Metatheria, and Eutheria.
Prototheria (e.g., platypus) lay eggs and lack a placenta. Metatheria (e.g.,
kangaroos) give birth to underdeveloped young that develop in pouches. Eutheria
(e.g., humans) give birth to fully developed young and have a complex placenta for
nurturing the embryo.
17. How do mammals differ from birds? What adaptations do they share?
Mammals differ from birds in having hair or fur instead of feathers and mammary
glands for feeding their young. However, both groups are endothermic and have
a four-chambered heart for efficient circulation. They also share adaptations like
specialized limbs for locomotion and keen sensory organs for survival.
18. Define/Describe/Explain briefly:
Diploblastic and Triploblastic animals: Diploblastic animals have two germ layers
(ectoderm and endoderm), e.g., Hydra. Triploblastic animals have three germ
layers (ectoderm, mesoderm, and endoderm), e.g., humans.
Radial and Bilateral symmetry: Radial symmetry (e.g., jellyfish) allows body parts
to be arranged around a central axis. Bilateral symmetry (e.g., mammals) divides
the body into identical left and right halves.
Nematocyst: Specialized stinging cells in cnidarians for capturing prey and
defense.
19. Write the difference between:
Acoelomate and Pseudocoelomate: Acoelomates (e.g., flatworms) lack a body
cavity, while pseudocoelomates (e.g., roundworms) have a body cavity not fully
lined with mesoderm.
Hydroids and Medusae: Hydroids (e.g., Hydra) are sessile, while medusae (e.g.,
jellyfish) are free-swimming.
Spongocoel and Gastrovascular cavity: Spongocoel is a central cavity in sponges,
while a gastrovascular cavity in cnidarians serves for digestion and circulation.
Section III: Extensive Answer Questions
A) Describe the characteristics economic importance and example of the
following.
(a) Sponges
General Characteristics: Sponges (phylum Porifera) are multicellular, sessile
aquatic animals with asymmetrical or radially symmetrical bodies. They lack true
tissues and organs but possess specialized cells such as choanocytes (collar cells)
for water filtration. Sponges have a porous body structure, supported by spicules
or spongin. Their reproduction is both sexual and asexual.
Economic Importance: Sponges are important for marine ecosystems as filter
feeders, maintaining water quality. Commercially, certain sponges (Euspongia) are
harvested for use as natural cleaning sponges.
Examples: Sycon, Euspongia, and Spongilla.
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(b) Cnidarians
General Characteristics: Cnidarians (phylum Cnidaria) are radially symmetrical,
diploblastic animals with a gastrovascular cavity. They possess specialized
stinging cells called nematocysts for capturing prey and defense. Cnidarians
exhibit two body forms: polyp (sessile) and medusa (free-swimming).
Economic Importance: Coral-forming cnidarians create coral reefs, vital for
marine biodiversity, coastal protection, and ecotourism. Jellyfish are used in
research and, in some cultures, as food.
Examples: Hydra, Aurelia (jellyfish), and Sea anemones.
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(c) Platyhelminthes
General Characteristics: Flatworms (phylum Platyhelminthes) are bilaterally
symmetrical, triploblastic, and acoelomate animals. They possess an incomplete
digestive system and show organ-level organization. Most flatworms are parasitic,
but some are free-living.
Economic Importance: Parasitic species like tapeworms and liver flukes cause
diseases in humans and livestock, leading to economic losses. Free-living
flatworms, such as Planaria, are studied for regeneration research.
Examples: Taenia (tapeworm), Fasciola (liver fluke), and Planaria.
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(d) Aschelminthes (Nematodes)
General Characteristics: Roundworms (phylum Nematoda) are unsegmented,
bilaterally symmetrical, triploblastic pseudocoelomates. They possess a complete
digestive system and exhibit sexual reproduction.
Economic Importance: Many nematodes are agricultural pests that damage crops,
while others, like Ascaris and Wuchereria, are parasitic to humans. Beneficial
nematodes are used for biological pest control.
Examples: Ascaris (intestinal parasite), Wuchereria (causes elephantiasis), and C.
elegans (a model organism in genetics).
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(e) Molluscs
General Characteristics: Molluscs (phylum Mollusca) are soft-bodied, coelomate
animals with a calcareous shell (in most species). They have a muscular foot for
movement, a visceral mass containing organs, and a mantle that secretes the shell.
Molluscs exhibit bilateral symmetry and a well-developed circulatory system.
Economic Importance: Molluscs provide food (oysters, clams) and pearls. Shells
are used in jewelry, and some molluscs are pests in agriculture.
Examples: Pila (apple snail), Mytilus (mussel), and Octopus.
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(f) Annelids
General Characteristics: Annelids (phylum Annelida) are segmented, bilaterally
symmetrical, coelomate animals. They have a closed circulatory system and
specialized structures like setae for locomotion. Annelids reproduce sexually,
with some species being hermaphroditic.
Economic Importance: Earthworms enrich soil fertility, while leeches (Hirudo
medicinalis) are used in medicine for bloodletting and wound healing.
Examples: Lumbricus (earthworm), Hirudo (leech), and Nereis (marine worm).
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(g) Arthropods
General Characteristics: Arthropods (phylum Arthropoda) are bilaterally
symmetrical, segmented animals with a chitinous exoskeleton and jointed
appendages. They undergo molting for growth and have highly specialized body
systems.
Economic Importance: Arthropods include pollinators like bees, pests like locusts,
and vectors of diseases like mosquitoes. Crustaceans like crabs and prawns are
economically significant as food.
Examples: Apis (honeybee), Anopheles (mosquito), and Penaeus (prawn).
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(h) Echinoderms
General Characteristics: Echinoderms (phylum Echinodermata) are radially
symmetrical, coelomate marine animals with a calcareous endoskeleton and water
vascular system for locomotion. They exhibit remarkable regeneration ability.
Economic Importance: Echinoderms like sea cucumbers are consumed as
delicacies, while others contribute to coral reef ecosystems.
Examples: Asterias (starfish), Holothuria (sea cucumber), and Echinus (sea
urchin).
B) Describe the general characteristics evolutionary adaptation and give
examples of the following classes
(a) Chondrichthyes (Cartilaginous Fishes)
General Characteristics: Members of class Chondrichthyes are marine animals
with a cartilaginous skeleton and paired fins. Their body is covered with placoid
scales, and they lack a swim bladder, relying on oil-filled livers for buoyancy.
Respiration occurs through gills.
Evolutionary Adaptations: Chondrichthyes exhibit streamlined bodies for
efficient swimming, electroreception (via ampullae of Lorenzini), and powerful
jaws with replaceable teeth for capturing prey. They also have internal
fertilization.
Examples: Sharks (Squalus), rays (Dasyatis), and skates (Raja).
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(b) Osteichthyes (Bony Fishes)
General Characteristics: Osteichthyes have a bony endoskeleton and scales
covering their body. They possess gills protected by an operculum and a swim
bladder for buoyancy. These fishes are ectothermic.
Evolutionary Adaptations: They show adaptive radiation, with diverse forms
suited to different aquatic environments. The swim bladder aids in buoyancy
control, and fins provide efficient locomotion.
Examples: Labeo (Rohu), Hippocampus (seahorse), and Clarias (catfish).
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(c) Amphibia
General Characteristics: Amphibians are cold-blooded vertebrates that live both
in water and on land. They have moist, glandular skin for cutaneous respiration,
and their larvae undergo metamorphosis into adults.
Evolutionary Adaptations: Amphibians developed lungs and limbs for terrestrial
life, while retaining aquatic breeding habits. Their moist skin aids in gas exchange,
and their vocal sacs are adapted for communication.
Examples: Frogs (Rana), toads (Bufo), and salamanders (Ambystoma).
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(d) Reptilia
General Characteristics: Reptiles are ectothermic vertebrates with dry, scaly
skin that prevents water loss. They have a three-chambered heart (except
crocodiles), and their eggs are covered with a leathery shell.
Evolutionary Adaptations: Reptiles are adapted for terrestrial life with amniotic
eggs, claws for movement and defense, and well-developed lungs for respiration.
Their scales provide protection against predators and desiccation.
Examples: Lizards (Hemidactylus), snakes (Naja), and crocodiles (Crocodylus).
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(e) Aves (Birds)
General Characteristics: Aves are warm-blooded vertebrates with feathers, a
beak, and lightweight hollow bones. They have a four-chambered heart and lay
hard-shelled eggs. Birds are highly adapted for flight.
Evolutionary Adaptations: Feathers provide insulation and enable flight. Their
wings, supported by strong muscles, and a unique respiratory system with air sacs
enhance flight efficiency. Beaks and claws are adapted for diverse feeding habits.
Examples: Columba (pigeon), Corvus (crow), and Psittacus (parrot).
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(f) Mammalia
C) Describe the characteristics and give the examples of sub-class.
General Characteristics: Mammals are warm-blooded vertebrates with hair or
fur. They possess mammary glands for feeding young, and most give birth to live
young (viviparous). Mammals have a four-chambered heart and highly developed
brains.
Evolutionary Adaptations: Mammals are highly adaptive, inhabiting diverse
habitats. Their body coverings (fur or blubber) regulate temperature, and
specialized teeth cater to varied diets. Parental care is advanced in mammals.
Examples: Humans (Homo sapiens), bats (Pteropus), and whales (Balaenoptera).
(a) Prototheria (Monotremes)
Characteristics:
Prototherians are egg-laying mammals (oviparous) with leathery shells. They
possess mammary glands but lack nipples; milk is secreted through specialized
ducts on the skin. They have a cloaca for excretion and reproduction, similar to
reptiles. Prototherians lack external ears and are found in restricted habitats.
Evolutionary Adaptations:
These mammals bridge the evolutionary gap between reptiles and mammals,
retaining primitive traits like egg-laying while having mammalian features like fur
and milk secretion. They are adapted to specific ecological niches, using
electroreceptors on their snouts to detect prey.
Examples: The platypus (Ornithorhynchus anatinus) and echidnas (Tachyglossus).
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(b) Metatheria (Marsupials)
Characteristics:
Metatherians give birth to underdeveloped young that complete development in
an external pouch (marsupium) attached to their mothers. They possess a
bifurcated reproductive system and lack a true placenta. Their offspring latch
onto nipples in the marsupium for nourishment.
Evolutionary Adaptations:
Metatherians are highly adapted for survival in diverse habitats, from deserts to
forests. The marsupium provides a safe environment for the offspring, and their
claws aid in climbing or digging, depending on their ecological roles.
Examples: Kangaroos (Macropus), opossums (Didelphis), and koalas
(Phascolarctos).
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(c) Eutheria (Placental Mammals)
Characteristics:
Eutherians are viviparous mammals with a highly developed placenta that
facilitates nutrient exchange between mother and fetus. They have prolonged
gestation periods, and offspring are well-developed at birth. Eutherians exhibit
significant diversity in size, behavior, and ecological roles.
Evolutionary Adaptations:
Placental mammals dominate diverse habitats globally, exhibiting specialized
features like long limbs for running (ungulates), wings for flying (bats), and
aquatic adaptations (whales). They also have advanced sensory organs and
cognitive abilities for survival.
Examples: Humans (Homo sapiens), elephants (Elephas), and dolphins (Delphinus).
D ) Arthopods and Vertebrates are highly successful group of animals on land.
What are the characteristics shared by arthopods and Vertebrates are
adaptive to a land excercise.
(a) Fishes
Adaptations:
Fishes have numerous adaptations for aquatic life. They possess gills for
extracting oxygen from water, a streamlined body for reducing water resistance,
and fins for stability and propulsion. Their skin is covered with scales, which
provide protection and reduce friction. Most fishes have a lateral line system for
detecting vibrations in the water. Additionally, bony fishes possess a swim
bladder for buoyancy control.
Examples: Cartilaginous fishes like sharks (Squalus) rely on oil-filled livers for
buoyancy, while bony fishes like rohu (Labeo) use a swim bladder for the same
purpose. Seahorses (Hippocampus) exhibit prehensile tails for anchoring
themselves to seaweed.
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(b) Amphibians
Adaptations:
Amphibians exhibit dual adaptations for both aquatic and terrestrial life. Their
larvae, such as tadpoles, are fully aquatic and possess gills for respiration. Adults
develop lungs and use moist skin for cutaneous respiration in water and on land.
Amphibians have webbed feet, which aid in swimming, and a lateral line system to
detect water currents.
Examples: Frogs (Rana) use powerful hind limbs for swimming, and toads (Bufo)
rely on their ability to absorb water through their skin. Salamanders
(Ambystoma) exhibit both gills and lungs, depending on their life stage.
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(c) Reptiles
Adaptations:
Some reptiles, such as marine turtles, have adaptations for aquatic life, including
paddle-like limbs for swimming and the ability to hold their breath for extended
periods. Their nostrils and eyes are positioned on top of the head, enabling them
to breathe and see while submerged. Salt glands in marine reptiles excrete
excess salt ingested during feeding.
Examples: Crocodiles (Crocodylus) have powerful tails for swimming, while sea
snakes (Hydrophis) are equipped with flattened tails for propulsion. Marine
turtles (Chelonia) return to land only for egg-laying.
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(d) Mammals
Adaptations:
Aquatic mammals like whales and dolphins have streamlined bodies to reduce drag
in water. They possess blubber for insulation in cold waters and can hold their
breath for extended periods due to specialized respiratory systems. Their
forelimbs are modified into flippers for swimming, and their tails have horizontal
flukes for propulsion.
Examples: Dolphins (Delphinus) are highly agile swimmers with echolocation
abilities. Whales (Balaenoptera) have large lungs for deep dives, while seals
(Phoca) have flexible spines for efficient movement in water.
