Chapter 10: Animalia

Select the correct answer:

1. All animals are

A) autotrophs

B) heterotrophs

C) unicellular

D) motile

Answer: B) heterotrophs

Explanation: All animals are heterotrophic, meaning they obtain their energy and nutrients by consuming other organisms, as they cannot produce their own food.

2. Sponges belong to the phylum.

A) aschelminthes

B) arthropoda

C) porifera

D) mollusca

Answer: C) porifera

Explanation: Sponges are simple, multicellular animals belonging to the phylum Porifera, characterized by having pores and canal systems for water flow.

3. Which of the following is not a parasite

A) annelida

B) nematode

C) platyhelminthes

D) porifera

Answer: A) annelida

Explanation: While some annelids are parasitic, the phylum Annelida is primarily composed of free-living segmented worms (like earthworms), unlike Nematoda and Platyhelminthes which have many parasitic members.

4. Reptiles are much more extensively adapted to life on land than amphibians in that reptiles

A) have shelled eggs

B) have a complete digestive tract

C) are endothermic

D) go through the larva stage

Answer: A) have shelled eggs

Explanation: The amniotic (shelled) egg is a key adaptation that allows reptiles to reproduce on land, preventing the embryo from drying out, unlike amphibians which require water for reproduction.

5. Amphibians arose from

A) cartilaginous fish

B) jawless fish

C) ray finned

D) bony fishes with lungs

Answer: D) bony fishes with lungs

Explanation: Evolutionary evidence suggests that amphibians evolved from lobe-finned bony fishes that possessed primitive lungs, allowing them to survive in shallow, oxygen-poor waters.

6. Which of these does not pertain to a deuterostome?

A) blastopore is associated with the anus

B) spiral cleavage

C) enterocoelom

D) echinoderms and chordates

Answer: B) spiral cleavage

Explanation: Deuterostomes are characterized by radial cleavage, while protostomes exhibit spiral cleavage. The other options (anus from blastopore, enterocoelom, echinoderms/chordates) are deuterostome characteristics.

7. Which of the following has a gastrovascular cavity?

A) sponges

B) earthworms

C) roundworms

D) flatworms

Answer: D) flatworms

Explanation: Flatworms (Platyhelminthes) have a gastrovascular cavity with a single opening that serves as both mouth and anus, for digestion and distribution of nutrients.

8. Which of the following animals have radial symmetry?

A) Jellyfish

B) Sea star

C) Sea anemone

D) All of the above

Answer: D) All of the above

Explanation: Jellyfish, sea stars, and sea anemones all exhibit radial symmetry, meaning their body parts are arranged around a central axis.

9. What is a radula?

A) A spiny ribbon of tissues used for feeding in snails

B) A gas exchange structure in insects

C) A supportive rod on the dorsal surface of chordates

D) A stinging cell used by sea anemones to capture prey

Answer: A) A spiny ribbon of tissues used for feeding in snails

Explanation: The radula is a unique feeding organ found in most mollusks (except bivalves), used for scraping or cutting food.

10. A land snail, a clam, and an octopus all share

A) gills

B) embryonic torsion

C) mantle

D) radula

Answer: C) mantle

Explanation: All mollusks possess a mantle, a fold of tissue that secretes the shell (if present) and encloses the visceral mass.

11. Which phylum is characterized by animals that have a segmented body?

A) cnidaria

B) porifera

C) arthropoda

D) mollusca

Answer: C) arthropoda

Explanation: Arthropods are characterized by a segmented body, jointed appendages, and a chitinous exoskeleton.

12. Which of the following characteristics is probably most responsible for the incredible diversification of insects on land?

A) Flight

B) Segmentation

C) Tracheal system

D) Bilateral symmetry

Answer: A) Flight

Explanation: The ability to fly allowed insects to escape predators, find new food sources, and disperse to new habitats, contributing significantly to their diversification.

13. The water vascular system of echinoderms

A) Functions as a circulatory system that distributes nutrients to the body cells.

B) Functions in locomotion, feeding and gas exchange.

C) Is bilateral in organization, even though the adult animal has radial anatomy.

D) Is analogous to gastrovascular cavity of flatworms

Answer: B) Functions in locomotion, feeding and gas exchange.

Explanation: The water vascular system is a unique feature of echinoderms, used for movement (tube feet), feeding, and gas exchange.

14. Which of the following combinations of phylum and description is correct?

A) Echinodermata- bilateral and radial symmetry, coelom from archenteron

B) Nematoda- roundworms, pseudocoelomate

C) Cnidaria- radial symmetry, polyp medusa body forms

D) Porifera- gastrovascular cavity, coelom

Answer: C) Cnidaria- radial symmetry, polyp medusa body forms

Explanation: Cnidarians exhibit radial symmetry and can exist in two body forms: the sessile polyp and the motile medusa.

15. Mammal and living birds share all of the following characteristics except:

A) endothermy

B) a hole behind the eye socket on each side of the skull

C) a dorsal hollow nerve cord

D) an amniotic egg

Answer: B) a hole behind the eye socket on each side of the skull

Explanation: While mammals have a single hole (fenestra) behind the eye socket, birds (diapsids) have two holes. Both share endothermy, a dorsal hollow nerve cord, and an amniotic egg.

16. Unlike eutherians, both monotremes and marsupials

A) have some embryonic development outside the mother's uterus

B) lay eggs

C) lack nipples

D) are found in Australia and Africa

Answer: A) have some embryonic development outside the mother's uterus

Explanation: Monotremes lay eggs, and marsupials give birth to very undeveloped young that complete development in a pouch. Eutherians (placental mammals) have prolonged internal development.

1. Write distinct features of animals.

Answer: Animals are multicellular, eukaryotic organisms that are heterotrophic, meaning they obtain their energy by consuming other organisms. They lack cell walls and chlorophyll. Most animals are motile at some stage of their life cycle. They have specialized tissues, organs, and organ systems. They reproduce sexually, with a diploid stage dominating the life cycle. They develop from a blastula and have a characteristic embryonic development. They are diverse in form, size, and habitat.

2. Describe the body layers of sponges.

Answer: Sponges (phylum Porifera) have a simple body structure with two main cell layers: the outer pinacoderm (made of pinacocytes) and the inner choanoderm (made of choanocytes or collar cells). Between these two layers is a gelatinous, non- cellular layer called the mesohyl, which contains amoebocytes and skeletal elements (spicules or spongin). The body is perforated by numerous pores (ostia) that lead to a central cavity (spongocoel) and out through a large opening (osculum). They lack true tissues and organs.

3. What are nematocysts?

Answer: Nematocysts are specialized stinging cells found in cnidarians (jellyfish, sea anemones, corals). They are located within specialized cells called cnidocytes. Each nematocyst is a capsule containing a coiled, hollow thread. When triggered by touch or chemical stimuli, the thread everts rapidly, injecting toxins into prey or predators. They are used for capturing prey, defense, and adhesion. Nematocysts are a defining characteristic of the phylum Cnidaria.

4. Give three features of platyhelminthes for parasitic mode of life.

Answer: Three features of platyhelminthes (flatworms) for a parasitic mode of life are:

1. Suckers and Hooks: They possess suckers and hooks for attachment to the host's tissues.

2. Loss of Digestive System: Many parasitic flatworms (like tapeworms) lack a digestive system and absorb pre-digested nutrients directly from the host's intestine.

3. Thick Cuticle: They have a protective outer covering (tegument) that resists the host's digestive enzymes and immune responses.

4. High Reproductive Capacity: They produce large numbers of eggs to ensure transmission to new hosts.

5. Give three distinguishing features of Aschelminthes.

Answer: Three distinguishing features of Aschelminthes (Nematodes/roundworms) are:

1. Pseudocoelom: They have a body cavity (pseudocoelom) that is not completely lined by mesoderm.

2. Round, Unsegmented Body: They have a cylindrical, unsegmented body with bilateral symmetry.

3. Complete Digestive Tract: They have a complete digestive system with a mouth and an anus.

4. Cuticle: They have a tough, non-cellular cuticle that is molted as they grow.

6. How locomotion takes place in Annelids?

Answer: Locomotion in annelids (segmented worms) occurs through the coordinated action of circular and longitudinal muscles in each segment, working against a hydrostatic skeleton. The coelomic fluid provides turgor pressure. Circular muscles contract to elongate the segment, while longitudinal muscles contract to shorten and widen it. This peristaltic wave of contraction and relaxation moves the worm forward. Chaetae (bristles) provide grip on the substrate. In earthworms, this results in crawling; in leeches, it involves looping movements.

7. Write five salient features of phylum Arthropoda.

Answer: Five salient features of phylum Arthropoda are:

1. Segmented Body: The body is segmented and divided into regions (head, thorax, abdomen).

2. Jointed Appendages: They possess jointed appendages, which are modified for various functions (walking, swimming, feeding, sensory).

3. Exoskeleton: They have a chitinous exoskeleton that provides protection and support, and is molted periodically (ecdysis).

4. Bilateral Symmetry: They exhibit bilateral symmetry.

5. Open Circulatory System: They have an open circulatory system with a dorsal heart and hemocoel.

8. List any four harmful roles of insects.

Answer: Four harmful roles of insects are:

1. Disease Vectors: Mosquitoes transmit malaria, dengue, and yellow fever; fleas transmit plague; tsetse flies transmit sleeping sickness.

2. Crop Pests: Locusts, aphids, and bollworms destroy crops, reducing agricultural yield.

3. Stored Product Pests: Weevils and moths damage stored grains and food products.

4. Property Damage: Termites destroy wood and wooden structures.

5. Parasites: Lice, fleas, and bedbugs are ectoparasites that cause irritation and transmit diseases.

9. List the similarities between echinoderms and chordates.

Answer: Echinoderms and chordates share several similarities based on their embryonic development:

1. Deuterostome Development: In both, the blastopore develops into the anus (deuterostome condition).

2. Radial Cleavage: The early embryonic cleavage is radial and indeterminate.

3. Enterocoely: The coelom forms from outpocketings of the archenteron (enterocoelom).

4. Mesodermal Origin: The mesoderm arises from the archenteron. These similarities suggest a close evolutionary relationship between echinoderms and chordates.

10. What does the term amphibian mean? Why amphibians are not considered a very successful group of vertebrates?

Answer: The term "amphibian" means "both lives," referring to their dual life cycle: an aquatic larval stage (tadpole) and a terrestrial adult stage. Amphibians are not considered a very successful group of vertebrates because they are still dependent on water for reproduction (their eggs lack shells and dry out on land). Their skin is moist and permeable, making them susceptible to desiccation and pollution. They are ectothermic, so they are limited by temperature. They have not diversified as widely as reptiles, birds, or mammals.

11. Describe the ways, which amphibians are adapted to life on land, and in what ways they are still restricted to a watery or moist environment.

Answer:

Adaptations to Land: Lungs for breathing air; limbs for walking on land; moist skin for cutaneous respiration; eyelids

and tear glands to protect eyes; a more developed nervous system. Restrictions to Water/Moist Environment: Their eggs lack a shell and must be laid in water or moist places; their skin is permeable and loses water rapidly; fertilization is external in most species and requires water; larvae are aquatic and have gills. These restrictions tie amphibians to moist environments.

12. List the adaptations that distinguish reptiles from amphibians and help them adapt to life in dry terrestrial environment.

Answer: Adaptations that distinguish reptiles from amphibians include:

1. Amniotic Egg: A shelled egg that protects the embryo from drying out, allowing reproduction on land.

2. Dry, Scaly Skin: Keratinized scales prevent water loss.

3. Internal Fertilization: Sperm is deposited inside the female's body, eliminating the need for water for fertilization.

4. Efficient Lungs: Better developed lungs for breathing air.

5. Excretion: They excrete uric acid (semi-solid) to conserve water.

6. Strong Limbs: Limbs are positioned to support the body on land.

13. Give an example of ectothermic and endothermic animals.

Answer:

Ectothermic: Animals that rely on external sources for body heat (e.g., reptiles like lizards, amphibians like frogs, fish, and most invertebrates). Endothermic: Animals that generate their own body heat internally (e.g., birds and mammals like humans, dogs, and eagles).

14. Name two phyla of animals that are radially symmetrical and two that are bilaterally, symmetrical.

Answer:

Radially Symmetrical: Cnidaria (e.g., jellyfish) and Echinodermata (adults, e.g., sea stars). Bilaterally Symmetrical: Arthropoda (e.g., insects) and Chordata (e.g., mammals).

15. List the vertebrate class (or classes) in which we find each of the following:

(a) A two-chambered heart

Answer: Fish (Osteichthyes and Chondrichthyes)

(b) The amniotic egg

Answer: Reptilia, Aves, Mammalia

(c) A four chambered heart

Answer: Aves, Mammalia (and some Reptilia like crocodiles)

(d) Lungs supplemented by air sacs

Answer: Aves (e) Placenta

Answer: Mammalia (Eutheria)

16. Write three main differences between prototheria, metatheria and eutheria.

Answer:

17. How do mammals differ from birds? And what adaptations do they share?

Answer:

Differences: Mammals have hair/fur, mammary glands, and a diaphragm; birds have feathers, beaks, and no diaphragm. Mammals have a four-chambered heart; birds also have a four-chambered heart. Mammals are viviparous (mostly); birds are oviparous. Mammals have teeth; birds have beaks. Shared Adaptations: Both are endothermic (warm-blooded), have a four-chambered heart, are amniotes, and have efficient respiratory systems. Both have a high metabolic rate.

18. Define/Describe/Explain briefly:

Answer:

animals: Multicellular, heterotrophic eukaryotes. diploblastic animals: Animals with two germ layers (ectoderm and endoderm), e.g., Cnidarians. triploblastic animals: Animals with three germ layers (ectoderm, mesoderm, endoderm), e.g., most animals. radial symmetry: Body parts arranged around a central axis, e.g., jellyfish.

bilateral symmetry: Body can be divided into two mirror-image halves along one plane, e.g., insects. coelom: A true body cavity completely lined by mesoderm. nematocyst: Stinging cell in cnidarians. mesoglea: Jelly-like layer between ectoderm and endoderm in cnidarians. zooId: Individual polyp in a colonial cnidarian. radula: Feeding organ in mollusks. trochophore larva: Free-swimming larval stage of some mollusks and annelids. parapodia: Paired, unjointed appendages in polychaete annelids. haemocoel: The blood cavity in arthropods and mollusks (open circulatory system). metamorphosis: Change in body form during development (e.g., caterpillar to butterfly). water vascular system: Network of canals in echinoderms for locomotion and feeding. notochord: Flexible rod on the dorsal side of chordates. swim bladder: Gas-filled sac in bony fish for buoyancy. ammion: Membrane that surrounds the embryo in amniotes. placenta: Organ in eutherian mammals for exchange between mother and fetus.

19. Write the difference between:

(a) diploblastic and triploblastic animals

Answer: Diploblastic animals have two germ layers (ectoderm, endoderm); triploblastic have three (ectoderm, mesoderm, endoderm).

(b) radial symmetry and bilateral symmetry

Answer: Radial symmetry: body parts arranged around a central axis. Bilateral symmetry: body has a left and right half that are mirror images.

(c) acoelomate and pseudocoelomate

Answer: Acoelomate: no body cavity. Pseudocoelomate: a body cavity not completely lined by mesoderm.

(d) pinacoderm and choanoderm

Answer: Pinacoderm is the outer layer of sponge cells (pinacocytes). Choanoderm is the inner layer of flagellated collar cells (choanocytes). (e) spongocoel and gastrovascular cavity

Answer: Spongocoel is the central cavity of sponges. Gastrovascular cavity is the digestive cavity of cnidarians and flatworms. (f) hydroids and medusa

Answer: Hydroid is the sessile polyp form; medusa is the free-swimming jellyfish form. (g) endotherm and ectotherm

Answer: Endotherms generate their own body heat; ectotherms rely on external heat sources.

1. Describe the general characteristics, economic importance and examples of the following: (a) Sponges (b) Cnidarians (c) Platyhelminthes (d) Aschelminthes (Nematodes) (e) Molluscs (f) Annelids (g) Arthropods (h) Echinoderms

Answer:

(a) Sponges (Porifera):

Characteristics: Simple, multicellular, sessile aquatic animals. They lack true tissues and organs. Body has pores (ostia) and a central cavity (spongocoel). They have choanocytes for water flow and filter feeding. Skeleton made of spicules or spongin. Economic Importance: Used as bath sponges; source of bioactive compounds for medicine. Examples: Sycon, Spongilla, Euplectella.

(b) Cnidarians:

Characteristics: Radially symmetrical, diploblastic, aquatic animals. They have a gastrovascular cavity with a single opening. They possess stinging cells (cnidocytes) with nematocysts. Two body forms: polyp and medusa.

Economic Importance: Source of jewelry (corals); reef formation; some are toxic; used in research. Examples: Jellyfish, sea anemones, corals, Hydra.

(c) Platyhelminthes:

Characteristics: Flatworms; bilaterally symmetrical, triploblastic, acoelomate. They have a gastrovascular cavity with one opening. Many are parasitic. Economic Importance: Parasites cause diseases (e.g., schistosomiasis, tapeworm infections). Some are free-living. Examples: Planaria, Taenia (tapeworm), Fasciola (liver fluke).

(d) Aschelminthes (Nematodes):

Characteristics: Roundworms; bilaterally symmetrical, triploblastic, pseudocoelomate. They have a complete digestive tract. Body is covered by a tough cuticle. Economic Importance: Parasites cause diseases (e.g., ascariasis, filariasis). Some are beneficial (decomposers, insect pathogens). Examples: Ascaris, Wuchereria, Caenorhabditis elegans.

(e) Molluscs:

Characteristics: Soft-bodied, bilaterally symmetrical (mostly), triploblastic, coelomate. They have a mantle, a muscular foot, and a visceral mass. Many have a shell. They have a radula (except bivalves). Economic Importance: Food (oysters, clams, squid); pearls; sources of shell and dyes; pests. Examples: Snails, clams, octopus, squid.

(f) Annelids:

Characteristics: Segmented worms; bilaterally symmetrical, triploblastic, coelomate. They have a true coelom and a closed circulatory system. They have chaetae for locomotion. Economic Importance: Earthworms improve soil fertility; leeches used in medicine; some are pests. Examples: Earthworm, leech, Nereis.

(g) Arthropods:

Characteristics: Largest phylum; segmented body, jointed appendages, chitinous exoskeleton. They have an open circulatory system and bilateral symmetry. Economic Importance: Pollinators, food (crustaceans), silk production, disease vectors, pests. Examples: Insects, spiders, crabs, centipedes.

(h) Echinoderms:

Characteristics: Marine animals with radial symmetry (adults) and bilateral symmetry (larvae). They have a water vascular system, tube feet, and an endoskeleton of ossicles. Economic Importance: Food (sea cucumbers, sea urchins); research; some are pests of shellfish beds. Examples: Sea star, sea urchin, sea cucumber.

2. Describe the general characteristics, evolutionary adaptations and give examples of the following classes: (a) Chondrichthyes (b) Osteichthyes (c) Amphibia (d) Reptilia (e) Aves (f) Mammalia

Answer:

(a) Chondrichthyes (Cartilaginous Fish):

Characteristics: Skeleton made of cartilage; jaws; paired fins; placoid scales; gill slits; no swim bladder; internal fertilization. Adaptations: Efficient predators; electroreception; oil in liver for buoyancy. Examples: Sharks, rays, skates.

(b) Osteichthyes (Bony Fish):

Characteristics: Skeleton made of bone; jaws; paired fins; cycloid/ctenoid scales; gills covered by operculum; swim bladder present.

Adaptations: Swim bladder for buoyancy; efficient gills; lateral line system. Examples: Salmon, trout, tuna, eels.

(c) Amphibia:

Characteristics: Ectothermic; moist, glandular skin; lungs and cutaneous respiration; three-chambered heart; external fertilization (mostly); aquatic larvae. Adaptations: Limbs for walking; lungs for air breathing; eyelids. Examples: Frogs, toads, salamanders, caecilians.

(d) Reptilia:

Characteristics: Ectothermic; dry, scaly skin; lungs; three-chambered heart (four in crocodiles); internal fertilization; amniotic egg. Adaptations: Amniotic egg; keratinized scales; efficient water conservation (uric acid). Examples: Lizards, snakes, turtles, crocodiles.

(e) Aves (Birds):

Characteristics: Endothermic; feathers; beak; wings; four-chambered heart; air sacs; amniotic egg; oviparous. Adaptations: Flight (hollow bones, air sacs, wings); endothermy; efficient respiration. Examples: Eagle, sparrow, ostrich, penguin.

(f) Mammalia:

Characteristics: Endothermic; hair/fur; mammary glands; diaphragm; four-chambered heart; internal fertilization; viviparous (mostly). Adaptations: Mammary glands for nursing young; hair for insulation; differentiated teeth; large brain. Examples: Humans, whales, bats, kangaroos.

3. Describe the characteristics and give examples of subclass: (a) Prototheria (b) Metatheria (c) Eutheria

Answer:

(a) Prototheria (Monotremes):

Characteristics: Egg-laying mammals. They have a cloaca (single opening for digestive, reproductive, and urinary tracts). They lack nipples; young lick milk from mammary glands. They have a reptilian-like shoulder girdle. Examples: Platypus, Echidna (spiny anteater). Distribution: Australia and New Guinea.

(b) Metatheria (Marsupials):

Characteristics: Give birth to very undeveloped young that complete development in a pouch (marsupium) on the mother's abdomen. They have a short gestation period. The young attach to a nipple inside the pouch. Examples: Kangaroo, Koala, Opossum, Wombat. Distribution: Mostly Australia, some in the Americas.

(c) Eutheria (Placental Mammals):

Characteristics: Give birth to relatively developed young. The fetus develops in the uterus and is nourished via a placenta. They have a longer gestation period. They lack a pouch. Examples: Humans, dogs, whales, bats, elephants. Distribution: Worldwide.

In summary, Prototheria lay eggs, Metatheria have pouches, and Eutheria have placentas. These reproductive strategies reflect different evolutionary adaptations to their environments.

4. Arthropods and vertebrates are highly successful groups of animals on land. What characteristics shared by arthropods and vertebrates are adaptive to a land existence?

Answer: Arthropods and vertebrates are both highly successful on land due to several shared adaptive characteristics, despite their different evolutionary origins.

1. Efficient Respiratory Systems:

Arthropods use tracheae (insects) or book lungs (spiders) to breathe air directly. Vertebrates use lungs to breathe air. Both systems allow for efficient gas exchange in a terrestrial environment.

2. Water Conservation:

Arthropods have a waxy cuticle on their exoskeleton to prevent water loss. Vertebrates have keratinized skin (scales, feathers, hair) to prevent desiccation. Both groups excrete nitrogenous waste in concentrated forms (uric acid in insects/birds/reptiles) to conserve water.

3. Support and Locomotion:

Arthropods have a rigid exoskeleton and jointed appendages for support and movement on land. Vertebrates have an endoskeleton and strong limbs for support and movement. Both allow for efficient locomotion without the buoyancy of water.

4. Internal Fertilization:

Both groups (mostly) use internal fertilization, which protects gametes from drying out. They produce amniotic eggs (in reptiles, birds, mammals) or shelled eggs (in insects) that protect the embryo from desiccation.

5. Nervous System and Sensory Organs:

Both have well-developed nervous systems and sensory organs (eyes, antennae, etc.) adapted for life on land.

6. Excretion:

Both have efficient excretory systems (Malpighian tubules in insects, kidneys in vertebrates) to conserve water and remove waste.

In summary, arthropods and vertebrates share adaptations for respiration, water conservation, support, locomotion, reproduction, and excretion that have enabled them to thrive on land. These adaptations are examples of convergent evolution.