Unit 10: Kingdom Animalia, a cornerstone of your first-year Biology journey. In this chapter of exploration, we delve into the mesmerizing diversity of the animal kingdom, uncovering the intricate web of life that encompasses everything from the tiniest microorganisms to the grandeur of complex multicellular organisms.
These meticulously crafted notes are your passport to unraveling the myriad forms, functions, and classifications of the captivating creatures that share our planet. Join us as we embark on a voyage through the rich tapestry of animal life, revealing the remarkable adaptations and evolutionary wonders that have shaped the captivating inhabitants of Kingdom Animalia.
Unit 10 Biology of 1st Year Short Answers Questions
What does the term “Animalia” mean in Latin?
The term “Animalia” is derived from Latin, where “anima” refers to breath or soul.
How were multicellular animals distinguished from one-celled animals in traditional two-kingdom systems?
In traditional two-kingdom systems, multicellular animals were referred to as Metazoa, while one-celled animals were called Protozoa.
What is the main characteristic that defines animals in the kingdom Animalia?
Animals in the kingdom Animalia are multicellular, diploid eukaryotic organisms, and they are ingestive heterotrophs. They develop from two dissimilar haploid gametes: a larger egg and a smaller sperm.
- 1st Year Biology Unit No.1 Introduction Notes
- 1st Year Biology Unit No. 2 Biological Molecules Notes
- 1st Year Biology Unit No. 3 Enzymes Notes
- 1st Year Biology Unit No. 4 The Cell Notes
- 1st Year Biology Unit No. 5 Variety of Life Notes
Which classification system for kingdoms is followed?
The five-kingdom classification system introduced by Robert Whittaker.
Which group of animals lacks tissues organized into organs and has an indeterminate shape?
The animals belonging to the subkingdom Parazoa (phylum Porifera) lack tissues organized into organs and have an indeterminate shape.
What distinguishes animals in the subkingdom Eumetazoa from those in the subkingdom Parazoa?
Animals in the subkingdom Eumetazoa have tissues organized into organs and organ systems, whereas those in the subkingdom Parazoa lack this organization.
How are animals in the subkingdom Eumetazoa further categorized based on symmetry?
Animals in the subkingdom Eumetazoa are categorized into radially symmetrical animals (grade Radiata) and bilaterally symmetrical animals (grade Bilateria).
What are the three groups of animals in the subkingdom Eumetazoa based on the type of body cavity?
The three groups of animals in the subkingdom Eumetazoa are Acoelomata (no body cavity), Pseudocoelomata (pseudocoele), and Coelomata (true coelom).
What is the significance of multicellularity in animals’ development?
Multicellularity in animals has evolved impressively, with cells joined by complex junctions that facilitate communication and material flow between cells.
Which phylum includes the simplest animals in the subkingdom Eumetazoa?
The phylum Cnidaria, which belongs to the grade Radiata, includes the simplest animals in the subkingdom Eumetazoa.
What is Grade Radiata?
Grade Radiata includes animals with radial symmetry and diploblastic organization.
How is radial symmetry defined?
Radial symmetry is when an animal’s body parts are arranged around a central axis, with planes passing through the axis dividing the animal into mirror image halves.
Give an example of an animal with radial symmetry.
An example of an animal with radial symmetry is a sea anemone.
What is Grade Bilateria?
Grade Bilateria includes animals with bilateral symmetry and triploblastic organization.
What distinguishes bilateral symmetry?
Bilateral symmetry is characterized by a distinct left and right side, with an anterior (head) and posterior (tail) end, as well as dorsal and ventral surfaces.
Name some phyla included in Grade Bilateria.
Phyla Platyhelminthes, Nematoda, Annelida, Mollusca, Arthropoda, Echinodermata, Hemichordata, and Chordata are included in Grade Bilateria.
How is the coelom formed in Proterostomes?
In Proterostomes, the coelom forms through splitting of mesoderm (schizocoelous development).
How is the coelom formed in Deuterostomes?
In Deuterostomes, the coelom develops as an outpouching of the archenteron (enterocoelous development).
Explain spiral and determinate cleavage.
Spiral and determinate cleavage produces unequal cells diagonally around the polar axis, with predetermined roles for each blastomere in embryo formation.
Describe radial and indeterminate cleavage.
Radial and indeterminate cleavage produces symmetrical tiers of cells around the polar axis, with blastomeres having undetermined fates.
What is the key feature of diploblastic animals?
Diploblastic animals have two cell layers: ectoderm and endoderm, and a central cavity called the gastrovascular cavity.
What is the primary body organization of triploblastic animals?
Triploblastic animals have three cell layers: ectoderm, mesoderm, and endoderm, giving rise to specialized organs and systems.
What are the functions of mesoderm in triploblastic animals?
Mesoderm gives rise to muscular, skeletal, and reproductive systems in triploblastic animals.
Which phylum is included in Diploblastic organization?
Animals with diploblastic organization belong to the phylum Cnidaria (coelenterate).
What is the body cavity like in acoelomates?
Acoelomates lack a true body cavity (coelom). Instead, they have a loose tissue called mesenchyma or parenchyma between ectoderm and endoderm.
What is the main function of the mesenchyma in acoelomates?
The mesenchyma provides support and protection around internal organs.
How does the gut of acoelomates differ from coelomates?
Acoelomates have a sac-type gut and lack a specialized transport system.
What is the term used to describe the false body cavity in pseudocoelomates?
Pseudocoelom is the term for the false body cavity in pseudocoelomates.
How is pseudocoelom different from true coelom?
Pseudocoelom is not lined by coelomic epithelium and isn’t related to reproductive and excretory organs.
From where does pseudocoelom develop in embryos of pseudocoelomates?
Pseudocoelom develops from the blastocoel of the embryo.
What is the key feature of a coelomate’s body structure?
Coelomates have a true body cavity called coelom, lined by mesoderm.
What fills the coelomic cavity in coelomates?
The coelomic cavity is filled with coelomic fluid.
What systems are well developed in coelomates compared to acoelomates and pseudocoelomates?
Coelomates have well-developed nervous, excretory, circulatory, respiratory, and reproductive systems.
What are the two layers that make up the body wall of sponges?
The body wall of sponges consists of an outer layer called pinacoderm and an inner layer called choanoderm.
How do sponges obtain their food and oxygen?
Sponges rely on water currents created by the movement of choanocytes’ flagella to bring in food and oxygen.
What are the openings through which water enters and leaves a sponge’s body?
Water enters through pores called ostia and exits through the osculum.
What provides structural support in sponges?
Sponges have a skeleton of needle-like structures called spicules, which can be calcareous or siliceous.
How do sponges reproduce?
Sponges reproduce through both asexual and sexual methods.
What is a gemmule in sponges?
Gemmules are internal buds in sponges that develop into new individuals.
How do most sponge species reproduce sexually?
Most sponge species are hermaphroditic and protandrous, with male sex cells developing first.
How does fertilization occur in sponges?
Sperms released in water are carried to the eggs by amoeboid cells, and fertilization occurs in the mesenchyme.
What are examples of sponges?
Examples of sponges include Sycon, Leucoselenia, Euplectella, and Spongilla.
Why are natural sponges valuable?
Natural sponges are used for washing, bathing, surgical operations, and sound absorption in buildings.
What are cnidocytes in Cnidaria?
Cnidocytes are special cells in Cnidarians that produce nematocysts, stinging cells.
How are Cnidarians organized in terms of germ layers?
Cnidarians have two germinal layers: ectoderm (outer covering) and endoderm (digestive cells), separated by a jelly-like mesoglea.
What is the primary cavity in coelenterates?
Coelenterates have a gastrovascular cavity that serves as both a digestive and body cavity, with a single opening, the mouth.
How do coelenterates capture and digest food?
Coelenterates immobilize prey with nematocysts on their tentacles, then digest the food in the gastrovascular cavity.
What is the arrangement of body parts in coelenterates?
The arrangement of body parts in coelenterates is symmetrical around a centralized axis, known as radial symmetry.
What is the significance of radial symmetry in coelenterates?
Radial symmetry in coelenterates means that they have a correspondence in form and arrangement of parts, allowing a plane passing through the center to divide them into similar halves.
What are the two basic forms of cnidarians and their functions?
The two basic forms of cnidarians are polyps and medusae. Polyps are usually nutritive and cylindrical, while medusae are umbrella-like and involved in sexual reproduction.
How do coelenterates immobilize and consume their prey?
Coelenterates immobilize their prey using stinging cells or nematocysts on their tentacles. The immobilized organisms are then taken into the digestive cavity for digestion and distribution.
What is the nature of the nervous system in coelenterates?
Coelenterates have a nervous system in the form of a network of neuron cells forming an irregular plexus in the body wall. They lack a central nervous system.
How do colonial coelenterates like corals create their exoskeleton?
Colonial coelenterates, such as corals, produce an exoskeleton made of calcium carbonate (CaCO3) secreted by epidermal cells using lime from sea water.
How does reproduction occur in coelenterates like Hydra?
Coelenterates like Hydra reproduce both asexually and sexually. Hydra forms buds on its surface that develop into new individuals, which then separate from the parent.
What is the alternation of generations in coelenterates?
The life cycle of coelenterates is characterized by alternation of generations, where two diploid generations (asexual and sexual) alternate with one another. For example, Obelia exhibits this alternation.
What is the role of medusae in the reproductive process of coelenterates?
Medusae, a free-swimming form of cnidarians, are involved in sexual reproduction as they bear reproductive organs that produce gametes. These gametes unite to form zygotes, leading to the formation of new colonies.
What is polymorphism in coelenterates?
Polymorphism refers to the occurrence of different types of individuals (zooids) within the same organism, each performing distinct functions.
Give an example of polymorphism in coelenterates.
Obelia exhibits polymorphism with feeding individuals (gastrozooids), asexual reproduction individuals (gonozooids), and sexually reproducing individuals (medusae).
What is an example of a freshwater coelenterate without alternation of generations?
Hydra is a freshwater coelenterate that exists only in the polyp form, lacking alternation of generations.
Which coelenterate exhibits alternation of generations?
Obelia is a marine colonial coelenterate that displays alternation of generations.
What is the dominant form in Aurelia (jellyfish)?
Aurelia (jellyfish) has a dominant medusa form, with the polyp form reduced.
How is the body of Actinia (sea anemone) structured?
Actinia’s body consists only of a polyp, and its enteron (digestive cavity) is divided by large partitions known as mesenteries.
What is the primary component that forms the hard calcareous skeleton in Madrepora (corals)?
The hard calcareous skeleton in Madrepora (corals) is primarily formed of calcium carbonate.
What are coral reefs and how are they formed?
Coral reefs are formed from the secretions of specialized polyps that become covered by stony cups due to secretions hardening. The stony masses formed are called coral reefs, mostly composed of calcium carbonate.
Where are coral reefs commonly found?
Coral reefs are found in coastal waters, including locations such as Florida, West Indies, East Coast of Africa, Australia, and the Coral Sea.
Where are living polyps located in coral reefs?
Living polyps are found on the surface layer of coral reefs, while the mass underneath consists of dead stony structures without polyps.
What are Platyhelminthes?
Platyhelminthes are soft-bodied, dorsoventrally compressed triploblastic animals with bilateral symmetry and an unsegmented body.
What does the name “Platyhelminthes” mean?
The name “Platyhelminthes” means “flatworms,” referring to their flat and thin body structure.
What type of symmetry do Platyhelminthes exhibit?
Platyhelminthes exhibit bilateral symmetry.
What is the general body plan of Platyhelminthes?
Platyhelminthes have three germ layers (ectoderm, mesoderm, endoderm), lack a body cavity (acoelomate), and have an unsegmented body.
Where are Platyhelminthes commonly found?
Many Platyhelminthes are parasites, often living inside their hosts. Some species are free-living in freshwater environments.
Give examples of parasitic Platyhelminthes and the diseases they can cause.
Examples include Taenia solium (tapeworm), Fasciola hepatica (liver fluke), and Schistosoma (blood fluke), which can cause diseases in humans.
How do free-living Platyhelminthes feed?
Free-living Platyhelminthes, such as Planaria, feed on small animals and decaying organic matter.
What type of digestive system do Platyhelminthes have?
Platyhelminthes possess a branching sac-type digestive system.
How do Platyhelminthes move?
Free-living Platyhelminthes move using cilia on their undersides, while movement in parasitic forms is limited.
How do Platyhelminthes reproduce?
Platyhelminthes reproduce both sexually and asexually. Asexual reproduction includes fission, while sexually reproducing species are hermaphrodites.
What adaptations do parasitic Platyhelminthes exhibit?
Parasitic Platyhelminthes have adaptations like resistant cuticles, adhesive organs for attachment, degeneration of certain systems, and complex reproductive strategies due to their parasitic lifestyle.
How does the development of the zygote in Taenia (tape worm) begin?
The development of the zygote in Taenia begins while it is still inside the uterus of the female.
What is the fate of fully mature proglottids in Taenia?
Fully mature proglottids break off from the body and pass out of the human body along with feces.
What is the significance of the six chitinous hooks in the embryo of Taenia?
The embryo inside the egg of Taenia has six chitinous hooks, which aid in limited movement and contraction.
What is the secondary host for Taenia?
The second host for Taenia can be a cow, in which the parasite remains embedded in the voluntary muscles.
How can improperly cooked beef lead to Taenia infestation in humans?
If a person consumes improperly cooked beef containing live parasites, the parasite can develop further in the human intestine.
What is the method for disinfestation of Taenia infestation in humans?
Properly cooking beef and taking appropriate medicines are methods to remove the parasite. Anema is also used for complete removal.
What is the general shape and body characteristic of animals in Phylum Nematoda?
Animals in Phylum Nematoda have an elongated worm-like body with pointed ends, exhibiting bilateral symmetry.
What is the source of the pseudocoelom in nematodes?
The pseudocoelom in nematodes is derived from the blastocoel, a hollow space present in the blastula during embryonic development.
How does the excretory system work in nematodes?
Nematodes have two longitudinally running excretory canals that unite at the anterior end, forming a single canal that opens through an excretory pore.
How do nematodes achieve locomotion?
Nematodes achieve locomotion through undulating waves of contraction and relaxation of muscles arranged in four bands.
What are the reproductive organs in female and male nematodes?
Female nematodes have ovaries producing eggs, while male nematodes have testes producing sperm. A larval stage is present in their life cycle.
Which parasitic nematode causes intense itching and inflammation of the anus?
Enterobius vermicularis, commonly known as pinworm, is a parasitic nematode causing intense itching and inflammation of the anus.
How does Ancylostoma duodenale (hookworm) affect its host?
Ancylostoma duodenale, a hookworm, attaches to the small intestine, sucks blood, and releases anticoagulant, causing anemia and growth retardation in children.
What are the general characteristics of animals in Phylum Annelida?
Most annelids are segmented and commonly called annelids due to their ring-like segments.
They are triploblastic and coelomate, showing bilateral symmetry.
Body systems like the gut, blood vessels, and nerve cord are continuous throughout the segments.
What is the function of septa in annelids’ bodies?
Septa separate the segments internally and extend across the coelom.
How is the digestive system structured in annelids?
Annelids have an alimentary canal with distinct parts for specific functions, including mouth and anus.
What is the role of coelom in annelids?
Coelom is a fluid-filled space between the parietal and visceral layers of mesoderm, serving as a hydrostatic skeleton.
How does excretion occur in annelids?
Excretion happens through ciliated organs called nephridia present in each body segment.
Describe the nervous system of annelids.
Annelids have a central nervous system with a simple brain and a double ventral nerve cord. Nerves arise from the cord in each segment.
What is the mode of circulatory system in annelids?
Annelids have a closed circulatory system with blood flowing through a network of blood vessels.
How do annelids exchange gases?
Gaseous exchange occurs through diffusion across the skin into blood capillaries, kept moist by mucus and coelomic fluid.
What are the two types of muscles in annelids’ body wall?
Circular muscles are arranged along the circumference, and longitudinal muscles are arranged along the length of the body.
How does annelid locomotion occur?
Locomotion results from the interaction of muscles and the hydrostatic skeleton. Contraction of circular and longitudinal muscles changes the body shape.
What are chaetae and their role in annelids?
Chaetae are chitinous bristles or setae that aid in locomotion; they are embedded in sacs (earthworm) or on parapodia (e.g., Nereis).
How do most annelids reproduce?
Most annelids are hermaphrodites and reproduce sexually.
What is the significance of earthworms’ burrowing activity?
Earthworms improve soil aeration, drainage, and root growth by burrowing and mixing soil.
Name the three classes within Phylum Annelida. The three classes are Polychaeta, Oligochaeta, and Hirudinea.
What is a trochophore larva, and which class of annelids produces it?
A trochophore larva is a free-swimming larval stage. It is produced in the Polychaeta class during development.
What is the characteristic segmentation pattern of animals in Class Oligochaeta?
They have both internal and external segmentation.
How do animals in Class Oligochaeta move?
They use setae (bristle-like structures) as organs of locomotion.
Are animals in Class Oligochaeta hermaphrodite or unisexual?
They are hermaphrodite (bisexual).
Do animals in Class Oligochaeta undergo larval development?
No, they do not form larvae during development.
What are the additional circular rings or markings on the segments of animals in Class Hirudinea called?
They are called annuli.
How do animals in Class Hirudinea move?
They move by contracting their body and using suckers.
What is the larval form that develops during the life cycle of animals in Class Hirudinea?
Trochophore larva is formed during their development.
How do leeches obtain blood from their hosts, and what secretion aids in this process?
Leeches have chitinous jaws for making a puncture in the host’s skin. They also release an anticoagulant secretion to facilitate blood flow.
What is the main defining feature of animals in the phylum Arthropoda?
They have jointed appendages and a segmented body.
How do arthropods respire?
Arthropods can respire through a tracheal system or gills, depending on whether they are terrestrial or aquatic.
What is the external covering that serves as the skeleton in arthropods?
They have an exoskeleton made primarily of chitin.
How does the circulatory system of arthropods differ from that of vertebrates?
Arthropods have an open circulatory system where blood bathes the tissues directly, without vessels. They lack hemoglobin in their blood.
What are some examples of arthropods?
Insects like cockroaches, grasshoppers, butterflies, and mosquitoes are common examples of arthropods.
What is the significance of metamorphosis in the life history of insects?
Metamorphosis is an abrupt change of form during an insect’s life cycle, including distinct stages of egg, larva, pupa, and adult. It allows insects to adapt to different ecological niches efficiently.
What are the three morphologically distinct stages in the life cycle of insects undergoing complete metamorphosis?
The three stages are egg, larva, and pupa. The egg develops into a larva, which then transforms into a motionless pupa before developing into an adult.
What are nymphs in the context of insect metamorphosis?
In some primitive insects, metamorphosis is incomplete. The larva resembles the adult and is called a nymph or instar, living in the same habitat as the adult.
What are the characteristics of Class Crustacea in the phylum Arthropoda?
Class Crustacea includes aquatic arthropods with gills for respiration, a dorsal exoskeleton (carapace), modified appendages for various functions, and mostly separate sexes. Examples include crabs, lobsters, and prawns.
Describe the characteristics of insects in Class Insecta.
Insects in Class Insecta have three distinct body regions (head, thorax, abdomen), compound eyes, jointed legs, and often wings. They undergo metamorphosis and have separate sexes. Examples include mosquitoes, butterflies, and beetles.
What are the distinguishing features of Class Arachnida in the phylum Arthropoda?
Class Arachnida includes arthropods with a fused cephalothorax, chelicerae with claws, pedipalps, and four pairs of legs. They lack antennae and true jaws, and some have book lungs for respiration. Examples are spiders, scorpions, mites, and ticks.
How is the body of Class Myriapoda organized?
Class Myriapoda comprises arthropods with numerous segments, each having a pair of legs. They possess antennae and eyes on the head. Examples include centipedes and millipedes.
What are the main achievements of arthropods in terms of evolution and adaptation?
Arthropods have developed chitinous exoskeletons and versatile locomotory mechanisms. Their jointed appendages serve various functions, including movement, defense, and reproduction.
What role does chitin play in the success of arthropods?
Chitin, a non-living substance, forms the exoskeleton of arthropods, providing protection, support, and lever for muscle movement. It is also shed during growth, allowing for adaptation to different habitats.
How is segmentation in arthropods different from that in annelids?
While both arthropods and annelids have segmented bodies, arthropod segmentation is not metameric. Each somite in arthropods typically has a pair of jointed appendages, specialized for various functions in different habitats.
Why are insects of economic importance to humans?
Answer: Insects can cause economic losses by damaging crops, property, and spreading diseases. Some insects are harmful, transmitting diseases like malaria and cholera, while others damage commercial crops like fruits and vegetables.
How do harmful insects affect human and animal health?
Answer: Harmful insects like mosquitoes, flies, and bugs transmit disease-causing organisms to humans and domestic animals, leading to diseases such as malaria, sleeping sickness, and skin diseases.
Give examples of harmful insects that damage crops.
Answer: Locusts and various insect species lay eggs on fruits and crops like sugarcane, maize, and cotton, causing economic loss to farmers when the larvae damage these crops.
Name a beneficial insect and its products.
Answer: The honey bee provides honey and wax, while the silk worm gives us silk, making them economically valuable insects.
What is the general characteristic of the phylum Mollusca?
Answer: The phylum Mollusca includes diverse organisms like snails, clams, and cephalopods. These animals have bilateral symmetry, most possess shells, and exhibit a variety of forms.
How do molluscs exhibit diversity in habitat?
Answer: Molluscs are widely distributed, with some living exclusively in aquatic environments (e.g., cephalopods), while others inhabit freshwater, marine, or even terrestrial habitats.
Describe the basic body plan of molluscs.
Answer: Molluscs have an unsegmented, soft body divided into head, ventral muscular foot, and dorsal visceral mass containing internal organs. Many possess a mantle that secretes shells.
What is the function of the radula in molluscs?
Answer: Many molluscs have a radula, a tongue-like structure with horny teeth, used for feeding and scraping food.
Explain the circulatory system in molluscs.
Answer: Except for Cephalopoda, molluscs have an open circulatory system with sinuses or blood spaces. The heart pumps blood into these sinuses. They also have a blue-colored respiratory pigment called haemocyanin.
How do molluscs contribute to the ecosystems?
Answer: Molluscs play important roles in ecosystems as scavengers, predators of harmful insects, and as a source of food for other animals, such as fish.
How does gaseous exchange primarily occur in molluscs?
Answer: Gaseous exchange in molluscs mostly occurs through gills. In certain cases, like snails, the mantle cavity is converted into a lung.
What is the composition of the nervous system in molluscs?
Answer: The nervous system in molluscs consists of three pairs of interconnected ganglia located in the head, foot, and body regions.
What is the primary organ of locomotion in molluscs?
Answer: The muscular foot serves as the organ of locomotion in molluscs, although some species exhibit slow movement, and others are sessile.
How are the sexes typically organized in molluscs?
Answer: Molluscs have separate sexes, meaning they are dioecious, with distinct male and female individuals.
What larval form develops during the embryological development of molluscs?
Answer: The trochophore larva is the developmental stage that emerges during the embryological development of molluscs.
Which major classes are molluscs classified into?
Answer: Molluscs are classified into six classes, with the major classes being Gastropoda, Bivalvia (Pelecypoda), and Cephalopoda.
Describe the characteristics of Gastropoda.
Answer: Gastropods have asymmetrical bodies often covered by a coiled one-piece shell. They can withdraw into their shells. Some have aquatic gills, while others have mantle cavities converted into lungs.
Provide examples of molluscs belonging to the class Gastropoda.
Answer: Examples of Gastropods include Helix aspersa, commonly known as the garden snail, and Limax, the slug.
How is respiration achieved in bivalves?
Answer: Bivalves respire through plate-like gills. They are aquatic, bilaterally symmetrical molluscs enclosed by two shells.
Name a few examples of bivalves.
Answer: Examples of bivalves include Mytilus (marine mussel), Anodonta (freshwater mussel), and Ostrea (oyster).
What are the characteristics of Cephalopoda?
Answer: Cephalopods have bilaterally symmetrical, dorso-ventrally flattened bodies. Many species lack a shell or have a reduced internal shell. They are highly developed and active aquatic animals.
Give examples of Cephalopods.
Answer: Examples of Cephalopods include Loligo (squid), Sepia (cuttlefish), and Octopus.
How can molluscs be economically important to humans?
Answer: Some molluscs are harmful, like slugs damaging gardens, and shipworms harming ships. However, many molluscs are valuable food sources. Clams, oysters, and mussels are consumed in various parts of the world.
How are mollusk shells used in industries and other applications?
Answer: Freshwater mussel shells are used in the button industry. Oyster shells mixed with tar are used in road construction. Some shells are utilized for making ornaments, and certain oysters produce valuable pearls.
What is the main habitat of echinoderms?
Answer: Echinoderms primarily inhabit marine environments, specifically the sea bottom.
What is the origin of the echinoderm endoskeleton?
Answer: The echinoderm endoskeleton develops from mesodermal cells and may bear spines. It is called endoskeleton due to its mesodermal origin.
How do echinoderms exhibit symmetry?
Answer: Echinoderms exhibit radial symmetry, with the mouth located on the lower surface (oral) and the anus on the upper surface (aboral).
Where are most echinoderms found within the marine environment?
Answer: Most echinoderms are found at the bottom along shorelines in shallow seas.
What is the purpose of the water vascular system in echinoderms?
Answer: The water vascular system is a complex system of tubes and spaces that aids in movement and other functions. Water circulates through these channels, entering through the madreporite.
How do echinoderms move using tube feet?
Answer: Motile echinoderms use soft saclike structures called tube feet, which are located along the grooves of their arms, for movement.
Do echinoderms have specialized organs for respiration or excretion?
Answer: No, echinoderms lack specialized organs for respiration or excretion. Their level of organization is relatively low in these aspects.
What is a unique feature of echinoderm larvae compared to adults?
Answer: Echinoderm larvae exhibit bilateral symmetry, while adults show radial symmetry as an adaptation for their mode of life.
Which characteristic do echinoderms share with chordates during embryonic development?
Answer: Echinoderms and chordates both exhibit radial cleavage during embryo development and have the blastopore forming the anus (deuterostomy).
What is a common example of an echinoderm with the ability to regenerate lost organs?
Answer: Starfish, sea cucumber, sea lily, brittle star, and sea urchin are examples of echinoderms that can regenerate lost organs.
What are some common examples of echinoderms?
Answer: Asterias (starfish), sea urchin, sea cucumber, cake urchin, and brittle star are common examples of echinoderms.
What is the relationship between echinoderms and hemichordates?
Answer: Echinoderms and hemichordates both belong to the deuterostome branch and share certain characteristics, including the formation of coelom and retention of blastopore as the future anus.
Why are echinoderms considered to have a close resemblance to chordates?
Answer: Echinoderms share similarities with chordates such as mesodermal skeleton and deuterostomy. Their early development is also comparable, which is why they are placed closer to phylum Chordata.
What is the significance of the term “prechordates” in relation to hemichordates?
Answer: Hemichordates are referred to as “prechordates” due to their close relationship to chordates and shared characteristics with both echinoderms and chordates.
What is a soft-bodied worm-like animal?
Answer: Balanoglossus and Saccoglossus are examples of such animals.
How is the body of these animals divided?
Answer: The body is divided into an anterior proboscis, collar, and trunk.
What is the composition of the body wall?
Answer: The body wall is made of unicellular epidermis with mucus-secreting cells.
How does the digestive tract appear in these animals?
Answer: The digestive tract is straight but may show variations.
How do the coelomic cavities correspond to body regions?
Answer: Each of the three body regions has corresponding coelomic pouches.
Describe the circulatory system in these animals.
Answer: The circulatory system consists of a median dorsal and a median ventral vessel.
What makes up the respiratory system in these animals?
Answer: The respiratory system consists of gill-slits forming a dorsal row behind the collar.
Explain the excretory system in these animals.
Answer: The excretory system includes a single glomerulus connected to blood vessels.
What is the nature of the nervous system?
Answer: The nervous system consists of a sub-epidermal plexus of cells and fibers.
What kingdom do these animals belong to?
Answer: They belong to the Kingdom Animalia.
What is the defining characteristic of the phylum Chordata?
Answer: The notochord is the defining characteristic of Phylum Chordata.
How many basic characters do all chordates possess?
Answer: All chordates possess three basic characters.
What are the three basic characters of chordates?
Answer: The three basic characters are the presence of a notochord, a dorsal central nervous system, and paired gill openings in the embryonic stage.
What are the two main categories within Phylum Chordata?
Answer: The two main categories are lower chordates (e.g., Amphioxus) and higher chordates (vertebrates).
What distinguishes vertebrates from other chordates?
Answer: Vertebrates have a vertebral column and a bony brain case (cranium).
What are the two superclasses of vertebrates?
Answer: The two superclasses are Pisces (Fishes) and Tetrapoda (Four-footed).
Name three classes within the superclass Pisces.
Answer: The classes are cyclostomata, chondrichthyes, and osteichthyes.
What is a distinguishing feature of class cyclostomata?
Answer: Class cyclostomata includes primitive vertebrates without jaws.
How many pairs of gills do lampreys have?
Answer: Lampreys have six to fourteen pairs of gills.
Are lampreys and hagfishes separate sexes?
Answer: Yes, lampreys have separate sexes, while hagfishes are hermaphrodites.
What is the class name for animals with a cartilaginous skeleton resembling bony fishes?
Class Chondrichthyes.
What are the main characteristics of Chondrichthyes?
Body fusiform, placoid scales, cartilaginous endoskeleton, J-shaped stomach, gills without operculum, no swim bladder, sexes separate, oviparous or viviparous.
Which group of Chondrichthyes have enlarged pectoral fins used for swimming like wings?
Skates and rays.
How do sting rays and electric rays differ in terms of their special features?
Sting rays have whip-like tails with sharp spines, while electric rays have dorsal muscles modified into powerful electric organs.
What is the economic importance of sharks?
Sharks are used for food in some regions, shark liver oil is extracted for vitamins A and D, and shark skin leather is used for making articles.
What are some characteristics of bony fishes?
They have a bony skeleton, dermal scales, various types of fins, terminal mouth, gills covered by an operculum, and a swim bladder for buoyancy.
How do swim bladders contribute to a fish’s buoyancy?
Swim bladders are hydrostatic organs that can be filled with gas to adjust the fish’s buoyancy in water.
What adaptations do fishes have for an aquatic life?
Streamlined body, swim bladder, various types of fins for balance and movement, and specialized respiratory organs (gills).
What is the defining feature of the class Amphibia?
Amphibians are the first vertebrates to transition from aquatic to terrestrial life, with adaptations like limbs, lungs, and skin modifications.
How do amphibians adapt to both aquatic and terrestrial environments?
They have limbs, lungs, and skin suited for life on land while retaining some aquatic characteristics like gills and aquatic habits in their larval stages.
What is the main adaptation that distinguishes reptiles from amphibians?
Reptiles have developed copulatory organs for internal fertilization, allowing them to reproduce on land.
How do reptile eggs differ from amphibian eggs?
Reptile eggs have leathery shells that resist dryness and injury, along with a large yolk, adapting them for terrestrial life.
What type of skin do reptiles possess and how is it suited for their habitat?
Reptiles have dry scaly skin adapted for life on land.
What are the protective embryonic membranes found in reptile eggs?
Reptile eggs have amnion, allantois, and chorion, which provide protection during development.
How does the heart of reptiles differ from that of crocodiles in terms of ventricular partitioning?
In reptiles, the ventricle of the heart is incompletely partitioned, ensuring efficient oxygen supply. However, in crocodiles, the ventricle is completely partitioned into two.
What adaptation do most reptiles have for locomotion?
Most reptiles have well-developed limbs adapted for efficient movement on land.
How do reptiles regulate their body temperature and behavior during winter?
Reptiles are cold-blooded (poikilothermic) and often hibernate during winter to cope with temperature changes.
Which group of reptiles has survived with little change and is native to New Zealand?
Tuatara (sphenodon) is a group of reptiles native to New Zealand that has survived with minimal change.
What major groups of reptiles exist today, and from which line are crocodiles derived?
The present-day reptiles include lizards, snakes, tuatara, and crocodiles. Crocodiles are an offshoot from the lineage that gave rise to modern birds.
What is the common belief regarding the evolution of birds and mammals from reptiles?
Both birds and mammals are believed to have evolved from reptiles along separate lines.
What is the significance of the archaeopteryx in understanding bird evolution?
Archaeopteryx, a bird fossil from the Jurassic period, serves as a transitional species with characteristics of both reptiles and birds, suggesting a link between the two groups.
What adaptations distinguish birds from reptiles?
Birds have a streamlined body, forelimbs modified into wings, and a 4-chambered heart. They lack teeth and have a unique vocal organ called a syrinx.
How do birds adapt to flying and maintain a lightweight skeleton?
Bird skeletons are lightweight due to air spaces, an adaptation for flying.
What is the function of air-sacs in bird respiratory systems?
Birds have air-sacs that extend into bones, aiding in respiration and maintaining efficient oxygen exchange.
How is the excretory system of birds different from other animals?
Birds lack a bladder, and their excreted waste, known as uric acid, is semi-solid.
What is the purpose of the gizzard in birds?
The gizzard, a muscular structure in some birds, is used for crushing and grinding food since birds lack teeth.
How is fertilization accomplished in birds, and what is unique about their eggs?
Birds have internal fertilization, and their eggs are large with a substantial yolk. Only one ovary and oviduct are functional in birds.
Which group of birds has lost the ability to fly and adapted for running?
Ostriches and similar birds have lost the ability to fly and are adapted for running.
What is a mammal?
A mammal is an animal that is nourished by milk from the breast of the mother. It is considered the highest group in the animal kingdom due to its advancements, particularly in brain evolution.
How did mammals evolve from reptilian ancestors?
Mammals evolved from reptilian ancestors called cotylosaurs. Fossil evidence supports this evolution, with mammal-like reptiles coexisting with reptiles during the Jurassic era.
What distinguishes mammals from reptiles in terms of body covering?
Most mammals have a body covering of hair instead of scales, which is a significant structural difference from reptiles.
What separates the thoracic and abdominal cavities in mammals?
Mammals have a muscular diaphragm that separates the thoracic and abdominal cavities, a feature not present in previous groups.
How is the lower jaw of mammals different from reptiles?
Mammals have a lower jaw composed of a single large bone that articulates directly with the skull, unlike reptiles.
What is the primary function of the three bones in the mammalian ear?
Mammals have a chain of three bones in the ear (Malleus, Incus & Stapes), which aid in hearing.
What is the significance of the presence of deciduous and permanent teeth in mammals?
Mammals possess both deciduous (milk) and permanent teeth, such as in humans, reflecting their evolutionary development.
How is the heart of mammals different from that of birds?
Mammals have a 4-chambered heart with only a left aortic arch, whereas birds have a right aortic arch.
What is meant by mammals being warm-blooded?
Mammals are warm-blooded animals, meaning they can regulate their body temperature internally.
How do mammals nourish their young?
Mammals feed their young on milk produced by mammary glands, a characteristic unique to this group.
What are the three sub-classes of mammals?
Mammals are classified into three sub-classes: Prototheria (egg-laying mammals), Metatheria (pouched mammals), and Eutheria (placental mammals, including humans).
What is the main characteristic of Sub-Class Prototheria?
Prototheria are a connecting link between reptiles and mammals, having characteristics of both. They lay eggs and have mammary glands.
How do Metatheria mammals care for their young?
Metatheria, or marsupials, rear their immature young in an abdominal pouch called the marsupium. The young are nourished with milk produced by the mother.
What is unique about Sub-Class Eutheria’s development?
Sub-Class Eutheria includes placental mammals, where the young develop to their maximum within the mother’s body, nourished through the placenta.
Unit 10 Biology of 1st Year Long Answer Questions
(i) What are Cnidaria? Explain the diploblastic origin, alternation of generations in cranidaria.
Cnidaria are a phylum of aquatic animals that include jellyfish, corals, sea anemones, and hydras. They exhibit a radial symmetry and possess specialized stinging cells called cnidocytes, which they use for defense and prey capture.
The diploblastic origin of Cnidaria refers to their embryonic development from two germ layers: the ectoderm and the endoderm. Unlike triploblastic animals that have a third germ layer (mesoderm), Cnidaria lack this layer, leading to a simpler body structure.
The alternation of generations in Cnidaria involves two distinct body forms: the medusa and the polyp. The medusa is a free-swimming, bell-shaped form, while the polyp is a sessile, cylindrical form attached to a substrate. This alternation of generations allows Cnidaria to adapt to different ecological niches. The medusa produces gametes (sex cells), which fuse to form a zygote. The zygote develops into a planula larva, which settles and transforms into a polyp. The polyp can reproduce asexually by budding, eventually giving rise to medusae through a process of strobilation.
(ii) Describe the parasitic adaptations in phylum platyhelminthes – How does tape worms afect a person.
Phylum Platyhelminthes includes flatworms, many of which are parasitic. These parasites have evolved various adaptations for survival within their host organisms.
Parasitic Adaptations:
Loss of Organs: Parasitic flatworms often exhibit simplified body structures, losing unnecessary organs to adapt to a parasitic lifestyle. They may lack digestive systems since they absorb nutrients directly from the host.
Attachment Structures: Parasitic flatworms possess specialized structures for attachment to the host’s tissues. Examples include hooks, suckers, and adhesive glands.
Reduced Nervous System: Parasites often have reduced nervous systems as they rely on the host for sustenance and protection, minimizing the need for complex sensory and motor functions.
Complex Life Cycles: Many parasitic flatworms have intricate life cycles involving multiple host species, allowing them to reach different developmental stages in different hosts.
Tapeworms (Cestodes)
Tapeworms are a type of parasitic flatworm that inhabit the intestines of vertebrates, including humans. They have a modified body structure suited for their parasitic lifestyle. Tapeworms lack a digestive system since they absorb nutrients through their body wall directly from the host’s digested food.
Human infection with tapeworms usually occurs through ingestion of undercooked or contaminated meat. Once inside the host’s intestines, tapeworms can grow and mature, producing segments called proglottids that contain eggs. These proglottids can detach and exit the host through feces, releasing eggs into the environment. If another host ingests these eggs, they can hatch into larvae that penetrate the host’s tissues, forming cysts.
Infection with tapeworms can lead to symptoms like abdominal pain, nausea, weight loss, and deficiencies due to nutrient absorption by the parasite. In severe cases, tapeworms can cause blockages or complications. Proper cooking of meat and good hygiene practices are essential to prevent tapeworm infections in humans.
(iii) Give the symptoms of the disease caused by certain nematodes.
Certain nematodes, commonly known as roundworms, can cause various diseases in humans and animals. The symptoms of diseases caused by these nematodes can vary depending on the specific species and the affected area. Some examples include:
Ascariasis: Caused by the roundworm Ascaris lumbricoides. Symptoms include abdominal pain, vomiting, diarrhea, and visible worms in stool or vomit.
Hookworm Infection: Hookworms (Ancylostoma duodenale and Necator americanus) cause symptoms like anemia, fatigue, abdominal pain, and itchy rash at the site of entry.
Trichuriasis: Caused by the whipworm Trichuris trichiura. Symptoms include abdominal pain, bloody diarrhea, and weight loss.
Filariasis: Wuchereria bancrofti and other filarial nematodes can cause lymphatic filariasis, leading to swelling of limbs, genitalia, and other body parts. This condition is known as elephantiasis.
Enterobiasis (Pinworm Infection): Pinworms (Enterobius vermicularis) can cause anal itching, especially at night.
(iv) Give an account of the major groups of Arthropods. What is the economic importance of insects?
Arthropods are a diverse group of invertebrate animals characterized by their jointed limbs and exoskeletons. They include insects, arachnids (spiders, scorpions, ticks, mites), crustaceans (crabs, lobsters, shrimp), and myriapods (centipedes and millipedes). Each group has distinct characteristics and plays various ecological roles.
Major Groups of Arthropods
Insects: The largest group, insects have six legs and typically three body segments (head, thorax, abdomen). They are incredibly diverse and have various roles in ecosystems, including pollination, decomposition, and serving as food for other organisms.
Arachnids: These include spiders, scorpions, ticks, and mites. Arachnids have two body segments (cephalothorax and abdomen) and usually eight legs. They play roles in predation, parasitism, and some are venomous.
Crustaceans: This group includes crabs, lobsters, shrimp, and crayfish. Crustaceans are primarily aquatic and have a hard exoskeleton. They are important in aquatic food chains and fisheries.
Myriapods: Centipedes and millipedes are examples of myriapods. They have elongated bodies with numerous segments, each with pairs of legs. Centipedes are carnivorous predators, while millipedes are herbivorous scavengers.
Economic Importance of Insects
Insects have significant economic importance due to their various roles in agriculture, ecology, and industry:
Pollination: Insects, especially bees, play a vital role in pollinating crops, contributing to agricultural productivity and food production.
Predation: Many insects are natural predators of agricultural pests, helping to control pest populations and reduce the need for chemical pesticides.
Decomposition: Insects like beetles and flies are essential in breaking down organic matter, aiding in decomposition and nutrient cycling.
Food Source: Insects are consumed as food in many cultures, providing a protein-rich alternative food source.
Silk and Honey Production: Silkworms produce silk, a valuable textile material. Bees produce honey, beeswax, and other products.
Research: Insects are studied for various scientific purposes, including genetics, behavior, and ecology.
Ecological Indicators: Changes in insect populations can indicate shifts in ecosystem health and environmental conditions.
Overall, insects have a profound impact on ecosystems, agriculture, and human societies, making their conservation and sustainable management crucial.
(v) Give the two major classes of the Pisces and explain the adaptations of aquatic mode of life in fishes.
There is some confusion in your question. The term “Pisces” is an older taxonomic grouping that used to encompass all fish species. However, in modern taxonomy, the term “Pisces” is not used as a formal classification. Instead, fish species are categorized into different classes based on their characteristics. The two major classes of fish are:
Class Chondrichthyes: This class includes cartilaginous fishes, such as sharks, rays, and skates. These fishes have skeletons made of cartilage instead of bone. Their adaptations for aquatic life include streamlined body shapes, powerful swimming muscles, and a highly developed sense of smell to locate prey. They have specialized fins for stability and maneuverability in water, and their skin is covered in scales or denticles that reduce drag and turbulence.
Class Osteichthyes: This class comprises bony fishes, which make up the majority of fish species. Bony fishes have skeletons made of bone, and they exhibit a wide range of adaptations for aquatic life. These adaptations include a swim bladder that helps control buoyancy, gills for extracting oxygen from water, fins for precise movement, and scales that provide protection and help streamline their bodies.
(vi) Give the adaptations for aerial mode of life in birds. What is their origin?
Birds have evolved a variety of adaptations that enable them to thrive in an aerial mode of life
Feathers: Feathers are specialized structures that provide insulation, aid in flight, and play a role in courtship displays. Different types of feathers serve different purposes, including contour feathers for flight and down feathers for insulation.
Hollow Bones: Bird bones are lightweight and have air cavities, making them more efficient for flight. Hollow bones reduce the bird’s overall weight, making it easier for them to take off and stay airborne.
Powerful Muscles: Birds have strong breast muscles, known as the pectoral muscles, which are responsible for the flapping motion during flight. These muscles are highly developed to provide the necessary power for sustained flight.
Keen Vision: Birds have excellent eyesight, with some species having the ability to see ultraviolet light. This enhanced vision helps them navigate in the air, spot prey from a distance, and avoid obstacles.
Efficient Respiratory System: Birds have a unique respiratory system that includes air sacs, allowing for a continuous flow of air through the lungs. This system ensures a constant supply of oxygen, even during both inhalation and exhalation.
Efficient Circulatory System: Birds have a four-chambered heart that efficiently pumps oxygenated blood to muscles and other organs during flight.
Beaks and Talons: The diversity of beak shapes and sizes in birds reflects their varied diets. Additionally, many birds have strong talons adapted for grasping and capturing prey.
The origin of birds can be traced back to theropod dinosaurs, particularly during the Late Jurassic period. Over time, some theropods evolved adaptations for flight, such as the development of feathers and changes in skeletal structure. Archaeopteryx, a transitional fossil, is often considered one of the earliest bird-like dinosaurs. This evolutionary process led to the emergence of modern birds with various adaptations for aerial life.
(vii) General Characteristics of Mammals and Differences Among Subclasses
General Characteristics of Mammals
Mammals share several distinct characteristics that set them apart from other animal groups:
- Hair covering instead of scales.
- Presence of a muscular diaphragm separating thoracic and abdominal cavities.
- Single, large bone composing the lower jaw that articulates directly with the skull.
- External ear or pinna, with a chain of three ear bones (Malleus, Incus & Stapes).
- Deciduous and permanent teeth.
- 4-chambered heart with a left aortic arch.
- Warm-blooded (homeothermic) nature.
- Non-nucleated red blood cells.
- Well-developed voice apparatus (larynx and epiglottis).
- Most mammals give birth to live young (viviparous).
- Young are nourished with milk from mammary glands.
Subclass Differences
Prototheria (Egg-laying mammals): These mammals, like the duck-billed platypus and echidna, lay eggs and have both reptilian and mammalian characteristics. They possess mammary glands but also show reptilian traits like cloacal openings.
Metatheria (Pouched mammals): Marsupials such as kangaroos and opossums give birth to relatively immature young, which continue developing in a pouch called a marsupium. The young are nourished with milk produced by mammary glands within the pouch.
Eutheria (Placental mammals): Placental mammals, including humans, have a placenta that nourishes the fully developed fetus within the mother’s body. They exhibit the most typical mammalian characteristics, but variations exist such as modified hair in pangolins and spines in porcupines.
(viii) Distinctions with Examples
a) Radial and Bilateral Symmetry
Radial Symmetry: It refers to an organism’s body plan where similar body parts radiate out from a central axis, like the spokes of a wheel. E.g., starfish.
Bilateral Symmetry: In this type, an organism’s body is divided into two mirror-image halves along a single plane. Most animals, including mammals, exhibit bilateral symmetry, enabling streamlined movement. E.g., humans.
b) Diploblastic and Triploblastic Animals
b) Diploblastic: Animals with two primary germ layers (ectoderm and endoderm) during embryonic development. E.g., jellyfish.
Triploblastic: Organisms with three germ layers (ectoderm, endoderm, and mesoderm), which give rise to more complex tissues and structures. Mammals are triploblastic animals.
c) Anamniotes and Amniotes
Anamniotes: These are vertebrates that lay eggs without an amniotic membrane protecting the embryo from desiccation. Examples include fish and amphibians.
Amniotes: Vertebrates that lay eggs with an amniotic membrane, which prevents water loss and provides protection to the developing embryo. Reptiles, birds, and mammals are amniotes.