Please refer to the Diversity In Living Organisms Notes Class 9 Science given below. These revision notes have been designed as per the latest NCERT, CBSE, and KVS books issued for the current academic year. Students will be able to understand the entire chapter in your class 9th Science book. We have provided chapter-wise Notes for Class 9 Science as per the latest examination pattern.
Revision Notes Chapter 7 Diversity In Living Organisms Class 9 Science
Students of Class 9 Science will be able to revise the entire chapter and also learn all important concepts based on the topic-wise notes given below. Our best teachers for Grade 9 have prepared these to help you get better marks in upcoming examinations. These revision notes cover all important topics given in this chapter.
1 Marks Questions
Question. Name the following :
(a) Free living Platyhelminthes ;
(b) Scientific name of pork tape worm.
Answer. (a) Planaria
(b) Taenia solium.
Question. What are flame cells?
Answer. Flame cells are excretory structures of Platyhelminthes. Besides excretion, they are also osmoregulatory in function.
Question. Why fungi are called saprophytes?
Answer. Fungi are known as saprophytes because they feed on dead and decaying organic matter.
Question. Name the locomotory organs of protozoans.
Answer. Locomotory organs of protozoans are cilia, flagella and pseudopodia.
Question. Name two groups of warm blooded animals with four-chambered heart.
Answer. (i) Aves
Question. What is the scientific name of humans?
Answer. Homo sapiens.
Question. What are the five classes of vertebrates? To which of these do human beings belong?
Answer. The five classes of vertebrates are: fishes, amphibians, reptiles, birds and mammals. Humans classify as mammals.
Question. What is meant by an incomplete digestive system?
Answer. Animals with an incomplete digestive system are those in which the digestive tube has only one opening (cnidarians, platyhelminthes).
Question. Name the term which is used for the following : –
(i) The left and right halves of the body have the same design.
(ii) Animal tissue differentiated from the three embryonic germ layers.
Answer. (i) Bilateral symmetry
Question. Shyam knew the correct scientific name of Mango, but did not follow the conventions while writing it and wrote it as Mangifera Indica. Rewrite the scientificname as per the conventions.
Answer. Mangifera indica.
Question. What is the lowermost category in the hierarchy of classification of groups of organisms?
Question. Name the phylum in which the animals have water vascular system.
Question. Name the group of sessile animals that also have numerous pores all over the body?
Answer. Kingdom Porifera.
Question. What is the common name of annelids?
Answer. Segmented worms.
Question. Define haemocoel:
Answer. When the coelomic cavity is filled with blood, it is known as haemocoel.
2 Marks Questions
Question. The body of an organism is streamlined and has feathers on its body. Identify the organism and write one specific feature of it.
Answer. Aves. Specific feature of Aves is that they are warm –blooded having a four chambered heart and modified forelimbs for flight.
Question. An animal is dorsoventrally flattened. It has three embryonic germ layers and is acoelomate. Which phylum does it belong to? What are they commonly called? Give one example.
Answer. The animal belongs to phylum Platyhelminthes.
They are commonly known ‘flatworms’.
One example – Planaria or liver fluke or tape worm.
Question. What is a parasite? Give two examples.
Answer. A parasite lives in a close relationship with another organism, its host, and causes it harm. The
parasite is dependent on its host for its life functions. E.g., Head lice, leech, bed bug.
Question. Kingdom Fungi have cell wall, but still it cannot be classified under kingdom Plantae? Give any two reasons.
Answer. Fungi are not classified in plant kingdom because their cell wall is different from plant cell and is made up of chitin. They also lack chlorophyll and hence cannot do photosynthesis and are autotrophic.
Question. (a) Name and define the mode of nutrition in Mushroom.
(b) Name the symbiotic life form, which is seen as slow, growing large, coloured patches on the bark of trees.
Answer. (a) Saprophytic nutrition – Organisms feed on dead or decaying organic matter are called saprophytes and their mode of nutrition as saprophytic nutrition (In Greek- ‘Sapros’ means rotten and ‘trophos’ means feeder).
Question. The cat, platypus and man are all mammals, yet one of the most unique features of mammals helps to divide them into two groups. What is that feature? Mention two other characteristic features that are common to all the three animals.
Answer. (a) Both cat, platypus are oviparous. Oviparous animals are animals that reproduce by laying eggs while man is viviparous. Viviparous animals bear live young that have developed inside the mother’s body.
(b) Characteristics of mammaliai)
i) They are warm blooded animals
ii) Mammary glands for the production of milk for their off springs
Question. What are the differences between animals belonging to the Aves group and those in the mammalian group?
Answer. In aves, body is covered with feathers; while in mammals, body is covered with hairs. Mammary glands are absent in aves. Forelimbs of aves are modified into wings which is not the case in mammals. Aves are oviparous, while most of the mammals are viviparous.
Question. Why are Protozoa regarded as early animals?
Answer. Protozoa are regarded as early or primitive animals because
(i) They have a cellular grade of organization, e.g. Amoeba, paramecium.
(ii) A single cell performs all functions; therefore there is no division of labour.
(iii) They are microscopic and exhibit a primitive mode of reproduction.
Question. Why are members of phylum Platyhelminthes called as flatworms?
Answer. Members of phylum Platyhelminthes are called flatworms because their bodies are flattened dorso-ventrally, meaning from top to bottom. Therefore, these creatures have aleaf-like or ribbon-like apperance. They include Fasciola hepatica (liver fluke), Taenia solium (tapeworm), Schistosoma (blood fluke), Planaria etc
Question. Mention the function and location of notochord.
Answer. Notochord is a supporting structure found in lower chordates and in embryos of all higher chordates. It functions as a major axial supporting structure just as vertebral column does in our body and it runs along the back of the animal separating the nervous tissue from the gut.
Question. (i)Name an animal that gives birth to poorly developed young ones and nurtures them into full development after birth.
(ii) Name two egg-laying mammals.
(ii) Echidna, Platypus.
Question. What is meant by nomenclature?
Answer. Nomenclature refers to assigning a unique name to an organism. Two types of names have been given to organisms- Common name and scientific name.
Question. What is meant by scientific name?
Answer. A scientific name is the one given by biologists and represents a particular organism in every part of the world. Scientists ensure that a name being given by them has not been used earlier for any other organisms.
Question. What is meant by characteristics?
Answer. By characteristic, we mean a particular form or particular function that are used to classify the diverse group of organisms into groups. For example- The five fingers on each hand of human beings is a characteristic. Similarly, the ability of human beings to run unlike plants is also a characteristic.
Question. On what basis did Aristotle classify organisms? Was it a correct way of classification? Why?
Answer. Aristotle classified organisms according to whether they lived on land, in water or air and on physical difference. It was not a correct way of classification because animals which live in water differ in many different ways. Same is the case with those in air and on land. Habitat is the only point they share in common
Question. What is the primary characteristic on which the first division of organisms is made?
Answer. The primary characteristic on which first division of organisms is based on whether the cells occur singly (unicellular) or they are grouped together and function as individual group (multicellular). Cell is considered to be the fundamental characteristic for classifying all living organisms.
Question. Who proposed division of Monera kingdom ? State the groups proposed
Answer. Carl Woese.
The groups are –
(i) Archaebacteria or Archaea
(ii) Eubacteria or Bacteria.
Question. What are the important features of Kingdom Plantae?
Answer. Important features of Plantae:
• Multicellular eukaryotic organisms
• Most of the plants contain chlorophyll. Hence, they are autotrophic
• Cell wall made of cellulose is present
Question. What are the important features of Kingdom Animalia?
Answer. Important features of Animalia:
• Multicellular eukaryotic organisms
• Chloroplast is absent. Hence, they have heterotrophic mode of nutrition
• Cell wall is absent
Question. Name the scientist who described the idea of organic evolution and the book in which he explained it. Name the scientists who classified organisms into kingdoms.
Answer. Charles Darwin first described the idea of evolution in his book ‘The Origin of Species’.
Ernst Haeckel, Robert Whittaker and Carl Woese are the scientists who classified organisms into kingdoms
Question. Give scientific terms for the following:
(a) True internal body cavity of animals.
(b) A solid, unjointed rod present in chordates at some stage of life.
(c) Creeping vertebrates.
(d) Pore bearing animals.
Answer. (a) Coelom
(d) Porifera (sponges).
Question. What are the advantages of scientific name?
Answer. The names are universally accepted and understood.
Every species has a specific name. No two species share a common specific name.
The names indicate relationship of a species with others present in the same genus.
Question. Rewrite the following scientific names correctly, if incorrect.
(i) Amoeba Histolytica;
(ii) Atthala rosea (holly-hock);
(iii) Brassica Comestris
Answer. (i) Entamoeba histolytica
(ii) Alcea rosea (common hollyhock)
(iii) Brassica campestris
(iv) Brassica oleracea (Cabbage)
Question. What is a notochord? What does it do?
Answer. The notochord is a long rod-like support structure (chord=string) that runs along the back of the animal separating the nervous tissue from the gut. It provides a place for muscles to attach for ease of movement.
Question. What is meant by classification?
Answer. Classification means identifying the similarities and dissimilarities between different kinds of organisms and placing the organisms with similar characteristics in one group and different organisms in different groups.
Question. What do we mean by biodiversity?
Answer. The vast variety and differences that are found in the living organisms of different ecosystems whether terrestrial, aquatic or marine collectively known as biodiversity.
Question. Which region is known as the region of mega diversity?
Answer. The warm and humid tropical regions of the Earth, between the tropic of Cancer and the tropic of Capricorn, are rich in diversity of plant and animal life. This is called the region of mega diversity.
3 Marks Questions
Question. What are the characteristic features of Pisces?
Answer. The characteristic features of Pisces are
• These are fish.
• They are exclusively water-living animals.
• Their skin is covered with scales/plate
• They obtain oxygen dissolved in water by using gills.
• The body is streamlined, and a muscular tail is used for movement.
• They are cold-blooded and their hearts have only two chambers.
• They lay eggs.
Some have skeletons made entirely of cartilage, such as sharks, and some with a skeleton made of both bone and cartilage, such as tuna or rohu
Question. Associate the following features with groups in which they first appeared.
(a) Vascular tissues
(c) Seeds inside fruits
Answer. (a) Vascular tissue- Gymnosperms
(b) Notochord- Cephalochordates
(c) Seeds inside fruits –Angiosperm
Question. What are the characteristic features of Amphibians?
Answer. The characteristic features of Amphibians are-
• Amphibia are the first land vertebrates.
• They are adapted to live in water and on land.
• Skin is smooth without scales and has mucus glands in the skin to keep the skin moist.
• Respiration is through either gills or lungs.
• They have a three-chambered heart and are cold-blooded animals.
• They lay eggs.
• Frogs, toads and salamanders are some examples
Question. Why do we keep both snake and turtle in the same class?
Answer. Both snake and turtle are kept in same class, because both
• Are cold-blooded.
• Have thick tough skin with scales.
• Breathe through lungs
• Have three-chambered heart.
• Lay leathery eggs.
Question. What are the characteristic features of Aves?
Answer. The characteristic features of Aves are-
• These are warm-blooded animals and have a four-chambered heart.
• They lay eggs.
• There is an outside covering of feathers, and two forelimbs are modified for flight.
• They breathe through lungs.
• All birds fall in this category
Question. What are the characteristic features of Mammals?
Answer. The characteristic features of mammals are
• Mammals are warm-blooded animals with four-chambered hearts.
• They have mammary glands for the production of milk to nourish their young.
• Their skin has hairs as well as sweat and oil glands.
• Most mammals familiar to us produce live young ones. However, a few of them, like the platypus and the echidna lay eggs, and some, like kangaroos give birth to very poorly developed young ones.
Question. Rahul and his mother were walking in the garden. Rahul saw mushrooms growing on decaying leaves. He tried to uproot them. He was stopped by his mother.
(i) Identify the kingdom to which the organism belongs to.
(ii) Write the mode of nutrition exhibited by the mushrooms.
(iii) Why did Rahul’s mother stop him?
Answer. (i) Fungi
(iii) All mushrooms are not edible. Some mushrooms can sicken or kill you if eaten. That was the reason that Rahul’s mother stopped him.
Question. What are the characteristic features of Reptilia?
Answer. The characteristic features of Reptilia are
• Reptilia are the first land vertebrates of the warmer regions.
• Horny scales cover the horny skin.
• These animals are cold-blooded
• They breathe through lungs.
• While most of them have a three-chambered heart, crocodiles have four heart chambers.
• They lay eggs with tough coverings and do not need to lay their eggs in water, unlike amphibians.
• Snakes, turtles, lizards and crocodiles fall in this category
Question. Which group – Pisces or Amphibia is advanced? Give two reasons.
Answer. The group-Amphibia is advanced than Pisces because:
(i) The amphibians have three-chambered heart whereas fishes have two-chamberedheart
(ii) Amphibians respire through gills or lungs while fishes have gills for respiration.
(iii) Amphibians are adapted to live in both land and water whereas Pisces can live only in water.
Question. What is meant by Binomial Nomenclature?
Answer. The system of scientific naming or nomenclature we use today was introduced by Carolus Linnaeus in the eighteenth century. The system developed by
Linnaeus is known asBinomial Nomenclature. Binomial Nomenclature is the system of assigning scientific names to plants and animals. It consists of two words, first generic and second specific.
Question. What conventions are followed while writing the scientific names?
Answer. Certain conventions are followed while writing the scientific names:
1. The name of the genus begins with a capital letter. E.g., Panthera
2. The name of the species begins with a small letter. E.g., tigris
3. When printed, the scientific name is given in italics. E.g., Panthera tigris
4. When written by hand, the genus name and the species name have to be underlined separately E.g., Panthera tigris
Question. How can the endoskeleton of echinoderms be characterized in comparison to analogous structures present in vertebrates, arthropods and molluscs?
Answer. The echinoderm skeleton is internal, i.e., it is an endoskeleton. It is made of calcium carbonate (calcareous).
Vertebrates also have internal skeleton made of bones and cartilages.
Arthropods have an external carapace made of chitin, a chitinous exoskeleton.
Some molluscs present a calcareous shell that works as exoskeleton.
Question. Difference between diploblastic and triploblatic:
Question. Mention the characteristic features of Protochordates
Answer. The characteristic features of Protochordates-
• These animals are bilaterally symmetrical, triploblastic and have a coelom.
• Notochord is present in early stages of development, which may persist or disappear later.
• Proto chordates are marine animals.
• Examples are Balanoglossus, Herdemania and Amphioxus
Question. Mention the characteristic features of chordates:
Answer. All chordates possess the following features:
(i) They have a notochord
(ii) All chordates have a dorsal nerve cord
(iii) They are triploblastic
(iv) They have paired gill pouches
(v) Chordates are coelomate.
Question. What is the importance of putting organisms in groups?
Answer. i) With such a vast number of organisms – both living and extinct, it becomes impossible to study every one of them at individual level.
ii) The task of studying the diversity of living organisms can be made easier and more effective if the various organisms are arranged in an orderly manner.
iii) It is also useful because it allows us to identify similarities and differences among living things.
Question. What is the difference between prokaryotic cell and Eukaryotic cell?
Answer. Eukaryotic cells contain membrane-bound organelles, such as the nucleus, while prokaryotic cells do not have membrane-bound organelles. The prokaryotes consists of bacteria and blue green algae and were first to rise in biological evolution The Eukaryotic cells are found in multicellular animals, plants and fungi. Eukaryotes have arisen probably a million year after prokaryotes and much larger and complex.
Question. What is taxonomy? Who is known as the father of taxonomy? Define taxon.
Answer. i) Taxonomy is a science of naming and arranging organisms into a classification system in order to examine their origin and history.
ii) Carl Linnaeus is known as father of taxonomy.
iii) Taxon is defined as a taxonomic group or category such as phylum, order, family or genus that are used while classifying living organisms.
Question. Give three examples of range variations that you see in life forms around you.
Answer. (a) Range of size: Microscopic bacteria of a few micrometre in size to blue whales and Redwood trees of California of approximate size of 30 metres and 100 metres respectively.
(b) Range of lifespan: Pine trees living for thousands of years to insects like mosquitoes which die within a few days.
(c) Range of colour: Life ranges from colourless worms to brightly coloured birds and flowers
Question. What are the advantages in classifying organisms?
Answer. Organic evolution has been taking place for 3.5 billion years. It is impossible to study every living organism from an individual level. Therefore, classification is necessary to facilitate easy study of organisms.
1. It makes the study of wide variety of organisms easy.
2. It determines the method of organising the diversity of life on Earth.
3. It helps to understand relationships and resemblances between various organisms
4. It helps in understanding the evolution of organisms
Question. State reasons for the following:
(a) Fungi are called saprophytes
(b) Platyhelminths are called so,
(c) Birds have hollow bones.
Answer. (a) Fungi cause decay by releasing enzymes onto the dead animal or plant. These break down complex compounds into simple soluble ones that can be absorbed by decomposers. Organisms that feed on dead material in this way are called saprophytes.
(b) Platyhelminths or flatworms are called so because they are dorsoventrally flattened.
(c) Birds have thin, hollow bones to lighten their weight and make it easier for them to fly.
Question. Explain how animals in vertebrata are classified into further subgroups:
Answer. Animals in vertebrata are classified into 5 classes namely
(i) Class Pisces
(ii) Class Amphibia
(iii) Class Reptilia
(iv) Class Aves
(iv) Class Mammalia
Question. What are the characteristic features of vertebrates?
Answer. The members of the sub-phylum vertebrates are advanced chordates. These animals have a true vertebral column and internal skeleton, allowing a completely different distribution of muscle attachment points to be used for movement. Vertebrates are bilaterally symmetrical, triploblastic, coelomic and segmented, with complex differentiation of body tissues and organs.
All chordates possess the following features:
(i) Have a notochord
(ii) Have a dorsal nerve cord
(iii) Are triploblastic
(iv) Have paired gill pouches
(v) Are coelomate.
5 Marks Questions
Question. State reasons for the following :
(a) Protists have appendages like cilia or flagella.
(b) Angiosperms are called so.
(c) Fish have scales on their body.
Answer. (a) Protista has appendages like cilia and flagella for locomotion and gathering food.
(b) ‘Angio’ means covered and ‘sperma’ means seed. This group is usually referred to as angiosperms because, as their name implies, their seeds are enclosed in a carpel (in a vessel). The carpel is the primary feature that distinguishes angiosperms from gymnosperms.
(c) Firstly, it acts as a protective layer so that harmful objects, fungus, bacteria and parasites cannot enter the fish body Secondly, they are present in overlapping pattern and only small part of scale is visible which makes the fish body smooth but itself the scales are hard. Scales allows the fish to move easily in vertical and horizontal direction in water Thirdly, it protects their bodies from rotting in water.
Question. Give reasons for the following:
(a) Echidna and platypus lay eggs, but are considered as mammals.
(b) Crocodile has four, chambered heart, but still is a reptile.
(c) Birds have pneumatic bones.
Answer. (a) Echidna and platypus lay eggs, but are considered as mammals because
(i) They are warm blooded animals
(ii) They all have four chambered heart
(iii) Mammary glands for the production of milk for their off springs
(iv) Their skin has hairs as well as sweat and oil glands.
(b) Crocodile has four, chambered heart, but still is a reptile because they have dry, nonglandular skin, epidermal scales are also present. They are also cold blooded and oviparous.
(c) Birds have light weighted bones with internal spaces filled with air. These bones are called pneumatic bones. This feature reduces the corporal density of the animal facilitating the flight.
Question. What are the characteristic features of Nematoda?
Answer. The phylum Aschelminthes is also known as Nematoda, and its members are nematodes. The members of this phylum are roundworms, and many are microscopic.
The characteristic features of Nematode are-
• The nematode body is also bilaterallysymmetrical and triploblastic.
• Body is cylindrical.
• Organ grade body organisation is found
• They also have a digestive tract open at both the mouth and anus. This tract is suspended in a body cavity that is said to be false, so it is called a pseudocoel.
• These are very familiar as parasitic worms causing diseases, such as the worms causing elephantiasis (filarialworms) or the worms in the intestines (roundworm or pinworms).
Question. What are the characteristic features of Annelida?
Answer. The characteristic features of Annelids are-
• Annelids are segmented worms
• They are triploblastic and bilaterally symmetrical
• They have true body cavity (coelome). This allows the true organs to be packaged in the body structure
• Extensive organ differentiation is found
• Digestive system is well developed
• Respiration is through gills or skin
• Circulatory system is usually closed.
• These animals are found in a variety of habitats– fresh water, marine water as well as land. Earthworms and leeches are familiar examples
Question. Propose three examples of characteristics used for hierarchical classification. Based on these, develop the definition of characteristics. Why the characteristics of body design used for classification of plants is different from those used for classifying animals?
Answer. (i) Characteristics used for hierarchical classification of living organism’s are-
(a) Their cellularity, whether unicellular or multicellular
(b) The mode of nutrition
(c) The mode of reproduction
(ii) Characteristics mean features or qualities of any organism.
(iii) The characteristics of body design used for classification of plants is different from those
used for classifying animals because the basic body designs are different based on the need to prepare food or obtain it by consuming other organisms. Plants have structures like chloroplasts which contain chlorophyll necessary for the synthesis of food. Organisms that acquire food lack such structures.
Question. (i) State two basis of classifying plants and animals into different categories.
(ii) List three characteristics features of fungi.
(iii) Some fungal species live in permanent, mutually dependent relationships with cyanobacteria.
What is this relationship called? Where are they found?
Answer. (i) Plants and animals are totally different from one another. They are classified on basis as follows:
Plants and animals are totally different from one another in the following ways-
(1) Food preparation
(3) Body parts
(ii) Three characteristic features of fungi area)
Cell wall is made of chitin
b) Mode of nutrition is heterotrophic
c) They are saprophytes.
(iii) Symbiotic relationship.
Symbiosis is a situation in which 2 different organisms live together in close association.
They occur as greyish-green growths on bare rock surfaces, mountain tops, rocky seashores, bark of trees, on the ground, stone walls etc.
Question. (a) List any two main feature of chordates.
(b) Name the classes of vertebrates which have the following characteristics
(i) Animals have streamlined body and gills for breathing.
(ii) Animals are found both on land and in water.
(iii) Animals have mammary glands for the production of milk to nourish their young ones.
Answer. The two main features of chordates are-
(i) They have notochord
(ii) They are true coelomate animals and triploblastic.
(i) Pisces have streamlined body and gills for breathing
(ii) Amphibians are found both on land and in water
(iii) Mammals have mammary glands for the production of milk to nourish their young ones.
Question. Write one point of difference each between the following
(a) Porifera and coelenterate
(b) Birds and reptiles
Answer. (a) Porifera and coelenterate
(b) Birds and reptiles(consider any one difference)
1. They have four-chambered hearts.
1. They have three-chambered heart.
Question. Name the five classes of vertebrates and compare any two on the basis of their:
(ii) Covering of skin
(iii) Respiratory organs
(iv) Chambers of heart
Question. What are the important features of Kingdom Fungi?
Answer. Commonly known fungi are Yeast, mushroom, Penicillium, Aspergillus, etc.
Important features of fungi:
• Multicellular eukaryotic organisms
• Always heterotrophic (saprophytes) as they do not have chlorophyll and cannot prepare their own food by photosynthesis, live as saprophytes, parasites and symbiotic.
• Cell wall made of chitin, a complex nitrogen containing sugar that imparts toughness to cell wall.
• Mostly multicellular, only yeast is unicellular.
• Plant body contain thread-like hyphae (network is called mycelium).
• Reproduction occurs by spore formation.
• Examples- Rhizopus, Aspergillius, Pencillium and Mushroom.
Question. State the list of names of five kingdom of organism with the names of organism they are composed of.
Question. What is the difference between unicellular and multicellular organisms?
Question. What are the major divisions in the plantae? What is the basis for these divisions?
Answer. Major divisions of Kingdom plantae are-
The division is based on the following features-
• The first level of classification among plants depends on whether the plant body is well differentiated or not.
• The next level of classification is based on whether the differentiated body has special vascular tissues(xylem and Phloem) for the transport of water and other substances.
• Further classification is based on the ability to bear seeds.
Further it is classified whether the seeds are naked or enclosed within the fruit.
Question. Describe the classifications of Phanerogams:
Answer. Phanerogams are divided into Gymnosperms and Angiosperms.
Gymnosperms: The term ‘Gymnosperms’ is made from two Greek words: gymno–
means naked and sperma– means seed. Seeds are naked and reproductive organs are cones. They are non- flowering plants and are usually perennial, evergreen and woody.
Example – Pinus, deodar, fir
Angiosperms: The Word ‘Angiosperms’ is made from two Greek words: angio means covered and sperma– means Angiosperm have covered seeds(they are enclosed inside fruits) They are flowering plants and flowers are the reproductive organs.
Example – Coconut, palm, mango
Question. In how many phyla, the animal kingdom is divided into?
Answer. Kingdom Animalia is divided into nine phyla based on the extent and type of the body design differentiation found-
• Coelentrata(jellyfish, corals etc)
• Arthropoda(insects, spiders, crabs etc)
• Mollusca(snails, oysters etc)
• Echinodermata(starfishes, sea urchins etc)
• Chordata(animals with backbone)
Question. What are the characteristic features of Kingdom Porifera?
Answer. Porifera are pore-bearing animals called sponges.
• Sponges are the simplest multicellular animals with cellular differention, lacking organisation of tissues.
• They are mostly marine, fixed to the substratum and look like plants.
• Body is asymmetrical.
• The body has numerous pores on the surface, a cavity in the centre called
• spongocoel and a single large opening at the upper end called osculum.
• Circulating water canal system distributes food and oxygen to all the cell
• The body is covered by a hard outside layer or skeleton.
• Reproduction occurs by regeneration, asexual and sexual methods.
Question. What are the characteristic features of Kingdom Coelenterate?
Answer. Coelenterates are aquatic mostly marine; Hydra is found in fresh water.
• They have tissue level of organisation.
• Body is radically symmetrical
• They have central cavity called coelenteron, which has one opening.
• The body is made of two layers of cells: one makes up cells on the outside of the
• body, and the other makes the inner lining of the body.
• Some of these species live in colonies (corals), while others have a solitary life – span (hydra ).
• Reproduction takes place by sexual and asexual methods.
• Hydra, jellyfish and sea anemones are common examples.
Question. What are the characteristic features of platyhelminthes?
Answer. The characteristic features of platyhelminthes-
• The body is flat, leaf-like or tape-like, bilaterally symmetrical (left and right side of the body are similar)
• They are triploblastic with organ system of organisation
• Respiratory and circulatory systems are under developed
• Excretion occurs through flame cells
• The nervous system is primitive but with a brain
• They are either free-living or parasitic. Some examples are free-living animals like planarians, or parasitic animals like liver flukes.
Question. Mention the characteristic features of Anthropoda?
Answer. The characteristic features of Anthropoda are-
• Anthropoda is the largest group of animals.
• These animals are triploblastic, bilaterally symmetrical and segmented.
• They have jointed legs (the word ‘arthropod’ means ‘jointed legs’).
• There is an open circulatory system, and so the blood does not flow in welldefined blood vessels.
• Coelomic cavity is blood-filled(haemocoel)
• Some familiar examples are prawns, butterflies, houseflies, spiders, scorpions and crabs
Question. Mention the characteristic features of Mollusca:
Answer. The characteristic features of Mollusca are-
• They have soft body covered with a protective shell of calcium carbonate.
• There is bilateral symmetry.
• The coelomic cavity is reduced.
• There is little segmentation.
• They have an open circulatory system and kidney-like organs for excretion.
• There is a foot that is used for moving around.
• Examples are snails and mussels
Question. Mention the characteristic features of Echinodermata:
Answer. The characteristic features of Echinodermata
• In Greek, echinos means hedgehog, and derma means skin. Thus, these are spiny skinned organisms.
• These are exclusively free-living marine animals.
• They are triploblastic and have a coelomic cavity.
• They also have a peculiar water-driven tube system that they use for moving around.
• They have hard calcium carbonate structures that they use as a skeleton.
• Examples are starfish and sea urchins.
Question. Sheela shouted there is wall lizard in the room running on the wall. She started throwing shoes and other articles to hurt the lizard. Her mother came in the room and cools down the daughter and said it will not harm you. Do not hurt or kill it.
Answer the following questions based on the above information:
(a) Whether the wall lizard is poisonous?
(b) What is its food and how can it run on the vertical wall?
(c) Give one reason to justify that Sheela’s mother action is environment friendly.
Answer. (a) Wall lizards found in our houses are not poisonous.
(b) It eats insects. Lizards have pads on their feet. These pads consist of wide plates or scales and are present below their fingers and toes. The outer layer of each plate or scale is composed of innumerable tiny hooks for-med by free, bent tips of cells. These minute hooks create the conditions like a suction pump and thus, enable lizards to run up on apparently smooth walls and even upside down on plaster ceilings.
(c) Sheela’s mother avoided the killing of a living organism by clearing the myths that were believed by her daughter and maintain the food chain.
Question. During a field-trip some students visited an agricultural farm and saw a few birds eating earthworms. They enjoyed the scene and then they also started picking and killing the earthworms for pleasure. The farmer strongly objected and asked them to leave the field.
Read the above passage and answer the following questions:
(a) What could be the reason behind such a behaviour of the farmer?
(b) Which phylum do earthworm belong to?
(c) Give any two identifying features of an earthworm
(d) What values do you find missing in the student’s behaviour?
Answer. (a) The earthworm is considered to be the friend of a farmer since they further turn and loosen the soil .Like microbes, they also add humus to it by decomposing the dead plants and animals in the soil This was the reason on which farmer reacted.
(b) Earthworm belongs to the phylum – Annelida.
(c) Two identifying features of earthworm are
(i) Segmented bodies are key identifying features of earthworms as well as important structural adaptations.
(ii) Type and position of body bristles or satae.
(d) Values which are missing in the student’s behaviour were destructive behaviour and sadistic behaviour of the kids
Question. List a few flight adaptations in birds.
Answer. Flight adaptations of the birds are the following:
• Their forelimbs have become modified into wings for flying.
• Bird’s bones are hollow which makes birds’ bodies lightweight.
• Birds have feathers that help them fly. The long flight feathers on the wings and tail help birds balance and steer.
• The respiratory system of birds is also adapted to the demands of flight. Their bodies have air sacs helping them in double respiration
• Keratin beak is much lighter than a bony jaw with teeth
• Rapid, efficient digestion minimizes weight of digesting food.
• Body is streamlined to reduce air resistance during its flight.
• Ovaries and testes are reduced in size except in the breeding season.
• Birds have short, light and compact body as compared to other animals.
• Eyes are large, with wide field of view and binocular vision
Question. Why whales are not grouped in the fishes?
Answer. Originally, people thought that whales were very large fish because their bodies have a similar shape to that of fish. In 1778, Swedish biologist, Linnaeus, recognized that whales were not fish but mammals.
They share some common characteristics of all mammals.
1. They are endothermic: Their body-core temperature stays the same; it does not change with the temperature of their environment.
2. They breathe air with lungs.
3. They give birth to live young. Mothers (called cows) suckle their young (calves), on milk secreted by mammary glands.
4. They have hair. Although they are not covered in hair or fur like many mammals, whales have some bristles, usually on their heads.
5. They have four-chambered heart like mammals unlike fishes that have a two chambered heart.
Question. What are the important features of Kingdom Protista?
Answer. Kingdom Protista: It Includes protozoans such as, Amoeba, Paramecium, diatoms etc
Important features of protista:
• Unicellular, eukaryotic organism
• The cell has well defined nucleus with nuclear membrane and organelles.
• Cell wall may or may not be present.
• Can be autotrophic or heterotrophic
• Examples-Unicellular algae- Chlamydomonas, Euglena, Diatoms and Protozoans
• like Amoeba and Paramecium.
Question. What is the characteristic feature of cryptogamae? Name the 3 divisions included in it.
Answer. In Greek, crypto means concealed or hidden and ‘gamos’ means marriage. The cryptograms are flowerless and seedless plants. They are simple plants like algae, mosses and ferns which do not produce flowers, fruits and seeds. Since they do not have external flowers or seeds they are considered to have hidden reproductive organs. Theyreproduce through spores. The plant body in these organisms is undifferentiated, i.e, the stems, roots and leaves don’t show borders between them.
Cryptograms are considered as lower plants.
They are divided into bryophyta, thallophyta and pteridophyta.
Question. What are the characteristic features of sub kingdom phanerogamae?
Answer. This division is made up of plants that bear flowers and seeds and make up the majority of the larger plants. The body is differentiated into true stem, leaves and roots. Propagation of the plant takes place with the help of seeds. Seeds are formed as a result of sexual reproduction. The male and female gametes (sex cells) fuse together inside the ovary (female part of the flower) and develop into the seed. In some plants seed is not produced inside an ovary.
Phanerogamae is made into two further divisions.
• Gymnosperms (naked seeded plants)
• Angiosperms (Seed borne within a fruit)
Question. How are animals belonging to protochordates different from animals belonging to vertebrates?
Answer. Animals that have notochord are categorised into chordata. Some animals like Balanoglossus, Herdmania, Amphioxus etc. have a notochord, which is not present at all stages in their lifecycle, nor does it run the entire length of an animal’s body. Therefore, these animals are kept in a separate sub-phylum named Protochordataunder phylum chordata. In animals where the notochord is present throughout the life cycle and also has given rise to the vertebral column are called vertebrates. The members of sub-phylum Vertebrata under Phylum Chordata are advanced chordates that include animals belonging to classes- Pisces,Amphibia, Reptilia, Aves and Mammalia..