Diversity in Living Organisms Class 9 Science Exam Questions

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Class 9 Science Exam Questions Diversity in Living Organisms

Class 9 Science students should read and understand the important questions and answers provided below for Diversity in Living Organisms which will help them to understand all important and difficult topics.

1 Marks Questions

Question. Define radial symmetry?
Answer. Radial symmetry means that the left and the right halves of the body have the same design.

Question. What is osculum?
Answer. The body of sponge is porous and the pores are called ostia. Single large opening or pore is called osculum.

Question. Name two phyla which have open circulation:
Answer. Anthropoda, Mollusca and Echinodermata

Question. Which type of symmetry is present ina)
a) Starfish
b) Earthworm
Answer. a) Starfish- Radial symmetry
b) Earthworm- bilateral symmetry

Question. Name two groups of warm blooded animals with four-chambered heart.
Answer. (i) Aves
(ii) Mammals.

Question. What are the two mains divisions of the Phylum Chordate?
Answer. Chordates are divided into protochordates and vertebrates.

Question. Give one use of lichen.
Answer. Lichens are great indicators in telling us how polluted the air is, because lichens aresensitive to polluted air and are the first to disappear in that case.

Question. Classify the following seeds into dicot and monocot : Wheat, Maize, Bean, Gram.
Answer. Dicot seeds – Bean, Gram.
Monocot seeds – Wheat, Maize

Question. What are flame cells?
Answer. Flame cells are excretory structures of Platyhelminthes. Besides excretion, they are also osmoregulatory in function.

Question. What is the scientific name of humans?
Answer. Homo sapiens.

Question. How many carnivores belonging to cat family did you see in the zoo? What is given to them to eat?
Answer. Three (Lion, Tiger, Leopard) – Flesh of animals is offered to them for eating.

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. What is chemical characteristics of fungal cell wall?
Answer. In fungi, the cell wall is made of chitin.

Question. Name the group of sessile animals that also have numerous pores all over the body?
Answer. Kingdom Porifera.

2 Marks Questions

Question. What is evolution?
Answer. Evolution is the gradual unfolding of organisms from the pre-existing ones through changes since the beginning of life.

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.

Question. What is the destination of the notochord in vertebrates and in protochordates?
Answer. In vertebrates, the notochord disappears and gives birth to the spinal column (vertebral column). In protochordates, the notochord remains for the rest of the life.

Question. Give one word for the following:
i. The smallest unit of classification
ii. The largest unit of classification
iii. A collection of related species
iv. A group of related families
Answer. i. Species
ii. Kingdom
iii. Genus
iv. Order

Question. Why are thallophytes called non-embryonic plants?
Answer. Thyllophytes have simple body (thallus) and their gametes are unicellular. After fertilisation, the zygote does not form an embryo. Therefore, these plants are called non-embryonic plants.

Question. What are the differences between vertebrates and the other chordates?
Answer. Vertebrates are different because they have a spinal column (vertebral column). In these animals the notochord of the embryonic stage is substituted by the vertebral column in adults.

Question. What are the differences between vertebrates and the other chordates?
Answer. Vertebrates are different because they have a spinal column (vertebral column). In these animals the notochord of the embryonic stage is substituted by the vertebral column in adults.

Question. Why are bryophytes called amphibians of the plant kingdom?
Answer. Bryophytes are also called amphibians of the plant kingdom because they can live on soilbut need water for sexual reproduction. They are usually found in damp, humid and shaded localities.

Question. Name the two subkingdoms of plant kingdom.
Answer. Eichler in 1883 suggested a system to classify the plant kingdom which is well accepted. He said that the plant kingdom is subdivided into two subkingdoms: Cryptogamae and Phanerogamae.

Question. Name the scientists who gave 2-kingdom and 5-kingdom classification respectively.
Answer. Two kingdom classification was given by Carolus Linnaeus
Five kingdom classifications were given by Robert H. Whittaker.

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. 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
(ii) Saprophytic
(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. How angiosperms are divided further?
Answer. Angiosperms are divided into 2 groups on the basis of the number of cotyledons present in the seed.
Monocotyledonous or monocots: These are the plants with seeds having a single cotyledon. E.g., maize, wheat, rice etc
Dicotyledonous or dicots: These are plants with seeds having two cotyledons. E.g., Pea, gram, bean etc

Question. Which type of circulatory system do molluscs have? How can it be compared to the circulatory system of annelids?
Answer. With the exception of few, most of the molluscs have an open circulatory system, i.e., the blood circulates within vessels, from the heart, but it also fills open cavities. In annelids, the circulatory system is closed, i.e., the blood circulates only inside blood vessels.

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. Name the locomotory organs in insects.
Answer. Many adult insects use six legs for walking. ie. They have three pairs of jointed legs that allows for rapid walking while always having a stable stance (posture). They also have two pairs of wings that are mostly used for flying.

Question. Why are air bladders present in fishes?
Answer. The air bladders help a fish to adjust its buoyancy in water. In other words it helps a fish float or sink no matter the size. Air bladder is also known as the swim bladder. The swim bladder allows the fish to move up and down through the water or remain motionless in one place.

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. Name the following :
Answer. (a) Free living Platyhelminthes ;
(b) Scientific name of pork tape worm.
(a) Planaria
(b) Taenia solium.

Question. Who proposed division of Monera kingdom ? State the groups proposed Carl Woese.
Answer. The groups are –
(i) Archaebacteria or Archaea
(ii) Eubacteria or Bacteria.

Question. Why blue green algae are included under Monera and not under Plantae?
Answer. (i) Nuclear material is not enclosed with nuclear membrane and cell organelles are also not enclosed with membrane.
(ii) Do not show multicellular body design.

Question. Based of which character the phylum Echinodermata has been named?
Answer. In Greek, echinos means hedgehog, and derma means skin. Thus, these are spiny skinned organisms. Thus, the phylum Echinodermata has been named based on the presence of spiny skin.

Question. In which habitats do molluscs live? Name some examples of the phylum Mollusca?
Answer. Molluscs can be found in the sea, freshwater and in terrestrial environments. Snails, octopuses, squids and oysters are examples of molluscs.

Question. Which are the morphological features that differentiate the beings of the phylum Annelida from nematodes and platyhelminthes?
Answer. Platyhelminthes are worms with flat bodies (flatworms), nematodes are worms with cylindrical but not segmented bodies (roundworms). Annelids are cylindrical worms with segmented bodies.

Question. Define Aschelminthes:
Answer. Aschelminthes is a phylum of unsegmented, triploblastic, pseudocoelomate, cylindricalor thread-like worms having bilateral symmetry and body wall covered with cuticle and epidermis.

3 Marks Questions

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. Give any 5 difference between monocot and dicot plants
Answer. 

Question. Give uses of lichens.
Answer. i) One of the most important uses of lichens is their sensitivity to pollution.
ii) Lichens have been used for centuries to create natural dyes for fabrics.
iii) Many lichens contain acids and other essential oils that are useful in making perfumes and scents.
iv) Some lichens are used in medicines

Question. Name some edible fungi and their uses.
Answer. Edible fungi and their uses are as follows
(i) Yeast has been used as leavening agent for the production of bread
(ii) The first antibioticused in modern medicine, penicillin, was isolated form Penicillium
(iii) Mushrooms have fleshy fruit body with certain aroma and flavors as well as good nutritional properties and are used mostly as food.
(iv) Fungi such as the Chinese caterpillar fungus, which parasitize insects, can be extremely useful for controlling insect pests of crops

Question. Bacteria, fungi and plants all have the cell wall, but they are placed in the different groups or division. Why?
Answer. Bacteria, fungi and plants showed a characteristic difference in their walls composition – In bacteria, the cell wall is made of peptidoglycans; In fungi, the cell wall is made of chitin (the same substance that makes the exoskeleton of arthropods) In plants, the cell wall is made of cellulose too. Therefore, bacteria, fungi and plants are placed in the different groups or division.

Question. While walking along roadside, Sunil asked his father, a biology teacher, whether some small, green, non-flowering, leafy and thalloid plants, having little differentiation of body and growing along pavement are of any use to us.
Father answered that these plants are small but they play very important role in maintaining green cover on the land.
(i) To which group these small thalloid, green, non-flowering plants belong?
(ii) In what way bryophytes are useful to us?
(iii)Which other groups of plants act as colonizers of barren rocks and make land suitable for growth of higher plants? Do these plants play some role in pollution monitoring?
Answer. (i) These small thalloid, green, non-flowering plants belong to the group calledbryophytes.
(ii) Bryophytes are also used in horticulture as soil additives, ornamental material for cultivation, and for beautification of gardens.
(iii) Mosses and Lichens act as colonizers of barren rocks and make land suitable for growth of higher plants. They are also good indicators of atmospheric quality.

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. 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. 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. 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. 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 bilaterally symmetrical 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. 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. 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. 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.
• Protochordates 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. 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..

Question. Difference between diploblastic and triploblatic:
Answer. 

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.

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. 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. Give scientific terms for the following:
Answer. (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.
(a) Coelom
(b) Notochord
(c) Reptilia
(d) Porifera (sponges).

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 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. 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. 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. 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. 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-chambered heart
(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 as Binomial 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 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. 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 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. 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. State reasons for the following:
Answer. (a) Fungi are called saprophytes
(b) Platyhelminths are called so,
(c) Birds have hollow bones.
(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.

4 Marks Questions

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. 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. (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
(2) Movement
(3) Body parts
(4) Respiration
(5) Reproduction
(ii) Three characteristic features of fungi area)
a) 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. 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

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