Class 9 Science Chapter 7 Important Questions

Class 9 Science Chapter 7 Important Questions of Diversity in Living Organisms. Class 9 Science Chapter 7 Extra Question Answers include all the intext questions as well as exercises questions.

These questions provide a perfect practice material for the revision of chapter and preparation of exams. Important Question answers take less time to revise and help to score better in all exams.

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Class 9 Science Chapter 7 Important Extra Questions for 2020-2021

Class: 9Science
Chapter: 7Diversity in Living Organisms
Contents:Important Questions with Answers

Class 9 Science Chapter 7 Important Extra Questions Set -1

Which organisms are called primitive?

Primitive organisms are those which have ancient body design and have not changed very much with the passage of time.

Name the branch of science that deals with classification.


What is biological classification?

The system of arrangement of different plants and animals in different groups on the basic of their similarities and differences is called biological classification.

Who was the first to classify animals according to their habitats?

Aristotle was the first one to classify animals according to whether they lived on land, in water or in air.

What is binomial nomenclature?

It is the system of naming in which the scientific name of an organism has two components, i.e. genus and species.

Class 9 Science Chapter 7 Important Extra Questions Set – 2

What is evolution?

The life forms that exist today have risen because of changes in their body design over a course of time to adapt themselves in the changing conditions. This is called evolution.

Who gave the idea of evolution for the first time in the book “Origin of Species”?

Charles Darwin.

What is a gene?

A genes is a group of related species.

Which groups of organisms do not have a defined nucleus or organelles?


Name the largest animal on the planet.

Blue whale (30 metres).

Classification of the Plant Kingdom

The plants have been classified on the following basis:

    • Phylogeny and evolution.
    • Presence or absence of vascular tissue for transport of food and water.
    • Presence or absence of seeds.
    • Presence or absence of fruits.

Class 9 Science Chapter 7 Important Extra Questions Set – 3

Name the largest tree on the Earth?

Redwood (100 metres).

Which plant has life span of more than one thousand years?

pine trees.

What are the tree aspects of systematic?

Identification, nomenclature and classification.

Name a coelenterate that occurs singly and is commonly found in freshwater ponds.


Name the group of sessile animals.


Class 9 Science Chapter 7 Important Extra Questions Set – 4

Name an organism that possesses flagella.


What are corals?

Corals are marine coelenterates that live in colonies firmly attached to rocks.

Name two marine solitary coelenterates?

Jelly fish and sea anemone.

Name the group of animals which developed nervous system for the first time?


In which sub-division does xylem possess vessels?


What are Amphibians?

Amphibians are the vertebrates that can live both on land and water. That is why they are also called the vertebrates leading two lives. Their body varies in form and the skin is not covered with scales. They lay eggs in water and their larval forms always live in water. Also amphibians are cold blooded animals having a three-chambered heart. They breathe through lungs or gills or skin.

Class 9 Science Chapter 7 Important Extra Questions Set – 5

Name the organism which has nervous system but no brain.


Which plants are perennial, evergreen and woody?


Name the reproductive organs of gymnosperm?


Name free living and parasitic flatworms.

Free living: Planaria; Parasitic: Tapeworm and liver fluke

What are hermaphrodites?

The animal that possess both male and female reproductive organ is called hermaphrodite; e.g. earthworm.

Class 9 Science Chapter 7 Important Extra Questions Set – 6

Name the group of animals which has primitive nervous system but with brain which is developed for the first time?


Name the first group of animals with true coelom.


Define metameric segmentation.

Metameric segmentation is a type of segmentation where external divisions correspond to internal divisions.

Name the cavity presents in the coelenterates.


What is haemocoel?

When a well defined cavity is absent and the spaces present contain colourless blood. i.e. haemolymph, it is called haemocoel.

What are Reptiles?

Reptiles are the crawling vertebrates that are cold blooded and have dry horn scales. They are mostly terrestrial and live in warmer regions. They breathe through lungs. The heart is three chambered, except for crocodiles which have four-chambered heart. Reptiles lay eggs with thick coverings.
Examples: Snakes, lizard, crocodiles, turtles etc.

Class 9 Science Chapter 7 Important Extra Questions Set – 7

Give the names of two groups of animals that are haemocoelomate.

Molluscs and arthropods.

What are the skeletal elements in sponges?

Needles called spicules and spongin fibres are the skeletal element in sponges.

What are excretory organs in flatworm?

Protonephridia or flame cells.

What are cnidoblasts?

The stinging cells present on the tentacles of coelenterates like Hydra, which inject hypnotoxin into the prey to hypnotise it.

What is the name given to the body cavity of nematodes?


Class 9 Science Chapter 7 Important Extra Questions Set – 8

Name a parasitic annelids.


What is polymorphism? Give an example.

The presence of more of more than two types of individual in a colony which differ in their structure and well as function is called polymorphism. Example honey bees.

Name two phyla which have open circulation.

Mollusca and Echinodermata

Name two phyla which have radial symmetry.

Echinodermata and coelenterate

Why do amphibians do not posses exoskeleton?

Amphibians do not posses exoskeleton as their skin is thin, moist and act as a respiratory organ.

The general characters of Kingdom Animalia

Sponge, molluscs, fishes, birds, reptiles and mammals all belong to kingdom Animalia.

    1. In kingdom Animalia, all the members are multicellular eukaryotes with tissue differentiation.
    2. They are heterotrophic with ingestive mode of intake of food.
    3. They posses a well developed nervous system.
    4. Muscular system is also well developed for locomotion.
    5. They exhibit sexual reproduction.

Class 9 Science Chapter 7 Important Extra Questions Set – 9

Why do birds posses hollow bones?

To make their body light in weight so as to make flying easier.

In which phylum are pharyngeal gill slits present?

Phylum chordata

What do you mean by characteristic?

Characteristic means a particular of any organism. For example, the presence of five fingers on each hand of human being is a characteristic.

Why was the method of classification of animals proposed by Aristotle not accepted?

Aristotle classified animals on the basic of their habitat, i.e. whether they live on land or in water. But these animals, otherwise are very different from each other in many respects and such a classification does not prove much helpful. So the method of classification by Aristotle was not accepted.

Describe the hierarchical system of classification currently followed.

Hierarchy of classification categories was established and designed by Linnaeus Hierarchy of classification is a system of arrangement of a framework in order of logical sequence. The currently followed hierarchical system for all organisms is (i) Kingdom (ii) Phylum/Division (iii) Class (iv) Order (v) Family (vi) Genus (vii) Species.

Class 9 Science Chapter 7 Important Extra Questions Set – 10

What are phanerogams?

Phanerogams or spermatophyta are the most advanced type of plants type of plants bearing seeds.They have roots, stems, leaves and flowers. They include gymnosperms and angiosperm.

What are mycoplasma?

Mycoplasma are the smallest and the simplest organisms. They are prokaryotes having nucleoid. They have heterotrophic mode of nutrition and their body can change forms easily. They are also called as MLO, i.e. Mycoplasma Like organisms.

What are lichens?

Lichens are compound plants as algae and fungi live together in close association, as a result of which both are benefited. This relationship is called symbiosis. They occur as greyish green growths on rocks, bark of the tree or on the ground.

Why are bryophytes called the amphibians of the plant kingdom?

Ans. The plant bodies of bryophytes are devoid of vascular tissues and roots. So they live in moist habitats in order to obtain water directly or through rhizoids. Moreover, like the amphibians of animal kingdom the sperms of bryophytes require an external water medium for reaching the eggs. Due to this reason, bryophytes are called the amphibians of the plant kingdom.

What is notochord? What is its functions?

Ans. Notochord is a long rod like support structures that runs along the back of the animals, separating the nervous tissue from the gut. It acts as a supporting structure by providing a place for muscles to attach for the case of movement.

Similarities between Plants and Animals
    • Plants and animals are both made up of cells.
    • Both contain protoplasm and the genetic material, DNA.
    • Both plants and animals show growth.
    • Both show response to external stimuli.
    • Both plants and animals reproduce and pass on their characters to the offspring by the same mechanism.

Class 9 Science Chapter 7 Important Extra Questions Set – 11

Why do we keep both snake and turtle in the same class?

Why do we keep both snake and turtle in the same class because both are (i) Cold-blooded, (ii) have scales (iii) Breath through lungs, (iv) have three chambered hearts and, (v) lay eggs with thick covering.

Give reasons why mosses are found in humid and moist areas.

The entire body of moss in damp humid places can absorb water. Moreover, sperms in mosses are flagellated and so they can reach the archegonia only in presence of water. Thus water is indispensable in the life cycle of mosses for reproduction as well as for performing other physiological functions.

What is binomial nomenclature?

In binomial nomenclature name of every organism is composed of two components the first one is generic (genus) and the second one is specific. Also the generic name starts with a capital letter whereas the specific name starts with small letter. For example, the scientific name of man is Homo species. Here “Homo” is the generic and “sapiens” is the specific name.

Which organism is more complex is more complex and evolved among bacteria, mushroom and mango tree? Give reasons.

Mango tree is more complex and evolved because it is eukaryotic, autotrophic, terrestrial and a sporophyte which covered seed. The bacteria is a unicellular prokaryotic and fungi is heterotrophic, simple thallophyte with no tissue system

Endoskeleton of fishes are made up of cartilage and bone. Classify the following fishes as cartilaginous or bony: Torpedo, Sting ray, Dog fish, Rohu, Angler fish, Exocoetus

Torpedo – Cartilagenous
Dog fish – Cartilagenous
Angler fish – Cartilageous
Sting ray – Cartilagenous
Rohu – Bony
Exocoetus – Bony

Class 9 Science Chapter 7 Important Extra Questions Set – 12

What is a species? Give its main features.

Species is defined as a dynamic group of organism, which resemble each other in all essential aspects, i.e., structure and function and interbreed to produce fertile young ones of their own kind. The members of a species are reproductively isolated from the groups. They have descended from a common ancestor and have similar genetic material.

State reasons for each of the following: (i) Echidna and platypus lay eggs but are considered as mammals. (ii) Forelimbs of bird are modified. (iii) Crocodile have four chambered heart but are still reptiles.

(i) They have mammary glands for the production of milk to nourish their young ones.
(ii) To reduce body weight for flight, forelimbs of birds are modified.
(iii) Crocodiles are cold blooded, lay eggs and have scale on their body. These characteristic make them reptile.

Different between species and taxon.

Species and taxon different in the following ways:
(i) Species represents the basic taxonomic category while the taxon represents any level of taxonomic category.
(ii) Species is always monophyletic while taxon may be monophyletic or polyphyletic.
(iii) Species, being a rank, is an abstract term while a taxon represents a group of various living beings.

Enlist the main features of organisms placed under Protista.

(i) Most of the members are unicellular and primarily aquatic.
(ii) They have nucleus and typical eukaryotic cell organelles.
(iii) Most of the organisms bear flagella or cilia for movements.
(iv) Mode of nutrition is absorptive, ingestive or photo-autotrophic.
(v) Reproduction may be asexual or sexual.

Give the main features of kingdom Fungi.

(i) They are non-green because of the absence of chlorophyll.
(ii) They are heterotrophic and obtain food from dead and decaying organic matter by absorption.
(iii) The body organization is mycelial or secondarily unicellular.
(iv) Cell wall is chitinous and cellulosic.
(v) Asexual reproduction is by spore formation. Some also exhibits sexual reproduction.

The important features of class Mammalia

The important features of class Mammalia are:

    1. They are warm blooded animals.
    2. Their heart is four chambered.
    3. They have mammary glands which produce milk with which they nourish their young ones.
    4. They give birth to young ones with the exception of platypus and echidna. Kangaroos gives birth to very poorly young ones.

Class 9 Science Chapter 7 Important Extra Questions Set – 13

Write the main characteristic of kingdom Plantae.

(i) They are all complex multicellular plants which prepare their own food by photosynthesis.
(ii) They posses cell wall made of cellulose.
(iii) Plants are immobile and do not show locomotion.
(iv) They have unlimited growth and grow throughout their lives.

Give the main features of algae.

(i) They are autotrophic as they posses chlorophyll.
(ii) They are mainly aquatic but some also grow in moist places.
(iii) They body is not divided into root, stem and leaves.

Give the important features of division Bryophyta.

(i) Bryphyta are called the amphibians of the plant kingdom.
(ii) The plant body is commonly differentiated to form stem and leaf-like structures. But there is no specific tissue for conduction of water and other substance.
(iii) Vegetative reproduction is very common.
(iv) Sexual reproduction is of oogamous type i.e. the male gamete is small and motile and the female gamete is non-motile and large for example moss, funaria and marchantia.

Give the main features of Pteridophyta.

Following are the main features of Pterodophyta:
(i) The plant body is divided into root, stem and leaves.
(ii) The fertilised eggs form embryo.
(iii) They are also called vascular cryptogams as they have a developed vascular system.
(iv) They have multicellular reproductive system.

Blue green algae have been included under the group Monera and not under Plantae. Why?

Monera is a kingdom of prokaryotes while organism of kingdom Plantae are eukaryotes with defined nucleus membrane bound organelles and multicellular body design. Blue- Green algae are prokaryotes having nucleoid with naked DNA. The cell organelle is also not enclosed in membrane as they also do not posses multicellular body design, these characters bring them closer to monera and exclude them from the kingdom plantae.

Class 9 Science Chapter 7 Important Extra Questions Set – 14

What are the difference between bilateral and radial symmetry?

An animal is said to have bilateral symmetry if it has two equal but opposite right and left halves when cut lengthwise in the middle vertical plane example, frog. On the other hand, an animal is said to have radial symmetry, if it is symmetrical with respect to any plane passing through its longitudinal axis. IN other words, any plane passing longitudinally through any diameter divides the body into equal halves example Hydra.

How is notochord different from nerve cord?

Notochord is the skeletal rod which lies lengthwise between the central nervous system and the alimentary canal or the gut and the chordates possess it at young stage of development. In adult vertebrates it is replaced by vertebral column. On the other hand, a nerve cord is a solid strand of nervous tissue, forming part of central nervous system, especially of invertebrates. The main difference between the two is that notochord is a part of skeleton system whereas nervous cord is a part of nervous system.

Define the term and give one example of each. (i) Coelom (ii) Triploblastic

(i) Coelom is the internal body cavity between visceral organs and body wall in which well-developed organs can be accommodated for example in butterfly.
(ii) Animals having three layers of cells from which differentiated tissue can be made are called triplolastic for example star fish.

Classify the following organisms based on the absence/presence of true coeloem (i.e) aceolmate, [pseudocoelomate and coelomate] Spongilla, sea anemone, Planaria, Liver fluke wuchereria, Ascaris, Nereis, Earthworm, Scorpion. Birds, Fishes. Horse.

Spongilla – Acoelmate
Planaria – Acoelomata
Wuchereria – Pseudocoelomate
Nereis – Coelmata
Earth worm- Coelmate
Sea anemone – Acoelomate
Liver fluke – Acoelomate
Ascaris – Pseudocoelomate
Scorpion – Coelmate
Birds, Fishes and Horse- Coelomate.

List some four feature in cat, rat and bat.

Bat, rat and cat belong to the class mammalia and all have following common features:
(i) have notochord at some stage of life cycle.
(ii) are warm-blooded
(iii) have four chambered heart
(iv) have skin covered with hair and sweat and oil glands.

Class 9 Science Chapter 7 Important Extra Questions Set – 15

Give the main feature of the phylum Porifera.

(i) They are primitive animals.
(ii) They are generally multicellular organisms with specialised cells but these cells do not group together to form tissues.
(iii) Most of them are marine i.e. found in the seas. Some of them are also found in ponds and rivers.
(iv) They posses pores all over the body.
(v) Reproduction cab be by both sexual and asexual methods.
(vi) Sensory system is absent.
(vii) Mouth and anus are absent.
(viii) A distinct canal system with inlets and outlets for water circulation inside the body is present. They obtain food and oxygen by means of water. The collar cells filter out food particles from the water current flowing through the canal system.
Example are: Sycon, Spongilla and Euplectella.

Give the main feature of coelenterates.

(i) Diploblastic animals with tissue level organisation in the body.
(ii) The body is radially symmetrical.
(iii) The body bears tentacles supplied with special stinging cells called cnidoblasts.
(iv) There is a cavity in the body.
(v) Body is made up of two layers of cells.
(vi) Simple gonads without gonaducts are present.
(vii) Reproduction is usually asexual (budding) in polyp form sexual in medusae form.
(viii) They show polymorphism.
Examples: Hydra, Obelia and jelly fish.

(i) List three characteristic distinguish amphibians from pieces: (ii) Classify the following living organisms as cold-blooded and warm-blooded animals: Shark, Lizard, Sparrow, Rohu.

(i) Following characteristic distinguish amphibians from pieces:
1. Amphibians lack scales whereas skin of pisces are covered with scale.
2. Amphibians have mucous glands.
3. Amphibians have a three chambered heart unlike pisces, their hearts have only two chambered.
(ii) Cold-blooded: Shark, rohu, Lizard
Warm-blooded: Sparrow.

Describe the feature of phylum Platyhelminthes.

(i) They show bilateral body symmetry.
(ii) Their body is dorsoventrally flattened like a ribbon. So they are also called flatworms.
(iii) Most of them are parasitic only a few are free living.
(iv) They are mostly hermaphrodites.
(v) There are three embryonic layers of cells in their body. So they are triploblastic.
(vi) They body dies not have any pore or cavity.
(vii) They have power of regeneration.
Examples: Fasciola and Taenia solium.

Write the important features of phylum Aschelminthes (Nematoda)

(i) Most of them are small and cylindrical. So they are also called as round worms.
(ii) The body size ranges from microscopic to a few centimeters in length.
(iii) They all are mainly heterotrophic animals.
(iv) They are triploblastic.
(v) Body cavity has a true coelom.
(vi) Respiratory and circulatory systems are absent.
(vii) They have complete alimentary canal.
(viii) Sexes are separate.
Examples: Ascaris, Enterobius and Wuchereria.

Difference between Chordates and Non-Chordates

1. Vertebral column is present.1. vertebral column is absent.
2. it is hollow and dorsal.2. Central nervous system is solid and ventral.
3. Heart is ventral.3. If heart is present it is dorsal.
4. Haemoglobin is present in the red blood corpuscles.4. Haemoglobin, if present is dissolved in plasma.
5. A post-anal tail is present.5. The anus is posterior, so no post-anal tail.
6. Examples: Pisces, Aves, Reptilia, Mammals.6. Examples: Protozoa, Arthropoda, Annelida.

Class 9 Science Chapter 7 Important Extra Questions Set – 16

Enlist the main features of phylum Annelida. Give examples.

(i) Body of annelids are bilaterally symmetrical.
(ii) They are triploblastic.
(iii) Metameric segmentation is present.
(iv) Nephridia for execration and osmoregulation are present.
(v) Closed circulatory system with respiratory pigment dissolved in the plasma.
(vi) These animals are found in a variety of habits like fresh water, marine water as well as on land.
Examples are: Nereis (sand worm or calm worm), Aphrodite (sea mouse), Pheretima (earthworm).

Give the important distinguishing features of Arthropoda.

(i) These animals are bilaterally symmetrical and segmented.
(ii) Body is converted with chitinous exoskeleton.
(iii) One or two pairs of joined legs are present.
(iv) The body cavity is blood-filled and is called haemocoel.
(v) Body bears jointed appendages, and is divided into head, thorax and abdomen.
(vi) Circulatory system is open i.e., blood doesn’t flow inblood vessels.
Examples are: Palaemon, cockroach and butterfly.

What are vertebrates? What are their main features?

Vertebrates are the animals included in the phylum chordata in which the spinal chord is made of small vertebra.
There are five classes of vertebrates:
(i) Pisces (ii) Amphibians (iii) Reptiles (iv) Aves and (v) Mammalia.
The main features of vertebrates are given as under:
(i) They possess a solid notochord
(ii) The body has bilateral symmetry.
(iii) They have a true vertebral column.
(iv) They have a dorsal hollow nerve cord.
(v) They are triploblastic.
(vi) The terrestrial forms respire through lungs and the aquatic forms through gills.
(vii) They are coelomate.

What are the characteristics of kingdom monera?

Following are the characteristics of kingdom Monera:
(i) The organism do not possess a clearly defined nucleus i.e. the nucleus is not enclosed by a nuclear membrane.
(ii) Cell organelles are also not covered with a membrane.
(iii) Organisms are unicellular, microscopic prokaryotes living in moist conditions.
(iv) Cell wall may or may not be present.
(v) The mode of nutrition may be autotrophic or heterotrophic.
(vi) Reproduction is primarily asexual by binary fission or budding.