CBSE Class 9 Science Diversity in Organisms Sure Shot Questions Set 01

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ASSIGNMENT QUESTIONS SET - 1
CLASS IX : CHAPTER - 7
DIVERSITY IN ORGANISMS

1. What do you mean by bio diversity?

Answer: Biodiversity is the variety of life on Earth, covering the different plants, animals and microorganisms, their genes, and the ecosystems they form.

Teacher's Note:
a) Biodiversity includes three levels: genetic, species and ecosystem diversity.
b) Do not confuse it with the number of species alone; variety in genes and habitats counts too.

2. Why do we classify organisms?

Answer: We classify organisms so that the huge number of living beings can be studied in an orderly way, their similarities and differences understood, and their evolutionary relationships known.

Teacher's Note:
a) Classification groups organisms with similar features together.
b) A student should link classification with the idea of studying a large number of organisms easily.

3. What are the advantages of classification?

Answer: The advantages are that organisms can be identified and named easily, their relationships become clear, and a large number of organisms can be organised and studied in a systematic manner.

Teacher's Note:
a) Classification gives a universal system of naming, which all scientists use.
b) It also helps in predicting features of organisms that belong to the same group.
c) Write the key term first, then the explanation, so that the answer is complete.

4. Define Taxonomy.

Answer: Taxonomy is the branch of biology that deals with the identification, naming and classification of organisms.

Teacher's Note:
a) Taxonomy comes from the Greek words taxis (arrangement) and nomos (law).
b) Do not write only 'classification'; the term also includes naming and identification.

5. Who is known as father of taxonomy?

Answer: Carolus Linnaeus is known as the father of taxonomy.

Teacher's Note:
a) Linnaeus introduced the binomial system of naming organisms.
b) He is also remembered for the hierarchy of classification levels.

6. Give three examples of the range of variations that you see in lifeforms around you.

Answer: Three examples are the variation in size (from a tiny ant to a tall tree), the variation in colour (red and white flowers of the same plant type), and the variation in habitat (fish living in water and birds living in air).

Teacher's Note:
a) Variations in size, colour, shape and habitat are all examples of diversity.
b) Give examples from your own surroundings to make the answer clear.
c) Write the key term first, then the explanation, so that the answer is complete.

7. What is the primary reason for such a huge diversity we find in animals and plants?

Answer: The primary reason is evolution, which results in genetic variation and adaptation of organisms to different habitats over long periods of time.

Teacher's Note:
a) Evolution produces new species from existing ones.
b) Different environments favour different features, so diversity increases.

8. Which do you think is a more basic characteristic for classifying organisms? (a) the place where they live. (b) the kind of cells they are made of. Why?

Answer: The kind of cells they are made of (option b) is the more basic characteristic. It reflects the fundamental organisation of the body, whereas the place where an organism lives can be shared by unrelated organisms.

Teacher's Note:
a) Cell type (prokaryotic or eukaryotic) is a stable, inherited feature.
b) Habitat can change with environment, so it is not a reliable basis for grouping.

9. What is the primary characteristic on which the first division of organisms is made?

Answer: The first division of organisms is made on the basis of the type of cell organisation, that is, whether the cells are prokaryotic (no well-defined nucleus) or eukaryotic (well-defined nucleus).

Teacher's Note:
a) Prokaryotes include bacteria and blue-green algae.
b) Eukaryotes include protists, fungi, plants and animals.
c) Write the key term first, then the explanation, so that the answer is complete.

10. Define Taxon.

Answer: A taxon is a taxonomic unit at any level of classification, such as a kingdom, phylum, class, order, family, genus or species.

Teacher's Note:
a) Taxon is the plural of taxa.
b) Each level of the hierarchy is a taxon.

11. On what bases are plants and animals put into different categories?

Answer: Plants and animals are put into different categories on the basis of their cell structure, body organisation, mode of nutrition, presence or absence of chlorophyll and cell wall, and mode of reproduction.

Teacher's Note:
a) Animals are heterotrophic and generally lack cell walls, whereas plants are autotrophic.
b) Chlorophyll is the key feature that separates most plants from animals.

12. Who wrote the book The Origin of Species?

Answer: Charles Darwin wrote the book The Origin of Species.

Teacher's Note:
a) Darwin proposed the theory of natural selection in this book.
b) The book was published in 1859.
c) Write the key term first, then the explanation, so that the answer is complete.

13. Which region of the earth is called the region of megadiversity?

Answer: The tropical regions of the earth are called the region of megadiversity, because they have the highest number of species.

Teacher's Note:
a) Megadiversity regions have very high species richness and many endemic species.
b) The tropics receive abundant sunlight, water and warmth, which support high diversity.

14. Name five countries that lie in the region of megadiversity.

Answer: Five countries in the region of megadiversity are Brazil, Colombia, Ecuador, Peru and Mexico.

Teacher's Note:
a) Other examples include Indonesia, India and Madagascar.
b) Only five names are needed for this answer.

15. Define evolution.

Answer: Evolution is the gradual change in the characteristics of populations of organisms over successive generations, which can lead to the formation of new species.

Teacher's Note:
a) Evolution occurs through variation and natural selection.
b) Evolution is slow and happens over long periods of time.
c) Write the key term first, then the explanation, so that the answer is complete.

16. Based on evolution, primarily how organisms are categorized?

Answer: Based on evolution, organisms are categorised according to their evolutionary relationships, that is, how closely they are related through common ancestors.

Teacher's Note:
a) Organisms with more common ancestors are placed in the same group.
b) This approach shows the evolutionary history of living beings.

17. Which organisms are called primitive and how are they different from the so-called advanced organisms?

Answer: Organisms with simple body designs that appeared early in evolution are called primitive organisms (for example, bacteria and algae). They differ from advanced organisms, which have more complex and specialised body structures and appeared later in evolution.

Teacher's Note:
a) Primitive organisms often have simple cells or simple body plans.
b) Advanced organisms show specialised tissues and organs.

18. Will advanced organisms be the same as complex organisms? Why?

Answer: No, advanced organisms are not always complex. Advancement refers to the evolutionary position of an organism, while complexity refers to the structure of its body. Some organisms are simple yet recently evolved.

Teacher's Note:
a) Advanced and complex are different ideas and should not be used as synonyms.
b) Evolutionary position depends on the lineage, not only on structure.
c) Write the key term first, then the explanation, so that the answer is complete.

19. Name the book written by Carolus Linnaeus on classification of organisms.

Answer: The book is Systema Naturae.

Teacher's Note:
a) Linnaeus first published Systema Naturae in 1735.
b) The book introduced a systematic way of naming and classifying organisms.

20. In how many kingdoms Carolus Linnaeus diving living beings?

Answer: Carolus Linnaeus divided living beings into two kingdoms: Plantae and Animalia.

Teacher's Note:
a) Plantae included all plants, and Animalia included all animals.
b) Linnaeus did not have a separate kingdom for microorganisms.

21. Name the levels of classification proposed by Linnaeus. What happens to similarities among organisms as we go from top to bottom level?

Answer: The levels of classification are kingdom, phylum (division for plants), class, order, family, genus and species. As we go from the top level to the bottom level, the similarities among organisms increase, and the number of organisms in each group decreases.

Teacher's Note:
a) Remember the order: King Philip Came Over For Good Soup.
b) At the species level, the organisms are most similar.
c) Write the key term first, then the explanation, so that the answer is complete.

22. In the hierarchy of classification, which grouping will have the smallest number of organisms with a maximum of characteristics in common and which will have the largest number of organisms?

Answer: The species level has the smallest number of organisms with the maximum characteristics in common. The kingdom level has the largest number of organisms.

Teacher's Note:
a) A species is a group of organisms that can interbreed and produce fertile offspring.
b) The kingdom is the highest taxonomic category.

23. Name the scientist who created the third kingdom for all microscopic unicellular organisms. What did he call it?

Answer: Ernst Haeckel created the third kingdom for all microscopic unicellular organisms, and he called it Protista.

Teacher's Note:
a) Haeckel proposed Protista as a kingdom between plants and animals.
b) Protists are mostly unicellular eukaryotes.

24. Who identified the Fungi as a separate multicellular eucaryotic kingdom and introduced five kingdoms? Name the five kingdoms.

Answer: R.H. Whittaker identified Fungi as a separate multicellular eukaryotic kingdom and introduced the five-kingdom system. The five kingdoms are Monera, Protista, Fungi, Plantae and Animalia.

Teacher's Note:
a) Whittaker proposed this system in 1969.
b) Fungi were earlier placed in the plant kingdom.
c) Write the key term first, then the explanation, so that the answer is complete.

25. Explain the basis for grouping organisms into five kingdoms.

Answer: Organisms are grouped into five kingdoms on the basis of cell structure (prokaryotic or eukaryotic), body organisation (unicellular or multicellular), mode of nutrition (autotrophic or heterotrophic), and phylogenetic relationships.

Teacher's Note:
a) Mode of nutrition helps separate plants (autotrophic) from animals (heterotrophic).
b) Cell type separates Monera from the other four kingdoms.

26. What is the criterion for classification of organisms as belonging to kingdom Monera or Protista?

Answer: Monera are prokaryotic organisms without a well-defined nucleus, while Protista are unicellular eukaryotic organisms with a well-defined nucleus.

Teacher's Note:
a) The presence or absence of a nuclear membrane is the key difference.
b) Bacteria belong to Monera, and Amoeba belongs to Protista.

27. In which kingdom will you place an organism which is singlecelled, eukaryotic and photosynthetic?

Answer: Such an organism is placed in the kingdom Protista, for example Chlamydomonas or Euglena.

Teacher's Note:
a) Single-celled and eukaryotic features point to Protista.
b) Photosynthesis is found in some protists, such as algae.
c) Write the key term first, then the explanation, so that the answer is complete.

28. In which kingdom you will place an organism which is multicellular, eukaryotic, non-green heterotroph or saprophytic, lacks chlorophyll and has absorptive mode of nutrition?

Answer: Such an organism is placed in the kingdom Fungi, for example bread mould or mushroom.

Teacher's Note:
a) Fungi absorb digested food from dead and decaying matter.
b) Fungi have cell walls made of chitin.

29. In which kingdom, you will place an organism which is multicellular, eukaryotic, heterotroph, lacks chlorophyll and has ingestive mode of nutrition.

Answer: Such an organism is placed in the kingdom Animalia, because animals are multicellular, heterotrophic and take food by ingestion.

Teacher's Note:
a) Ingestion means taking food into the body and digesting it internally.
b) Animals lack cell walls and chlorophyll.

30. What is the contribution of Carl Woese (1977) in classification of living beings?

Answer: In 1977 Carl Woese showed, by comparing ribosomal RNA sequences, that archaebacteria are distinct from other bacteria. His work led to the three-domain system of Archaea, Bacteria and Eukarya.

Teacher's Note:
a) His work was based on molecular evidence rather than only on body structure.
b) Woese's findings changed the view of the evolution of prokaryotes.
c) Write the key term first, then the explanation, so that the answer is complete.

31. Name the organisms which are outside the classification.

Answer: Viruses and viroids are outside the five-kingdom classification, because they are non-cellular.

Teacher's Note:
a) Viruses are made of nucleic acid and a protein coat only.
b) Viruses reproduce only inside a host cell.

32. According to the five-kingdom system, which kingdom contains organisms whose structure is composed of prokaryotic cells?

Answer: The kingdom Monera contains organisms whose structure is composed of prokaryotic cells.

Teacher's Note:
a) Monera includes bacteria, cyanobacteria and archaebacteria.
b) Prokaryotic cells lack a well-defined nucleus.

33. Blue green algae are classified with bacteria and placed in kingdom Monera.

Answer: This statement is correct. Blue-green algae (cyanobacteria) are prokaryotic, so they are placed with bacteria in the kingdom Monera.

Teacher's Note:
a) Blue-green algae are prokaryotes, not true algae.
b) They are also known as cyanobacteria.
c) Write the key term first, then the explanation, so that the answer is complete.

34. What (a) What are saprophytes? (b) Name the kingdom to which they belong. (c) What is the cell wall of fungi made up of?

Answer: (a) Saprophytes are organisms that feed on dead and decaying organic matter. (b) Most saprophytes belong to the kingdom Fungi. (c) The cell wall of fungi is made up of chitin.

Teacher's Note:
a) Saprophytes release digestive enzymes outside their body.
b) Chitin is also found in the exoskeleton of arthropods.

35. How do the saprophytes get their food? Give two examples of a saprophyte.

Answer: Saprophytes release digestive enzymes onto dead and decaying matter, digest it outside the body, and then absorb the nutrients. Two examples are bread mould (Rhizopus) and mushroom.

Teacher's Note:
a) This mode of nutrition is called extracellular digestion or absorptive nutrition.
b) Saprophytes help in the recycling of nutrients in nature.

36. What is Symbiotic? Give example of organisms which exhibit this relationship.

Answer: Symbiosis is a close and long-term association between two different organisms in which both, or at least one, benefit. Examples are lichens (a fungus and an alga living together) and Rhizobium bacteria living in the root nodules of leguminous plants.

Teacher's Note:
a) Lichen is a classic example of mutualism.
b) Rhizobium fixes atmospheric nitrogen for the plant.
c) Write the key term first, then the explanation, so that the answer is complete.

37. Classify the following organisms into their respective kingdoms as per Whittaker's five-kingdom system.

Answer: The list of organisms that should be classified is not printed in the PDF, so the answer cannot be completed from this paper. The student should classify each organism using the five-kingdom features of cell type, body organisation and mode of nutrition.

Teacher's Note:
a) Use cell type first to separate Monera from the eukaryotic kingdoms.
b) Then use body organisation and mode of nutrition to place each organism.

38. What are the major divisions in the Plantae? What is the basis for these divisions?

Answer: The major divisions in Plantae are Thallophyta, Bryophyta, Pteridophyta, Gymnosperms and Angiosperms. The basis for these divisions is the presence or absence of a differentiated plant body, vascular tissues and seeds.

Teacher's Note:
a) Thallophytes have an undifferentiated thallus.
b) Pteridophytes have vascular tissues but no seeds.

39. Give examples of Thallophyta plants.

Answer: Examples of Thallophyta are Spirogyra, Ulothrix and Chara.

Teacher's Note:
a) These are mainly algae.
b) Thallophytes have a simple, undifferentiated body called a thallus.
c) Write the key term first, then the explanation, so that the answer is complete.

40. Why are Thallophytes called non-embryonic plants?

Answer: Thallophytes are called non-embryonic plants because they do not form an embryo at any stage of their life cycle; the zygote develops directly without being protected inside a multicellular embryo.

Teacher's Note:
a) Plants that form an embryo are called embryophytes.
b) Bryophytes, pteridophytes and seed plants are embryophytes.

41. Which division among plants has the simplest organisms?

Answer: The division Thallophyta has the simplest organisms among plants.

Teacher's Note:
a) Thallophytes have no true roots, stems or leaves.
b) They are mostly aquatic.

42. What is a thallus?

Answer: A thallus is the undifferentiated plant body of thallophytes, which is not divided into true roots, stems and leaves.

Teacher's Note:
a) Algae and fungi have a thallus.
b) The thallus may be unicellular or multicellular.
c) Write the key term first, then the explanation, so that the answer is complete.

43. Why bryophytes are called the amphibians of the plant kingdom?

Answer: Bryophytes are called the amphibians of the plant kingdom because they can live on land but need water for the fertilisation of their egg by the male gamete.

Teacher's Note:
a) Male gametes swim in water to reach the female gamete.
b) Bryophytes grow in moist and shady places.

44. List important characteristics (at least three) of bryophytes.

Answer: Three important characteristics of bryophytes are: (i) they grow in damp and shady places; (ii) they have no true roots, stems or leaves, and have rhizoids for attachment; and (iii) they lack vascular tissues and reproduce by spores.

Teacher's Note:
a) Bryophytes are the first plants to live on land.
b) They are called the amphibians of the plant kingdom.

45. Give examples of bryophytes.

Answer: Examples of bryophytes are Riccia, Marchantia and Funaria.

Teacher's Note:
a) Marchantia is a liverwort.
b) Funaria is a moss.
c) Write the key term first, then the explanation, so that the answer is complete.

46. What are the uses of bryophytes?

Answer: Bryophytes are used to prevent soil erosion, they help in soil formation on bare rocks, and Sphagnum (peat moss) is used as fuel and packing material.

Teacher's Note:
a) Sphagnum is also used as a dressing material for wounds.
b) Bryophytes are often the first colonisers of bare rock.

47. How are Pteridophytes' bodies organised?

Answer: The bodies of pteridophytes are organised into true roots, stems and leaves, which contain vascular tissues (xylem and phloem).

Teacher's Note:
a) Pteridophytes are the first vascular land plants.
b) They reproduce by spores, not by seeds.

48. How do thallophytes and pteridophytes differ from each other? Write two differences.

Answer: Two differences are: (i) thallophytes have an undifferentiated thallus without true roots, stems or leaves, whereas pteridophytes have a differentiated body with true roots, stems and leaves; and (ii) thallophytes have no vascular tissues, whereas pteridophytes have xylem and phloem.

Teacher's Note:
a) Vascular tissue is the key feature that separates the two groups.
b) Both groups reproduce by spores.
c) Write the key term first, then the explanation, so that the answer is complete.

49. Name the plants that are called "First vascular land plants".

Answer: The pteridophytes are called the first vascular land plants, for example ferns and horsetails.

Teacher's Note:
a) Vascular tissues help in conducting water and food.
b) Ferns are the most familiar pteridophytes.

50. On what basis plants are divided into two sub-kingdoms?

Answer: Plants are divided into two sub-kingdoms, Cryptogamae and Phanerogamae, on the basis of whether they produce visible reproductive organs (flowers and seeds).

Teacher's Note:
a) Cryptogams have hidden reproductive organs.
b) Phanerogams are seed-bearing plants.

51. How are pteridophytes different from the phanerogams?

Answer: Pteridophytes are cryptogams that reproduce by spores and do not produce seeds or flowers, whereas phanerogams produce flowers and seeds.

Teacher's Note:
a) Pteridophytes have hidden reproductive organs.
b) Phanerogams have visible reproductive organs.
c) Write the key term first, then the explanation, so that the answer is complete.

52. How Phanerograms are divided further chiefly?

Answer: Phanerograms are divided into two groups: Gymnosperms (naked-seeded plants) and Angiosperms (plants with seeds enclosed in fruits).

Teacher's Note:
a) Gymnosperms do not form fruits.
b) Angiosperms have flowers and fruits.

53. What are naked-seeded plants are called?

Answer: Naked-seeded plants are called Gymnosperms.

Teacher's Note:
a) In gymnosperms, seeds are not enclosed in fruits.
b) Pinus and Cycas are gymnosperms.

54. Give two examples of Gymnosperms.

Answer: Two examples of gymnosperms are Pinus and Cycas.

Teacher's Note:
a) Gymnosperms are mostly woody and evergreen.
b) Their leaves are often needle-like.
c) Write the key term first, then the explanation, so that the answer is complete.

55. Define Cryptograms.

Answer: Cryptograms are plants that do not produce flowers or seeds, and whose reproductive organs are hidden. They reproduce by spores.

Teacher's Note:
a) Algae, bryophytes and pteridophytes are cryptogams.
b) The name cryptogam means hidden reproduction.

56. How do gymnosperms and angiosperms differ from each other?

Answer: Gymnosperms have naked seeds that are not enclosed in fruits and do not have flowers, whereas angiosperms have flowers and seeds enclosed inside fruits.

Teacher's Note:
a) Gymnosperms are mostly trees and shrubs.
b) Angiosperms are the most diverse group of plants.

57. How Angiosperms are divided further?

Answer: Angiosperms are divided into two classes: monocotyledons (monocots) and dicotyledons (dicots), on the basis of the number of cotyledons in the seed.

Teacher's Note:
a) Monocots have one cotyledon in the seed.
b) Dicots have two cotyledons in the seed.
c) Write the key term first, then the explanation, so that the answer is complete.

58. Write the diffenences between monocots and dicots.

Answer: The differences between monocots and dicots are given in the table below.

Teacher's Note:
a) Look at the number of cotyledons first, as it is the basic difference.
b) Venation and root system are useful for identifying plants in the field.

59. What are the general characteristics found in all animals?

Answer: All animals are multicellular, eukaryotic and heterotrophic. They take food by ingestion, lack cell walls, and show a well-organised body with specialised tissues.

Teacher's Note:
a) Animals are heterotrophic and cannot make their own food.
b) Most animals reproduce sexually.

60. In how many Phyla, the animal kingdom is divided into?

Answer: The animal kingdom is divided into nine major phyla, from Porifera to Chordata.

Teacher's Note:
a) Porifera, Coelenterata, Platyhelminthes, Aschelminthes, Annelida, Arthropoda, Mollusca, Echinodermata and Chordata are the nine phyla.
b) Phylum is a major level of classification below kingdom.
c) Write the key term first, then the explanation, so that the answer is complete.

61. Name the phylum to which the following are included. (i) Spider (ii) Cockroach (iii) Prawn (iv) Housefly

Answer: (i) Spider: Arthropoda. (ii) Cockroach: Arthropoda. (iii) Prawn: Arthropoda. (iv) Housefly: Arthropoda.

Teacher's Note:
a) All four have jointed legs and an exoskeleton.
b) Arthropoda is the largest phylum of animals.

62. Write two important characteristics of sponges (Phylum: Porifera)

Answer: Two important characteristics of sponges are: (i) their body is porous, with many small openings called ostia through which water enters; and (ii) they have a central cavity called the spongocoel, and they do not have true tissues or organs.

Teacher's Note:
a) Sponges are mostly marine and sessile.
b) They feed by filtering water.

63. What is osculum?

Answer: The osculum is a large opening at the top of a sponge through which water leaves the body.

Teacher's Note:
a) Water enters through ostia and exits through the osculum.
b) The osculum is part of the sponge's water canal system.
c) Write the key term first, then the explanation, so that the answer is complete.

64. Do sponges have nervous system?

Answer: No, sponges do not have a nervous system or nerve cells.

Teacher's Note:
a) Sponges respond to stimuli through their individual cells.
b) Lack of a nervous system is a feature of Porifera.

65. Give examples of Porifera or Sponges.

Answer: Examples of sponges are Sycon, Spongilla and Euspongia.

Teacher's Note:
a) Euspongia is the bath sponge.
b) Spongilla is a freshwater sponge.

66. Identify the phylum having following characteristics: multi-cellular, radially symmetrical, aquatic, hollow gut.

Answer: The phylum is Coelenterata (Cnidaria), which includes animals such as hydra, jellyfish and sea anemone.

Teacher's Note:
a) Coelenterates have a hollow gut called the gastrovascular cavity.
b) Radial symmetry is a key feature of this phylum.
c) Write the key term first, then the explanation, so that the answer is complete.

67. What are four main features of phylum coelenterata?

Answer: Four main features of Coelenterata are: (i) the body is diploblastic, with two germ layers; (ii) it is radially symmetrical; (iii) it has a central gastrovascular cavity with a single opening; and (iv) it has stinging cells called cnidoblasts or nematocysts.

Teacher's Note:
a) Tentacles around the mouth help in capturing food.
b) Coelenterates show tissue-level organisation.

68. 'Animals belong to phylum coelenterata are diploblastic.' What do you mean by the term diploblastic?

Answer: Diploblastic means that the body is made of two embryonic layers, the outer ectoderm and the inner endoderm, with a jelly-like layer called mesoglea between them.

Teacher's Note:
a) Triploblastic animals have a third layer, the mesoderm.
b) Coelenterates are the main diploblastic phylum.

69. Which animal phylum is commonly called as flatworms?

Answer: The phylum Platyhelminthes is commonly called flatworms.

Teacher's Note:
a) Flatworms have a dorsoventrally flattened body.
b) Tapeworm and liver fluke belong to this phylum.
c) Write the key term first, then the explanation, so that the answer is complete.

70. Which animal phylum is considered to be first triploblastic animals?

Answer: The phylum Platyhelminthes is considered to be the first triploblastic animals.

Teacher's Note:
a) Triploblastic animals have three germ layers: ectoderm, mesoderm and endoderm.
b) This is the first phylum with a mesoderm layer.

71. Write important features about Phylum Platihelminthes.

Answer: Important features of Platyhelminthes are: (i) the body is dorsoventrally flattened and bilaterally symmetrical; (ii) the body is triploblastic but has no true body cavity; and (iii) many parasitic forms have hooks and suckers, for example tapeworm and liver fluke.

Teacher's Note:
a) Excretion takes place through flame cells.
b) Flatworms are either free-living or parasitic.

72. How do poriferan animals differ from coelenterate animals?

Answer: Poriferans have a porous body with a central cavity and no true tissues, whereas coelenterates have tissue-level organisation, a gastrovascular cavity with a single opening, and stinging cells for capturing prey.

Teacher's Note:
a) Porifera lack nerve cells, but coelenterates have a simple nerve net.
b) Porifera are asymmetrical or radially symmetrical, while coelenterates are radially symmetrical.
c) Write the key term first, then the explanation, so that the answer is complete.

73. Which phylum is commonly called roundworms or pinworms?

Answer: The phylum Aschelminthes (Nematoda) is commonly called roundworms or pinworms.

Teacher's Note:
a) Nematodes have an unsegmented cylindrical body.
b) Their body cavity is a pseudocoelom, which is a false body cavity.

74. Give examples of animals belong to Nematoda.

Answer: Examples of Nematoda are Ascaris (roundworm), Wuchereria (filarial worm) and Enterobius (pinworm).

Teacher's Note:
a) Ascaris is found in the intestines of humans.
b) Wuchereria causes filariasis in humans.

75. Name a parasitic disease caused by members of Nematoda.

Answer: Filariasis (elephantiasis) is a parasitic disease caused by Wuchereria, a member of Nematoda.

Teacher's Note:
a) Filariasis is spread by the bite of infected mosquitoes.
b) Ascariasis is another disease caused by a nematode.
c) Write the key term first, then the explanation, so that the answer is complete.

76. Name the first animals (phylum) that have true body cavity.

Answer: Annelida is the first phylum of animals that has a true body cavity, called a coelom.

Teacher's Note:
a) Nematodes have only a pseudocoelom, which is a false body cavity.
b) Earthworm and leech are annelids.

77. Leeches and Earthworms belong to which phylum?

Answer: Leeches and earthworms belong to the phylum Annelida.

Teacher's Note:
a) Annelids have a segmented body.
b) Annelids are also called segmented worms.

78. Differentiate between Annelida and Nematode.

Answer: The differences between Annelida and Nematoda are given in the table below.

Teacher's Note:
a) Annelids have a true coelom, while nematodes have a pseudocoelom.
b) Annelids have a closed circulatory system, while nematodes lack a circulatory system.
c) Write the key term first, then the explanation, so that the answer is complete.

79. Name the largest group (phylum) of animals.

Answer: Arthropoda is the largest group (phylum) of animals.

Teacher's Note:
a) Insects are the largest group within Arthropoda.
b) Arthropoda includes more than half of all named animal species.

80. Give examples of Arthropod animals.

Answer: Examples of arthropods are prawn, spider, cockroach, housefly, crab and scorpion.

Teacher's Note:
a) All arthropods have jointed legs.
b) Insects, arachnids and crustaceans are the main groups.

81. What is the most striking feature of phylum Arthropoda?

Answer: The most striking feature of Arthropoda is the presence of jointed appendages (legs and other body parts).

Teacher's Note:
a) The name Arthropoda means jointed feet.
b) Arthropods also have a hard chitinous exoskeleton.
c) Write the key term first, then the explanation, so that the answer is complete.

82. How is body of Arthropods segmented?

Answer: The body of arthropods is divided into segments, which are grouped into a head, thorax and abdomen (or head-thorax, called cephalothorax, and abdomen in some groups).

Teacher's Note:
a) Each segment may bear a pair of jointed appendages.
b) Segmentation helps in efficient movement.

83. What is the type of circulatory system present in Arthropods?

Answer: Arthropods have an open circulatory system, in which the blood (haemolymph) flows through body cavities rather than through closed vessels.

Teacher's Note:
a) Arthropod blood is called haemolymph.
b) The body cavity in arthropods is called the haemocoel.

84. How do annelid animals differ from arthropods?

Answer: Annelids have a soft, segmented body without jointed appendages and a closed circulatory system, whereas arthropods have jointed appendages, a hard exoskeleton and an open circulatory system.

Teacher's Note:
a) Annelids have a true coelom, while arthropods have a haemocoel.
b) Earthworm is an annelid, while prawn is an arthropod.
c) Write the key term first, then the explanation, so that the answer is complete.

85. Give examples of animals that belong to Phylum Mollusca.

Answer: Examples of Mollusca are snail, octopus and mussel.

Teacher's Note:
a) Molluscs have a soft body covered by a shell in many forms.
b) Octopus and squid are cephalopod molluscs.

86. What kind of circulatory system is found in animals from Mollusca phylum?

Answer: Molluscs have an open circulatory system, with a heart pumping blood into the body cavity.

Teacher's Note:
a) The body cavity in molluscs is called haemocoel.
b) Open circulation is also found in arthropods.

87. How is locomotion brought in animals belonging to Mollusca phylum?

Answer: Locomotion in most molluscs takes place with the help of a muscular foot, which is used for creeping or crawling.

Teacher's Note:
a) Snails move by gliding over a mucus layer on the muscular foot.
b) Some molluscs, like squid, move by jet propulsion.
c) Write the key term first, then the explanation, so that the answer is complete.

88. Name the phylum to which Start fish and Sea urchin belong to?

Answer: Starfish and sea urchins belong to the phylum Echinodermata.

Teacher's Note:
a) Echinoderms have a spiny skin and a water vascular system.
b) Echinoderms show radial symmetry as adults.

89. Name the phylum to which this organism belongs. Write any two characteristic feature of the phylum.

Answer: The image of the organism referred to in this question is not present in the PDF, so the phylum cannot be identified from this paper. The image should be added to complete this answer.

Teacher's Note:
a) The question depends on a picture that is missing from the source.
b) Once the picture is added, identify its body plan and features to name the phylum.

90. Label A to H in the given diagram of hydra.

Answer: A - tentacles; B - hypostome (mouth region); C - bud; D - body column (body wall); E - ectoderm (outer layer); F - endoderm (inner layer); G - gastrovascular cavity; H - basal disc (foot).

Teacher's Note:
a) The labels are given in the order shown in the diagram, from top to bottom.
b) Hydra belongs to the phylum Coelenterata.
c) Write the key term first, then the explanation, so that the answer is complete.

91. What is a notochord? What does it do?

Answer: A notochord is a rod-like, flexible structure made of cells, present in chordates at some stage of life. It provides support to the body and acts as a skeletal rod.

Teacher's Note:
a) Notochord is present in all chordates at some stage.
b) In vertebrates it is replaced by the backbone.

92. Give examples of organisms which belong to Phylum Protochordata.

Answer: Examples of protochordates are Amphioxus (Branchiostoma) and Herdmania (sea squirt).

Teacher's Note:
a) Protochordates are marine animals.
b) Amphioxus is also called lancelet.

93. List three important characteristics of Phylum Protochordata.

Answer: Three important characteristics of protochordates are: (i) a notochord present at least in the larval stage; (ii) a dorsal, hollow nerve cord; and (iii) pharyngeal gill slits.

Teacher's Note:
a) These features show the link between invertebrates and vertebrates.
b) Protochordates have a post-anal tail.
c) Write the key term first, then the explanation, so that the answer is complete.

94. Why are Bats and whales classified as mammals?

Answer: Bats and whales are classified as mammals because they have mammary glands that produce milk to feed their young, and they give birth to live young ones. They also have hair at some stage and are warm-blooded.

Teacher's Note:
a) Mammary glands are the key feature of mammals.
b) Whales look like fish but are mammals.

95. A plant specimen was found without differentiated roots.(a) Which plant structure helps in attaching this plant to the substratum?(b) To which group you will keep this plant?(c) Which plant could it be?

Answer: (a) Rhizoids help in attaching the plant to the substratum. (b) The plant belongs to the group Bryophyta. (c) It could be a moss such as Funaria or a liverwort such as Marchantia.

Teacher's Note:
a) Rhizoids are thread-like structures that anchor the plant but do not absorb water like true roots.
b) Bryophytes do not have true roots, stems or leaves.

96. Why is there a need for classification and systematic naming of living organisms?

Answer: Classification and systematic naming are needed to organise the huge number of living organisms, to understand their relationships and evolutionary history, and to identify and name each organism in the same way all over the world.

Teacher's Note:
a) Binomial nomenclature gives every species a two-part scientific name.
b) A common system prevents confusion between local names.
c) Write the key term first, then the explanation, so that the answer is complete.

Please click the link below to download CBSE Class 9 Science Diversity in Organisms Sure Shot Questions A.