Class 9 Science Chapter 7 Diversity in Living Organisms
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Diversity in Living Organisms
Answers to Questions Within the Lesson(1)
Q1. Why do we classify living organisms?
Ans: There are innumerable animals and plants on Earth, and they live in different habitats. To acquire knowledge about these organisms easily and systematically, we classify them.
Q2. Give three examples of differences observed among the various living organisms around you.
Ans: The differences among the living organisms around us are—
(i) Their size can range from microscopic to several meters. For example, microorganisms may be as small as 0.001 micrometre, while the length of a blue whale can be up to 30 meters.
(ii) A pine tree may live for a thousand years, whereas a mosquito lives only for a few days.
(iii) Different organisms and birds may have different colours or may even be colourless.
Answers to Questions Within the Lesson(2)
Q1. While classifying living organisms, which characteristic do you consider more important and why?
(a) The place where they live?
(b) The type of cells are involved in the formation of their body? Why?
Ans: (a) Classification of organisms is not done on the basis of habitat.
For example, aquatic animals such as corals, whales, and octopuses have very different characteristics, which creates difficulty in classification based solely on habitat.
(b) Classification of organisms is done on the basis of the type of cells. In this case, organisms are divided into two groups: organisms with primitive cells and organisms with well-developed (eukaryotic) cells. Classification based on cell structure makes the study of living organisms more systematic and convenient.
Q2. What is the primary characteristic considered at the first stage of classification of living organisms?
Ans: The nature of the cell.
Q3. On the basis of which characteristics are plants and animals placed into two separate groups?
Ans: Plants and animals are placed into different groups based on the mode of nutrition, cell organization, different organs, and their level of complexity.
Answers to Questions Within the Lesson(3)
Q1. Which organisms are called lower organisms and how are they different from higher organisms?
Ans: Organisms whose body structure has not undergone significant evolutionary changes are called primitive or lower organisms. The differences between lower and higher organisms cannot be stated very precisely.
Q2. Are higher organisms the same as complex organisms? If yes, why?
Ans: No. As evolution progresses, the body structure of organisms develops from simple to complex forms. Therefore, organisms of the past were simpler, while present-day organisms are more complex.
Answers to Questions Within the Lesson(4)
Q1. On what distinguishing characteristics are organisms of the kingdoms Monera and Protista separated?
Ans: Organisms are included in the kingdom Monera based on the following characteristics—
(i) Organisms in this kingdom are very simple.
(ii) Their cells do not have a true nucleus (prokaryotic).
(iii) They may be autotrophic or heterotrophic.
Organisms are included in the kingdom Protista based on the following characteristics—
(i) Organisms in this kingdom are simple but more advanced than those in Monera.
(ii) Their cells have a true nucleus (eukaryotic).
(iii) They may be autotrophic or heterotrophic.
Q2. Under which kingdom would you place unicellular organisms with eukaryotic cells capable of photosynthesis?
Ans: Kingdom Protista.
Q3. In the hierarchical system of classification, which level contains the least number of organisms and which level contains the greatest number of organisms sharing common characteristics?
Ans: Classification is an important branch of biology because identification of organisms is not possible without it. Therefore, organisms are arranged in a hierarchy according to definite rules. The smallest unit of classification is species, and the largest group is kingdom. The kingdom level contains the greatest number of organisms.
Answers to Questions Within the Lesson(5)
Q1. Which division of the plant kingdom includes the simplest plants?
Ans: Thallophyta (thalloid plants).
Q2. In what way are pteridophytes different from flowering plants (angiosperms)?
Ans: In pteridophytes, seeds are not formed; they reproduce by spores.
On the other hand, in flowering plants (angiosperms), seeds are enclosed within fruits.
Q3. What is the difference between gymnosperms and angiosperms?
Ans: Gymnosperms bear naked seeds, i.e., the seeds are not enclosed within fruits. They do not produce flowers.
On the other hand, angiosperms bear seeds enclosed within fruits and they produce flowers.
Answers to Questions Within the Lesson(6)
Q1. How can coelenterates be distinguished from platyhelminthes?
Ans: Coelenterates (Cnidarians) have a single opening that serves as both mouth and anus, and their body is radially symmetrical.
On the other hand, platyhelminthes (flatworms) have a more developed body structure with bilateral symmetry and a distinct digestive system, although incomplete.
Q2. How can annelids be distinguished from arthropods?
Ans: Annelids have a segmented body with a soft structure and lack jointed appendages. Their body segments are similar.
In contrast, arthropods have a segmented body with jointed appendages and a hard exoskeleton. Their body is divided into distinct regions such ashead, thorax, and abdomen.
Q3. What is the difference between amphibians and reptiles?
Ans: Amphibians can live both on land and in water. They have moist skin and usually lay eggs in water. Reptiles primarily live on land, have dry and scaly skin, and lay eggs with protective coverings (shells).
Q4. What are the differences between birds (Aves) and mammals?
Ans: Birds have feathers, wings, and a beak, and they lay eggs. Their bones are light and adapted for flight. Mammals have hair or fur, possess mammary glands to feed their young, and most of them give birth to young ones.
Exercise: Questions and Answers
Q1. What are the advantages of the classification of living organisms?
Ans: The advantages of classification of living organisms are—
(i) It makes identification of organisms easier.
(ii) It helps in studying the characteristic features, properties, and modes of reproduction of organisms.
(iii) It facilitates the study of biodiversity.
(iv) For convenience of study, all multicellular animals (except primitive unicellular organisms) are placed under the animal kingdom, and all plants are placed under the plant kingdom.
Q2. How would you carry out classification considering the characteristics among organisms?
Ans: First, one must consider the characteristics on the basis of which organisms can be divided into broad groups. After that, further classifications should be done by considering additional characteristics to divide them into classes, subclasses, or subdivisions.
Q3. Describe the basis of the five-kingdom classification of living organisms.
Ans: The bases of the five-kingdom classification are—
(i) Nature of the cell: Whether the organisms are prokaryotic or eukaryotic.
(ii) Number of cells: Whether the organisms are unicellular or multicellular.
(iii) Presence of cell wall: Whether the cells have a cell wall or not.
(iv) Mode of nutrition: Whether the organisms are autotrophic or heterotrophic.
Q4. What are the main subdivisions of the plant kingdom? On what basis are they classified?
Ans: The plant kingdom is divided into five main groups—
(i) Thallophyta (thalloid plants): The plants in this group do not have differentiated tissues; hence their body structure is simple.
(ii) Bryophyta (moss-like plants): These are multicellular plants. They have simple tissue organization and perform various life processes. The body may be thallus-like or may have structures resembling leaves, stems, and roots.
(iii) Pteridophyta (fern-like plants): These plants have a well-organized body, are independent and autotrophic. Their body is differentiated into roots,
stems, and leaves.
(iv) Gymnosperms: These plants produce seeds from flowers, but the seeds are not enclosed within fruits. Most of them are woody, perennial plants with strong stems.
(v) Angiosperms: These plants bear seeds enclosed within fruits. They include herbs, shrubs, trees, and climbers. They prepare food by photosynthesis.
Q5. What is the difference between the basis of classification of plants and animals?
Ans: The basis of classification of plants includes—
(i) Differentiation of plant body.
(ii) Presence or absence of well-developed vascular tissues.
(iii) Ability to produce seeds.
(iv) Whether seeds are enclosed within fruits or not. The basis of classification of animals includes—
(i) Body organization.
(ii) Nature of body covering and skeleton.
(iii) Absence of chlorophyll in animal cells.
(iv) Whether the animals are invertebrates or vertebrates.
Q6. How are vertebrates subdivided?
Ans: Vertebrates are subdivided on the basis of—
(i) Nature of the heart, i.e., number of chambers.
(ii) Presence or absence of scales.
(iii) Whether they are cold-blooded or warm-blooded.
(iv) Whether they give birth to young ones or lay eggs.
(v) Whether respiration occurs through lungs or gills.
(vi) Presence of scales.
(vii) Whether eggs have shells or not.
(viii) Whether the body is fully or partially covered with hair.
Additional Questions & Answers
Q1. Into which groups did the Greek philosopher Aristotle classify living organisms?
Ans: Terrestrial, aquatic, and aerial.
Q2. Into how many main groups is the living world divided and what are they?
Ans: The living world is divided into five main groups—
(i) Monera
(ii) Protista
(iii) Fungi
(iv) Plantae
(v) Animalia
Q3. Who proposed the five-kingdom classification?
Ans: Robert Whittaker.
Q4. Write short notes on Monera, Protista, Fungi, Plantae, and Animalia.
Ans: Monera: Organisms in this kingdom lack a true nucleus and membrane-bound organelles. They are unicellular. Some have a cell wall while others do not. Their nutrition may be autotrophic or heterotrophic.
Examples: bacteria, blue-green algae, Mycoplasma.
Protista: This kingdom includes unicellular eukaryotic organisms. Some move with the help of cilia or flagella. Their nutrition may be autotrophic or heterotrophic. Examples: unicellular algae, diatoms, protozoa.
Fungi: These are eukaryotic organisms with heterotrophic nutrition. They obtain food from decaying organic matter. Their cell wall is made of chitin.
Examples: yeast, mushroom.
Plantae: These are multicellular eukaryotic organisms. They are autotrophic and perform photosynthesis with the help of chlorophyll. All plants belong to this kingdom.
Animalia: These are multicellular eukaryotic organisms without cell walls. All are heterotrophic.
Q5. Into how many groups is the plant kingdom divided and what are they?
Ans: The plant kingdom is divided into five groups—
(i) Thallophyta
(ii) Bryophyta
(iii) Pteridophyta
(iv) Gymnosperms
(v) Angiosperms
Q6. Into how many groups is the animal kingdom divided and what are they?
Ans: The animal kingdom is divided into ten groups—
(i) Coelenterates
(ii) Platyhelminthes
(iii) Flatworms
(iv) Roundworms
(v) Annelids
(vi) Arthropods
(vii) Molluscs
(viii) Echinoderms
(ix) Protochordates
(x) Vertebrates
Q7. Write the characteristics of vertebrates.
Ans: The characteristics of vertebrates are—
(i) Presence of a backbone (vertebral column).
(ii) Presence of a dorsal nerve cord.
(iii) They are triploblastic.
(iv) Presence of paired gill slits at some stage of life.
(v) Body cavity is present.
Q8. Into how many classes are vertebrates divided? Give examples of each.
Ans: Vertebrates are divided into five classes—
(i) Pisces (fishes): Rohu fish, catfish, dogfish, etc.
(ii) Amphibia: Frog, tree frog, salamander, etc.
(iii) Reptilia: Snake, turtle, lizard, chameleon, etc.
(iv) Aves (birds): Crow, sparrow, pigeon, ostrich, etc.
(v) Mammalia: Human, cat, bat, rat, etc.
Multiple Choice Questions (MCQ)
1. Why do we classify living organisms?
(a) To increase their number
(b) To study them easily and systematically
(c) To change their characteristics
(d) To reduce biodiversity
Ans: (b)
2. Which is the smallest unit of classification?
(a) Kingdom
(b) Phylum
(c) Species
(d) Class
Ans: (c)
3. Which is the largest unit of classification?
(a) Species
(b) Genus
(c) Family
(d) Kingdom
Ans: (d)
4. Who proposed the five-kingdom classification?
(a) Aristotle
(b) Linnaeus
(c) Robert Whittaker
(d) Darwin
Ans: (c)
5. Which of the following is a prokaryotic organism?
(a) Amoeba
(b) Bacteria
(c) Fungi
(d) Algae
Ans: (b)
6. Which kingdom includes unicellular eukaryotic organisms?
(a) Monera
(b) Protista
(c) Fungi
(d) Plantae
Ans: (b)
7. Which kingdom includes organisms with chitin cell walls?
(a) Plantae
(b) Protista
(c) Fungi
(d) Animalia
Ans: (c)
8. Which organisms are autotrophic?
(a) Animals
(b) Fungi
(c) Plants
(d) Bacteria
Ans: (c)
9. Which organisms lack a cell wall?
(a) Plants
(b) Animals
(c) Fungi
(d) Algae
Ans: (b)
10. Which of the following is a characteristic of Monera?
(a) Multicellular
(b) Eukaryotic
(c) No true nucleus
(d) Complex body
Ans: (c)
11. Which group includes blue-green algae?
(a) Protista
(b) Monera
(c) Fungi
(d) Plantae
Ans: (b)
12. Which type of nutrition is found in fungi?
(a) Autotrophic
(b) Heterotrophic
(c) Both
(d) None
Ans: (b)
13. Which group has a thallus body?
(a) Bryophyta
(b) Thallophyta
(c) Pteridophyta
(d) Gymnosperms
Ans: (b)
14. Which plants are called amphibians of the plant kingdom?
(a) Thallophyta
(b) Bryophyta
(c) Pteridophyta
(d) Angiosperms
Ans: (b)
15. Which group has vascular tissues?
(a) Bryophyta
(b) Thallophyta
(c) Pteridophyta
(d) Algae
Ans: (c)
16. Which plants have naked seeds?
(a) Angiosperms
(b) Gymnosperms
(c) Bryophyta
(d) Pteridophyta
Ans: (b)
17. Which plants have seeds enclosed in fruits?
(a) Gymnosperms
(b) Angiosperms
(c) Bryophyta
(d) Thallophyta
Ans: (b)
18. Which organisms reproduce by spores?
(a) Gymnosperms
(b) Angiosperms
(c) Pteridophytes
(d) Mammals
Ans: (c)
19. Which symmetry is found in coelenterates?
(a) Bilateral
(b) Radial
(c) Asymmetrical
(d) None
Ans: (b)
20. Which animals have bilateral symmetry?
(a) Coelenterates
(b) Platyhelminthes
(c) Sponges
(d) Cnidarians
Ans: (b)
21. Which animals have a segmented body?
(a) Molluscs
(b) Annelids
(c) Arthropods
(d) Echinoderms
Ans: (b)
22. Which animals have jointed appendages?
(a) Annelids
(b) Arthropods
(c) Molluscs
(d) Fishes
Ans: (b)
23. Which animals have soft bodies?
(a) Arthropods
(b) Molluscs
(c) Annelids
(d) Reptiles
Ans: (b)
24. Which animals have spiny skin?
(a) Molluscs
(b) Echinoderms
(c) Arthropods
(d) Annelids
Ans: (b)
25. Which group includes fishes?
(a) Amphibia
(b) Pisces
(c) Reptilia
(d) Aves
Ans: (b)
26. Which animals live both on land and in water?
(a) Reptiles
(b) Amphibians
(c) Birds
(d) Mammals
Ans: (b)
27. Which animals have dry scaly skin?
(a) Amphibians
(b) Reptiles
(c) Birds
(d) Mammals
Ans: (b)
28. Which animals have feathers?
(a) Mammals
(b) Birds
(c) Reptiles
(d) Amphibians
Ans: (b)
29. Which animals give birth to young ones?
(a) Birds
(b) Reptiles
(c) Mammals
(d) Fishes
Ans: (c)
30. Which animals are warm-blooded?
(a) Fishes
(b) Amphibians
(c) Birds
(d) Reptiles
Ans: (c)
31. Which animals breathe through gills?
(a) Birds
(b) Mammals
(c) Fishes
(d) Reptiles
Ans: (c)
32. Which animals have a four-chambered heart?
(a) Fishes
(b) Amphibians
(c) Birds
(d) Reptiles
Ans: (c)
33. Which animals are cold-blooded?
(a) Birds
(b) Mammals
(c) Reptiles
(d) Humans
Ans: (c)
34. Which of the following is a unicellular organism?
(a) Human
(b) Amoeba
(c) Dog
(d) Mango tree
Ans: (b)
35. Which organism belongs to Protista?
(a) Bacteria
(b) Amoeba
(c) Mushroom
(d) Fern
Ans: (b)
36. Which organism belongs to Fungi?
(a) Algae
(b) Yeast
(c) Moss
(d) Fern
Ans: (b)
37. Which organism belongs to Plantae?
(a) Mushroom
(b) Amoeba
(c) Mango tree
(d) Bacteria
Ans: (c)
38. Which organism belongs to Animalia?
(a) Algae
(b) Bacteria
(c) Human
(d) Yeast
Ans: (c)
39. Which basis is used in five-kingdom classification?
(a) Colour only
(b) Size only
(c) Cell type and nutrition
(d) Shape only
Ans: (c)
40. Which of the following is an example of vertebrate?
(a) Earthworm
(b) Cockroach
(c) Fish
(d) Sponge
Ans: (c)
