Basis of Classification — Exercise Solutions
Samacheer Kalvi Tamil Nadu State Board Class 7 Science Term 2 Chapter 5 exercise solutions. Covers MCQs, fill-in-the-blanks, true/false, match the following, assertion and reason, very short, short, detailed answers, and HOTS questions.
I. Choose the Correct Answer (MCQ)
Q1. The following characteristics are essential for classification. (a) Similarities (b) Differences (c) Both of them (d) None of them Answer: (c) Both of them ✓ — Classification requires both similarities and differences to group organisms.
Q2. Approximately ___ species of living organisms found in the earth. (a) 8.7 million (b) 8.6 million (c) 8.5 million (d) 8.8 million Answer: (a) 8.7 million ✓ — Approximately 8.7 million species exist on Earth.
Q3. The largest division of the living world is (a) Order (b) Kingdom (c) Phylum (d) Family Answer: (b) Kingdom ✓ — Kingdom is the highest category in the hierarchy of classification.
Q4. Who proposed the five kingdom classification? (a) Aristotle (b) Linnaeus (c) Whittaker (d) Plato Answer: (c) Whittaker ✓ — R.H. Whittaker proposed the five kingdom classification in 1969.
Q5. The binomial name of pigeon is (a) Homo sapiens (b) Rattus rattus (c) Mangifera indica (d) Columba livia Answer: (d) Columba livia ✓ — Pigeon's scientific name is Columba livia.
Additional MCQs
Q6. ___ belongs to Phylum Platyhelminthes. (a) Ascaris (b) Liver fluke (c) Leucosolenia (d) Euglena Answer: (b) Liver fluke ✓ — Liver fluke is a flatworm belonging to Platyhelminthes.
Q7. ___ are diploblastic. (a) Protozoa (b) Annelida (c) Coelenterata (d) Echinodermata Answer: (c) Coelenterata ✓ — Coelenterates have two germ layers (ectoderm and endoderm).
Q8. ___ is not a characteristic of Phylum Echinodermata. (a) Water vascular system (b) Tube feet (c) Pores in the body (d) Spicules Answer: (c) Pores in the body ✓ — Pores are a characteristic of Phylum Porifera, not Echinodermata.
Q9. Bones with air cavities are seen in ___ (a) snail (b) pigeon (c) bats (d) cuttle fish Answer: (b) pigeon ✓ — Birds have pneumatic (hollow) bones for flight.
Q10. ___ is not oviparous. (a) Snake (b) Crow (c) Frog (d) Human being Answer: (d) Human being ✓ — Human beings are viviparous (give birth to young ones).
Q11. Plant is a thallus in ___ (a) Algae (b) Ferns (c) Bacteria (d) Pinus Answer: (a) Algae ✓ — Algae have a thallus-like body (undifferentiated into root, stem, leaves).
Q12. Naked ovules are seen in ___ (a) Cycas (b) Funaria (c) Mango (d) Chara Answer: (a) Cycas ✓ — Gymnosperms like Cycas have naked ovules not enclosed in an ovary.
Q13. ___ is not a fungus. (a) Yeast (b) Chlamydomonas (c) Rhizopus (d) Agaricus Answer: (b) Chlamydomonas ✓ — Chlamydomonas is an alga (Protista), not a fungus.
Q14. ___ belong to Monera. (a) Blue green algae (b) Yeast (c) Mushrooms (d) Red algae Answer: (a) Blue green algae ✓ — Blue green algae (cyanobacteria) are prokaryotic and belong to Monera.
Q15. ___ are called Amphibious plants. (a) Ferns (b) Mosses (c) Fungi (d) Gymnosperms Answer: (b) Mosses ✓ — Mosses need water for fertilization and are called amphibians of the plant kingdom.
II. Fill in the Blanks
1. Gaspard Bauhin in 1623, introduced the binomial nomenclature. 2. Species is the basic unit of classification. 3. Fungi are non-green and non-photosynthetic in nature. 4. The binomial name of onion is Allium sativum. 5. Carolus Linnaeus is known as the Father of Modern Taxonomy.
Additional Fill in the Blanks
6. Aristotle was a Greek philosopher who classified animals. 7. Paired and jointed legs are seen in phylum Arthropoda. 8. Giving birth to young ones is described as viviparous. 9. Animals belonging to phylum Aschelminthes are mostly parasites. 10. Flowering plants belong to Angiosperms. 11. Ferns are considered to be first land plants. 12. Angiosperms are dominant plant forms of present day. 13. All prokaryotic belong to kingdom Monera. 14. Scientific name for Human being is Homo sapiens. 15. Cones are produced by gymnosperms.
III. True or False (with corrections)
Q1. Animals belonging to phylum Protozoa reproduce by fission. Answer: True. ✓ — Protozoans like Amoeba reproduce by binary fission.
Q2. Specialised vascular tissues for conduction of food and water are seen in mosses. Answer: False. Specialised vascular tissues for conduction of food and water are seen in ferns. Mosses lack vascular tissues.
Q3. Angiosperms are divided into monocots and dicots. Answer: True. ✓ — Angiosperms are classified based on seed cotyledons.
Q4. The angiosperms are evergreen trees. Answer: False. The gymnosperms are evergreen trees. Angiosperms may be deciduous or evergreen.
Q5. Fungi need water to complete their life cycle. Answer: False. Mosses need water to complete their life cycle. Fungi do not need water for fertilization.
IV. Match the Following
Set 1
| Column A | Column B | Answer |
|---|---|---|
| 1. Monera | Moulds | Bacteria |
| 2. Protista | Bacteria | Euglena |
| 3. Fungi | Neem | Moulds |
| 4. Plantae | Butterfly | Neem |
| 5. Animalia | Euglena | Butterfly |
Set 2
| Column A | Column B | Answer |
|---|---|---|
| 1. Protozoa | (a) Spongy bones | (e) Conjugation |
| 2. Annelida | (b) Hermaphrodite | (b) Hermaphrodite |
| 3. Coelenterata | (c) Soft body | (d) Colonial forms |
| 4. Aves | (d) Colonial forms | (a) Spongy bones |
| 5. Mollusca | (e) Conjugation | (c) Soft body |
Set 3
| Column A | Column B | Answer |
|---|---|---|
| 1. Fungi | (a) Funaria | (d) Agaricus |
| 2. Mosses | (b) Cycas | (a) Funaria |
| 3. Gymnosperms | (c) Adiantum | (b) Cycas |
| 4. Flowering Plants | (d) Agaricus | (e) Tamarind |
| 5. Ferns | (e) Tamarind | (c) Adiantum |
V. Assertion and Reason
Q1. Assertion: "Binomial name is the universal name and contains two names." Reason: "It was first introduced by Carolus Linnaeus." Answer: (b) Assertion is correct, Reasoning is incorrect. ✓ — Binomial nomenclature was first introduced by Gaspard Bauhin in 1623; Linnaeus implemented it in 1753.
Q2. Assertion: "Identification, assortment and grouping are essential for classification." Reason: "These are basic steps of taxonomy." Answer: (a) Assertion is correct, Reasoning is correct. ✓
Additional Assertion and Reason
Q3. Assertion: "Angiosperms have ovary in the flower." Reason: "They produce fruits and seeds." Answer: (a) Assertion is correct, Reasoning is correct. ✓
Q4. Assertion: "Blue green algae are prokaryotes." Reason: "They do not have a true nucleus." Answer: (a) Assertion is correct, Reasoning is correct. ✓
Q5. Assertion: "Xylem does not have vessels in angiosperms." Reason: "They conduct food." Answer: (d) Assertion and Reasoning are both incorrect. ✓ — Xylem does have vessels in angiosperms, and xylem conducts water (not food — that is phloem).
Q6. Assertion: "Reptiles are warm blooded animals." Reason: "They have scales." Answer: (c) Assertion is incorrect, Reasoning is correct. ✓ — Reptiles are cold-blooded; scales are a correct characteristic.
VI. Very Short Answer Questions
Q1. What is classification? Answer: The method of arranging the organisms into groups based on their similarities and differences is called classification.
Q2. List out the five kingdoms classification. Answer: Monera, Protista, Fungi, Plantae, and Animalia.
Q3. Define — dichotomous key. Answer: It is a tool used to classify organisms based on their similarities and differences. It presents two contrasting choices at each step.
Q4. Write two examples of Monera. Answer: Bacteria and Blue green algae (cyanobacteria).
Q5. What is binomial nomenclature? Answer: Binomial nomenclature is a universal system of naming organisms. Each organism has two names — the first is the Genus name (capital letter) and the second is the Species name (small letter). Example: Homo sapiens.
Q6. Write the binomial name of (a) Human being (b) Paddy. Answer: (a) Homo sapiens (b) Oryza sativa.
Q7. Write two features of Protista. Answer: 1. Includes unicellular and few simple multicellular eukaryotes. 2. Includes plant-like protists (Algae) and animal-like protists (Protozoans).
Additional Very Short Answers
Q8. Name the following: (1) A phylum with diploblastic animals (2) A phylum which has hermaphrodite animal. Answer: (1) Phylum Coelenterata (2) Phylum Annelida / Phylum Platyhelminthes.
Q9. Mention two features of phylum Echinodermata. Answer: Water vascular system and tube feet.
Q10. Mention two salient features of class Mammalia. Answer: Viviparous animals and heterodont dentition (different types of teeth).
Q11. What is heterodont dentition? Answer: Presence of different kinds of teeth (incisors, canines, premolars, molars) in the same jaw.
Q12. Why do Aves have bones with air cavities? Answer: It makes the body lighter and helps in flight.
Q13. Name the vascular tissues seen in plants. Answer: Xylem (conducts water) and Phloem (conducts food).
Q14. Gymnosperms do not produce fruits. Give reason. Answer: The ovules are naked, without an ovary. Hence gymnosperms do not produce fruits.
VII. Short Answer Questions
Q1. Write the levels of classification. Answer: There are seven main categories of hierarchies: Kingdom, Phylum, Class, Order, Family, Genus, and Species. Species is the basic unit of classification.
Q2. Differentiate Plantae and Animalia.
| Feature | Kingdom Plantae | Kingdom Animalia |
|---|---|---|
| Cell type | Multicellular eukaryotes | Multicellular eukaryotes |
| Nutrition | Autotrophic (photosynthesis) | Heterotrophic |
| Cell wall | Present | Absent |
| Movement | Cannot move from place to place | Can move from place to place |
| Examples | Ferns, cone-bearing plants, flowering plants | Invertebrates and Vertebrates |
Q3. Write any two merits of Five Kingdom classification. Answer: 1. This system of classification is more scientific and natural. 2. It clearly indicates the cellular organization, mode of nutrition, and characters for early evolution of life.
Additional Short Answers
Q4. List two demerits of five kingdom system of classification. Answer: 1. Viruses have not been given a proper place in this system. 2. Multicellular organisms have originated several times from protists.
Q5. Write a note on kingdom Fungi. Answer: 1. Fungi are eukaryotic, mostly multicellular organisms 2. They secrete enzymes to digest food and absorb it after digestion (saprophytic nutrition) 3. Fungi exist as saprophytes (decomposers) or as parasites 4. Kingdom Fungi includes moulds, mildews, mushrooms, and yeast
Q6. Differentiate Angiosperms and Gymnosperms.
| Feature | Angiosperms | Gymnosperms |
|---|---|---|
| Seeds | Enclosed in fruit | Naked (not enclosed in fruit) |
| Reproductive structure | Flowers | Cones |
| Fruit formation | Produce fruits | Do not produce fruits |
| Classification | Monocots and Dicots | Not classified |
| Vascular tissue | Well developed xylem and phloem | Xylem lacks vessels, phloem lacks companion cells |
| Examples | Mango, Neem, Tamarind | Cycas, Pinus |
VIII. Detailed Answer Questions
Q1. Explain about five kingdom classification. Answer: The five kingdom classification was proposed by R.H. Whittaker in 1969. He classified organisms into five kingdoms on the basis of characteristics like cell structure, mode of nutrition, source of nutrition, and body organization.
1. Monera: Prokaryotic, unicellular organisms. No true nucleus. Examples: Bacteria, Blue green algae. Mode of nutrition: Autotrophic or heterotrophic.
2. Protista: Eukaryotic, mostly unicellular organisms. Includes plant-like protists (Algae) and animal-like protists (Protozoans). Examples: Amoeba, Euglena, Paramecium.
3. Fungi: Eukaryotic, mostly multicellular, non-green organisms. They are saprophytic or parasitic. Examples: Yeast, Rhizopus, Agaricus (Mushroom).
4. Plantae: Multicellular, eukaryotic, autotrophic organisms with cell walls. Examples: Ferns, Gymnosperms, Angiosperms.
5. Animalia: Multicellular, eukaryotic, heterotrophic organisms without cell walls. Examples: Invertebrates and Vertebrates.
Q2. Write short notes on — Binomial Nomenclature. Answer: (i) Gaspard Bauhin in 1623 introduced naming organisms with two names, known as binomial nomenclature. It was implemented by Carolus Linnaeus in 1753. (ii) It is a universal system where each organism has two names — Genus name first (capital letter), Species name second (small letter). (iii) The binomial name is always written in italics or underlined. Example: Onion is Allium sativum. (iv) Vernacular name is a local name familiar for a particular place. Binomial name is universal and never changes. (v) Binomial nomenclature and classification help scientists identify organisms and place them at a particular hierarchy.
Q3. Give an account on the classification of invertebrates with few general features and examples.
| S.No | Phylum | General Characters | Examples |
|---|---|---|---|
| 1 | Protozoa | Microscopic unicellular; pseudopodia/flagella/cilia for locomotion; reproduce by fission or conjugation | Amoeba, Euglena |
| 2 | Porifera | Multicellular with pores (ostia); skeleton of spicules; asexual and sexual reproduction | Leucosolenia, Sycon |
| 3 | Coelenterata | Diploblastic; sessile or free swimming; solitary or colonial; asexual and sexual reproduction | Hydra, Jelly fish |
| 4 | Platyhelminthes | Acoelomates; parasites in animals and humans; mostly hermaphrodite | Planaria, Liver fluke |
| 5 | Aschelminthes/Nematoda | Unsegmented body; mostly parasites causing diseases; asexual reproduction | Ascaris |
| 6 | Annelida | Triploblastic; segmented body; mostly hermaphrodite | Earthworm, Leech |
| 7 | Arthropoda | Segmented body; chitinous exoskeleton; paired jointed legs; unisexual; sexual dimorphism | Crab, Prawn, Butterfly |
| 8 | Mollusca | Soft bodied; unsegmented; muscular head/foot/visceral mass; mantle; calcareous shell; sexual reproduction | Cuttle fish, Snail |
| 9 | Echinodermata | Exclusively marine; spines/spicules; water vascular system; tube feet; sexual reproduction | Starfish, Sea-Urchin |
Q4. Write the merits and demerits of five kingdom classification.
Merits: 1. This system of classification is more scientific and natural. 2. It clearly indicates the cellular organization, mode of nutrition, and characters for early evolution of life. 3. It is the most accepted system of modern classification as the different groups of organisms are placed phylogenetically. 4. It indicates gradual evolution of complex organisms from simpler ones.
Demerits: 1. Viruses have not been given a proper place in this system. 2. Multicellular organisms have originated several times from protists. 3. This type of classification has drawn criticism with reference to the lower forms of life. 4. Some organisms included under Protista are not eukaryotic.
IX. Higher Order Thinking Skills (HOTS)
Q1. Which kingdom has saprophytic, parasitic and symbiotic nutrition? Why? Answer: Kingdom Fungi. They are heterotrophic and lack chlorophyll, so they show: 1. Saprophytic — nutrition from dead matter. Example: Mucor 2. Parasitic — nutrition from living organisms. Example: Cercospora 3. Symbiotic — mutually beneficial relationship. Example: Lichens (fungus + alga)
Q2. Blue green algae are not placed under kingdom Protista whereas other algae are placed under it. Answer: Blue green algae have prokaryotic cells like bacteria. The cells lack a proper nucleus and membrane-bound organelles, therefore they are placed with bacteria in kingdom Monera. Other algae are eukaryotic and belong to kingdom Protista.
Q3. How can you differentiate a prokaryotic cell from a eukaryotic cell? Answer: Prokaryotic cells lack a true nucleus covered by a nuclear membrane and lack membrane-bound organelles (e.g., bacteria, blue green algae). Eukaryotic cells possess a well-defined nucleus enclosed by a nuclear membrane and have membrane-bound organelles like mitochondria, Golgi bodies, etc. (e.g., Amoeba, plant and animal cells).
Common Mistakes to Avoid
1. Confusing classification levels — Kingdom is the broadest; Species is the narrowest. Remember: King → Phylum → Class → Order → Family → Genus → Species. 2. Saying Linnaeus introduced binomial nomenclature — Gaspard Bauhin introduced it in 1623; Linnaeus implemented it in 1753. 3. Calling mosses vascular plants — Mosses (Bryophyta) lack vascular tissues; ferns (Pteridophyta) were the first vascular plants. 4. Mixing up Monera and Protista — Monera are prokaryotes (no true nucleus); Protista are eukaryotes (true nucleus present). 5. Confusing diploblastic and triploblastic — Diploblastic = two germ layers (Coelenterata); Triploblastic = three germ layers (Annelida, Arthropoda, etc.). 6. Saying gymnosperms produce fruits — Gymnosperms have naked ovules and do not produce fruits; only angiosperms produce fruits. 7. Confusing oviparous and viviparous — Oviparous = lay eggs (birds, reptiles); Viviparous = give birth to young ones (mammals).
Exam Checklist
- [ ] Can define classification and explain why it is needed
- [ ] Know the seven levels of classification hierarchy (Kingdom to Species)
- [ ] Can list the five kingdoms with examples and key characteristics
- [ ] Can explain binomial nomenclature with rules (Genus capital, species lowercase, italics/underline)
- [ ] Can differentiate Plantae and Animalia
- [ ] Can differentiate Angiosperms and Gymnosperms
- [ ] Can list invertebrate phyla with general characters and examples
- [ ] Can explain the merits and demerits of five kingdom classification
- [ ] Can distinguish prokaryotic and eukaryotic cells
- [ ] Can explain why blue green algae are in Monera (not Protista)
- [ ] Can use a dichotomous key for identification