Unit 2 Classification of Living Beings

1. Summary: Classification of Living Beings

2.1 Choose the correct options for the following questions:

2.2 Differentiate between:

(a) Plant Kingdom and Animal Kingdom

Feature	Plant Kingdom (Plantae)	Animal Kingdom (Animalia)
Nutrition	Autotrophic (photosynthetic)	Heterotrophic (holozoic, parasitic, etc.)
Cell Wall	Present (made of cellulose)	Absent
Locomotion	Generally fixed/immobile (sedentary)	Generally motile (move from place to place)
Growth	Indeterminate (grows throughout life at tips)	Determinate (stops after reaching maturity)
Reserve Food	Starch	Glycogen
Centrosome	Absent in cells	Present in cells (helps in division)

(b) Fish and Starfish

Feature	Fish (Pisces)	Starfish (Echinodermata)
Kingdom/Phylum	Phylum Chordata (Vertebrate)	Phylum Echinodermata (Invertebrate)
Habitat	Found in fresh and marine water	Found exclusively in marine water
Skeleton	Internal skeleton of bone or cartilage	Spiny exoskeleton of calcareous plates
Locomotion	Swims using fins	Moves using tube feet
Heart	Two-chambered heart present	Heart is absent (Water vascular system)
Body Shape	Streamlined body	Star-shaped / Radial symmetry

(c) Jellyfish and Cuttlefish

Feature	Jellyfish	Cuttlefish
Phylum	Coelenterata (Cnidaria)	Mollusca
Symmetry	Radially symmetrical	Bilaterally symmetrical
Body Cavity	Coelenteron (Gastro-vascular cavity)	Haemocoel (reduced coelom)
Tentacles	Present around the mouth with cnidoblasts	Present around the head (arms/tentacles)
Organization	Tissue level of organization	Organ-system level of organization
Stinging Cells	Present (Cnidocytes)	Absent

(d) Moss and Club Moss

Feature	Moss	Club Moss
Division	Bryophyta	Pteridophyta
Vascular Tissue	Absent (No xylem/phloem)	Present (Xylem and phloem)
Plant Body	Thallus-like or leafy structure; root-like rhizoids	Differentiated into true roots, stem, and leaves
Dominant Phase	Gametophyte is dominant	Sporophyte is dominant
Habitat	Damp, shady places (Amphibians of plant kingdom)	Cool, shady terrestrial places

(e) Pinus and Peepal

Feature	Pinus	Peepal
Sub-division	Gymnosperm	Angiosperm (Dicot)
Seeds	Naked seeds (not inside fruit)	Enclosed seeds (inside fruit)
Flowers	Bears cones (unisexual)	Bears true flowers (bisexual or unisexual)
Pollination	Exclusively by wind	By insects, wind, animals, etc.
Leaf Structure	Needle-shaped leaves	Broad, flat leaves with reticulate venation

(f) Fish and Whale

Feature	Fish	Whale
Class	Pisces	Mammalia
Respiration	Through gills	Through lungs
Heart	Two-chambered (venous heart)	Four-chambered
Reproduction	Oviparous (lays eggs)	Viviparous (gives birth to live young)
Body Temperature	Cold-blooded (Poikilothermic)	Warm-blooded (Homeothermic)
Skin	Covered with scales (usually)	Smooth skin, blubber underneath

(g) Dove and Bat

Feature	Dove	Bat
Class	Aves (Birds)	Mammalia
Body Covering	Feathers	Hair/Fur
Wings	Modified forelimbs with feathers	Patagium (skin stretched over finger bones)
Reproduction	Oviparous (lays eggs)	Viviparous (gives birth)
Teeth	Absent (has a beak)	Present (heterodont)
Ears	Pinna (external ear) absent	Pinna present

2.3 Give reason:

(a) Living beings need to be classified.

Reason: Classification is necessary because there are millions of species of living organisms. It is impossible to study each one individually. Classification helps to:

• Identify organisms easily

• Understand the inter-relationship between different groups of organisms

• Study the evolutionary history of organisms

• Make the study of living beings systematic and scientific

(b) Fucus and Marchantia look alike, but Fucus is classified as algae while Marchantia is classified as bryophyta.

Reason: Fucus is an alga because its body is a simple thallus completely adapted to aquatic life and it lacks any differentiation of tissues or multicellular sex organs surrounded by a sterile jacket. Marchantia is a bryophyte because although thalloid, it is adapted to land (damp places), has rhizoids for anchorage, and possesses multicellular sex organs, showing a slightly higher level of differentiation than algae.

(c) Gymnosperms do not bear fruit.

Reason: Fruits develop from the ovary of a flower after fertilization. Gymnosperms lack a true ovary; their ovules are borne naked on the surface of scales (megasporophylls) in cones. Since there is no ovary to ripen into a fruit, gymnosperms do not bear fruit.

(d) Although a crocodile has a four-chambered heart, it belongs to the reptilian class.

Reason: Generally, reptiles have a three-chambered heart. The crocodile is an exception with a four-chambered heart. However, it is classified as a reptile because it possesses all other fundamental reptilian characters: it is cold-blooded (poikilothermic), has dry scaly skin, lays eggs with hard shells (oviparous), and creeps on land.

(e) Although bats and whales have dissimilar characteristics, they belong to the same class.

Reason: Bats (aerial) and whales (aquatic) look very different due to adaptation to different habitats, but they share the fundamental characteristics of Class Mammalia:

• Both possess mammary glands and suckle their young

• Both give birth to live young (viviparous)

• Both have a four-chambered heart and are warm-blooded

• Both respire through lungs

(f) Riccia is an amphibian plant.

Reason: Riccia (a bryophyte) is called an amphibian plant because it lives on land (damp soil) but requires water essentially for fertilization. The male gametes need to swim through a film of water to reach the female gamete, similar to how amphibians live on land but need water to reproduce.

(g) Fern is not a flowering plant; Cycas bears flower-like cones but no fruit; banana bears flower and fruit. However, all these plants are kept in the same division.

Reason: Fern (Pteridophyte), Cycas (Gymnosperm), and Banana (Angiosperm) are all kept in the division Tracheophyta because they all possess vascular tissues (xylem and phloem). The presence of conducting tissue is the primary basis for grouping them into Tracheophyta, despite their differences in reproduction (spores vs. naked seeds vs. covered seeds).

2.4 Answer the following questions:

(a) Into how many divisions are the organisms in the plant kingdom divided?

Answer: According to the modern classification (Eichler/Engler), the Plant Kingdom is broadly divided into two sub-kingdoms: Cryptogams and Phanerogams. These are further divided into divisions.

Commonly in Grade 10 level, we study them under five main groups/divisions:

• Algae (Thallophyta)

• Bryophyta

• Pteridophyta

• Gymnosperm

• Angiosperm

(Alternatively, they can be classified into three divisions under Tracheophyta: Pteridophyta, Gymnosperm, and Angiosperm, with Algae and Bryophyta separate).

(b) Write the main features of kingdom Plantae.

Answer: The main features of Kingdom Plantae are:

• They are multicellular eukaryotic organisms

• Their cells contain a cell wall made of cellulose

• They contain plastids (chlorophyll) and prepare their own food by photosynthesis (autotrophic)

• They are mostly immobile (fixed to the substratum)

• They store food in the form of starch

(c) Write the similarities of plants which belong to gymnosperm and angiosperm.

Answer: Similarities between Gymnosperms and Angiosperms:

• Both belong to the division Tracheophyta (have vascular tissues)

• Both are Phanerogams (produce seeds)

• Both have a differentiated plant body with root, stem, and leaves

• In both, the sporophyte generation is dominant

• Both have pollen grains for reproduction

(d) If you are given only the leaves of some plants in tracheophyta and asked to distinguish their subdivisions using the taxonomic knowledge you have acquired in class, is it possible to do so? Give your arguments.

Answer: Yes, it is possible to distinguish subdivisions based on leaves to a significant extent:

• Pteridophyta (Ferns): Leaves are usually feather-like compound leaves (fronds) with leaflets. Young leaves show circinate vernation (coiled like a spring). They may possess spores (sori) on the ventral surface.

• Gymnosperms: Leaves are often needle-like (e.g., Pinus) or scale-like to reduce water loss. They are tough and leathery.

• Angiosperms: Leaves are usually broad and flat.

– Monocots: Leaves have parallel venation (e.g., Maize, Bamboo)

– Dicots: Leaves have reticulate (net-like) venation (e.g., Mango, Rose)

(e) What are the main characteristics of pteridophyta?

Answer:

• They are the first vascular plants (have xylem and phloem)

• The plant body is differentiated into true root, stem, and leaves

• They reproduce by spores formed in sporangia (often aggregated into sori on the back of leaves)

• They do not produce flowers or seeds (Cryptogams)

• Example: Fern, Lycopodium, Equisetum

(f) Roshni observed only the flowers of a new plant in her garden and concluded that the plant belongs to monocotyledon. Is observation of only the flowers a right way to identify monocotyledon? Give reasons.

Answer: Yes, observing the flower is a correct and reliable way to identify a monocotyledon.

Reason: Monocot flowers are trimerous, meaning their floral parts (petals, sepals) are in multiples of three (e.g., 3 or 6 petals). In contrast, dicot flowers are tetramerous or pentamerous (multiples of 4 or 5). If Roshni observed parts in multiples of three, her conclusion is scientifically valid.

(g) Two plants are shown in the picture. Observe both pictures and answer the following questions:

i. Compare and write their similarities and differences.

Similarities: Both are green, autotrophic (make their own food), have distinct roots, stems, and leaves, possess vascular tissues (xylem and phloem), and produce seeds.

Differences:

• Orange: It bears flowers and produces seeds enclosed within fruits (Angiosperm)

• Cycas: It produces cones and has “naked” seeds that are not enclosed in fruits (Gymnosperm)

ii. Mention their subdivisions. Also write the reason for placing them in these subdivisions.

Orange:

• Subdivision: Angiosperm

• Reason: It produces flowers, and its seeds are enclosed inside a fruit

Cycas:

• Subdivision: Gymnosperm

• Reason: It does not produce flowers or fruits; its seeds are naked (usually found in cones)

iii. Which one of them is more advanced? Clarify with reasons.

Answer: The Orange plant is more advanced than the Cycas plant.

Reasons:

• Seeds Enclosed in Fruit: The Orange produces seeds protected inside a fruit (ovary), which ensures better protection and dispersal. Cycas seeds are naked and exposed

• Flowers: The Orange bears flowers, which are highly specialized reproductive structures often adapted for efficient pollination (e.g., by insects), whereas Cycas uses primitive cones and relies mostly on wind pollination

• Vascular Tissue: Angiosperms (Orange) possess vessels in their xylem for efficient water conduction, whereas Gymnosperms (Cycas) generally lack vessels and rely only on tracheids

(h) Following chart shows the group of four animals. In which group does fish belong to?

Chart: A (Invert/Terr), B (Invert/Aqua), C (Vert/Terr), D (Vert/Aqua)

Answer: Fish belongs to group D (Vertebrates and Aquatic)

Reason: Fish have a backbone (Vertebrate) and live in water (Aquatic)

(i) Digestive system is not developed in the animals of phylum Porifera. How do they digest food? Write.

Answer: Animals of Phylum Porifera (Sponges) digest food through intracellular digestion. Water enters their body through minute pores (ostia) carrying food particles. Specialized cells called choanocytes (collar cells) trap and ingest these particles. The digestion then occurs inside the food vacuoles within the cells.

(j) Rakesh saw an animal while he was playing in the ground. How can he identify the phylum of that animal by using taxonomic knowledge of kingdom Animalia? Explain.

Answer: Rakesh can identify the phylum by observing external morphological features:

• Body Shape/Symmetry: Is it segmented? (Annelida/Arthropoda). Is it flat? (Platyhelminthes). Is it cylindrical? (Nematoda)

• Appendages: Does it have jointed legs? (Arthropoda). Does it have tentacles? (Coelenterata/Mollusca)

• Skeleton: Is there a hard shell? (Mollusca). Is there spiny skin? (Echinodermata)

• Habitat: Is it moist skin/dry scales?

Example: If it has jointed legs and a segmented body, it is Phylum Arthropoda. If it is soft-bodied with a shell, it is Phylum Mollusca.

(k) Shark and whale both live in water. Based on their features, which is a more developed animal? Explain with reasons.

Answer: The Whale is more developed.

Reasons:

• Class: Whale is a Mammal (highest class), while Shark is Pisces (lower vertebrate)

• Heart: Whale has a 4-chambered heart (complete separation of oxygenated/deoxygenated blood), Shark has a 2-chambered heart

• Respiration: Whale breathes air via lungs (advanced), Shark uses gills

• Reproduction: Whale is viviparous (births live young) and cares for them with milk; Shark is ovoviviparous or oviparous

• Thermoregulation: Whale is warm-blooded; Shark is cold-blooded

(l) Pictures of two animals are shown below, compare them and answer the following questions:

i. In which phylum and class do they belong?

Bat (Chamera): Phylum Chordata, Class Mammalia

Eagle (Baaj): Phylum Chordata, Class Aves

ii. Write any two similarities and dissimilarities between them.

Similarities:

• Both organisms have wings on their bodies

• Their bones are hollow (pneumatic)

Dissimilarities:

• The Bat belongs to the Mammal class, whereas the Eagle belongs to the Aves class

• The Bat gives birth to babies directly (viviparous), whereas the Eagle lays eggs (oviparous)

iii. How does the study of these animals clarify the concept of evolution?

Answer: Looking at the evolutionary history of these organisms, evidence is found that they originated from the same ancestor. Therefore, a close relationship between Aves and Mammalia is seen, and it appears that Mammalia originated from the evolution of the Aves class.

(m) Explain the relation between classification of living beings and evolution.

Answer: Classification is the arrangement of organisms based on similarities and differences. Evolution is the process of gradual change.

• Classification is based on common characteristics inherited from common ancestors

• Organisms with fewer differences are closely related and share a recent common ancestor

• Primitive organisms (e.g., Monera, Porifera) are placed at the beginning of the classification system, while complex organisms (e.g., Mammalia, Angiosperms) are placed at the end

• Conclusion: The hierarchy of classification reflects the evolutionary history (phylogeny) of life

(n) Draw a chart to show classification of kingdom Plantae according to the five kingdom system.

(o) Draw a chart to show classification of kingdom Animalia according to the five kingdom system.

(p) Look at the picture below and answer the following questions:

i. Which animal has a two-chambered heart?

The Fish (e.g., Rohu, Seahorse)

ii. Which animal suckles milk to its young?

The Mammal: Tiger

iii. Write any two similarities between frogs and snakes.

• Both are Vertebrates (Phylum Chordata)

• Both are Cold-blooded (Poikilothermic)

• Both lay eggs (Oviparous)

iv. Which of these animals have air sacs in their bodies?

The Bird (Class Aves). Air sacs help in double respiration and flight.