Classification of Living Beings

(b) Due to locomotion with the help of tube-feet.

Sea-urchin is an echinoderm; the water-vascular system with tube feet is the characteristic feature of the phylum Echinodermata.

Fern, cycas and banana are all kept in the division Tracheophyta (vascular plants) because:

1. They all have vascular tissues (xylem and phloem) to conduct water and food.
2. They all have well-differentiated true roots, stem and leaves.

(c) P-3, Q-1, R-4, S-2.

• Pine tree grows in cold places (3).
• Tiger eats flesh, so it is carnivorous (1).
• Fish has a streamlined body for swimming (4).
• Frog is amphibian and lives in both land and water (2).

(i) Chlamydomonas.

Chlamydomonas is a unicellular green alga. Moss and liverworts are bryophytes, and Rhizopus is a fungus.

• Link with vertebrates: Amphioxus has a notochord, dorsal hollow nerve cord and gill slits like vertebrates, but it has no backbone (vertebral column), so it is a link between invertebrates and vertebrates.
• Link with evolution: It shows that chordates (vertebrates) evolved from invertebrate ancestors, so it is an evidence of evolution.

(c) has cone instead of flower and the seed is naked.

Cycas bears cones, not true flowers, and its ovules/seeds are not enclosed in an ovary or fruit, so it is a gymnosperm (naked-seeded plant).

1. The body is covered with dry scales; they are cold-blooded (poikilothermic).
2. They lay eggs with a leathery shell on land and breathe through lungs; the heart is three-chambered (crocodile has four).

(Any two.)

1. The body is covered with feathers, the forelimbs are modified into wings and the mouth has a beak without teeth.
2. They are warm-blooded (homoeothermic), have a four-chambered heart, breathe through lungs and lay eggs.

(Any two.)

1. Its leaf gel is applied to burns, wounds and skin problems, and used in cosmetics.
2. Its juice is taken to relieve constipation and improve digestion.

The plant is aloe-vera. Other uses:

1. Its juice is taken to cure constipation and help digestion.
2. It is used to make cosmetics (creams, shampoo) and to treat skin problems and wounds.

The bat is a mammal and is viviparous: it gives birth to young ones and feeds them with milk. The eagle is a bird and is oviparous: it lays eggs. Because of this difference in reproduction, they are kept in different classes (Mammalia and Aves) though both can fly.

The plant is a leafy vascular plant (such as a fern/flowering plant), and it is kept in the division Tracheophyta.

Reason: It has vascular tissues (xylem and phloem) and true roots, stem and leaves.

Both have two cotyledons in the seed, with reticulate venation and taproot, so both are dicotyledons (class Dicotyledonae).

(Any two rows.)

Grouping by evolution (lower to higher):

• Lower group: (i) Segmented body, phylum Annelida.
• Higher group: (ii) Tentacles and eyes in head, phylum Mollusca.

(i) Phylum Annelida (earthworm).

(ii) Sub-division Gymnosperm of division Tracheophyta (pine).

(iii) Class Monocotyledonae (maize, paddy).

(iv) Class Reptilia (scaly body; crocodile has a four-chambered heart).

Ascending order of complexity: Sea horse (fish) → Hyla (amphibian) → Snake (reptile) → Parrot (bird) → Elephant (mammal).

(Any two rows.)

It falls in the class Dicotyledonae (dicot), because dicot plants have a taproot.

Medicinal plants such as aloe-vera, turmeric and Cordyceps are collected, grown and sold in the country and exported abroad, which creates jobs and earns foreign money, so they strengthen the national economy.

(i) Ascending order of evolution: (c) → (b) → (d) → (a).

• (c) Undifferentiated root and stem: algae (Thallophyta).
• (b) Needs water for reproduction: bryophytes.
• (d) Feather-like leaves: pteridophytes (ferns), not gymnosperms.
• (a) Petals in 4 or 5 or their multiples: dicot angiosperms.

(ii) The aquatic plant group from above is (c), algae. It belongs to the Kingdom Plantae, division Thallophyta (plant body is thallus, without true root, stem and leaves).

Snake has a three-chambered heart (reptile; the crocodile has a four-chambered heart). Another animal in the same class Reptilia is a lizard (or tortoise).

(c) Aves.

Pigeon has feathers, wings and a beak, so it is a bird.

Chlamydomonas lies in the division Thallophyta (algae), as it is a green alga without true root, stem and leaves.

Group A: Jelly fish → Protochordate → Sea horse → Snake.

Group B: Volvox → Moss → Cycas → Banyan.

Annelida (for example earthworm), as these animals have cylindrical segmented bodies and excrete through nephridia.

• Sparrow: class Aves.
• Fern: division Pteridophyta (sub-division of Tracheophyta).

• Mammal: Whale.
• Least developed animal: Sea-horse (a fish), because fishes are the lowest vertebrates among these.

(d) salamander, toad, frog.

All three live on land and in water and have moist skin. Crocodile and tortoise are reptiles; sea-horse is a fish.

(d) Cure respiratory diseases.

Holy basil (tulsi) is used for cough, cold, asthma and other respiratory problems.

(iii) It moves with the help of tentacles.

Coelenterates such as Hydra and jelly fish are aquatic, multicellular animals with tentacles. Pores belong to sponges and unicellular forms to Protozoa.

• Moss is in the division Bryophyta (a division of Plantae without vascular tissue).
• Banana is in the division Tracheophyta (sub-division Angiosperm).

Phylum Arthropoda; its body is covered by a chitinous exoskeleton. Example: cockroach (or butterfly/grasshopper).

B, the shark (a fish), is less developed than the whale (a mammal).

(a) Antheridium.

Antheridium produces male gametes (sperms); archegonium produces the egg.

(d) have beak and feathers.

Birds are lung-breathing, warm-blooded and oviparous, with a beak and feathers.

Both are warm-blooded (homoeothermic), have a four-chambered heart and breathe through lungs.

1. Honey bees produce honey and bee-wax, which are used as food and medicine and sold for income.
2. They help pollination of flowers, increasing crop and fruit production.

(d) Fungi, Plantae, Monera.

Bacteria (Monera), fungi and plants have cell walls; animal cells have no cell wall.

(ii) Maize.

It is a flowering monocot with fibrous roots and an unbranched stem. Fern and cycas do not bear true flowers, and mustard has a taproot and branches.

(i) Slug: phylum Mollusca.

(ii) Sea-cucumber: phylum Echinodermata.

1. The octopus has a soft body with head, visceral mass, muscular foot and mantle, which is a mollusc feature.
2. It lacks the tube-feet and spiny skin of echinoderms, and its body is bilaterally symmetrical, whereas echinoderms have radial symmetry.

So it belongs to Mollusca.

1. Pteridophytes have vascular tissues (xylem and phloem), but bryophytes do not.
2. Pteridophytes have true roots, stem and leaves, but bryophytes only have root-like rhizoids and leaf-like parts.

(d) Annelida, Arthropoda, Chordata.

Earthworm (Annelida) is the simplest, butterfly (Arthropoda) is higher, and frog (Chordata) is the most developed.

(c) Calamus (bojho).

Calamus has antimicrobial property and is used in traditional medicine for digestive problems and throat-related disorders. Holy basil is mainly used for respiratory problems, aloe-vera for skin and burns, and turmeric as an antiseptic.

Similarity: Both are flowering plants (angiosperms) with true roots, stem and leaves, and vascular tissue.

Dissimilarity: Paddy is a monocot (one cotyledon, parallel venation, fibrous root), while mustard is a dicot (two cotyledons, reticulate venation, taproot).

(b) Asiatic pennywort (ghodtapre).

It has antioxidant and antimicrobial properties and is used to relieve stress, depression and anxiety, and to improve memory. Gurjo is mainly used to boost immunity and treat fever, turmeric is an antiseptic, and neem is used for skin and blood purification.

It is a sponge (phylum Porifera). It respires through its general body surface by diffusion of oxygen from water entering through the pores; it has no special respiratory organ.

(i) Plant A (fern) belongs to the sub-division Pteridophyta.

(ii) Plant B (cycad) is more advanced because it produces seeds (in cones), while fern reproduces by spores.

(c) Algae.

Algae belong to the plant kingdom (Thallophyta). Fungi, Protista and Monera are separate kingdoms.

Earthworm → Cockroach → Fish → Frog.

(c) Caterpillar fungus.

Cordyceps sinensis (yarsagumba) is a fungus growing on caterpillars.

Similarity: Both can fly with wings and are warm-blooded with a four-chambered heart.

Dissimilarity: The bird (A) has feathers and lays eggs, whereas the bat (B) has hair on its body, gives birth to young ones and feeds them milk.

The creature (scaly skin, egg-laying on dry land with shell) belongs to the class Reptilia.

Heart: reptiles have a three-chambered heart (two auricles and one ventricle), while mammals have a four-chambered heart (two auricles and two ventricles).

(iv) Z.

Fish has a backbone and lives in water, so it is an aquatic vertebrate.

Both are mammals: they give birth to young ones (viviparous), feed them milk through mammary glands, have hair and a four-chambered heart, so they are in class Mammalia.

Yes, it is possible to identify them from leaves.

• Fern (Pteridophyta): leaves are feather-like, bear spore cases (sori) underneath.
• Cycas/pine (Gymnosperm): leaves are feathery or needle-like and tough.
• Flowering plants (Angiosperm): broad leaves with parallel venation (monocot) or net venation (dicot).

(a) Organism A is hermaphrodite whereas organism B is unisexual.

A (segmented, cylindrical) is an annelid such as an earthworm, which has both male and female organs. B (unsegmented, cylindrical) is a nemathelminth such as Ascaris, which has separate sexes. Both are triploblastic.

(b) It has naked seeds.

In pine the seeds are borne on cones and are not covered by an ovary or fruit wall. This naked seed character places it in the sub-division Gymnosperm.

1. They can live both on land and in water; the skin is moist, smooth and without scales.
2. Larvae (tadpoles) breathe by gills, adults by lungs and skin; the heart is three-chambered (two auricles, one ventricle) and they are poikilothermic.

(Any two.)

1. Plants are multicellular (mostly) eukaryotic organisms whose cells have a cell wall made of cellulose.
2. They contain chlorophyll and make their own food by photosynthesis, so they are autotrophs.

(Any two.)

1. Seeds are naked, i.e. not enclosed in a fruit; they are borne on cones instead of flowers.
2. They are woody plants with well-developed roots, stem and needle-like or feather-like leaves; vascular tissue is present. Examples: pine, cycas.

(Any two.)

1. The seed has a single cotyledon.
2. Leaves show parallel venation, roots are fibrous, and flower parts are in multiples of three.

(Any two.) Examples: maize, paddy, banana.

(d) Requires water for fertilization.

The male gametes of mosses and ferns are flagellated and must swim through water to reach the egg, so these plants live in moist, shady places.

(d) Platyhelminthes, Nemathelminthes, Annelida.

These three phyla come one after another in the evolutionary sequence (flatworms, roundworms, annelids), all being worm-like triploblastic animals, so they are closely related. The other options jump across distant phyla.

Figure (a): The plant (neem-like medicinal tree with pinnate leaves) is a medicinal plant; its leaves and bark have antimicrobial properties and are used to treat skin diseases and infections.

Figure (b): In turmeric the rhizome (underground stem) is the more useful part; it is used as a spice, antiseptic, and to treat wounds and colds.

(a) Body is divided into head, visceral mass, muscular foot and mantle.

The soft body with head, visceral mass, muscular foot and a mantle (usually secreting a shell) is the characteristic feature of the phylum Mollusca.

(b) Body of P bears pores whereas body of Q bears coelenteron.

P, the first multicellular animal, is a sponge (Porifera) with many pores. Q, the first tissue-grade animal, is a coelenterate with a central cavity (coelenteron).