1. (a) True.
2. (b) True.

1. (a) Species
2. (b) Chlorophyll

1. (a) Nematodes (Pseudocoelomates)
2. (b) Liver fluke (Platyhelminthes)

1. Protozoa are called early animals because "pro" means ancient and "zoo" means animals.
2. They have continued to exist on earth since the origin of life and are unicellular.

1. Cell structure is used as a criterion for placing an organism in Monera or Protista.
2. In Monera, the cells are prokaryotic; membrane-bound cell organelles are absent. In Protista, the cells are eukaryotic; membrane-bound cell organelles are present.
3. Protista contains only unicellular eukaryotes, while Monera may have unicellular or multicellular forms.

1. Monera is a kingdom of prokaryotes, while organisms of kingdom Plantae show a definite nucleus, membrane-bound organelles, and multicellular body design.
2. Blue-green algae are prokaryotes having a nucleoid with naked DNA. Their cell organelles are also not enclosed in a membrane.
3. As they also do not possess a multicellular body design, these characters bring them closer to Monera and exclude them from kingdom Plantae.

1. Structural modifications help animals survive in their specific habitats. Fins and gills support movement and breathing in water, while feathers and hollow bones enable flight in birds.
2. In harsh environments, adaptations like fat storage in camels and thick fur in polar bears provide insulation and energy.
3. Mammary glands in mammals improve offspring survival, showing how body structures meet environmental challenges.

1. The stem is erect, aerial, branched or unbranched.
2. The leaves are usually dimorphic, i.e. presence of two types of leaves on a plant.
3. These are naked seeded plants, i.e. their ovules are not enclosed in the ovary.
4. The microsporophyll (male reproductive organ) and megasporophyll (female reproductive organ) are compactly arranged around the central axis, forming male cone and female cone respectively.

1. Forelimbs are modified into wings.
2. Body is covered by an exoskeleton of feathers.
3. Long bones are pneumatic, having air cavities.
4. Body is streamlined to reduce air resistance.
5. Well developed flight muscles.
6. Presence of air sacs to help in double respiration.
7. Tail feathers form a steering apparatus, nourished by preen glands.
8. They have acute vision.

1. Amphibians are vertebrates that can live both on land and in water, hence also called "vertebrates leading two lives".
2. Their body varies in form and their skin is not covered with scales.
3. They lay eggs in water and their larval forms always live in water.
4. They are cold-blooded animals having a three-chambered heart.
5. They breathe through lungs or gills or skin.

1. Classification provides a structured framework for organizing and studying the vast biological diversity present today.
2. It allows scientists to systematically group organisms based on shared characteristics, revealing evolutionary relationships and patterns.
3. This systematic approach is essential for comprehending the complexity and origins of different life forms and their interconnections.

1. Lichens are called compound plants as algae and fungi live together in close association, as a result of which both are benefitted.

Characteristics of lichens

1. Lichens are a group of plants of composite thalloid nature, formed by the association of algae and fungi.
2. The algal partner produces carbohydrate through photosynthesis, which is utilised by both, and the fungal partner serves the function of absorption and retention of water.
3. Based on the morphological structure of thalli, they are of three types: crustose, foliose, and fruticose.
4. Lichen reproduces by all three means: vegetative, asexual, and sexual.

1. In bony fishes, the skeleton is bony (made up of bones).
2. In cartilaginous fishes, the skeleton is made up of cartilage.

1. (i) Following scientific protocol, being observant, and not relying on recalling ability — these are the values reflected in Group A's approach.
2. (ii) Group B won't be able to draw any conclusions from their observations because a photograph doesn't allow a detailed analysis of the organism.
3. (iii) Group A, because this group follows a scientific method and promotes scientific attitude.

1. Specific geographical and climatic conditions, such as unique soil types, temperature ranges, and rainfall patterns found within a particular region, create distinct habitats.
2. These conditions can foster the evolution and survival of species that are highly adapted to that environment.
3. As a result, these species become restricted to that region, unable to thrive naturally elsewhere, thus becoming endemic to that specific area due to their specialized adaptations.

1. To classify a unicellular organism under Kingdom Fungi, the key identifying features should include heterotrophic nutrition (saprophytic or parasitic) and the presence of a cell wall made of chitin.
2. Although most fungi are multicellular, some (like yeast) are unicellular eukaryotes. Unlike protists, fungi do not perform photosynthesis and absorb nutrients from organic matter.
3. Thus, a eukaryotic, unicellular organism with a chitinous cell wall and heterotrophic mode of nutrition can be placed in Kingdom Fungi.

1. (i) Mushrooms can be cooked and eaten in daily life.
2. (ii) Mushrooms exhibit saprophytic nutrition.
3. (iii) Rohit's mother stopped him because the mushroom may be poisonous, and it is unsafe to uproot or handle unknown mushrooms without proper knowledge.

1. A single-celled organism carries out all life processes within one cell using specialised organelles. Each organelle performs a specific function, such as respiration, digestion and excretion.
2. In multicellular organisms, these functions are divided among many specialised cells and tissues.
3. Thus, while multicellular organisms require many cells for efficiency, a unicellular organism can perform all functions within a single cell due to its simpler organisation.

1. (i) The diagram shows ferns that belong to Pteridophytes. They are found mainly in shady or damp places.
2. (ii) Yes, they have a well-developed vascular system (xylem and phloem) for the conduction of water and other substances from one part of the plant body to another, as the plant body is divided into root, stem, and leaves.
3. (iii) These plants have no flowers and hence do not produce seeds.

1. In the classification hierarchy, a genus has fewer members but more features in common than a class.
2. This is because classification proceeds from broader groups to more specific ones. A class contains many different organisms with fewer similarities, while a genus includes closely related species that share a large number of characteristics.
3. Thus, as we move from class to genus, the number of organisms decreases but the similarity among them increases.

1. (i) It would have contributed to disturbing the ecological balance.
2. (ii) Because he is conserving biodiversity by not unnecessarily killing organisms.
3. (iii) Creating sensitivity by spreading awareness in other community members about the importance of biodiversity, and by developing empathy and love for all living organisms.

1. To identify the organism as belonging to Kingdom Protista, the scientist should look for unicellular organisation and a well-defined nucleus (eukaryotic cell).
2. Although the organism shows locomotion and autotrophic nutrition (like Euglena), these features alone are not sufficient. The key identifying characters of protists are that they are single-celled eukaryotes, often showing both plant-like and animal-like features.
3. Thus, the presence of a unicellular, eukaryotic body structure would confirm its placement in Protista.

1. Organisms without a notochord (invertebrates) exhibit a remarkable progression in body organization, ranging from simple cellular aggregations to complex organ systems.
2. This evolutionary advancement is evident in traits like the development of tissue-level organization in cnidarians, facilitating specialized functions and active feeding.
3. Bilateral symmetry in flatworms allows for directional movement. Subsequent groups show specialized adaptations for locomotion and nutrient acquisition, such as segmented bodies in annelids for flexible movement, and jointed appendages and external skeletons in arthropods for protection and efficient movement in varied environments.

1. (i) Biodiversity refers to the variety of living organisms present on Earth, including plants, animals, and microorganisms, along with the ecosystems they form and interact within.
2. (ii) One major cause of biodiversity loss is deforestation, where forests are cleared for agriculture, urban development, or industrial use, leading to habitat destruction.
3. (iii) The loss of one species can disrupt food chains and ecological balance, affecting other species that depend on it, ultimately leading to further decline in biodiversity and ecosystem instability.

OR

1. Conservation of biodiversity is important because ecosystems provide essential services such as food, clean air, water, and climate regulation. Protecting biodiversity ensures ecological stability and prevents species extinction. It also supports agriculture, medicine, and livelihoods, making it essential for both environmental sustainability and human survival.

1. (i) Green, brown, red algae, liverworts and mosses, ferns, and seed plants with or without flowers.
2. (ii) Photosynthetic (autotrophic) mode of nutrition.
3. (iii) Thallophyta (e.g. Spirogyra, Ulothrix, Cladophora and Chara) lacks a well-differentiated body.

OR

1. Primitive: Thallophyta; Advanced: Angiosperms.

1. (i) Biodiversity is the result of continuous evolutionary changes occurring over millions of years, shaped by interactions between organisms and their environment, leading to the development of a wide variety of life forms.
2. (ii) Variations help organisms adapt to environmental changes. Individuals with beneficial traits survive and reproduce more successfully, passing those traits to future generations, which drives the process of natural selection.
3. (iii) Evolution leads to new species through gradual accumulation of variations over generations. These differences improve survival and reproduction in changing conditions, eventually resulting in distinct organisms that differ significantly from their ancestors.

OR

1. Classification is important because it organises the vast diversity of organisms into groups based on similarities and differences. It helps scientists study relationships between species, understand evolutionary history, and communicate universally. Classification also simplifies identification of organisms and supports research in biodiversity conservation and ecological studies.

1. (i) Endemic species are organisms that are found naturally only in a specific geographic region and nowhere else in the world. Their restricted distribution makes them especially vulnerable to environmental changes and habitat destruction.
2. (ii) One biodiversity hotspot in India is the Western Ghats, known for its rich variety of endemic plants and animals and high levels of biodiversity.
3. (iii) Biodiversity hotspots are important because they support a large number of endemic species and maintain ecological balance. They help sustain food chains, preserve genetic diversity, and provide essential ecosystem services like clean air, water, and fertile soil.

OR

1. Biodiversity hotspots face threats mainly from deforestation, urbanisation, pollution, and climate change. Human activities lead to habitat destruction and fragmentation, reducing species populations. Overexploitation of resources further increases pressure on ecosystems, potentially causing irreversible loss of biodiversity.

1. (i) Euplectella belongs to phylum Porifera. They have pores all over the body; water enters through these pores and flows through the canals inside the body. Feather star is an Echinodermata, and they have tubular projections called tube feet, which work on hydraulic pressure. Tube feet help in capturing food, locomotion, respiration, etc.
2. (ii) The skeleton of a shark is made of cartilage, while the skeleton of a sea-horse is made of both bone and cartilage.
3. (iii) Tadpoles respire through gills. Frogs respire through their skin and lungs.
4. (iv) Forelimbs of birds are modified to form wings that help them to fly. Forelimbs of lizards help them to move.
5. (v) The skin of a tree frog has mucous glands, i.e. it is slimy; they also respire through their skin. The skin of humans has sweat glands which help in thermoregulation and excretion, and they also have hair on their skin.

1. (i) Thallophyta includes plants with the simplest body design.
2. (ii) Pinus and Cycas belong to Gymnosperms.
3. (iii) Flowering plants are also called Angiosperms. They are divided into two groups based on the number of cotyledons present in the seed:

1. Monocotyledonous — Plants with seeds having a single cotyledon, e.g. maize.
2. Dicotyledonous — Plants with seeds having two cotyledons, e.g. pea.

1. (i) The Monera kingdom was established due to the crucial observation that bacteria, unlike organisms in Protista, lack a true, membrane-bound nucleus. This significant structural difference in their cell organization necessitated a separate classification.
2. (ii) Fungi were separated into their own kingdom because, unlike plants, they do not synthesize their own food (heterotrophic) and primarily obtain nutrients by absorption, often from dead or decaying matter. This distinct nutritional strategy fundamentally differentiates them from plants.
3. (iii) A two-kingdom system broadly classifies living organisms into Plantae and Animalia based on movement and food synthesis. A five-kingdom system, on the other hand, recognizes Monera (prokaryotic unicellular), Protista (eukaryotic unicellular), Fungi (absorptive heterotrophs), Plantae (photosynthetic autotrophs), and Animalia (ingestive heterotrophs). This expansion reflects a more refined understanding of cellular structure, mode of nutrition, and evolutionary divergences.

Labelled diagram of Paramecium showing Cilia, Cytosome, Food vacuole, Water vacuole, Micronucleus, and Macronucleus

1. (i) The outer covering of the paramecium is called the pellicle. A contractile vacuole is present for the storage of water. Cilia are similar to flagella in shape but different in size, and are the main locomotive part of the paramecium body. There are two types of nucleus present in the paramecium. There is an oral groove working as the mouth.

(ii) Similarities between Amoeba and Paramecium

1. Both are unicellular organisms.
2. Both contain a food vacuole.

Differences between Amoeba and Paramecium

1. Amoeba has one nucleus, whereas Paramecium has two nuclei (i.e. macronucleus and micronucleus).
2. Amoeba moves with the help of pseudopodia, while Paramecium moves with the help of cilia.

Reasons

1. (a) Bryophytes are called amphibians of the plant kingdom as they can live in soil, but are dependent on water for sexual reproduction.
2. (b) Spiders and scorpions are placed in phylum Arthropoda because they possess jointed legs.
3. (c) In nematodes, a true body cavity is absent. So, it is said that they possess a pseudocoelom.

Names

1. (a) An earthworm has a segmented body.
2. (b) Frog is a tail-less amphibian.