Answer:

Biodiversity refers to the immense variety of living organisms found on Earth. It includes all life forms – from microscopic organisms to giant trees, and from glowing jellyfish to soaring eagles. Biodiversity exists in countless forms and habitats across the planet.

Answer:

Grouping or classification of organisms helps us understand diversity by:

• Organising information about millions of species in a systematic way.
• Understanding the similarities and differences among organisms.
• Identifying how different organisms are related to one another.
• Studying life forms more efficiently and making predictions about their characteristics.

Answer:

Plants and animals are classified based on several criteria:

• External features – shape, size, body organisation.
• Mode of nutrition – autotrophic or heterotrophic.
• Internal structures – skeletal patterns, presence/absence of organs and tissues.
• Cell structure – unicellular/multicellular, prokaryotic/eukaryotic, presence/absence of cell wall.
• Ecological role – producer, consumer, or decomposer.
• Reproduction – asexual and/or sexual methods.
• Genetic similarity – similarities in DNA.

Answer:

Classification helps in farming by:

• Identifying crop varieties with useful traits like drought tolerance, pest resistance, and ability to grow in nutrient-poor soils.
• Helping farmers select the right crops for specific environments.
• Reducing the risk of crop failure by promoting diverse varieties.
• Strengthening food security through systematic understanding of crop diversity.

Answer:

Yes, organisms that share common features often share a common ancestry. Similarities in external features, internal structures, cellular organisation, and genetic material suggest that organisms have evolved from common ancestors. Scientists study these similarities to understand evolutionary relationships.

Answer:

A single-celled organism carries out all life processes within a single cell because:

• The cell is highly specialised and contains all necessary organelles for life processes.
• It has a large surface area to volume ratio, allowing efficient exchange of materials with the environment.
• In multicellular organisms, cells are differentiated to perform specific functions, requiring many cells to work together.
• Unicellular organisms have evolved efficient mechanisms for nutrition, respiration, excretion, and reproduction within one cell.

Answer:

Bryophytes (mosses and liverworts) have features that reduce their dependence on water but still require moist conditions:

• They have root-like structures (rhizoids) for anchorage and absorption.
• They have leaf-like and stem-like structures for photosynthesis and support.
• They lack vascular tissues (xylem and phloem), so they rely on moisture for transport.
• They require water for reproduction because their male reproductive cells must swim to reach female cells.

Answer:

Taller plants need specialised transport tissues (xylem and phloem) because:

• Xylem transports water and minerals from roots to all parts of the plant against gravity.
• Phloem transports food (sugars) from leaves to other parts of the plant.
• Without these tissues, water and nutrients could not reach the upper parts of tall plants.
• Transport tissues allow plants to grow taller and colonise diverse habitats.

Answer:

Seeds and fruits affect plant survival and distribution by:

• Seeds protect the developing embryo and provide stored food, increasing the chances of survival.
• Fruits aid in seed dispersal through wind, water, animals, or insects.
• Plants with seeds and fruits can colonise new areas and survive in diverse environments.
• Seeds allow plants to reproduce without water, unlike bryophytes and pteridophytes.

Answer:

The beetle's hard external skeleton (exoskeleton) helps it survive by:

• Providing protection against predators and physical damage.
• Reducing water loss, allowing it to survive in dry environments.
• Supporting powerful muscles for movement and locomotion.
• Enabling survival in exposed and harsh environments where earthworms cannot thrive.

Answer:

Biodiversity is not just about the variety of organisms. It also encompasses:

• Genetic diversity – variations within species.
• Species diversity – variety of species in an ecosystem.
• Ecosystem diversity – variety of habitats and ecological processes.
• Ecological interactions – relationships between organisms and their environment.

Answer:

To classify a new organism found in a pond, I would observe:

• Cell type – prokaryotic or eukaryotic (to determine kingdom).
• Number of cells – unicellular or multicellular.
• Cell wall – presence/absence and composition (cellulose, chitin, etc.).
• Mode of nutrition – autotrophic or heterotrophic.
• Locomotion – whether it moves and how.
• Reproduction – sexual or asexual.
• Level of organisation – cellular, tissue, organ, or organ system.

Answer:

Genetic studies provide deep information because:

• DNA carries the instructions for growth and function of all organisms.
• Organisms with similar DNA are considered to have a common ancestry.
• Genetic studies help trace evolutionary relationships more accurately than physical features alone.
• They reveal the true relationships between organisms that may look similar but are not closely related.

Answer:

Climate change affects biodiversity in several ways:

• Changes in temperature and rainfall can destroy habitats.
• Species that cannot adapt to new conditions may become extinct.
• Migration patterns and breeding cycles of animals may be disrupted.
• Plant growth and food availability for animals may decline.
• Ecosystems may lose their balance and stability.

Answer:

The correct option is (ii) Body with jointed legs.

Explanation: Insects belong to the phylum Arthropoda, which is characterised by jointed legs and an exoskeleton. Earthworms (Annelida) have a cylindrical, segmented body without jointed legs. Both have bilateral symmetry, so that feature alone cannot distinguish them.

Answer:

The correct option is (iii) Presence of a cell membrane.

Explanation: Sponges are animals because their cells have a cell membrane (not a cell wall) and are heterotrophic. They lack mitochondria? No, they have mitochondria. They do not photosynthesise, and they do not have a cell wall (which is a plant/fungal feature). The presence of a cell membrane is a fundamental characteristic of animal cells.

Answer:

Sample answer: Consider a cat and a butterfly.

• Cat: Has a backbone (vertebrate), four legs, fur, mammary glands, gives birth to live young.
• Butterfly: Lacks a backbone (invertebrate), six jointed legs, exoskeleton, wings, undergoes metamorphosis.

These features place the cat in Chordata (Mammalia) and the butterfly in Arthropoda (Insecta).

Answer:

A scientist would justify choosing cellular organisation as a more fundamental characteristic because:

• Cellular organisation (prokaryotic/eukaryotic, unicellular/multicellular) is a basic feature of all living organisms.
• It determines the level of complexity of an organism.
• Xylem and phloem are specific features found only in certain plants (vascular plants).
• Using cellular organisation allows broader and more consistent classification across all life forms.

Answer:

It would most likely belong to the kingdom Protista.

Reasons:

• It is single-celled (unicellular).
• It has a well-defined nucleus – eukaryotic.
• Cilia are used for locomotion, a common feature in many protists like Paramecium.

Answer:

Biodiversity contributes to ecosystem balance and stability by:

• Producers (plants) capture sunlight and produce food.
• Consumers (animals) help in pollination, seed dispersal, and population control.
• Decomposers (fungi, bacteria) recycle nutrients and maintain soil fertility.
• Interconnections among species create food webs that stabilise the ecosystem.
• Diverse ecosystems are more resilient to changes and disturbances.

Answer:

If all unicellular organisms were grouped into a single kingdom:

• Prokaryotes (bacteria) and eukaryotes (protists) would be grouped together despite major differences in cell structure.
• Organisms with different modes of nutrition (autotrophic, heterotrophic) would be mixed.
• It would not reflect evolutionary relationships accurately.
• The classification would be unscientific and confusing.

Answer:

Viruses are not placed in any of the five kingdoms because:

• They lack cellular organisation – no cell membrane, cytoplasm, or organelles.
• They are acellular (not made of cells).
• They are inactive outside a host cell and cannot carry out life processes independently.
• They do not fit into the criteria used for classification (cell type, number of cells, mode of nutrition).

Answer:

Sample answer:

I would keep viruses outside the five kingdom system because they are acellular and do not have the characteristics of living organisms. Creating a separate category for them would still not make them fit into the same classification system as cellular life. This shows that scientific classification is evolving and that classification systems have limitations. New discoveries may lead to changes in how we classify life.

Answer:

Features that prevent viruses from fitting:

• Lack of cellular structure (no cell membrane, cytoplasm, organelles).
• Cannot carry out life processes independently.
• No cell wall or mode of nutrition.

Limitation: Classification systems are based on cellular life forms. Acellular entities like viruses show that no single classification system can perfectly accommodate all forms of life, and classification is an ongoing process.

Answer:

Bryophytes:

• Have a simple body (thallus-like) with no true roots, stems, or leaves.
• Lack vascular tissues (xylem and phloem).
• Require water for reproduction.

Pteridophytes:

• Have true roots, stems, and leaves.
• Have vascular tissues (xylem and phloem) for transport.
• Still require water for reproduction but are better adapted to land.

They are placed in different groups because of differences in body organisation and presence of vascular tissues.

Answer:

Genus has fewer members but more features in common.

Explanation: In the hierarchical classification, a genus is a more specific group than a class. It contains fewer organisms that share a greater number of common features. For example, the genus Panthera includes only a few species (tiger, lion, leopard) that share many characteristics. A class (e.g., Mammalia) includes many more organisms with broader, less specific shared features.

Answer:

To identify the organism as belonging to Protista, the scientist would look for:

• Unicellular (single-celled) structure.
• Eukaryotic cell (well-defined nucleus).
• Autotrophic nutrition (photosynthesis) – like Euglena.
• Locomotion using flagella, cilia, or pseudopodia.

Examples: Euglena is a protist that is both autotrophic (photosynthetic) and capable of locomotion.

Answer:

To place a unicellular eukaryotic organism in Kingdom Fungi, the key identification features would be:

• Cell wall made of chitin (not cellulose).
• Heterotrophic mode of nutrition (absorptive).
• Lack of chlorophyll (not photosynthetic).
• Unicellular (e.g., yeast) but with fungal cell wall composition.

Answer:

Organisms	Key Observations
P	Microscopic; no true nucleus; rigid cell covering; survives high salinity and temperature
Q	Multicellular; filamentous body; cell wall present; no chlorophyll; grows on dead organic matter
R	Unicellular; true nucleus; contractile vacuole present; moves using flagella; shows photosynthesis in light but heterotrophic in the absence of light
S	Multicellular; well-differentiated tissues; backbone present; aquatic respiration during early life stage
T	Acellular; contains genetic material; remains inactive outside a host cell

(i) Identify one organism that clearly belongs to the Kingdom Fungi. State one observation that supports your answer.

Organism Q belongs to Kingdom Fungi. Observation: Multicellular, filamentous body, cell wall present, no chlorophyll, grows on dead organic matter (saprophytic).

(ii) Which organism would be placed in the Kingdom Monera? Mention one characteristic that justifies this placement.

Organism P belongs to Kingdom Monera. Characteristic: No true nucleus (prokaryotic); rigid cell covering; survives extreme conditions.

(iii) Organisms R and Q are both eukaryotic, yet they are placed in different kingdoms. Analyse the criteria that separate them.

• R (Protista): Unicellular, may be autotrophic or heterotrophic, moves using flagella.
• Q (Fungi): Multicellular (mostly), cell wall made of chitin, heterotrophic (absorptive nutrition), no chlorophyll.

(iv) Explain why organism S cannot be classified using the mode of nutrition alone.

Mode of nutrition only tells how an organism obtains food, but S has a backbone (vertebrate), well-differentiated tissues, and aquatic respiration during early life – features that place it in Animalia (Vertebrata).

(v) Organism T does not fit into any of the five kingdoms. Which fundamental characteristic used in classification does it lack and what does this reveal about the limitations of classification systems?

Organism T (virus) lacks cellular organisation – no cell membrane, cytoplasm, or organelles. This reveals that classification systems are based on cellular life and have limitations in accommodating acellular entities.

(vi) If classification were based only on habitat, which organisms might be incorrectly grouped together? Explain the scientific consequences of such a classification.

Organisms like fish and frogs (both aquatic) might be grouped together, even though they belong to different groups (fish = Pisces, frog = Amphibia). This would lead to incorrect evolutionary relationships and poor understanding of biodiversity.

(vii) Imagine scientists discover a new organism that is multicellular, eukaryotic, lacks chlorophyll and absorbs nutrients from a host externally. Should it be placed under fungi or animalia? Justify your reasoning using classification criteria.

It should be placed under Fungi because: It is multicellular and eukaryotic; lacks chlorophyll (not a plant); absorbs nutrients externally (like fungi – saprophytic/parasitic). Animalia would have internal digestion and active locomotion.