Living Creatures: Exploring their Characteristics

A still shell may be part of a living snail. A moving car remains a machine. These opening examples show why movement alone does not identify life. Plants usually stay rooted in one place while their parts grow or move.

Activity 10.1 asks you to classify familiar things, give a reason, then revise your answer after learning more. Keep the original guess and the reason for any change. Use evidence of organised life processes over time rather than testing every item by whether it moves when watched.

Living organisms obtain and use materials and energy, grow and develop, respond to conditions and remove wastes. Reproduction produces new organisms of one’s own kind and maintains continuity between generations. These processes need not all be visible at the same moment. A resting animal, an adult no longer increasing in size, a viable unsprouted seed or an individual that cannot reproduce is not thereby non-living.

Death involves the irreversible end of an organism’s life processes. It should not be inferred from a single missing response or a brief period without growth. A wooden log comes from a once-living tree, but that origin alone does not make the log a living organism.

Growth is an increase associated with the organism’s own living processes; development includes changes in form and function. Comparing a childhood photograph with a later one shows change over years, while seedling growth may be recorded over days. Increasing size by adding material to a non-living object is a different process.

Nutrition supplies materials and energy for life. Green plants make food using light and also obtain water and mineral nutrients. Carnivorous plants such as Drosera capture prey for additional nutrients in nutrient-poor surroundings; this does not mean they obtain everything they need from insects.

The chapter suggests observing breaths after ordinary activities. Record your actual counts instead of treating a class example as a fixed rate for everyone. Do not hold your breath or provoke distress to make a comparison.

A stimulus is a change or event that prompts a response. Withdrawing from a thorn or a hot object is an example to explain, not an experiment to perform. In plants, touch-me-not leaves fold after touch; some leaves, including amla leaves, change position with the daily light–dark cycle.

Drosera has sticky structures that can move around captured prey. Flowers open and climbers wind around supports. Some plant movements occur quickly; others are growth changes visible only over a longer period. Do not conclude that a plant is non-living because a short observation shows no obvious change.

Jagadish Chandra Bose developed instruments including the crescograph to record small plant growth responses. The useful lesson is that instruments can reveal changes too small or slow for unaided observation. A plant’s response does not imply a human-like conscious reaction.

Germination begins the seed’s development into a seedling. Water uptake supports the embryo’s renewed growth and softens the seed coat. A seed contains a young plant and stored reserves; the sprout does not have to make all its food by photosynthesis before it can emerge.

Activity 10.2 uses four similar pots, each with four bean seeds. NCERT proposes keeping the setups for 15 days and regularly recording germination over the first 7–10 days. The table below describes the comparison and expected interpretation; it is not a record of experiments performed for this webpage.

Seeds need suitable moisture, access to oxygen and a suitable temperature. Waterlogged soil can limit oxygen reaching them; “excess water” does not establish that absolutely no oxygen is present unless that is measured. Soil supports the setup, but seeds can also germinate on moist paper with suitable conditions.

Bean seeds can germinate in darkness. After germination, the seedling needs suitable light for sustained growth. Other species may require light, darkness or additional conditions for germination. The book contrasts Coleus and Petunia with Calendula and Zinnia; follow guidance for the actual seed rather than applying one rule to every species.

A failure to sprout does not alone show that a seed was dead: unsuitable conditions or dormancy may prevent germination. Use several comparable seeds and record how many germinate. Do not replace missing observations in Tables 10.2 or 10.3 with invented counts.

End question 9 asks about temperature. Compare similar seeds at two suitably different, measured temperatures while keeping moisture, air, light, growing medium and observation time comparable. Extremely hot or cold treatment is unnecessary. The original four-pot comparison does not itself isolate temperature.

1. 1

   State the question and prediction

   Choose one factor, such as moisture or light. Label each setup, state the predicted outcome and identify the comparison before looking for sprouts.

2. 2

   Keep other conditions comparable

   Use the same kind and similar quality of seeds, equal numbers and similar containers. Maintain suitable temperature and monitor moisture. A dark cupboard may differ from a sunny window in more than light.

3. 3

   Record what actually happens

   Date observations; count germinated seeds and sketch visible changes. Distinguish first germination from later seedling growth, and note drying, mould or other changes that could affect interpretation.

4. 4

   Compare and qualify

   Compare results with the prediction and repeat if evidence is unclear. A few seeds are a small sample. State which explanation the evidence supports and which variables or species were not tested.

Activity 10.3 compares seedlings held upright, inverted, and exposed to light from one direction. Germinate bean or gram seeds first; attach seedlings gently to moist blotting paper on plates without damaging them. The paper can draw moisture from water below while the seedlings remain above the waterline.

For the upright comparison, roots generally grow down and shoots up. After inversion, new root growth curves down and new shoot growth curves up. When light reaches an upright seedling mainly from one side, the shoot generally bends towards it while the root continues mainly downwards. These are growth responses, not the whole plant turning like a rotating object.

Gravity helps orient roots and shoots, while light can influence shoot direction. The names gravitropism and phototropism describe these responses; detailed hormone mechanisms are beyond this chapter. Record separate root and shoot predictions and observations in Table 10.3.

For the sideways pot in Figure 10.9, predict the direction of new growth rather than drawing the entire existing plant instantly upright. Figure 10.10 compares different starting orientations of young seedlings: look for roots reorienting down and shoots up over time. The drawing alone cannot supply a measured growth rate.

Activity 10.4 proposes regular observations over about three months. Date the appearance of roots, leaves, flowers and pods in Table 10.4. Use actual observations: varieties and growing conditions affect timing, so a flower cannot be assigned the same day in every trial.

A life cycle connects the development of an individual with production of a new generation. An annual bean plant may yellow and die after completing its cycle even while watered. Do not generalise that every plant dies immediately after fruiting; many plants flower and fruit in several seasons.

1. 1

   Seed and germination

   A viable seed takes up water and, in suitable conditions, the embryo begins growing.

2. 2

   Seedling and leaves

   The root and shoot extend; leaves develop as the young plant grows.

3. 3

   Mature flowering plant

   The plant matures and produces flowers under suitable conditions.

4. 4

   Fruit containing seeds

   Following successful reproduction, a bean pod develops and contains seeds. Not every flower necessarily becomes a pod.

5. 5

   Next generation

   Seeds can give rise to new plants. The original plant’s death is not a step that turns its body back into a seed.

A mosquito develops through egg, larva, pupa and adult. Larvae and pupae are distinct aquatic stages; the adult emerges from the pupa and flies. Many larvae and pupae obtain air at the water surface. Adults and immature stages differ markedly in form.

Egg-laying details vary by species: some eggs are laid on water, while Aedes can lay above the waterline on container walls. The book’s adult survival example of 10–15 days is not a universal lifespan. Development and survival depend on species and conditions.

Activity 10.5 asks how evidence could establish whether larva or pupa comes first. Use an existing recorded sequence or supervised images to follow identifiable individuals through changes. Seeing one adult appear first in a mixed sample is insufficient if the individuals’ starting stages and ages are unknown. Do not maintain open containers to breed mosquitoes for this task.

Female mosquitoes of relevant species can transmit infections such as malaria, dengue or chikungunya; this does not mean every mosquito carries every disease. Reducing breeding sites helps prevention. Empty and clean suitable water-holding containers, cover stored water and follow local vector-control guidance. The book’s oil-film example illustrates interference with surface breathing; it is not a recommendation to pour kerosene into water.

Activity 10.6 observes a pond without disturbing its occupants. Frog spawn is a jelly-like group of eggs; embryos develop within them. In the typical pond-frog cycle shown by NCERT, eggs hatch into aquatic tadpoles, which later develop legs, become froglets and then adults.

A tadpole’s tail helps it swim. Legs develop before the tail has completely disappeared; froglets still have a tail remnant while spending more time near or on land. During metamorphosis, body form and breathing structures change as the animal develops. Adult frogs in this model can use land and water.

Figure 10.8 groups six pictured forms into four main stages: egg/embryo, tadpole, froglet and adult. Its illustrative labels run from day 1 through approximately 14 weeks. They are not fixed times for every species or environment, and the drawing does not establish a universally shortest stage. Some frogs have different developmental routes.

Both mosquitoes and these frogs have immature aquatic stages and major changes in form. A frog has no pupal stage; an adult mosquito is an insect, while a frog is an amphibian. A silk moth also has egg, larva, pupa and adult stages; its larva produces silk fibres and the cocoon surrounds the pupa. The cocoon and pupa are not the same structure.

Use these prompts to revisit the nine end questions and further-learning tasks. An observation, the proposed explanation and an untested assumption should remain distinguishable.

1. Interpret the growth–respiration grid

   A pencil neither grows biologically nor respires. A living adult can respire without visibly increasing in size. A growing seedling both grows and respires. Size increase without respiration may describe material accumulating on a non-living object, such as a growing crystal; it is not the same as an organism’s biological growth. State the time interval and meaning of “growth”.

2. Use germination knowledge for storage

   Keep grains and pulses appropriately dry to discourage unwanted sprouting, with suitable storage conditions to prevent deterioration. Dry storage does not mean every seed is dead; maintaining viability and preventing spoilage are separate questions.

3. Compare life cycles without forcing identical stages

   Both plants and animals develop and can produce a next generation. A bean makes flowers and pods; a frog has tadpole and froglet stages; a mosquito has larva and pupa stages. Birds develop from eggs without following the mosquito’s larva–pupa sequence. Stage names must match the organism.

4. Explain the wooden-log disagreement

   A tree’s origin explains where wood came from, while evidence of current life processes identifies the living organism. Lack of locomotion alone is not a sound argument: an intact rooted tree is living. Do not classify all tree-derived objects as alive.

5. Extend observation without inventing a timetable

   Ask a gardener about species and conditions; keep dated sketches of several plants and compare actual stages. Plants can also reproduce vegetatively, for example through a stem cutting or a potato tuber, so not every new plant begins from a newly germinated seed. Observe butterflies or moths using existing images or undisturbed stages; investigate temperature, moisture and food rather than claiming one schedule for all insects.

6. Keep the investigation compatible with conservation

   Observe eggs, tadpoles and insects from a safe distance with a responsible facilitator. Do not collect spawn, disturb ponds or spread mosquitoes. The book’s poem can be adapted into an accurate stage sequence rather than a required game or performance.

These original questions ask you to use evidence and distinguish stages. They are learning checks, not claimed UPSC previous-year questions.