Chapter 1: Living World
Sometime in the early years of the twentieth century, a young Indian botanist named S. P. Agharkar was studying the plants and animals of the Western Ghats. Born in Malvan in Maharashtra in November 1884, he had trained himself to look closely at things most people walk past. In a body of fresh water he noticed something that did not belong there — a small, soft, transparent, umbrella-shaped creature drifting slowly in the water. It looked like a jellyfish. But jellyfish belong to the sea, and this particular kind had, until then, been reported only from Africa.
Agharkar could not simply say, “I have seen something new.” He had to prove it. That meant collecting the specimen, preserving it, labelling exactly where and when it was found, examining it under a microscope, and comparing it with descriptions of species already known to science. Dr. Annandale, then Superintendent of the Indian Museum in Kolkata, helped him with this work. The finding was published in the scientific journal Nature in 1912. Today the research institute ARI in Pune carries Agharkar’s name.
Look carefully at the scene in Fig. 1.0 and think about the two questions hidden inside it: how did he know the drifting blob was living at all, and how did he find out what it was?
Diagram
Fig. 1.0 – A naturalist crouching beside a freshwater pool in the Western Ghats, hand lens in hand, observing a small transparent jellyfish in the water; a collecting jar, a field notebook and a labelled specimen sheet lie beside him.
Keep these questions in mind as you read. By the end of this chapter, you will be able to answer every one of them.
1.1 Basic Principles of Life
Our planet is built out of two kinds of components. The abiotic components are the non-living ones — air, water, soil, rocks, sunlight, temperature. The biotic components are the living ones — every bacterium, fungus, plant and animal around us, including you.
Telling the two apart looks easy at first. A dog is living, a stone is not. But biology needs a firmer answer than “we can just see it.” So the real question is this: on what scientific grounds do we call something living, and how exactly does it differ from a non-living object?
Biologists answer the question using a set of properties that living beings show together. Let us take them one at a time.
Metabolism: The Chemistry That Keeps You Alive
Once a living being is born or produced, its first task is simply to stay alive. Survival costs energy, and it also needs a constant supply of chemical molecules to build and repair the body. Both of these come from metabolism.
Metabolism is not one reaction but the entire set of chemical reactions going on inside the body. These reactions run in two directions. In catabolism, larger molecules are broken down, and this breakdown releases the energy the organism needs. In anabolism, smaller molecules are joined together to make new, larger molecules — the ones needed for growth and repair.
The two halves are not independent. Catabolism supplies the energy that anabolism spends, so an organism is constantly demolishing and rebuilding itself at the molecular level. This is why no non-living object can imitate life for long: a stone neither earns energy nor spends it.
Growth That Comes from Within
From birth onwards, every organism shows growth and development. Growth is an increase in mass and in the number of cells; development is the orderly change in form and function that accompanies it. Neither happens randomly — growth in a living being is a well-orchestrated process, controlled from inside the body by its own genetic instructions and enzymes.
You may have noticed that a sand mound on a beach also gets bigger, and that a boulder or a heap of soil seems to “grow” over time. But look at where the increase comes from. Material is simply added on the outside, by wind, water or gravity. Nothing inside the mound decides how big it should get or in what shape.
That is the crucial difference. In living beings growth is intrinsic — new material is added from within, by cell division and by the making of new cell material. In non-living objects growth is extrinsic — material only piles on from outside. Sand mounds and boulders therefore are not living beings.
Ageing: Growth Has a Time Limit
Growth and development do not go on forever. Beyond a certain point in time, the molecules, organs and organ systems of the body slowly begin to lose their effective working. Enzymes function less efficiently, repair becomes slower than damage, and the body becomes old. This gradual, natural decline in the working efficiency of the body is called ageing.
Ageing tells us something important about life: a living body is not a machine with permanent parts, but a system that must keep repairing itself, and that eventually loses the race against wear and damage.
Reproduction: Making Life Continue
An individual organism cannot last forever, so life has to be perpetuated — carried forward into the next generation. Every organism therefore tries to produce a young one like itself. This is reproduction, and it may be asexual (a single parent, offspring essentially identical to it) or sexual (usually two parents, with mixing of characters). Reproduction is what ensures continuity of the race even though individuals die.
But is reproduction an all-inclusive characteristic of life — that is, is it shown by every living thing without exception? Consider a mule, the offspring of a horse and a donkey. A mule is unmistakably alive: it eats, respires, grows, moves and responds. Yet it is sterile and cannot reproduce. The same is true of the sterile worker bees in a honeybee colony, which work all their lives without ever producing young ones.
This distinction is a favourite in NEET and board assertion–reason questions, which often pair the statement “reproduction is a defining property of living organisms” with the mule or worker-bee example as the reason. Read such statements carefully: continuity of the race and aliveness of the individual are two different claims.
Death: No Organism Is Immortal
As the body ages, its capacity to perform metabolism falls. When that capacity is finally lost, the organism dies. Death is therefore not an accident added to life from outside; it follows from the same chemistry that keeps the body running. No living organism remains immortal.
Responsiveness: Sensing and Reacting to the World
Every living being responds to changes in its surroundings — thermal changes such as a rise in temperature, chemical changes such as the presence of a nutrient or a poison, and biological changes such as the approach of a predator or a pathogen. This ability to sense a stimulus and react to it is called responsiveness or irritability, and it is regarded as a unique property of living beings.
Diversity of Life and the Need for Taxonomical Aids
Living organisms are not merely alive; they are astonishingly varied. Since time immemorial an immense variety of organisms has been living together on the earth, differing in size, shape, habitat and way of life.
This diversity is not just a curiosity. To understand the interrelations between living and non-living components, and between one living group and another, a systematic study of organisms is essential. The data collected from such study matters far beyond the classroom — various industries and agriculture depend on knowing exactly which organism they are dealing with.
Such knowledge is not obtained casually. Intensive laboratory work and field study, carried out in order to identify and classify organisms, form the strong base on which the collected data can be put to meaningful use.
To study this diversity, biologists use certain aids called taxonomical aids. These include herbaria, botanical gardens, museums, biodiversity parks, zoological parks and keys. The full set is shown in FC 1.1, and each of them is taken up one by one in the sections that follow.
Flowchart
FC 1.1 – Taxonomical aids: Taxonomical aids → branches into: Herbarium; Botanical garden; Museum; Biodiversity park; Zoological park; Key
1.2 Herbarium
The word herbarium (plural: herbaria) was coined by Pitton de Tournefort in his book ‘Elemens’. The art of the herbarium was initiated by the Italian taxonomist Luca Ghini (1490–1556), and herbaria have remained effective tools in taxonomic studies ever since.
What a Herbarium Is
A herbarium is essentially a dried plant specimen that is pressed, treated in various ways, and then mounted on a standard-size sheet in order to preserve it. The same word is also used for the room or building in which thousands of such mounted sheets are stored in an organised, classified arrangement.
Drying and pressing are not decorative steps. Water in living tissue invites fungi and bacteria, so removing the water stops decay. Pressing flattens the plant so that its leaves, flowers and fruits all lie in one plane and can be examined later without disturbing the specimen. Even the standard size of the sheet has a purpose — uniform sheets can be stacked, filed and compared without damage. A completed herbarium sheet is shown in Fig. 1.1.
Diagram
Fig. 1.1 – A mounted herbarium sheet showing a pressed and dried plant with root, stem, leaves and flowers, fixed on a standard-size sheet, with the label placed at the lower right corner.
Flowchart
FC 1.2 – Preparation of a herbarium sheet: collecting the plant with all its parts → pressing between absorbent sheets in a plant press → drying → treating with preservative to protect against fungi and insects → mounting on a standard-size sheet → fixing the specimen in place → writing the label at the lower right corner → filing the sheet in the herbarium according to its classification
The Label: The Most Important Corner
The date and place of collection are recorded on the same sheet, along with the detailed classification of the plant and a highlighting of its ecological peculiarities and characters. Local names and the name of the collector may also be added. All this information is given at the lower right corner of the sheet and is called the label.
Without its label, a pressed plant is only a dried plant. With the label, it becomes a dated, located, named scientific record that any other worker can check and verify years later.
1.3 Botanical Gardens
A herbarium preserves plants that are no longer alive. A botanical garden does the opposite — it keeps them living.
Botanical gardens are places where living plants of different varieties, collected from different parts of the world, are grown in a scientific and systematic way in an in vivo manner. In vivo simply means “in the living state” — the plant continues to grow, flower and fruit, instead of being dried or preserved.
Every plant in the garden is labelled. The label-board shows the scientific name as well as the common name of the plant, so that a visitor learns not only what the plant is called locally but also the name by which biologists everywhere recognise it.
Because a plant brought from another part of the world may need a climate the local one cannot provide, botanical gardens also maintain greenhouses. In these enclosed glass or polythene houses, temperature, humidity and light can be controlled, so that species from colder or wetter regions survive, grow and remain available for study. One of the best-known gardens in our country is shown in Fig. 1.2.
Diagram
Fig. 1.2 – The Great Banyan Tree in the botanical garden at Kolkata, showing the massive canopy supported by numerous prop roots, with the garden’s information board in front of it.
Why Gardens Matter for Biodiversity
Biodiversity is the degree of variation of life forms in an ecosystem, and it is essential for maintaining ecological stability. The extent of complexity and the density of biodiversity can be regarded as a measure of the health of an ecosystem — the richer and more varied the life in a place, the better that ecosystem is usually working.
Population explosion and over-exploitation of resources have resulted in a loss of biodiversity at an alarming rate. Conservation is the response to this loss. It involves attempting to slow down, stop or even reverse the loss in the natural habitat of the organism, and this is known as in-situ conservation.
Why does the loss of biodiversity matter at all? For many people it is a simple moral or ethical issue — we share our planet with a huge range of other organisms, and we have no right to harm them. There is also a hard ecological reason. Biodiversity helps to maintain stability in an ecosystem, and the loss of even one variety of organisms can affect the entire ecosystem, because the surviving species depended on it in ways that are not always obvious until it is gone.
1.4 Museum
Museums are the repositories where collections of preserved plant and animal specimens are kept. A herbarium holds only plants, and a botanical garden only living ones; a museum keeps both plants and animals, and it keeps them long after they have died.
Preserving Specimens in Jars
Plant and animal specimens may be preserved in formalin, a solution containing 10% to 40% formaldehyde, in transparent jars, and the jars are labelled. Formaldehyde hardens the tissues and stops bacteria and fungi from acting on them, so the specimen keeps its shape, colour and internal detail for decades. A biological museum of this kind is shown in Fig. 1.3.
Diagram
Fig. 1.3 – Interior of a biological museum showing labelled transparent jars of preserved specimens on shelves, stuffed birds and mammals on display, and mounted skeletons and insect boxes.
Flowchart
FC 1.3 – Wet preservation of a specimen: collecting the specimen → cleaning it → fixing it in formalin (10% to 40% formaldehyde) → placing it in a transparent jar filled with the preservative → sealing the jar → labelling the jar → arranging it systematically in the museum
Taxidermy: Preserving Larger Animals
Larger animals such as birds and mammals are usually stuffed and preserved instead of being placed in jars. This science is known as taxidermy. The skin is carefully removed and treated, then mounted over a model of the animal’s body so that the specimen looks lifelike and shows the animal’s true posture, size and colour. Specimens in dried form are also exhibited in museums.
Flowchart
FC 1.4 – Taxidermy of a bird or mammal: collecting the dead animal → removing the skin carefully → treating the skin with preservative → stuffing it over a model of the body → mounting the specimen in a natural posture → labelling → placing it on display
Beyond Whole Organisms
Museums are not limited to complete specimens. We can even find systematic collections of shells, skeletons of animals, insect boxes and similar material in them. Each of these preserves a different kind of evidence — a shell records the shape of a mollusc’s covering, a skeleton records the plan of the bones, an insect box records tiny species that no jar could display well.
Thus, biological museums in educational institutes are reference hubs of biodiversity studies. When an identification is doubtful, the specimen in hand can be compared directly with one that has already been named, checked and stored.
1.5 Zoological Parks
A zoological park, generally known as a zoo, is a place of interest for the common man. In a zoo, wild animals are kept in captivity. They are protected, and care is taken to provide conditions similar to their natural habitat. Since the animal is being looked after outside its own natural home, this is called ex-situ conservation.
What a Zoo Makes Possible
A museum specimen can show what an animal looked like, but nothing more. In a zoo the animal is alive, and so a naturalist can study its food habits and its behaviour — what it eats and how often, how it hunts or forages, how it rests, calls, and interacts with others of its kind. This is knowledge that no preserved specimen can supply. A zoological park is shown in Fig. 1.4.
Diagram
Fig. 1.4 – Entrance and enclosure of a zoological park, showing animals in a spacious enclosure designed to resemble their natural habitat.
Other Tools for Keeping Biodiversity Records
Living collections are only part of the record. Flora, manuals, monographs and catalogues are some other tools of maintaining biodiversity records, and each answers a different question, as set out in FC 1.5.
Flowchart
FC 1.5 – Tools for maintaining biodiversity records: Biodiversity records → branches into: Flora (all plant life of an area at a given time); Manual (information and keys for identifying species of an area); Monograph (detailed account of one selected biological group); Catalogue (organised list of specimens or species with brief details)
Flora is the plant life occurring in a particular area at a time — an account of what actually grows there. A monograph describes any one selected biological group in complete detail, whereas a manual provides information and keys about the identification of species found in a particular area. A catalogue is an organised list, recording the specimens or species held or reported, with brief details for each.
1.6 Biodiversity Parks
A biodiversity park is an ecological assemblage of species that form self-sustaining communities on a degraded or barren landscape.
Read that description carefully, because two parts of it carry the whole idea. First, the land chosen is already damaged — barren, eroded, or stripped of its plant cover. Second, the aim is not merely to plant trees there but to build a self-sustaining community: a set of species chosen so that they support one another, so that soil, water and nutrients begin to cycle on their own, and so that the park keeps going without permanent outside help.
The Late Uttamrao Patil biodiversity park at Gureghar, Mahabaleshwar, is an example. It is regarded as the best model for the conservation of natural heritage within an urban landscape — a demonstration that land written off as waste can be brought back to life. Such a restored landscape is shown in Fig. 1.5.
Diagram
Fig. 1.5 – A biodiversity park developed on formerly barren land, showing restored native trees and shrubs, ground cover, a small water body, and birds and insects using the habitat.
Flowchart
FC 1.6 – Development of a biodiversity park: degraded or barren landscape → soil and water conservation measures taken → hardy native pioneer species planted → soil fertility and moisture improve → more native plant species establish → insects, birds and small animals arrive on their own → food chains and nutrient cycling become established → self-sustaining community
Why Studying Biodiversity Matters
Systematic classification of living organisms is helpful in understanding the interrelations between them. Once we know which organism belongs to which group, we can begin to see how the groups depend on one another — who eats whom, who pollinates whom, who recycles the remains.
In order to understand these interrelations between organisms, and to maintain harmony on planet earth, the study of biodiversity is a must. Every aid discussed in this chapter — the herbarium, the botanical garden, the museum, the zoological park and the biodiversity park — exists to make that study possible.
1.7 Key
A key is a taxonomical aid used for the classification of plants and animals. It is the tool a biologist reaches for when a specimen is in hand but its name is not yet known.
The keys generally used are dichotomous keys, which are based on contrasting characters. The word tells you how they work: di means two, so at every step the key offers exactly two opposed choices. One of the contrasting characters gets accepted and the other is rejected, and the rejected branch is abandoned along with everything that lay beyond it.
Each statement in a key is called a lead. A pair of contrasting leads forms one step, and accepting one lead sends the user on to the next pair. Normally keys are analytical in nature — instead of building a group up from its members, they take a large assemblage of organisms and cut it down, step by step, until only one name is left.
Flowchart
FC 1.7 – Working of a dichotomous key: unknown specimen in hand → first pair of contrasting leads → accept the lead that matches, reject the other → follow the accepted branch to the next pair of leads → accept and reject again → repeat until only one possibility remains → name of the organism
Diagram
Fig. 1.6 – A sample dichotomous key drawn as a branching chart, each step splitting into two contrasting leads, with rejected branches shown greyed out and the final branch ending in the name of the organism.
Keys work only because organisms have already been arranged into groups on the basis of shared and contrasting characters. How that arrangement is made — and on what principles living organisms are classified — is what we shall study in the next chapter.
1.8 Summary
The earth is made up of abiotic (non-living) and biotic (living) components. Biology begins by asking on what scientific grounds we call something living.
Metabolism is the sum of all chemical reactions in the body — breaking of molecules (catabolism), which releases energy, and making of new molecules (anabolism), which uses it. Every living organism needs metabolism to survive.
Growth and development occur from birth onwards and are well-orchestrated processes. In living beings the increase comes from within; in non-living objects such as sand mounds and boulders, material is only added from outside. Such objects are therefore not living.
Growth and development do not have an unlimited time span. After a point, the molecules, organs and systems begin to lose their effective working — this is ageing.
Life has to be perpetuated, so an organism produces a young one like itself by reproduction, which may be asexual or sexual. This ensures continuity of the race. However, mules and sterile worker bees never reproduce and are still living, so reproduction cannot be treated as an all-inclusive characteristic of life.
As the body loses its capacity to perform metabolism, the organism dies. No organism is immortal.
Every living being responds to thermal, chemical and biological changes in its surroundings. This responsiveness or irritability is a unique property of living beings.
There is immense diversity among living organisms. Systematic study of this diversity is essential for understanding interrelations between living and non-living components and between different groups of organisms, and the data are important for industry and agriculture.
The tools used to study this diversity are called taxonomical aids — herbaria, botanical gardens, museums, biodiversity parks, zoological parks and keys.
Flowchart
FC 1.8 – Chapter overview: living vs non-living → basic principles of life (metabolism → growth → ageing → reproduction → death → responsiveness) → immense diversity of organisms → need for systematic study → taxonomical aids → herbarium; botanical garden; museum; zoological park; biodiversity park; key → classification of living organisms (next chapter)
The word herbarium was coined by Pitton de Tournefort in the book ‘Elemens’, and the art of the herbarium was initiated by the Italian taxonomist Luca Ghini (1490–1556). A herbarium is a dried plant specimen, pressed, treated variously and mounted on a standard-size sheet to preserve it.
The date and place of collection, detailed classification, ecological peculiarities and characters of the plant are recorded on the same sheet, and local names and the collector’s name may be added. This information, written at the lower right corner, is the label.
Botanical gardens are places where living plants of different varieties, collected from different parts of the world, are grown scientifically and systematically in an in vivo manner. Plants are labelled, and the label-board carries the scientific as well as the common name. The world’s first botanical garden was established in 1543 by Prof. Luca Ghini at Pisa, Italy.
Biodiversity is the degree of variation of life forms in an ecosystem and is essential for ecological stability; its complexity and density indicate the health of an ecosystem. Population explosion and over-exploitation of resources are causing biodiversity loss at an alarming rate, and the loss of even one variety can affect the entire ecosystem.
Slowing down, stopping or reversing this loss within the organism’s own natural habitat is in-situ conservation; protecting an organism away from its natural habitat, as in a zoo, is ex-situ conservation.
Museums are repositories of preserved plant and animal specimens. Specimens may be preserved in formalin (10% to 40% formaldehyde) in labelled transparent jars, while larger animals such as birds and mammals are usually stuffed and preserved — the science of taxidermy. Dried specimens, and systematic collections of shells, skeletons and insect boxes, are also kept. Biological museums in educational institutes are reference hubs of biodiversity studies.
Zoological parks, or zoos, keep wild animals in captivity under protection, with conditions similar to their natural habitat (ex-situ). In a zoo, a naturalist can study the food habits and behaviour of animals.
Other tools for maintaining biodiversity records are flora (the plant life occurring in a particular area at a time), manual (information and keys for identifying species of a particular area), monograph (a detailed account of one selected biological group) and catalogue.
Biodiversity parks are ecological assemblages of species that form self-sustaining communities on degraded or barren landscapes. The Late Uttamrao Patil biodiversity park at Gureghar, Mahabaleshwar, is the best model for conservation of natural heritage in an urban landscape.
Forest plants conserved in the name of a holy place form a sacred grove; these are also recognised as sacred natural sites by the IUCN.
A key is a taxonomical aid used for the classification of plants and animals. Dichotomous keys are based on contrasting characters, one of which is accepted while the other is rejected. Each statement in a key is called a lead, and keys are normally analytical in nature.
Systematic classification of living organisms helps us understand the interrelations between them, and this understanding is necessary for maintaining harmony on planet earth.
1.9 Points to Ponder
Metabolic reactions can be demonstrated in a test tube, outside any body — such tests are called in vitro tests. The reactions are real, and the chemistry is the same as inside a cell. Would you then call the contents of that test tube living? Where exactly would you draw the line, and on what grounds?
Patients are sometimes declared ‘brain dead’ and kept on life support. Their cells continue to metabolise and their hearts continue to beat, but they show no sign of self-consciousness or of response to the surroundings. Are they living or non-living? Which property of life would you rely on to decide, and why that one?
Mules and sterile worker bees never produce young ones, yet nobody doubts that they are alive. If reproduction is not an all-inclusive characteristic of life, what does that tell us about the difference between the survival of an individual and the survival of a species?
A sand mound grows, a crystal grows, and a child grows. All three become larger with time. Is “growth” a useful word in biology at all if it must always be qualified? How would you word the property so that it excludes the mound and the crystal without excluding any living organism?
A herbarium sheet holds a plant that is dead, while a botanical garden holds the same species alive. For a taxonomist trying to settle the identity of a species a century from now, which of the two is the more dependable record, and what does your answer say about what taxonomy really needs?
Ex-situ conservation saves an organism when its habitat can no longer keep it safe. Can it ever be a full substitute for in-situ conservation, or is it only a support to it? Think about what is conserved in each case besides the organism itself.
Sacred groves have been protected for generations by belief and community custom, while national parks are protected by law. Which form of protection do you expect to last longer, and what conditions would each of them need in order to survive?
A biodiversity park rebuilds a self-sustaining community on land that had been degraded. Can such a restored community ever become identical to the natural ecosystem that once stood there? If not, is the effort still worth making?
The loss of even one variety of organisms can affect an entire ecosystem. Should a species be conserved even when it has no known use to human beings? Consider both the ecological argument and the moral one before you answer.
Every taxonomical aid in this chapter — herbarium, botanical garden, museum, zoological park, biodiversity park and key — records life in a different way, and each loses something in the process. For each aid, ask yourself: what is preserved, and what is unavoidably lost?
1.10 Check Your Concepts
Why is responsiveness (irritability) treated as the all-inclusive and unique characteristic of life, even though metabolism is present in every living organism?
Explain the difference between catabolism and anabolism, and state why an organism cannot survive on either one of them alone.
What happens if the capacity of a body to perform metabolism is lost? Relate your answer to ageing and to death.
A student writes: “A test tube in which metabolic reactions are running is living, because metabolism is the basic property of life.” Point out the flaw in this reasoning.
Why are plant specimens preserved by drying and pressing, while animal specimens are usually preserved in formalin? Answer with reference to the structure of the two kinds of specimens.
What would happen to the usefulness of a herbarium if the sheets were of different sizes and the labels were placed at different corners on each sheet?
Arrange the following steps in the correct sequence for preparing a herbarium sheet: mounting on a standard-size sheet; drying; collecting the plant; writing the label; pressing between absorbent sheets; treating with preservative; filing according to classification.
Draw a herbarium sheet and label the following on it: the mounted specimen, the standard-size mounting sheet, and the label with its position.
Why does a botanical garden need greenhouses, when the plants growing outside it in the same garden manage without them?
A herbarium sheet and a botanical garden both preserve plants. Compare them with reference to the state of the plant, what can be studied from each, and the limits of each.
Distinguish between in vivo and in vitro, giving one example of each from this chapter.
Why is taxidermy used for birds and mammals rather than preservation in jars? What information does a taxidermy specimen preserve, and what does it lose?
Biological museums are described as reference hubs of biodiversity studies. Explain what makes them “reference” collections rather than mere displays.
What happens if a wild animal in a zoo is fed and protected but is not given conditions resembling its natural habitat? Discuss the effect on both the animal’s welfare and the naturalist’s study of its behaviour.
Distinguish between in-situ and ex-situ conservation, and explain why ex-situ conservation is generally regarded as a support to in-situ conservation rather than a replacement for it.
Why is a biodiversity park established on a degraded or barren landscape rather than on land that is already fertile and well vegetated?
A newly created park is claimed to be a biodiversity park. What would you look for, over the next few years, to confirm that its community has genuinely become self-sustaining?
Arrange in correct sequence the stages by which a degraded landscape is converted into a biodiversity park: native pioneer species planted; food chains and nutrient cycling established; soil and water conservation measures taken; insects, birds and animals arrive on their own; degraded barren land; soil fertility and moisture improve.
Why must a dichotomous key be built on contrasting characters? What advantage does accepting one lead and rejecting the other give over simply comparing a specimen with full descriptions of many species?
Draw a simple branching chart of a dichotomous key with three steps, and label on it: a pair of leads, the accepted branch, the rejected branch, and the final identification.
For each of the following, name the taxonomical aid you would use and justify your choice in one line: (i) identifying an unknown insect collected in the field; (ii) knowing which plants occur in a particular district; (iii) studying the feeding behaviour of a leopard; (iv) preserving a rare plant collected from a remote hill so that others can verify it a century later.
The loss of one variety of organisms can affect an entire ecosystem. Explain this statement with reference to the interrelations between organisms, and state why the study of biodiversity is considered essential for maintaining harmony on the earth.
A student on a field trip finds a plant she cannot identify. Describe, step by step, how she could create a permanent scientific record of it and then arrive at its name, naming the taxonomical aid used at each step.
Distinguish between botanical gardens, zoological park and biodiversity park with reference to their characteristics.
Jijamata Udyan, the famous zoo in Mumbai, has acclimatised the Humbolt penguins. Why should penguins be acclimatised when kept at a place away from their natural habitat?
Riya found a peculiar plant on her visit to Himachal Pradesh. What are the ways she can show it to her biology teacher and get information about it?
At Andaman, authorities do not allow tourists to collect shells from beaches. Why must it be so?
Why do we have green houses in botanical gardens?
What do you understand from terms like in situ and ex situ conservation?
Write a short note on: Role of human beings in biodiversity conservation.
Write a short note on: Importance of botanical gardens.
How can you, as an individual, prevent the loss of biodiversity?
1.11 Objective Questions
- Which is not a property of a living being?
- Metabolism
- Decay
- Growth
- Reproduction
- A particular plant is strictly a seasonal plant. Which one of the following is best suited if it is to be studied in the laboratory?
- Herbarium
- Museum
- Botanical garden
- Flower exhibition
- A group of students found two cockroaches in the classroom. They had a debate whether they are alive or dead. Which life property will help them to decide?
- Metabolism
- Growth
- Irritability
- Reproduction
For this and the assertion–reason questions that follow, choose from: (a) both A and R are true and R is the correct explanation of A; (b) both A and R are true but R is not the correct explanation of A; (c) A is true but R is false; (d) A is false but R is true.
Assertion (A): An increase in size cannot by itself be taken as proof that an object is living. Reason (R): Sand mounds and boulders also become larger with time.
Assertion (A): A sterile worker bee is a living organism. Reason (R): Reproduction is an all-inclusive characteristic of life.
Assertion (A): A pressed plant without a label is of little scientific value. Reason (R): The label carries the date, place of collection, classification and collector’s name, which make the specimen verifiable.
Assertion (A): Metabolic reactions demonstrated in a test tube are not considered living. Reason (R): Catabolism releases energy that anabolism uses.
Match the items in Column A with those in Column B.
| Column A | Column B |
|---|---|
| a. Pitton de Tournefort | i. Statement in a key |
| b. Luca Ghini | ii. Coined the word ‘herbarium’ |
| c. Taxidermy | iii. Plant life of a particular area at a time |
| d. Lead | iv. Initiated the art of the herbarium and established the first botanical garden |
| e. Flora | v. Stuffing and mounting of larger animals |
- Match each biodiversity record tool with the question it answers.
| Column A | Column B |
|---|---|
| a. Flora | i. A detailed account of one selected biological group |
| b. Manual | ii. An organised list of specimens or species with brief details |
| c. Monograph | iii. A record of the plant life of a particular area |
| d. Catalogue | iv. Information and keys for identifying species of a particular area |