BIOZONE

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ECOLOGY UNIT
 BIOLOGY Theory
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ORGANISM AND POPULATION

IMPORTANT FACTS
Four levels of biological organisation in ecology are :
(a) Organism
(b) Population
(c) Community
(d) Biomes
♦ Organisms and Its Environment
1. Ecology at organism level is physiological ecology. It is essential to study it so that we can better understand the
adaptations and strategies of reproduction according to the environment.
2. Major biomes (rain forest, tundra, desert, etc) are formed by the combination of annual variation in precipitation
and adaptations of organisms.
3. Life may be found in favourable and extreme habitats (deep ocean trenches/high mountain tops/stinking compost
pits/ permafrost polar regions/ boiling thermal springs/our intestine) both.
4. A habitat is characterized by abiotic (physic-chemical components like temperature, water, light, soil, etc) and
biotic components (pathogens, predators, parasites, competitors, etc) both.
Major Abiotic Factors
• It is considered as the most ecologically relevant environmental factor.
• Average temperature on land varies according to the seasons, decreases gradually from the equator towards
the poles and from the base /plains to the mountain tops.
• Range : From subzero (in polar areas and high altitudes) to more than 50°C (in tropical deserts in summer).
Temperature may be even higher in thermal springs and deep-sea hydrothermal vents (> 100°C).
• All organisms live their favourable temperature region—Mango trees do not grow in temperate countries
1. Temperature (Canada, Germany, etc), Snow leopards are not found in Kerala forests and Tuna fish are rare found beyond
tropical latitudes in the ocean.
• Eurythermal: Only few organisms can tolerate wide range of temperatures. Such organisms are termed as
eurythermal.
• Stenothermal: Most of organisms can tolerate only a narrow range of temperatures. These are termed as
stenothermals.
• Due to global warming, temperature of the earth has been increased In recent years.
• After temperature, water is the most important ecologically important factor.
• Life on earth would have been impossible without water.
• The productivity and distribution of plants is also mostly dependent on water.
• Even aquatic organisms living in oceans, lakes and rivers face water related problems.
• Salt concentration (measured as salinity in parts per thousand (NCERT Correction)) in given resources:
2. Water 1. Inland waters : < 5.
2. In the sea water: 30 to 35.
3. Hypersaline lagoons : > 100.
• Euryhaline : Organisms tolerant to wide range of salinities.
• Stenohaline : Organisms tolerant to a narrow of salinities.
• Because of the osmotic problems, many freshwater animals cannot live for long in sea water and vice versa.
• Plants are dependent on sunlight for—photosynthesis, flowering, growth, etc.
• Sunlight regulate the diurnal and seasonal rhythms in animals and also affect timing of their foraging,
3. Light reproductive and migratory activities.
• As sun is the source of light and temperature both, so the light and temperature of that area are interlinked.
• Sunlight is absent in the deep part of oceans (>500m).
• Whether the soil is transported or residual, it depends upon the weathering process which itself depends upon
the environmental factors.
• Important characteristics of the soil that determine the percolation and water holding capacity of the soils
are—Soil composition, grain size and aggregation.
4. Soil
• Vegetation in any area depends upon the above mentioned factors and also pH, mineral composition and
topography.
• Type of animals depends upon the type of vegetation.
• In an aquatic ecosystem, sediment-characteristics often determine the type of benthic animals.

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Responses to Abiotic Factors
1. In varying external environmental conditions, organisms try to maintain the constancy of its internal environment
by a process called homeostasis, which is maintained by various means:
1. Regulation 2. Conform
(Thermoregulation and osmoregulation)
In these organisms, body temperature changes with the
These organisms are able to maintain homeostasis by mostly
ambient temperature or the osmotic concentration of the
physiological means which ensures constant body
body fluids change with ambient water osmotic
temperature, constant osmotic concentration, etc.
concentration (in aquatic animals).
Examples: Examples:
1. All birds and mammals. 1. Majority (99 %) of animals.
2. Very few lower vertebrates and invertebrate species. 2. Nearly all plants.
Some points about Regulation....
1. Evolutionary ‘success’ of mammals is largely due to their ability of thermoregulation so that they can thrive in
Antarctica or in the Sahara desert.
2. Thermoregulators (including human) maintain a constant body temperature (as 37°C in human) by sweating in
summer and shivering in winter.
3. Plants do not have any mechanisms to maintain internal temperature.
4. Thermoregulation is energetically expensive for many organisms specially small animals like shrews and
humming birds (larger surface area relative to their volume) that tend to lose body heat very fast. This is the main
reason why very small animals are rarely found in polar regions. If the organism is exposed to the stressful external
conditions for a short duration or if such conditions are localised, then organism has two other alternatives :
3. Migration 4. Suspend
It refers to the temporary movement away from the stressful Suspension is done by reducing their metabolic activity and
habitat to a relatively favourable area and again return going in a state of 'dormancy'.
when stressful period is over.
Examples: Examples :
1. During winter many animals specially birds, perform 1. Thick-walled spores formed in various bacteria, fungi
long-distance migrations to more hospitable areas. and lower plants.
Thousands of migratory birds come from Siberia and other 2. Seeds and some other vegetative reproductive structures
extremely cold northern regions during every winter to the formed in higher plants to overcome the period of stress.
famous Keoladeo National Park (Bharatpur) in Rajasthan. 3. Hibernation during winter.
4. Aestivation during summer, Examples : Some snails and
fishes.
5. Diapause (a stage of suspended development) in many
zooplankton species in lakes and ponds.
Adaptations
1. To survive in extreme environments, organisms acquire various adaptations which may be morphological,
physiological or behavioural.
2. Many adaptations have evolved over a long evolutionary time and are genetically fixed.
3. Examples :
(a) Even in the absence of water, Kangaroo rat in North American deserts is capable of meeting all its water
requirements from its internal fat oxidation in which water is produced as a by product. Also it can concentrate its
urine.
(b) Presence of thick cuticle on the leaf surface of many desert plants. Stomata may be arranged in deep pits to
minimize transpiration. Stomata remain closed during daytime due to a special photosynthetic pathway (CAM) in
them.
(c) In plants like Opuntia, leaves are reduced to spines while the function of the photosynthesis is done by the
flattened stems.
(d) Allen’s Rule : In colder climates, mammals generally have shorter ears and limbs to minimise heat loss.
(e) Presence of blubber in the polar seas aquatic mammals like seals which act as an insulator to reduce heat loss of
body.
(f) At very high altitudes (>3,500m Rohtang Pass near Manali and Mansarovar, in China occupied Tibet), altitude
sickness is observed which is symptoms like—nausea, fatigue and heart palpitations. This is basically due to oxygen
debt. But, gradually we get acclimatised (RBC production increases, binding affinity of hemoglobin decreases and
breathing rate increases) and stop experiencing altitude sickness.
(g) Due to some special adaptations, certain microbes (archaebacteria) flourish in hot springs and deep sea
hydrothermal vents where temperatures exceeds 100°C.
(h) Many fish in Antarctic waters can survive at below zero temperature.
(i) Lizard bask in the sun and absorb heat when their body temperature becomes low.
(j) Some species hide in the burrows in the soil to hide and escape from the above-ground heat.
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♦ Populations
Population Attributes
1. Majority of individuals of any species live in groups, interbreed, share or compete for
similar resources and form a constitute a population.
2. Population may be the result of sexual or asexual reproduction.
Examples :
(a) All cormorants in a wetland.
(b) Teakwood trees in a forest tract.
(c) Bacteria in a culture plate.
(d) Lotus plants in a pond.
(e) Rats in an abandoned dwelling.
3. Population ecology is an important aspect of ecology which links ecology to population
genetics and evolution.
4. An individual shows births and deaths, but a population has birth rates and death rates.
5. Population attributes are following :
(a) Birth rate and death rate Example 1 :
Number of lotus plants in pond last year = 20
Number of new lotus plants added by reproduction = 8 Total number of lotus plants in pond = 28
Birth rate = 8/20 = 0.4 individual per lotus per year.
Example 2 :
Number of fruitflies in a laboratory population = 40
Number of fruitflies died during a week = 4
Death rate in the population = 4/40 = 0.1 individual per fruitfly per week.
(b) Sex ratio
• It is the relative abundance of males and females in a population.
Example : In a population, 60 % are males and 40 % are females.
(c) Age pyramid
• It is the structure which is obtained when age distribution (% individuals of a given age or age grc ..p) is plotted for
the population.
• Age pyramids for human population usually have age distribution of males and females in a combined diagram.
• There are 3 types of Age pyramids on the basis of shape that reflect the growth status of the population whether it
is
- growing
- stable
- declining.
(d) Population size (more technically termed as Population density, N)
• Population size refer to the number of individuals in a population.
• It may be as low as <10 (Siberian cranes at Bharatpur wetlands in any year) or in millions (unicellular organisms
like Chlamydomonas in a pond).
6. Variations :
(a) If the organism is very large in size but the relative number is very low (single banyan tree in an area), then
biomass is more meaningful measure of the population size.
(b) If the organism is very small in size but the relative number is very high (bacteria in a petri-dish), then the
counting becomes either impossible or time-consuming. It is better to take a small sample and measure its density.
7. Sometimes relative densities of 2 populations can also be done without knowing the absolute population densities.
Example : Number of fishes caught per trap gives an idea about the total population density of fishes in the lake.
8. Indirect measures are also used sometimes to estimate population sizes. Example : The number of tigers in our
national parks and tiger reserves are often counted on the basis of pug marks and fecal pellets.
Population Growth
Nt+1 = Nt+[(B + D — (D + E)]
where, Nt+1 : Population after time t
Nt : Initial Population
B : Natality = Number of births during time t in the population
I : Immigration = Number of individuals of the same species that have entered the habitat during time t
D : Mortality = Number of deaths during time t in the population
E : Emigration = Number of individuals of the same species that have left the habitat during time t
1. Usually, births and deaths are the most important factors that affect the population density while the other 2 factors
become important only under special instances. Example : In a newly colonisd habitat, immigration may contribute
more in comparison to birth rates.

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Growth Models
Exponential (or geometric) Growth Logistic (or Verhulst-Pearl Logistic) Growth
Resource (food and space) availability is unlimited. Resource availability is limited.
Rate of change of population, Rate of change of population,
= (b-d)×N dT =
= rN [Let (b - d) = r] where,
N = Population density at time t
N = Size of a population
r = Intrinsic rate of natural increase
b = Per capita birth rate, d = Per capita death rate
K = Carrying capacity
r = Intrinsic rate of natural increase.
J-shaped curve is obtained when we plot N in relation to time. Sigmoid-shaped curve is obtained when we plot N in
relation to time.
Phases: Phases:
1. Lag phase (initially). 1. Lag phase (initially).
2. Phase of acceleration. 2. Phase of acceleration / deceleration.
3. Asymptote phase.
Population density grow beyond the carrying capacity (K). Population density reaches the carrying capacity (K) (during
Asymptote phase).
Less realistic. More realistic.
No population of any species in nature has at its disposal unlimited Natural populations follow Logistic growth.
resources to permit exponential growth.
Example : Paramecium undergoing binary fission and doubling in Example : Human population in India for the last 100
numbers everyday (provided food and space remain unlimited) years.
2. During exponential phase, growth equation becomes : Nt = N0 ert where,
Nt = Population density after time t
N0 = Population density at time zero
r = Intrinsic rate of natural increase
(Value of r for Norway rat = 0.015, Flour beetle = 0.12 and Human population in India in 1981 = 0.0205) e = the
base of natural logarithms (2.71828)
3. Darwin also observed while working on his theory of natural selection that if the resources are unlimited than each
species grow with enormous potential.
4. Nature’s carrying capacity (K): It refers to the maximum number of individuals which can be supported by the
resources of a given habitat. Beyond it, further growth is not possible.
♦ Life History Variation
1. During evolution, populations tend to maximise their reproductive fitness (or Darwinian fitness or High r value) in
the habitat in which they live.
2. Organisms tend to follow different but most efficient reproductive strategy according to their environment.
Reproductive strategy Examples
1. Organisms breeding only once in their life Pacific salmon fish and Bamboo
2. Organisms breeding many times during their life Most birds and mammals
3. Organisms producing a large number of small-sized offspring Oysters and Pelagic fishes
4. Organisms producing a small number of large-sized offspring Birds and Mammals
♦ Population Interactions
1. For any species, the minimal requirement is one more species on which it can feed.
2. Even a plant species, which makes its own food, cannot survive alone; it needs soil microbes to break down the
organic matter in soil and return the inorganic nutrients for absorption.
3. Even in minimal communities, many interactive linkages exist, although all may not be readily apparent.
4. Interspecific interactions : These are interactions in the populations of two different species which could be
beneficial, detrimental or neutral to one of the species or both.
Sp. Sp.
Interaction Description/E×amples
A B
Predation + - Examples :
1. Tiger and Deer.
2. Sparrow eating seeds.
3. Herbivores are also predators in a broad ecological context.
Important role of predators :
1. Act as conduits for energy transfer between the trophic levels.
2. Check on prey populations.
3. Biological control of an exotic, invasive and widespread species.
Example : The Prickly pear cactus was introduced in Australia in 1920. It has spread
rapidly over millions of hectares of rangeland. Finally it was brought under control after

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 introduction of its natural predator—Cactus-feeding Moth.
(Biological control methods are also used in agricultural pest control and are based on the
ability of predator to regulate prey population.)
4. Predators reduce the intensity of competition among competing prey species and help in
maintaining species diversity in a community. (In a field experiment done in a rocky
intertidal communities of American Pacific Coast, removal of starfish Pisaster (an important
predator) resulted in extinction of more than 10 species of invertebrates due to increased
inter-specific competition.)
• If a predator is too efficient/overexploits its prey, then it may result in extinction of the
prey followed by extinction of predator itself. So the predators in nature are 'prudent'.
• Various defenses have evolved in prey species of animals :
1. Some species of insects and frogs are cryptically-coloured (camouflaged) to avoid being
detected easily by the predator.
2. Monarch butterfly is highly distasteful to the predator (bird) because of a special chemical
in its body which is acquired by it during its caterpillar stage by feeding on a poisonous
weed.
• Various defenses have evolved in prey species of plants against herbivores (including
phytophagous insects being 25% of total insects):
1. Most common morphological mean of defense : Thorns.
Examples : Acacia, Cactus, etc.
2. Many plants produce toxic chemicals that make the herbivore sick or even kill it following
ingestion.
Example : Calotropis (a weed) growing in fields, produces highly poisonous cardiac
glycosides. So the cattle or goats avoid browsing on it.
3. Various chemicals that are commercially extracted from the plants (opium, nicotine,
caffeine, quinine, strychnine, etc.) are actually produced by them as a chemical defense
against herbivores.
Competition - - • According to Darwin, interspecific competition is also a potent force in organic evolution.
• Variations to the general belief that 'Competition occurs when closely related species
compete for the same resources that are limiting':
1. Totally unrelated species could also compete for the same resource.
Example : Visiting Flamingoes and resident Fishes, in some shallow South American lakes
compete for the zooplankton (common food).
2. Resources always need not be limiting for competition to occur.
Example : In interference competition, the feeding efficiency of one species might be reduced
due to the presence of another species even if the resources (food and space) are abundant.
• In Competition, fitness of one species (measured in terms of its Y — intrinsic rate of
increase) is significantly lowered in the presence of another species.
• 'Gause's Competitive Exclusion Principle'
If the resources are limited, two closely related species competing for the same resources
cannot co-exist indefinitely and the competitively inferior species have to be eliminated.
Example : Within a decade after introduction of goats in Galapagos Islands, Abingdon
tortoise became extinct due to the greater browsing efficiency of the goats.
• Concept of 'Competitive release'
Because of the presence of a competitively superior species, distribution of a species is
restricted to a small geographical area. This distributional range is dramatically increased if
the competing species is experimentally removed.
• Connell's elegant field experiments
It showed that on the rocky sea coasts of Scotland, barnacle Balanus (larger and
competitively superior) dominates the intertidal area and excludes the Chathamalus
(smaller barnacle) from that area.
• Generally, herbivores and plants are affected more adversely by competition in
comparison to carnivores.
• Sometimes the competing species may co-exist by avoiding competition by choosing
different times for feeding or different foraging patterns. This is 'Resource partitioning'.
Example : MacArthur showed that 5 closely related species of warblers if living on the same
tree avoid competition and co-exist due to behavioural differences in their foraging
activities.

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Parasitism + - • Many parasites are host-specific, i.e., these can parasitise only a single species of host.
• Parasitism is also an example of co-evolution.
• Special adaptations of the parasites :
1. Unnecessary sense organs are lost.
2. Presence of organs of attachment, e.g., adhesive organs /suckers.
3. Loss of digestive system.
4. High reproductive capacity.
5. Parasites may involve one or two intermediate hosts or vectors.
- Liver fluke has 2 intermediate hosts : A snail and a fish.
- Malarial parasite (Plasmodium): Human and Mosquito (vector).
• Parasites may reduce the survival, growth and reproduction of the host and reduce its
population density. Host might become physically weak.
• Parasites may be classified as :
A. Ectoparasites:
1. Lice on humans.
2. Ticks on dogs.
3. Ectoparasitic copepods on many marine fishes.
4. Cuscuta (parasitic plant) growing on hedge plants.
B. Endoparasites : These live inside the host and their life cycles are more complex because
of their extreme specialisation.
• Female mosquito is not considered as a parasite as mosquito needs our blood for
reproduction, not nutrition.
• Brood parasitism in birds (Fascinating example of parasitism)
- Parasitic bird lays its eggs in the nest of host and the host incubate them.
- During evolution, the eggs of the parasitic bird (Cuckoo or Koel) have evolved to resemble
the host's (Crow's) egg in size and colour to reduce the chances their detection.
Commensalism + 0 Examples :
1. An orchid plant growing as an epiphyte on a mango branch.
2. Barnacles growing on the back of a whale.
3. Cattle egret and grazing cattle (classic example of commensalism). As the cattle move,
insects flush out from the vegetation that would be otherwise difficult for the egrets to find.
4. Sea anemone and the Clown fish. Fish gets protection from predators due to stinging
tentacles of sea anemone.
Mutualism + + Mutualists are examples of co-evolution.
Examples :
1. Lichens (relationship between a fungusand photosynthesizing algae or cyanobacteria).
2. Mycorrhizae (associations between fungi and roots of higher plants). Fungi help the plant
in the absorption of nutrients while the plant provides energy-yielding carbohydrates to the
fungi.
3. Pollination of plants by animals (Most spectacular and evolutionarily fascinating
example).
4. Fig tree and Wasp (A fig species can be pollinated only by its 'partner' wasp species and
not by other species. Female wasp uses the fruit as an egg laying (oviposition) site and
developing seeds within fruit for nourishing its larvae.)
5. Orchids possess various floral patterns to attract the right pollinator insect (bees and
bumblebees).
6. All orchids do not offer rewards. Some orchids like Mediterranean orchid—Ophrys, uses
'sexual deceit' to get pollinated. One of the petals bears an resemblance to the female bee in
size, colour and markings. Male bee is attracted to such petal, 'pseudocopulates' with it and
during that act it gets dusted with pollen and when the same bee 'pseudocopulates' with
another flower, it transfers pollen to it . Thus pollination of flower occurs.
5. In predation, parasitism and commensalism, interacting species live closely with each other.
6. Amensalism is an interaction in which one species is neither harmed nor benefited, while another species is
harmed.

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 Practice Question of Organism and Population
1. In a water body, type of benthic animals depends on the:
(a) Sediment (b) Planktons (c) pH of water (d) Salinity of water
2. Maintaining the constancy of internal environment is:
(a) Adaptation (b) Homeostasis (c) Resistance (d) Homeothermism
3. Birds and mammals are respectively :
(a) Thermoconfirmers and osmoconfirmers (b) Thermoconfirmers and osmoregulators
(c) Thermoregulators and osmoconfirmers (d) Thermoregulators and osmoregulators
4. Most of invertebrates are :
(a) Osmoregulators (b) Thermoconfirmers
(c) Osmoregulators and thermoconfirmers (d) Thermoregulators
5. During unfavourable conditions, zooplankton species in lakes and ponds undergo a stage of suspended
development, known as :
(a) Dormancy (b) Aestivation (c) Diapause (d) Hibernation
6. Kangaroo rat (Dipodomys) is native of:
(a) North American deserts (b) Australian deserts
(c) African savannah grasslands (d) Australian forests
7. Which adaptation renders the kangaroo rat live in hardy conditions of deserts even in absence of water?
(a) It compensates its water requirements from internal fat oxidation
(b) It excretes highly concentrated urine
(c) Uricotelism
(d) Both (a) and (b)
8. Plants and most of aquatic animals are respectively:
(a) Osmoconfirmers and osmoregulators (b) Osmoconfirmers and osmoconfirmers
(c) Osmoregulators and osmoconfirmers (d) Osmoregulators and osmoregulators
9. Incorrect about thermoregulation :
(a) Expensive for small sized animals
(b) More expensive for animals with low body surface area: volume ratio
(c) It is done in summer months by sweating
(d) It is done by muscle contraction during winter
10. Small animals are rarely found in polar regions because :
(a) Their surface area is small (b) Their surface area and body mass ratio is low
(c) Their surface area and body mass ratio is high (d) Large sized animals can feed on them
11. During short term unfavourable conditions organisms usually perform :
(a) Thermoregulation and osmoregulation (b) Migration and suspension of activities
(c) Osmoconfirmation (d) Thermoconfirmation
12. Mary birds from Siberia move to this national park / sanctuary in India?
(a) Silent valley national park, Kerala
(b) Chilka lake bird sanctuary, Orissa
(c) Sultanpur lake bird sanctuary, Haryana
(d) Keoladeo national park, Bharatpur, Rajasthan
13. What are the two major factors that account for the formation of biomes?
(a) Light and precipitation (b) Soil and light
(c) Temperature and precipitation (d) Temperature and soil
14. Statement not applicable to habitat is :
(a) It results from a local and regional variation within a biome
(b) It consists of physico-chemical components
(c) It is influenced by biotic components
(d) It is having optimum conditions for survival but not for reproduction
15. Identify the correct statement:
(a) Most of the organisms can resist wide variation in temperature
(b) Most of the aquatic organisms can resist wide variation in salinities
(c) Most of the organisms can’t retain their body temperature constant
(d) None of these
16. In colder climate, mammals possess shorter ears and limbs to minimise heat loss. This is known as:
(a) Allen’s Rule (b) Bergman’s Rule (c) Gloger’s Rule (d) Lindeman’s Rule
17. What do the desert lizards do when their body temperature drops?
(a) They hide in the soil (b) They move to shades
(c) They bask in sun (d) They go to sleep
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18. Some snails and fishes undergo following to prevent themselves from dessication :
(a) Aestivation (b) Hibernation (c) Diapause (d) Dormancy
19. Which of the following is not an example of population?
(a) Bacteria in a culture plate (b) Lotus plants in a pond
(c) Teak wood trees in a forest (d) Tigers in India
20. Which of the following links ecology to population genetics and evolution?
(a) Population ecology (b) Physiological ecology
(c) Population density (d) Growth curves
21. Death rate and birth rate are the terms applicable to :
(a) Population (b) Individual
(c) Biological community (d) Ecosystem
22. In tiger reserves, tiger census is done by:
(a) Counting all live tigers (b) Pug marks
(c) Pug marks and fecal pellets (d) Both (a) and (b)
23. Diagrammatic representation of organismic response is given. Select the correct option:

A B
(a) Confirmers Regulators
(b) Regulators Partial regulators
(c) Confirmers Partial regulators
(d) Confirmers Partial confirmers
24. Which two processes results in decrease in population?
(a) Natality and Mortality (b) Natality and Emigration
(c) Mortality and Emigration (d) Mortality and Immigration
25. Barnacles grow on the back of whales. Similar type of relationship can be observed in :
(a) Clown fish and sea anemones (b) Cuckoo and koel
(c) Fig trees and wasp (d) Orchids and bees
26. Cuscuta growing on hedge plant is an example of:
(a) Epiphyte (b) Saprophyte (c) Parasite (d) Competitor
27. Under normal conditions which 2 factors are responsible for influencing population density?
(a) Emigration and immigration (b) Death and emigration
(c) Immigration and birth (d) Birth and death
28. Usually in nature, species follow:
(a) Logistic growth (b) Exponential growth
(c) Static growth (d) Geometric growth
29. In a laboratory, 120 fruitflies were reared for experiments. Out of them 30 died within a week. Calculate
the death rate (in terms of death of individual per fruitfly per week)?
(a) 0.1 (b) 0.2 (c) 0.25 (d) 0.4
30. Which of the following feature is not attributed to a population?
(a) Members share same gene pool
(b) Members share same resources
(c) Members are reproductively isolated from other populations of same species
(d) Members can interbreed sexually or asexually
31. Temperature of sulphur springs and hydrothermal vents is :
(a) < 25° C (b) 25-50°C (c) 50-80°C (d) > 80° C
32. Majority of organisms can tolerate narrow range of temperature. Such organisms are termed as:
(a) Thermoregulator (b) Thermoconfirmer (c) Eurythermal (d) Stenothermal
33. In higher plants, what are the means of perennating unfavourable conditions?
(a) Vegetative reproductive structures (b) seeds
(c) spore formation (d) Both (a) and (b)
34. In an age pyramid of human population, if pre-reproductive group is less than reproductive group, than
it indicates population is:
(a) Expanding (b) Static (c) Declining (d) Can’t interpret

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35. In an expanding type of population :
(a) children are more in number than adults (b) people of reproductive age group are more than children
(c) old people are more in number (d) death rate is more than birth rate
36. Population size is measured in terms of:
(a) Number only (b) Number and % cover
(c) Number, biomass and % cover (d) Relative richness only
37. In a logistic growth curve an equation was derived as : = rN, where r is intrinsic rate of natural
increase.
What is the value of r in terms of b and d (b = birth rate, d = death rate)?
(a) (b) b-d (c) (d) -1
38. Given r = intrinsic rate of natural increase few values of r are :
r1 (for Norway rat) = 0.015 r2 (for Flour beetle) = 0.12
r3 (for human population in India) = 0.02
Which of the following interpretation is correct?
(a) Norway rats grow at fastest rate
(b) In human population, death rate is intermediate
(c) In case of flour beetle, population grows at highest rate
(d) Growth rate of population cannot be interpretated by r values
39. In Verhulst-Pearl logistic growth, following equation was derived : = rN ( )
What does K refer to?
(a) A constant (b) Intrinsic rate of natural increase
(c) Population density (d) Carrying capacity
40. According to Darwin, species usually have :
(a) High r values (b) Low r values
(c) Low or high values (d) Intermediate values
41. Which of the following organisms breed once in life?
(a) Pacific Salmon fish and pelagic fishes (b) Pacific Salmon fish and Bamboo
(c) Birds and oysters (d) Birds and reptiles
42. At least plants require one of the following for their survival:
(a) Herbivore cattle (b) Insects to feed upon
(c) Decomposers (d) Birds to live upon
43. Few interactions are given following. How many of them are not examples of mutualism?
(1) Fungus and roots of higher plants—mycorrhiza (2) Clown fish and sea anemones
(3) Cuckoo and crow (4) Orchids and bumblebees
(5) Cuscuta and Hedge plants (6) Sparrow eating seeds
(a) 2 (b) 3 (c) 4 (d) 5
44. Generally which of the following is least affected by competition than others?
(a) Plants (b) Herbivores
(c) Carnivores (d) All are equally affected
45. Identify the incorrect statement?
(a) We can say that host specific parasites and their hosts are coevolved
(b) In competition, r (intrinsic rate of natural increase) of both competing species are decreased
(c) In case of brood parasitism, crow is unable to identify between its own eggs and cuckoos eggs
(d) Introduction of sheeps on Galapagos Islands has resulted in extinction of Abingdon tortoise
46. In an experimental study on competitive release, distribution of species A is restricted to a small
geographical area because of presence of species B. When species B is eliminated, distribution of A is
found to be increased. Which statement is correct?
(a) Species A is a dominant species (b) Species B is a dominant species
(c) Both species are dominant (d) None of the species is dominant
47. Mac Arthur observed that 5 species of Warblers (birds) can coexist on same Fig tree due to behavioural
differences in their foraging activities. This is an example of:
(a) Resource partitioning (b) Competitive release
(c) Competitive exclusion (d) Brood parasitism
48. Which of the following is an example of biological control?
(a) Moth feeding on cactus in Australia
(b) Liver fluke in human body
(c) Abingdon tortoise and goats competing for grass in Galapagos Islands
(d) Two species of barnacles—Balanus and Chathamalus competing in rocky sea coasts of Scotland
Page 9 of 11
49. r (intrinsic rate of increase) may remain constant or increase in which type of interaction?
(a) Parasitism (b) Predation (c) Competition (d) Commensalism
50. Connell’s elegant field experiment is illustration for:
(a) Competitive inhibition (b) competitive release
(c) coexistence (d) biological control
51. What is the magnitude of salinity in inland water?
(a) <5 ppm (b) 10-15 ppm (c) 30-35 ppm (d) > 50ppm
52. Competitive exclusion principle states that two closely related species if compete for same resources than:
(a) They can coexist indefinitely (b) They will develop mutual relationship
(c) One will become parasite on another (d) One species will eliminate inferior one
53. Which of following statement supports the Darwinian view of struggle of existence and survival of fittest?
(a) Interspecific competition is a potent source of evolution
(b) Totally unrelated species might also compete
(c) Not always the resources are limiting in case of competition
(d) None of the above
54. Below which depth in a water body, light becomes almost unavailable?
(a) 100 mtr (b) 200 mtr (c) 500 mtr (d) 2000 mtr
55. Type of fauna largely depends upon the :
(a) Type of vegetation (b) Photoperiod
(c) Relative humidity (d) soil
56. Which weed produces highly toxic cardiac glycosides? •
(a) Parthenium (b) Calotropis (c) Orchids (d) Eichhornia
57. In which type of inter specific interaction, none of the two species is harmed?
(a) Beneficial (b) Detrimental (c) Neutral (d) 2 of the above
58. '+/+' type interaction is observed in :
(a) Commensalism (b) Predation (c) Mutualism (d) Parasitism
59. In which pair of interspecific interactions,'+ /-' type of interaction is observed?
(a) Predation and amensalism (b) Mutualism and competition
(c) Commensalism and amensalism (d) Predation and parasitism
60. In which type of interaction, interacting species live closely together?
(a) Predation only (b) Predation and parasitism only
(c) Commensalism and parasitism only (d) Predation, commensalism and parasitism
61. An orchid growing on the branch of mango tree is an example of:
(a) Amensalism (b) Commensalism (c) Parasitism (d) Mutualism
62. Co-evolution can be observed in case of:
(a) Mutualism, parasitism (b) Predation, parasitism
(c) Amensalism, competition (d) Competition, commensalism
63. Few major biomes (P-S) are shown in the pictures. Which of them is incorrectly identified?

(a) Q-Deciduous forests (b) S-seacoast

(c) P-Coniferous forests (d) R-Desert

Page 10 of 11
64. Various age pyramids (P-R) for human population are shown below.Select the option with correct
identification.

Stable type Declining type

(a) P Q
(b) P R
(c) Q R
(d) Q P
65. Out of the following, how many benefits does the pollinator species of wasp receives from the fig tree?
(1) Site for egg-laying (oviposition) (2) Seeds for nourishment of larvae
(3) Protection for adult (4) Nector
(a) 1 (b) 2 (c) 3 (d) 4
66. In which plant, one of the petals of flower mimics female bee?
(a) Ophrys (b) Calotropis (c) Parthenium (d) Lantana
67. Biome distribution is shown with respect to annual temperature and precipitation. Correctly identify the
biomes.

Temperate forests Grasslands Arctic and Alpine tundra

(a) D B F
(b) C E A
(c) E B F
(d) F A C
68. In inland waters, salinity is expected to be : (NCERT Correction)
(a) < 5 ppt (b) 5-30 ppt (c) 30-100 ppt (d) >100 ppt
69. Salinity in sea water is in between : (NCERT Correction)
(a) < 5 ppt (b) 5-30 ppt (c) 30-35 ppt (d) >100 ppt

ANSWER KEY

1. (a) 2. (b) 3. (d) 4. (b) 5. (c) 6. (a) 7. (d) 8. (b) 9. (b) 10. (c)
11. (b) 12. (d) 13. (c) 14. (d) 15. (c) 16. (a) 17. (c) 18. (a) 19. (d) 20. (a)
21. (a) 22. (c) 23. (c) 24. (c) 25. (a) 26. (c) 27. (d) 28. (a) 29. (c) 30. (c)
31. (d) 32. (d) 33. (d) 34. (c) 35. (a) 36. (c) 37. (b) 38. (c) 39. (d) 40. (a)
41. (b) 42. (c) 43. (c) 44. (c) 45. (d) 46. (b) 47. (a) 48. (a) 49. (d) 50. (b)
51. (a) 52. (d) 53. (a) 54. (c) 55. (a) 56. (b) 57. (d) 58. (c) 59. (d) 60. (d)
61. (b) 62. (a) 63. (c) 64. (c) 65. (b) 66. (a) 67. (a) 68. (a) 69. (c)

Page 11 of 11
 BIOLOGY Theory
Add:- Padmavati Complex,
Opp. UCO Bank, P.L.
BY ANKUR DUTT Sharma Road, Meerut
(VISHWAS KA EK NAAM) Call Us @ +91-9719275249

ECOSYSTEM
IMPORTANT FACTS
1. An ecosystem is a functional unit of nature, in which the living organisms interact among themselves and also
with the surrounding physical environment.
2. Size of an ecosystem : It may vary greatly from a small pond to a large forest or a sea.
3. All possible ecosystems on Earth form Biosphere.
4. Types of ecosystems :
(a) Terrestrial ecosystems like forest, grassland and desert.s
(b) Aquatic ecosystems like pond, lake, wetland, river and estuary.
5. Crop fields and an aquarium are examples of man-made ecosystems.
♦ Ecosystem—Structure and Function
1. Biotic and abiotic components interaction each other and result in a physical structure that is characteristic for
each type of ecosystem.
2. Stratification : It refers to the vertical distribution of different species occupying different levels in an ecosystem.
Example : In a forest ecosystem,
• Top strata — formed by trees.
• Second strata — formed by shrubs.
• Bottom strata — formed by herbs and grasses.
3. Species composition of an ecosystem is done by identification and enumeration of plant and animal species
present in that ecosystem.
4. All components of an ecosystem function as a unit.
Four Basic components of an ecosystem

1. Productivity. 2. Decomposition.
3. Energy flow. 4. Nutrient cycling.
Understanding the concepts of ecosystem by taking pond as an example
1. Pond is a shallow water body which is having all the four basic components of an ecosystem.
2. Abiotic components : Water with dissolved inorganic and organic substances and the rich soil deposited at the
bottom of the pond.
3. Biotic components involve :
(a) Autotrophs : Phytoplankton, some algae and the floating, submerged and marginal plants found at the edges.
(b) Consumers : Zooplanktons, the free swimming and bottom dwelling forms.
(c) Decomposers : Fungi, bacteria and flagellates (usually abundant at the sea floor).
4. Pond is a self-sustainable unit.
5. Regulation of rate of function of the pond is by various factors like solar input, the cycle of temperature, day-
length and other climatic conditions.
6. Like other ecosystems, pond ecosystem also performs all the functions of any ecosystem :
(a) Conversion of inorganic into organic material by utilizing the solar energy (or radiant energy of the sun) by the
autotrophs.
(b) Consumption of the autotrophs by heterotrophs.
(c) Decomposition and mineralisation of the dead matter to return tlfem back to surrounding for reuse by autotrophs.
7. Energy moves unidirectionally from lower trophic level to the higher trophic level. A part of energy is also lost as
heat to the environment.
(1) Productivity
1. For an ecosystem to work, a constant input of solar energy is the basic requirement.
2. Primary production
(a) It is the amount of biomass or organic matter produced per unit area over a time period by the plants during
photosynthesis.
Page 1 of 15
(b) It is expressed in terms of weight (g-2) or energy (kcal m-2).
3. Primary productivity : The rate of biomass production and is expressed in terms of g-2 JT-1 or (kcal m-2 yr-1).
4. Primary productivity is of two types :
(a) Gross primary productivity (GPP) : It is the rate of production of organic matter during photosynthesis.
(b) Net primary productivity (NPP) : It is the biomass available for the consumption to heterotrophs (herbiviores
and decomposers).
5. A part of GPP is utilised by plants in respiration (R) while the remaining is available for the next trophic level. So,
NPP = GPP - R
6. Primary productivity depends various factors :
(a) Plant species inhabiting that ecosystem.
(b) Environmental factors.
(c) Availability of nutrients.
(d) Photosynthetic capacity of plants.
7. Primary productivity varies in different types of ecosystems.
8. Annual net primary productivity of the whole biosphere is 170 billion tons (dry weight) of organic matter, out of
which only 55 billion tons is contributed by oceans (despite occupying about 70 per cent of the surface of earth).
9. Secondary productivity is defined as the rate of formation of new organic matter by consumers.
(2) Decomposition
1. The process of breakdown of complex organic matter into inorganic substances like carbon dioxide, water and
nutrients is called decomposition.
2. Earthworm also help in the breakdown of complex organic matter as well as in loosening of the soil. That’s why it
is also known as farmer’s ‘friend’.
3. Detritus : It include dead plant remains (as leaves, bark, flowers, etc.) and dead remains and faecal matter of
animals.
It is the raw material for decomposition.
4. Steps in the process of decomposition are :
Step 1 : Fragmentation, leaching and catabolism (all steps occur simultaneously).
Step 2 : Humification.
Step 3 : Mineralisation.
Step 1 Fragementation It is the breakdown of detritus into smaller particles by detritivores like earthworm.
Leaching It is the movement of water soluble inorganic nutrients down into the soil horizon after which they
get precipitated as unavailable salts.
Catabolism Bacterial and fungal enzymes degrade detritus into simpler inorganic substances. This process is
called as catabolism.
Step 2 Humification It results in accumulation of a dark coloured amorphous substance called humus. Humus is highly
resistant to the microbial action and undergoes decomposition at an extremely slow rate. As the
humus is colloidal in nature it serves as a reservoir of nutrients.

Step 3 Mineralisation As the humus further degrades (by microbes), inorganic nutrients are released. This is known as
mineralization.
5. Decomposition depends upon following factors :
(a) Chemical composition of detritus
• If the detritus is rich in lignin and chitin, decomposition rate is slower while if the detritus is rich in nitrogen and
water-soluble substances like sugars, decomposition rate is faster.
(b) Climatic factors
• Rate of decomposition mainly depends upon the availability of oxygen.
• Anaerobic conditions (anaerobiosis) decreases the decomposition an as a result organic materials accumulate.
• Increase in temperature and soil moisture increases the activities of soil microbes, thus increasing the rate of
decomposition.
• Warm and moist environment promotes decomposition.

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(3) Energy Flow
1. For all ecosystems on Earth, sun is the only source of energy. Exception : Deep sea hydro-thermal ecosystem.
2. Photosynthetically active radiation (PAE) is less than 50% of the total incident solar radiations.
3. In an ecosystem, autotrophs (plants and photosynthetic bacteria (NCERT
Correction)) fix the radiant energy of sun to make organic food from simple inorganic materials.
4. Plants fix only 2-10 % of the PAR.
5. All organisms on Earth depend on producers for their food, either directly or indirectly.
6. Flow of energy
(a) Flow of energy is unidirectional: Sun → Producers → Consumers.
• No trapped energy in an organism remains in it forever, either it has to be passed on to a consumer or the organism
dies. Death of an organism indicates the starting of detritus food chain / web.
• Flow of energy follows 10 % law according to which only 10 % of the energy present at a trophic level will be
transferred to higher trophic level. This is the reason why the number of trophic levels are restricted in a food chain.
• Ecosystems follow Second Law of Thermodynamics. A constant supply of energy is essential for them for the
synthesis of the molecules they require, to prevent the universal tendency towards increasing disorderliness.
• A typical Food chain be represented as following :
Producers → Primary consumers → Secondary consumers → Tertiary consumers.
Producers • Major producers :
(First trophic 1. In a terrestrial ecosystem—Herbs and woody trees.
level) 2. In an aquatic ecosystem—Phytoplanktons, algae and higher plants.
Consumers • All animals depending upon plants (directly or indirectly) fortheirfood are called as consumers.
(heterotrop • Consumers may be classified as :
hs) A. Primary consumers or herbivores (Second trophic level)- If they feed on the producers. Examples: 1. In a
terrestrial ecosystem—Insects, birds and mammals.
2. In an aquatic ecosystem—Molluscs.
B. Secondary consumers or Primary carnivores (Third trophic level)—If they feed on herbivores.
C. Tertiary consumers or Secondary carnivores : If they feed on the carnivores.
♦ Grazing food chain (GFC)
A simple grazing food chain is : Grass (Producer) → Goat (Primary Consumer) → Man (Secondary consumer).
♦ Detritus Food Chain (DFC)
1. DFC begins with dead organic matter which is acted upon by decomposers (heterotrophic organisms mainly fungi
and bacteria) which meet their energy and nutrient requirements by degrading dead organic matter or detritus.
2. Decomposers are also known as saprotrophs.
3. Mechanism of action : Decomposers release digestive enzymes → Breakdown of dead and waste materials into
simple, inorganic materials → Absorption of such material by the decomposers.
4. In an aquatic ecosystem, major fraction of energy flows through GFC while in a terrestrial ecosystem, a much
larger fraction of energy flows through the DFC than through the GFC.
5. Connections between DFC and GFC :
(a) GFC animals can also prey upon the few members of DFC in a natural ecosystem.
(b) Some animals like cockroaches, crows, are omnivores.
6. Standing crop : It refers to the total biomass (mass of living material) at a particular time, in a particular trophic
level. It is measured in terms of mass of living organisms or their number per unit area.
♦ Ecological Pyramids
1. There are three types of ecological pyramids :
(a) Pyramid of number.
(b) Pyramid of biomass.
(c) Pyramid of energy.
2. In all pyramids, the base is represented by producers (or first trophic level) while the apex is represented by
tertiary or top level consumer.
3. All organisms at a particular trophic level are included without any generalizations based on few organisms.
4. As an organism may be present in more than 1 trophic levels, so the trophic level represents a functional level, not
a a particular species.
Example : A sparrow when eats seeds, fruits, peas, etc is a primary consumer and becomes secondary consumer
when it eats insects and worms.
Page 3 of 15
Types of Ecological Pyramid General Appearance Exceptions
1. Pyramid of No. Usually uptight 1. Single tree ecosystem
(Single Tree → Many insects Less number of Smaller birds
→ Very few Large birds)
2. Pyramid of Biomass Usually upright 1. Pyramid of biomass in sea
(Biomass of fishes is more than phytoplanktons)
3. Pyramid of energy Always upright No exception
5. Limitations of ecological pyramids :
(a) A single species cannot be given two or more trophic levels in an ecological pyramid.
(b) An ecological pyramid does not accommodate a food web, it assumes a simple food chain (that almost never
exists in nature.
(c) Saprophytes are not given any place in ecological pyramids inspite of their important role in the ecosystem.
♦ Ecological Succession
1. Population and community have an important characteristic that their composition and structure constantly change
in response to the changing environmental conditions.
2. These changes is orderly, sequential and parallel with the changes in the physical environment. These changes
finally result in a community that is nearly in equilibrium with the environment. This community is termed as climax
community.
3. The gradual and fairly predictable changes occurring in the species composition of a given area is termed as
ecological succession.
4. During succession some species adapt better, colonise the area and their populations become more numerous,
whereas populations of other species decline and even disappear. Thus everytime community composition is
changing.
5. Serai communities : The whole sequence of communities that successively change in a given area are called
sere(s). Each individual community that develop during the transitional phase are termed as serai stages or serai
communities.
6. Following changes occur in successive serai stages during succession :
(a) Ecological succession usually focuses on changes in vegetation.
(b) Changes in vegetation changes the food and shelter for various types of animals. So the numbers and types of
animals also change.
(c) Change in decomposers.
(d) Diversity of species of organisms changes.
(e) Number of species increase.
(f) Number of organisms increase.
(g) Total biomass increases.
7. The present day communities in the world are the result of succession that has occurred over millions of years
since life started on Earth. Succession and evolution would have been parallel processes at that time.
8. Types of succession :
Primary succession Secondary succession
It is a process that starts with those areas where no organisms It is a process that starts with those areas that somehow, lost all
ever existed. the living organisms that existed there.
Succession occurs at slower rate Succession occurs at faster rate
Soil is not there initially so it takes several hundred to several Some soil or sediment is already present.
thousand years to form a fertile soil on a bare area like rock.
Examples : 1. Bare rock. Examples: 1. Abandoned farmlands.
2. Newly cooled lava. 2. Burnt or cut forests.
3. Newly created pond or reservoir. 3. Lands that have been flooded.
8. At any time human induced disturbances (fire, deforestation, etc.) during primary or secondary succession can
convert a particular serai stage of succession to an earlier stage. This may again create new conditions that encourage
the growth of some species while discourage or eliminate other species.
♦ Succession of Plants
1. Types of succession on the basis of the nature of the habitat:
(a) Hydrarch: Succession in water (or very wet areas). Successional series progress from hydric to the mesic
conditions.
(b) Xerarch : Succession in very dry areas. Successional series progress from xeric to the mesic conditions.
Page 4 of 15
2. → →
3. Mesic conditions are moderate conditions — neither too dry (xeric) nor too wet (hydric).
4. Pioneer species : The species that first invade a bare area.
5. Primary succession on rocks
Lichens play the role of pioneer species in primary succession on rocks. Lichens secrete acids to dissolve rocks and
thus help in weathering and soil formation. Later on lichens make favourable conditions for the growth of very small
plants like bryophytes, which are able to hold small amount of soil. These are succeeded by bigger plants and after
several more serai stages a stable climax forest community is formed which remains stable as long as the
environment remains unchanged.
6. Primary succession in water : Small Phytoplanktons (pioneer species) → Replaced bx rooted-submerged
plants → Rooted-floating angiosperms → Free-floating plants → Reed-swamp → Marsh-meadow → Scrub →
Finally the trees → Climax is a forest (NCERT Correction).
7. Primary succession in water changes a water body into a land.
8. Which species is going to invade in a secondary succession depends upon :
(a) Condition of the soil.
(b) Availability of water.
(c) The environment (as it may possess seeds or other propagules).
♦ Nutrient Cycling (or Biogeochemical Cycling)
1. Nutrients are never lost from the ecosystems but are always in stage of recycling so that the organisms should get a
constant supply of nutrients to grow, reproduce and regulate various functions.
2. The movement of nutrient elements through the various components of an ecosystem is called nutrient cycling.
3. Standing state : It refers to the amount of nutrients (like carbon, nitrogen, phosphorus, calcium, etc.) present in the
soil at any given time. It is different for different kinds of ecosystems and may also vary according to the season.
4. Reservoir: It compensates the deficit which occurs due to imbalance in the rate of influx, and efflux of nutrients.
5. Release of nutrients into the atmosphere from the reservoir depends upon various factors, e.g., soil, moisture, pH,
temperature.
6. Nutrient cycles are of two types :
Gaseous cycle Sedimentary cycle
Reservoir exists in the atmosphere. Reservoir exists in Earth's crust.
Example : 1. Nitrogen cycle. 2. Carbon cycle Example : 1. Sulphur cycle. 2. Phosphorus cycle.
♦ Carbon Cycle
1. Carbon constitutes 49 % of dry weight of organisms and is next only to water.
2. 71 % of the total quantity of global carbon is found dissolved in oceans. Thus the amount of carbon dioxide in
the atmosphere is regulated by oceanic reservoirs.
3. Atmosphere contains only 1 % of the total global carbon.
4. Fossil fuel also represent a reservoir of carbon.
5. Carbon cycling occurs through atmosphere, ocean and through living and dead organisms.
6. Through photosynthesis, about 4 × 1013 kg of carbon is fixed in the biosphere annually.
7. CO2 to atmosphere is contributed by :
(a) Organisms (producers and consumers) return a significant amount of CO2 through their respiratory activities.
(b) Decomposers also contribute substantially to CO2 pool by decomposition of waste materials and dead organic
matter of land or oceans.
(c) Natural activities : Forest fires, volcanic activity, etc.
(d) Human activities : Burning of wood, combustion of organic matter, fossil fuel, etc.
8. Some amount of the fixed carbon is lost to sediments and removed from circulation.
9. Human activities (rapid deforestation, massive burning of fossil fuel for energy and transport, etc) have
significantly influenced the carbon cycle.

♦ Phosphorus Cycle
1. Biological role of Phosphorus : It is a major constituent of biological membranes, nucleic acids and cellular
energy transfer systems. It is also a major component of shells, bones and teeth.
2. Natural reservoir of phosphorus : Rock (as phosphates).
Page 5 of 15
3. During weathering of rocks, some amount of phosphates dissolve in soil solution and are absorbed by the roots of
the plants. Herbivores and other animals obtain this element from the plants.
4. Phosphate-solubilising bacteria decompose the waste products and the dead organisms releasing phosphorus.
5. Phosphorus is not released in respiration.
Carbon Cycle Phosphorus Cycle
Natural reservoir of Carbon : Oceans (as CO2 in dissolved Natural reservoir of phosphorus : Rock (as phosphates).
form).
Carbon cycle is a gaseous cycle. Phosphorus cycle is a sedimentary cycle.
Atmospheric inputs of carbon are more through Rainfall. Atmospheric inputs of phosphorus through rainfall are much
smaller than carbon inputs.
Exchanges of carbon between organisms and environment are Exchanges of phosphorus between organism and environment
significant. are negligible.
♦ Ecosystem Services
1. Healthy ecosystems provide a wide range of economic, environmental and aesthetic goods and services. The
products of ecosystem processes are named as ecosystem services. Examples of Ecosystem services :
(a) Purify air and water. (b) Mitigate droughts and floods.
(c) Cycling of nutrients. (d) Generate fertile soils.
(e) Provide wildlife habitat. (f) Maintain biodiversity.
(g) Pollination of crops. (h) Provide storage sites for carbon.
(i) Provide aesthetic, cultural and spiritual values.
2. Although value of such services of biodiversity is difficult to determine, but Robert Constanza and his
colleagues have put a price tag of US $ 33 trillion a year on nature’s life-support services which is nearly twice the
value of the global gross national product GNP which is (US $ 18 trillion).
3. Out of the total cost, few contributors are following :
(a) Soil formation : 50%. (b) Recreation : 10%
(c) Nutrient cycling : 10% (d) Glimate regulation : 6%
(e) Habitat for wildlife : 6%

Page 6 of 15
 Practice Question of Ecosystem
1. Unit for expression of primary productivity is :
(a) gm-2 yr-1 (b) kcal m-2 yr-1
(c) joules / yr (d) Both (a) and (b)
2. Primary productivity can be considered as biomass produced by trophic level:
(a) T1 (b) T2 (c) T1 + T2 (d) Either T1 or T2
3. Rate of production of organic matter during photosynthesis :
(a) Productivity (b) Gross primary productivity
(c) Net primary productivity (d) Secondary productivity
4. If, A = Gross primary productivity, B = Net primary productivity and C = Respiration losses, than what
will be the correct relation between them?
(a) A + B = C (b) A + B + C = 1 (c) A - C = B (d) B - C = A
5. It is estimated that 170 billion tonnes (dry weight) of organic weight is produced annually. What
contribution is expected by oceans?
(a) 20% (b) 35% (c) 50% (d) 90%
6. During the process of decomposition, many steps are involved. If A = Fragmentation, B = Leaching, C =
Humification, D = Mineralization and E = Catabolism, than which of the following statement is true?
(a) C is the first process to occur (b) A and C occur simultaneously
(c) D is the last process to occur (d) D is followed by A
7. During decomposition detritus is converted to simpler inorganic substances by the action of bacterial
and fungal enzymes. This step is:
(a) Fragmentation (b) Leaching
(c) Catabolism (d) Mineralization
8. Decomposition is primarily :
(a) An aerobic process (b) An anaerobic process
(c) A process on which there is no effect of 02 (d) Dependent on large sized animals
9. Identify the incorrect statement:
(a) Sun is not the source of energy for deep sea hydrothermal ecosystem
(b) According to Lindemann’s 10% law, plants fix 10% of PAR
(c) Ecosystems also follow second law of thermodynamics
(d) Death of organism is beginning of detritus food chain
10. In a food chain involving 4 trophic levels, secondary consumer is :
(a) Producers (b) Herbivores (c) Carnivores (d) Top carnivores
11. Standing crop is :
(a) A crop ready to harvest
(b) Tiomass at a particular trophic level
(c) Energy fixed by autotrophs
(d) Number of individuals at a particular trophic level
12. How many types of ecological pyramids are there?
(a) 1 (b) 2 (c) 3 (d) 4
13. Which ecological pyramid is never inverted?
(a) Energy (b) Biomass (c) Number (d) Both (a) and (b)
14. In which of the following, pyramid of number is inverted?
(a) Single tree ecosystem (b) Pond (c) Grassland (d) Aquarium
15. Succession finally results in :
(a) Formation of a sere (b) Climax community
(c) Deprivation of humus content in soil (d) Conversion of food webs into food chains
16. In an area, all living organisms were lost because of flood. After sometime, a biological community or
sere is developed. This is :
(a) Acclimatization (b) Primary succession
(c) Secondary succession (d) Rejuvenation
Page 7 of 15
17. Succession is termed as primary when :
(a) One sere is replaced by another
(b) It occurs in an area where soil is already formed
(c) It occurs in a barren area
(d) There is no change in sere
18. Which of the following is not an example of primary succession?
(a) Succession on bare rock (b) Succession in a newly created reservoir
(c) Succession in previously flooded area (d) Succession in a new cooled lava
19. In comparison to secondary succession, primary succession :
(a) Takes less time (b) Occurs in relatively barren area
(c) Consists of less hardy plants (d) Involves more biodiversity
20. Results of hydrarch and xerarch succession are respectively :
(a) Mesic and mesic conditions (b) Aquatic and mesic conditions
(c) Mesic and dry conditions (d) Aquatic and dry conditions
21. Pioneer species in case of xerarch succession are usually:
(a) Lichens (b) Mosses (c) Grasses (d) Sedges
22. Hydrarch succession is given :
Small phytoplanktons → Free floating angiosperms → A → B → C →Trees.
A, B and C are respectively:
(a) Sedges, rooted hydrophytes, grasses (b) Rooted hydrophytes, sedges, grasses
(c) Mosses, grasses, sedges (d) Rooted hydrophytes, grasses, mosses
23. What is the role of lichens in a xerarch succession occurring on a bare rock?
(a) It add nutrients to soil
(b) It performs photosynthesis at higher rate
(c) It is essential for growth of decomposers
(d) It helps in soil formation by secreting acids to dissolve rocks
24. Amount of nutrients present in the soil at any given time is termed as :
(a) Standing crop (b) Humus (c) Standing state (d) Nutrient cycling
25. Caseous type of nutrient cycle is observed in:
(a) Nitrogen (b) Carbon (c) Sulphur (d) Both (a) and (b)
26. Most of the global content of carbon is found in :
(a) Atmosphere (b) Hydrosphere (c) Lithosphere (d) In living organisms
27. Incorrect about phosphorus cycle is:
(a) It is an example of sedimentary cycle
(b) Atmospheric inputs of phosphorus through rainfall are very less than carbon inputs
(c) Natural reservoir is ocean
(d) Gaseous exchange of phosphorus between organism and environment is negligible
28. Ecosystem services are:
(a) Products of ecosystem processes
(b) Liabilities of human towards ecosystem
(c) Actions taken by government to protect environment
(d) Initiations taken by local people to protect ecosystem
29. What is correct about the size of ecosystems?
(a) These are usually very small
(b) These are always very small
(c) These are always large sized
(d) Their size may vary from a small pond upto a large forest
30. All ecosystems on earth if taken together will constitute :
(a) Biological community (b) Biome (c) Ecology (d) Biosphere
31. Select the incorrect match :
(a) Aquatic ecosystem—Eustary (b) Artificial ecosystem—Aquarium
(c) Autotroph in a lake ecosystem—Zooplanktons (d) Decomposer consumer—Bacteria
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32. Vertical distribution of different species occupying different levels in an ecosystem is termed is:
(a) Stratification (b) Scarification (c) Niche formation (d) Succession
33. Bottom strata in a forest ecosystem will be formed by :
(a) Trees only (b) Trees and herbs
(c) Herbs and grasses (d) Herbs, shrubs and grasses
34. Incorrect about a pond ecosystem is :
(a) It is not a self sustained unit because it has to depend upon solar energy for working
(b) Fungi and bacteria are predominant decomposers
(c) Phytoplanktons and algae act as producers
(d) Soil at the bottom is also an abiotic component
35. Species composition in an ecosystem is done by :
(a) Identification of plant species
(b) Identification of plant and animal species
(c) Enumeration of plant and animal species
(d) Enumeration and identification of plant and animal species
36. There are 4 basic components of an ecosystem 1 2 3 and 4 In a pond ecosystem, phytoplanktons are
responsible for 1 and the bacteria and fungi are responsible for 2 3 is always unidirectional.
Which is incorrect?
(a) 2 — Decomposition (b) 4 — Nutrient cycling
(c) 1 — Productivity (d) 3 — Mineralisation
37. In an ecosystem flow of energy is :
(a) Unidirectional from lower trophic level to higher
(b) Unidirectional from higher trophic level to lower
(c) Bidirectional between lower and higher trophic level
(d) Multidirectional
38. In a primary succession, initially :
(a) No soil was there (b) Some soil was there
(c) Well developed soil was there (d) Soil was there but water content was less
39. Present day communities in world are the result of succession that has occurred over:
(a) Last 50 years (b) Last 300 years
(c) Last 1000 years (d) Millions of years since life has started on earth
40. Primary succession is observed in :
(a) Burnt forests (b) Newly cooled lava
(c) Flooded lands (d) Cut forests
41. Productivity can be expressed in terms of energy as :
(a) g-2 (b) Kcal (c) Kcal/m2 (d) Kcal/m2/yr.
42. Mineralisation ensures the availability of nutrients for:
(a) Autotrophs (b) Decomposers
(c) Consumers only (d) Consumers and decomposers only
43. For an ecosystem to work, first primary need is :
(a) Constant input of nutrients (b) Constant input of solar energy
(c) Decomposition (d) Predation
44. In an ecological succession, saprophytes belong to :
(a) T1 (b) T2 (c) Either T2 or T3 (d) None of these
45. Functionally an insectivores plant may belong to:
(a) T1 only (b) T1 and T2 (c) T2 and T3 (d) T1 and T3
46. A food chain is represented as:B→C→A→D Correct representation in an ecological pyramid will be:

(a) (b) (c) (d)

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47. Which pyramid is always upright?
(a) Pyramid of energy (b) Pyramid of biomass
(c) Pyramids of number (d) Both (a) and (c)
48. Biomass available for the consumption to heterotrophs is termed as :
(a) Gross primary productivity (b) Net primary productivity
(c) Secondary productivity (d) Productivity
49. Given pyramid is observed in :

(a) Pyramid of number without any exception (b) Pyramid of energy without any exception
(c) Pyramid of biomass without any exception (d) Both (a) and (c)
50. All of the following are basic components of an ecosystem except:
(a) Productivity (b) Decomposition (c) Nutrient cycling (d) Stratification
51. Primary productivity depends on following factors except:
(a) Plant species (b) Environmental factor
(c) Herbivore species (d) Availability of nutrients
52. In terms of dry weight of organic matter, what is the annual net primary productivity of whole
biosphere?
(a) 12 billion tonnes (b) 55 billion tonnes
(c) 170 billion tonnes (d) 265 billion tonnes
53. Primary carnivores belong to :
(a) T1 (b) T2 (c) T3 (d) T4
54. If tree = A, Large Birds = B, Insects = C and Small Birds = D, then in a single tree ecosystem, the
pyramid of number stays correct in all of the following except:
(a) C > D > A (b) D > A > B (c) C > B < A (d) D > B > C
55. In a single tree ecosystem, if P, Q, R and S represents the smaller birds, tree, insects and larger birds
respectively, then which will be second most abundant in numbers?
(a) P (b) Q (c) R (d) S
56. In spite of occupying % of the earth surface area, oceans contribute % of the total NPP (Net Primary
Productivity) of whole biosphere.
(a) 50,30 (b) 30,10 (c) 60,10 (d) 70,35
57. Annual NPP of oceans in terms of dry weight of organic matter is :
(a) 55 billion tonnes (b) 110 billion tonnes
(c) 170 billion tonnes (d) 235 billion tonnes
58. Rate of formation of new organic matter by consumers is :
(a) Primary productivity (b) Gross primary productivity
(c) Net primary productivity (d) Secondary productivity
59. A and B are two ecological pyramids. Select the correct statement:

(a) A - Pyramid of biomass in forest ecosystem (b) B - Pyramid of energy in sea ecosystem
(c) A - Pyramid of energy in pond ecosystem (d) B - Pyramid of number in single tree ecosystem
Page 10 of 15
60. In given diagram various stages of hydrarch succession are given. Arrange them in correct sequence:

(a) D→F→C→A→G→B→E (b) F→ C → D → A → B → G → E

(c) C→F→D→A→G→B→E (d) F→D→C→G→A→B→E
61. Select the incorrect statement:
(a) Earthworm is known as farmer’s friends
(h) In annual net productivity of whole biosphere, oceans contribute more than 50%
(c) Decomposers are abundant at sea floor
(d) Nutrient cycling is one of the four basic components of ecosystem
62. Organic detritus is degraded to inorganic substances during :
(a) Fragmentation (b) Leaching (c) Mineralisation (d) Catabolism
63. Extremely slow rate of decomposition can be observed in :
(a) Intact debris (b) Fragmented debris (c) Humus (d) Both (b) and (c)
64. Humus is a 1 coloured amorphous substance which is highly 2 to microbial action and undergo
decomposition at a very 3 rate.
(a) 1 — light, 3 — slow (b) 1 — light, 2 — susceptible
(c) 2 — resistant, 3 — fast (d) 1 — dark, 3 — slow
65. During decomposition earthworm is involved in :
(a) Fragmentation (b) Leaching (c) Humification (d) Mineralisation
66. Smallest functional unit of nature is :
(a) Biome (b) Ecosystem (c) Individual (d) Population
67. What is incorrect about ecosystem?
(a) Its size can vary from small sized pond to large sized sea
(b) These may be anthropogenic in origin
(c) These may be temporary or permanent
(d) These involve flow of energy but not recycling of nutrients
68. Which of the following is not an ecosystem?
(a) Crop field (b) Wetland
(c) Grassland (d) Rats in an abandoned dwelling
69. An ecological pyramid accommodate :
(a) Only food chain (b) Only food web
(c) Both food chains and food webs (d) Neither food chains nor food webs
70. Ecological succession mainly focusses on :
(a) Changes in number of animals (b) Changes in behaviour of animals
(c) Changes in decomposers (d) Changes in vegetation
71. All of the following increases during an ecological succession except:
(a) Number of species (b) Biomass at a trophic level
(c) Number of individuals of a particular species (d) Percentage of inorganic content in soil
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72. Least stable community in an ecological succession is :
(a) First community (b) Serai community
(c) Climax community (d) Both (b) and (c)
73. Number of serai communities are in primary succession in comparison to secondary succession:
(a) More (b) Less (c) Equal (d) Can’t say
74. What is correct regarding secondary succession in comparison with primary succession?
(a) It occurs at a slower pace
(b) Soil was initially absent
(c) No biological communities were present initially
(d) It involves less number of serai communities
75. Phosphorus cycling is shown below. Identify the processes A and B.

A B
(a) Decomposition Ammonification
(b) Decomposition Weathering
(c) Weathering Nitrification
(d) Weathering Decomposition
76. Any disturbance during succession :
(a) Encourage the growth of some species (b) Discourage the growth of some species
(c) Make some species extinct (d) All of these
77. If stratification is done in a forest, which of the following will occupy middle strata or layer?
(a) Tree canopy (b) Herbs (c) Shrubs (d) Grasses
78. In a pond, autotrophic component include :
(a) Phytoplanktons and zooplanktons (b) Phytoplanktons and algae
(c) Phytoplanktons, algae and marginal plants (d) Algae and marginal plants
79. Read the following properties:
(1) Susceptible to microbial action (2) Light coloured
(3) Result of mineralization (4) Fast decomposing
(5) Form true solution of nutrients
How many of the above properties are applicable to humus?
(a) Three (b) Two (c) One (d) None of these
80. Most important factor for determining the rate of decomposition is:
(a) Availability of 02 (b) Relative humidity
(c) pH of soil (d) Nitrogen content
81. Which of the following decreases the rate of decomposition?
(a) Increase in nitrogen content of debris (b) Decrease in lignin content of debris
(c) Decrease in 02 content in atmosphere (d) Increase in moisture content of atmosphere
82. Of the total incident solar radiations, photo-synthetically active radiation (PAR) is :
(a) <50% (b) 50-60% (c) 60-70% (d) >70%
83. Plants fix about % of PAR :
(a) 2-10 (b) 10-20 (c) 20-25 (d) 25-50
84. In an ecosystem, autotrophs fix energy into energy.
(a) Radiant, electrical (b) Chemical, electrical
(c) Radiant, chemical (d) Chemical, radiant
85. 10% law for flow of energy works between :
(a) Sun and first trophic level (b) All trophic levels
(c) T3 and T4 (d) All of these
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86. Trophic levels are restricted in a food chain. Most appropriate reason is:
(a) Lack of food
(b) Deficiency of water in an ecosystem
(c) Only 10% of energy is being transferred to next
(d) Biomagnifications in lower trophic levels
87. Sun is the source of energy following in ecosystems except:
(a) Pond ecosystem (b) Grazing food chain
(c) Deep sea hydro thermal ecosystem (d) Scrub forest
88. In an aquatic ecosystem a mollusc typically belongs to:
(a) T1 (b) T2 (c) T3 (d) T4
89. Which of the following is not an omnivore?
(a) Crows (b) Sparrow (c) Hyena (d) Human
90. Inorganic nutrients are released from humus by the microbial action during :
(a) Fragmentation (b) Leaching (c) Catabolism (d) Mineralisation
91. Identify the process in which water soluble inorganic nutrients are precipitated as unavailable salts:
(a) Fragmentation (b) Leaching (c) Catabolism (d) Mineralisation
92. Secondary carnivores feed on the members of:
(a) T1 (b) T2 (c) T3 (d) T4
93. Total biomass at a particular trophic level is termed as:
(a) Standing crop (b) Pioneer species (c) Succession (d) Standing state
94. Which of the following belong to a different trophic level?
(a) Buffalo (b) Goat (c) Deer (d) Jackel
95. Omnivores feed upon the members belonging to :
(a) T1 only (b) T2 only (c) T1 and T2 both (d) Decomposition
96. In all ecological pyramids base is represented by the organisms that:
(a) Fix radiant energy (b) Feed on herbivores (c) Feed on T1 (d) Top carnivore
97. In all of the following pyramids of biomass, base is represented by autotrophs except:
(a) In forest (b) In grassland (c) In pond (d) None of these
98. In the given pyramid, B represents:

(a) T1 (b) T (c) T3 (d) T4

99. In a pyramid of biomass in sea, if A = phytoplanktons, B = small fishes and C = large fishes, then what is
correct?
(a) A = C (b) B > A (c) C > A (d) B = C
100. Which pair is not correctly related?
(a) GPP — Photosynthetic organisms (b) Middle strata of forest ecosystem — Shrubs
(c) Abundancy of decomposers — Sea surface (d) Flow of energy — Always unidirectional
101. Physical breakdown of detritus into smaller particles during decomposition is mediated by:
(a) Bacteria (b) Bacteria and fungus
(c) Earthworm (d) Earthworm, bacteria and fungus.
102. If A = Humification, B = Leaching, C = Catabolism, D = Fragmentation and E = Mineralisation, then
which of the steps occur almost simultaneously during decomposition?
(a) A, B (b) B, E (c) C, D, E (d) B, C, D
103. Decomposition rate will be slower if the detritus is rich in :
(a) Sugars (b) Lignin (c) Water soluble substances (d) Nitrogen
104. Detritus food chain begins with :
(a) Bacteria (b) Fungi (c) Algae (d) Detritus
105. A sparrow has eaten an earthworm in morning while a seed in evening. It has been shifted from to
(a) T1, T2 (b) T2, T3 (c) T3, T2 (d) T3, T4
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106. Exception to pyramid of energy is :
(a) Aquatic ecosystem (b) Parasitic food chain (c) Detritus food chain (d) None of these
107. What is meant by the term 'hydrarch'?
(a) Any water resource (b) Any fresh water resource
(c) Biological community in an aquatic resource (d) Succession in a wet area
108. If hydric conditions are P, xeric condition are Q and mesic conditions are R, then Xerarch succession
can be represented as :
(a) Q→P (b) P→Q (c) Q→R (d) R→Q
109. Incorrect about pioneer species:
(a) First invade in a bare area. (b) Adapted to grow in hardy conditions
(c) Consists of trees and shrubs. (d) Very important in initiating soil formation
110. Lichens play the role of A species, during the succession on/in B It secretes C to D weathering of rocks
and soil formation.
(a) A — Pioneer, B — Rocks, C — Alkalies, D — Promote
(b) A — Climax, B — Rocks, C — Alkalies, D — Delay
(c) A — Pioneer, B — Rocks, C — Acids, D — Promote
(d) A — Climax, B — Water, C — Acids, D — Promote
111. Succession in water ultimatelγ results in :
(a) Hydric conditions (b) Xeric conditions (c) Mesic conditions (d) Saline
112. Role of pioneer species in a primary succession on rocks is played by :
(a) Bryophytes (b) Tall trees (c) Lichens (d) Shrubs
113. Climax community in Xerarch succession comprises of:
(a) Lichens only (b) Shrubs only (c) Shrubs and trees (d) Lichens and bryophytes
114. In the given food-chain, goat is :
Grass → Goat → Man
(a) Producer (b) Decomposer (c) Primary consumer (d) Secondary consumer
115. Match the column :
Column A Column B
A. Fourth trophic level 1. 1. Birds, Fishes, wolf
B. First trophic level 2. 2. Zooplankton, grasshopper and cow
C. Second trophic level 3. 3. Phytoplankton, grass, trees
D. Third trophic level 4. 4. Man, lion
(a) A-4, B-3, C-2, D-1 (b) A-3, B-4, C-2, D-1
(c) A-3, B-4, C-1, D-2 (d) A-4, B-3, C-1, D-2
116. How many of the following will act as a decomposer in a pond ecosystem?
(A) Phytoplanktons (B) Submerged plants
(C) Bacteria (D) Flagellates
(E) Zooplanktons (F) Fungi
(a) One (b) Two (c) Three (d) Four
117. In a pond ecosystem, abiotic component is represented by:
(a) Water with dissolved inorganic substances
(b) Water with dissolved inorganic and organic substances
(c) Water with dissolved inorganic and organic substances and also the soil at the bottom
(d) Water without any dissolved substances
118. Pyramid of biomass is shown.

It belongs to 1 ecosystem and A and B represent respectively 2 and 3

1 2 3
(a) Forest Trees Insects
(b) Forest Grasses Herbivores
(c) Pond phytoplankton Zooplankton
(d) Pond Zooplankton phytoplankton
Page 14 of 15
119. 3 stages of hydrarch succession are given. Identify them correctly.

A B C
(a) Marsh meadow Submerged tree floating Submerged
(b) Reed swamp Plankton Marsh meadow
(c) Scrub Plankton Marsh meadow
(d) Reed swamp Submerged tree floating Submerged
120. Why pyramid of biomass is inverted in sea?
(a) Biomass of phytoplanktons is more than zooplanktons
(b) Biomass of small fishes is less than predators
(c) Biomass of fishes is more than phytoplanktons
(d) Biomass of fishes is less than zooplanktons.
121. If A: Chemoautotrophs, B: plants, C: photoautotrophs and D: chemoheterotrophs, then which set fix
the radiant energy of sun to form organic food? (NCERT Correction)
(a) A, B and D (b) B and C (c) C and D (d) A, B and C
122. Various stages of primary succession in water are given below: (NCERT Correction)
(A) Scrub (B) Marsh meadow
(C) Rooted submerged plants (D) Free floating angiosperms
(E) Rooted floating angiosperms (F) Trees
(C) Reed swamp (H) Small phytoplanktons
Arrange the stages in sequence and select the 3rd and 5th stages to occur:
(a) A and D (b) E and G (c) B and H (d) C and F
123. Identify the pioneer species in primary succession in water: (NCERT Correction)
(a) Small phytoplanktons (b) Rooted submerged plants
(c) Rooted floating angiosperms (d) Scrub

ANSWER KEY
1. (d) 2. (a) 3. (b) 4. (c) 5. (b) 6. (c) 7. (c) 8. (a) 9. (b) 10. (c)
11. (b) 12. (c) 13. (a) 14. (a) 15. (b) 16. (c) 17. (c) 18. (c) 19. (b) 20. (a)
21. (a) 22. (b) 23. (d) 24. (c) 25. (d) 26. (b) 27. (C) 28. (a) 29. (d) 30. (d)
31. (c) 32. (a) 33. (c) 34. (a) 35. (d) 36. (d) 37. (a) 38. (a) 39. (d) 40. (b)
41. (c) 42. (a) 43. (b) 44. (d) 45. (d) 46. (b) 47. (a) 48. (b) 49. (b) 50. (d)
51. (c) 52. (c) 53. (c) 54. (d) 55. (a) 56. (d) 57. (a) 58. (d) 59. (b) 60. (a)
61. (b) 62. (d) 63. (c) 64. (d) 65. (a) 66. (b) 67. (d) 68. (d) 69. (a) 70. (d)
71. (d) 72. (a) 73. (a) 74. (d) 75. (b) 76. (d) 77. (c) 78. (c) 79. (d) 80. (a)
81. (c) 82. (a) 83. (a) 84. (c) 85. (b) 86. (c) 87. (c) 88. (b) 89. (c) 90. (d)
91. (b) 92. (c) 93. (a) 94. (d) 95. (c) 96. (a) 97. (d) 98. (c) 99. (b) 100. (c)
101. (c) 102. (d) 103. (b) 104. (d) 105. (c) 106. (d) 107. (d) 108. (c) 109. (c) 110. (c)
111. (c) 112. (c) 113. (c) 114. (c) 115. (a) 116. (c) 117. (c) 118. (c) 119. (b) 120. (c)
121. (b) 122. (b) 123. (a)

Page 15 of 15
 BIOLOGY Theory
Add:- Padmavati Complex,
Opp. UCO Bank, P.L.
BY ANKUR DUTT Sharma Road, Meerut
(VISHWAS KA EK NAAM) Call Us @ +91-9719275249

BIODIVERSITY AND CONSERVATION

IMPORTANT FACTS
♦ Biodiversity (Term popularized by Edward Wilson)
1. Ranging from the macromolecules within the cell upto the biomes, biodiversity in our biosphere is immense,
2. According to Edward Wilson, biodiversity is the combined diversity at all the levels of biological organization.
3. Gaining the present rich diversity in nature has taken millions of years of evolution but if the present rates of
species losses continue, it will be lost in less than two centuries.
4. Most important type of biodiversities are :
(a) Genetic diversity
• At the genetic level, a single species may show high diversity over its distributional range.
• Example 1 : Rauwolfia vomitoria (a medicinal plant) growing in different Himalayan ranges show genetic
variation in terms of potency and concentration of the active chemical (reserpine) produced by the plant.
Example 2 : In India, more than 50,000 genetically different strains of rice are found.
Example 3 : In India, more than 1,000 varieties of mango are found.
(b) Species diversity
• It is the diversity at species level.
• Example : Amphibian species diversity is more rich in the Western Ghats in comparison to the Eastern Ghats.
(c) Ecological diversity
• It is the diversity at ecosystem level.
• Example : Deserts, rain forests, mangroves, coral reefs, wetlands, estuaries and alpine meadows in India have
greater ecological diversity in comparison to a Scandinavian country like Norway.
♦ How Many Species are there on Earth and How Many in India?
1. According to the IUCN (2004), the total number of known plant and animal species so far is a little more than 1.5
million, but we do not know actually how many species are existing on earth today that are yet to be discovered.
2. Biologists suggest that most of the species waiting to be discovered are in the tropical areas.
3. According to Robert May, the global species diversity is about 7 million. If we accept May’s global estimates,
only 22 per cent of the total species have been recorded so far.
4. Biologists are not sure about how many prokaryotic species there might be.
5. Some interesting aspects about earth’s biodiversity are :
1. Animal species >70% • Insects are forming the most species-rich taxonomic group
(> 70 % of the total animals).
• Among vertebrates, half of the species belong to fishes.
2. Plant species (including algae, fungi, bryophytes, • Number of Fungi species > Combined number of species of
gymnosperms and angiosperms) > 22% fishes, amphibians, reptiles and mammals.
• Among plant species, fungi and angiosperms individually
form a little less than half number of species.
3. Other species < 8 % • These include prokaryotic and protistan species.
♦ Few facts about Biodiversity in India
1. India has only 2.4% of the world’s land area but the global species diversity is 8.1%.
2. India is one of the 12 mega diversity countries of the world.
3. About 45,000 species of plants and 90,000 species of animals have been recorded from India.
4. Estimate number of living species waiting to be discovered in India (accepting May’s global estimates)—Probably
more than 1,00,000 plant species and more than 3,00, 000 animal species.
♦ Patterns of Biodiversity (1) Latitudinal gradients
1. Latitudinal gradient is the most well-known pattern in diversity.
2. Generally the species diversity decreases as we move away from the equator towards the poles. So we can say that
tropics (latitudinal range of 23.5° N to 23.5° S) harbour more species than temperate or polar areas (although few
exceptions are there).
Example 1: Amazonian rain forest (largely tropical) in South America has the greatest biodiversity on earth. It has
more than 40,000 species of plants, 3,000 of fishes, 1,300 of birds, 427 of mammals, 427 of amphibians, 378 of
reptiles and of more than 1,25,000
invertebrates. Scientists estimate that at least two million insect species waiting to be discovered might be in rain
forests.
Example 2 : Variation in number of species of birds

Page 1 of 13
Colombia (located near the equator) - nearly 1,400 species > India (much of land area in the tropical latitudes) -
nearly 1,200 species > New York at 41° N - 105 species > Greenland at 71° N - only 56 species.
Example 3 : Forests in tropical regions like Equador have up to 10 times as many species of vascular plants in
comparison to the forests of equal area in temperate regions like the Midwest of the USA.
What is so special about tropics that might account for their greater biological diversity?
Some important hypotheses are :
(a) Speciation is generally a function of time. Frequent glaciations has occurred in temperate regions in the past but
tropical latitudes have remained relatively undisturbed for millions of years (long evolutionary time for greater
species diversification).
(b) Seasonal variations are nil in tropical environments in comparison to the temperate ones. So a more constant and
predictable environment was there to promote niche specialization, leading to a greater species diversity.
(c) As the tropics receive more solar energy, these have higher productivity. This higher productivity might indirectly
contributed to greater diversity.
(2) Species-Area Relationships
1. German naturalist and geographer Alexander von Humboldt, during his explorations in the South American
jungles, observed that—Within a region species richness increased with increasing explored area, but only up
to a limit.
2. The relation between species richness and area for a wide variety of taxa (angiosperm plants, birds, bats, fresh
water fishes) becomes a rectangular hyperbola. On a logarithmic scale, the relationship is a straight line described
by the equation :
log S = logC + Z log A
where,
S = Species richness A = Area Z = slope of the line (regression coefficient) C = Y-intercept
3. Value of Z : It lies in the range of 0.1 to 0.2, irrespective of the taxonomic group or the region (whether it is plants
in Britain, birds in California or molluscs in New York state, the slopes of the regression line are amazingly similar).
But the slope of the line to be much steeper (Z values in the range of 0.6 to 1.2) if we analyse the species-area
relationships for very large areas like the entire continents. Example : Value of Z for frugivorous (fruit-eating) birds
and mammals in the tropical forests of different continents is found to be 1.15.
♦ The importance of Species Diversity to the Ecosystem
1. Generally it is believed that presence of more species in a community make it more stable.
2. According to David Tilman‟s long-term ecosystem experiments using outdoor plots, it can be said :
(a) A stable community shows very little year-to-year variation in total biomass.
(b) If diversity increases, productivity of an ecosystem also increases.
(c) A stable community is either resistant or resilient to the disturbances (natural or man-made). Also it must be
resistant to invasions by alien species.
3. At present, we are losing species at an alarming pace.
4. „Rivet Popper hypothesis‟ (by Stanford Ecologist—Paul Ehrlich)
5. This hypothesis explains the importance of diversity on earth.
6. In this hypothesis, an airplane is considered as equivalent to an ecosystem, in which all parts are joined together by
using thousands of rivets (that are equivalent to species). Now if every passenger starts popping a rivet (indicating
the extinction of a species), initially it may not affect the safety of flight (stability and functioning of the ecosystem),
but as more and more rivets are removed (gradual extinction of species), the plane will become dangerously weak
over a period of time (stability of ecosystem is dangerously threatened). Position of rivet from which it is removed
may also be critical, e.g., loss of rivets from the wings (key species that drive major ecosystem functions) is more
serious threat to the safety of flight in comparison to the loss of rivets from the seats or windows inside the plane.
♦ Loss of Biodiversity
1. At present, human activities are the most important threat to the biological wealth of our planet and is resulting in
extinction of many species and declining the diversity. Example 1. More than 2,000 species of native birds became
extinct after the colonisation of tropical Pacific Islands by humans.
Example 2. In the last 500 years, IUCN Red List (2004) indicates the extinction of 784 species (including 338
vertebrates, 359 invertebrates and 87 plants). Some examples of recent extinctions are :
(a) Dodo (Mauritius).
(b) Quagga (Africa).
(c) Thylacine (Australia).
(d) Steller‟s Sea Cow (Russia)
(e) 3 subspecies (Bali, Javan, Caspian) of tiger.
2. Extinction of 27 species has occurred in just last 20 years only.
3. Analysis of records shows that:
(a) Amphibians appear to be more vulnerable to extinction.

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(b) Presently more than 15,500 species world-wide (of which > 650 are from India) are facing the threat of
extinction (12% of bird species, 23% of mammal species (every 4th mammalian species), 32% of all amphibian
species and 31% of all gymnosperm species).
(c) Nearly 700 species have become extinct in recent times.
4. Mass extinctions
(a) It refers to the large-scale loss of species.
(b) Fossil records indicate that 5 episodes of mass extinction have already occurred on earth (even before the
evolution of human).
(c) ‘Sixth Extinction’ is presently in progress and its pace (rate of extinction of species) is estimated to be 100 to
1,000 times faster than previous 5 mass extinctions. Human activities have enhanced the rate.
(d) If present scenario continues, almost half of all the species on earth will become extinct in coming next 100 years.
Effects of Loss of Biodiversity
Loss of biodiversity in a region results in following :
1. Plant production is declined.
2. Resistance against the conditions / environmental perturbations like drought is lowered.
3. Variability in certain ecosystem processes like plant productivity, water use, pest and disease cycles, etc are
increased.
Causes of Biodiversity Losses
Four major causes—„The Evil Quartet‟
1. Habitat loss and fragmentation.
2. Over-exploitation.
3. Alien species invasions.
4. Co-extinctions.
1. Habitat loss and fragmentation
(a) It is the most important cause for the extinction of plants and animals species.
(b) Urbanisation is the root cause.
Example : Tropical rain forests, once covering more than 14 % of the earth’s land surface are now restricted to 6 %.
The Amazon rain forest (also known as the lungs of the planet‟ because of its huge size) is habitat for millions
species, is largely being cut and cleared for cultivation of soya beans and grasslands (for rearing beef cattle).
(c) Pollution is another threat for the survival of many species in many habitats.
(d) Many times human activities result in breaking of large habitats into small fragments which is termed as
fragmentation. Fragmentation results in decline of populations of specially mammals and birds as these require
large territories. It also affects those animals which have migratory habits.
2. Over-exploitation
(a) Over-exploitation of natural resources (including species of animals) for food and shelter has resulted in loss of
many species in last 500 years, e.g., Steller‟s sea cow, Passenger pigeon, etc.
(b) Presently many commercially important marine fish species are endangered due to their over-harvestment.
3. Alien species invasions
(a) Introduction of alien species, many times result in extinction of indigenous species. Examples :
• Introduction of Nile perch (alien fresh water fish) into Lake Victoria in east Africa resulted in extinction of more
than 200 species of Cichlid fish (indigenous fresh water fish).
• Invasive weed species like carrot grass (Parthenium), Lantana and water hyacinth (Eicchornia) are potential
threat to our native species.
• Recently, illegal introduction of an African catfish (Clarias gariepinus) for aquaculture is posing a threat to the
indigenous catfishes in our rivers.
4. Co-extinctions
(a) With the extinction of a species, the plant and animal species obligatorily associated with it also become extinct.
This is termed as co-extinction.
Examples :
• If a fish species (host) becomes extinct, its parasites also meet the same fate.
• Plants and their pollinators are coevolved (mutualism). Extinction of any of them will definitely result in extinction
of other.
♦ Biodiversity Conservation
Reasons for the conservation of biodiversity can be grouped into 3 categories :
1. Narrowly utilitarian.
(a) Humans derive many direct economic benefits from the nature like :
• Food (cereals, pulses, fruits).
• Firewood.
• Fibres.
• Medicinal importance.
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• Construction material
• Industrial products (tannins, lubricants, dyes, resins, perfumes, etc).
(b) More than 25 % of drugs sold in the market worldwide are derived from plants.
(c) Native people around the world use about 25,000 species of plants for traditional medicines.
(d) Bioprospecting : It refers to exploring the molecular, genetic and species-level diversity for products of
economic importance so the product may be obtained in more in quantity.
2. Broadly utilitarian.
(a) According to the broadly utilitarian argument, biodiversity plays a major role in many ecosystem services.
(b) The fast-dwindling (diminishing) Amazon forest produces about 20 % the total oxygen in the earth’s atmosphere
through photosynthesis.
(c) Pollination is also another service which include pollinators like bees, bumblebees, birds and bats.
(d) Examples of some intangible (non-physical) benefits derived from nature — Aesthetic pleasures of walking
through thick woods, watching spring flowers in full bloom or waking up to a bulbul’s song in the morning.
3. Ethical.
(a) We need to realise that every species on earth has an intrinsic value, even if it is not of. current or any economic
value to us.
(b) It is our moral duty to care for the well-being of species with which we share our habitat and pass them on to the
future generations.
♦ Modes of Conservation of Biodiversity
(A) In situ conservation
1. If we conserve and protect the whole ecosystem and its biodiversity at all levels in a forest to save the tiger, this
approach will be termed as in situ conservation (at site or on site).
2. Examples :
(a) Identification and conservation of „biodiversity hotspots‟.
• „Biodiversity hotspots‟ : These are the regions that are characterized with :
(i) Very high levels of species richness.
(ii) High degree of endemism (species found in only a specific region and nowhere else).
• Number of Biodiversity hotspots’ worldwide : Initially 25, now 34.
• These hotspots are also the regions of accelerated habitat loss. If strict protection of these hotspots is done, it may
reduce the ongoing mass extinctions by almost 30%.
• In India, 3 hotspots are there—
(i) Western Ghats and Sri Lanka, (ii) Indo-Burma. (iii) Himalaya.
• All the biodiversity hotspots cover less than 2 % of the earth’s land area but the species diversity is very high.
(b) To create legally protected areas like biosphere reserves (14), national parks (90) and sanctuaries (448).
(c) Sacred grooves and their Conservation
• In India, in many cultures trees and wildlife are given total protection. These are known as Sacred grooves.
• Examples :
- In Khasi and Jaintia Hills in Meghalaya (last refuges for many species of rare and threatened plants)
- In Aravalli Hills of Rajasthan.
- In Western Ghat regions of Karnataka and Maharashtra.
- In Sarguja, Chanda and Bastar areas of Madhya Pradesh.
(B) Ex situ Conservation
1. In this mode of conservation, an endangered or threatened animal or plant species needs urgent measures to save it
from extinction by ex situ (off site or away from the site of occurrence) approach.
2. Examples :
(a) Creation of Zoological parks, botanical gardens and wildlife safari parks.
• Threatened animals and plants are shifted from their natural habitat and placed in above mentioned special settings
where they can be protected and given special care.
• Many animals that have become extinct in the wild but are maintained in zoological parks.
(b) In vitro fertilisation, tissue culture propagation and cryopreservation of
gametes.
• Gametes of threatened species can be kept viable and fertile for long periods using cryopreservation techniques.
• Eggs can be fertilized in vitro and the plants can be propagated using tissue culture methods.
(c) Creation of Seed banks to conserve seeds for long periods.
• Convention on Biological Diversity („The Earth Summit‟)
• It was a historic Convention on Biological Diversity held in Rio de Janeiro in 1992 to take appropriate measures
for conservation of biodiversity and sustainable utilization of its benefits.
• As a follow-up, the World Summit on Sustainable Development held in 2002 in Johannesburg, South Africa.
It was having 190 member countries who pledged their commitment to achieve a significant reduction in the current
rate of biodiversity loss at global, regional and local levels by 2010.
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 Practice Question of Biodiversity and Conservation
1. Based on earth s biodiversity, which of the statements can be considered as incorrect?
(a) Every 2nd vertebrate species is that of fishes
(b) Every 2nd plant species is that of angiospermss
(c) Out of every 10 animal species, 7 belong to insects
(d) Out of every 10 plant species, 5 belong to either angiosperm or fungi
2. What is correct about our country?
(a) India is having 2 hot spots
(b) About 45000 plant and animal species are found in India
(c) India is included among 12 megadiversity countries in world
(d) India occupies 5.1 % of world’s land area
3. If diversity increases, productivity:
(a) Also increases (b) Decreases
(c) Initially increases slightly and become constant (d) Remains unchanged
4. 'Rivet popper hypothesis' for conservation of species on earth was given by :
(a) David Tilman (b) Robert May (c) Edward Wilson (d) Paul Ehrlich
5. 'Biodiversity' term was popularized by :
(a) Edward Wilson (b) Gauss (c) Robert May (d) Connell
6. In last 500 years, how many species have become extinct in world?
(a) 232 (b) 384 (c) 512 (d) 784
7. Some recently extinct species and their area of existence are given. Identify the incorrect match?
(a) Steller’s Sea cow — Russia (b) Dodo — Mauritius
(c) Quagga —South America (d) Thylacine — Australia
8. Presently how many known species are facing threat of extinction?
(a) 5,800 (b) 15,500 (c) 25,200 (d) 30,600
9. Presently many species are facing threat of extinction. This is true for:
(a) Every 4th mammalian species (b) Every 5th bird species
th
(c) Every 3 amphibian species (d) Every 11th gymnosperm species
10. Since origin of earth, 5 mass extinctions have already occurred on earth. If present scenario is considered
as 6th mass extinction that how it is different from previous ones?
(a) It is slower and of natural origin. (b) It is faster and of anthropogenic action
(c) It is faster and of natural origin. (d) It is slower and of anthropogenic origin
11. Which of the following is not the component of evil quartet?
(a) Habitat loss and fragmentation (b) Co-extinction
(c) Alien species invasions (d) Succession
12. What is known as 'lungs of the planet'?
(a) Amazon rain forests (b) Temperate forests
(c) Sahara desert (d) Savannah grasslands
13. Why Amazon rain forests are being cut at a high rate?
(a) For cultivation of soyabean (b) For conversion grasslands for raising beef cattle
(c) For construction of multistoreyes (d) Both (a) and (b)
14. Diversity within a species is termed as diversity.
(a) Genetic (b) Ecological (c) Species (d) Population
15. If the species richness of Western Chats in case of amphibians is more than Eastern Chats, than which
statement is correct?
(a) Particular species of amphibians is having more individuals in Western Ghats
(b) Species diversity of amphibians in Western Ghats is high
(c) Every species of amphibians in Western Ghats is richer than the same in Eastern Ghats
(d) Genetic diversity of amphibians in more in Western Ghats
16. In last 500 years, IUCN Red list (2004) indicates the extinction of species worldwide.
(a) 50 (b) 784 (c) 87 (d) 359
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17. Loss of biodiversity in Amazon rain forests is mainly due to :
(a) Habitat loss and fragmentation (b) Co-extinctions
(c) Alien species invasion (d) Over-exploitation
18. Extinction of Steller‟s sea cow has resulted from :
(a) Mutualism (b) Over-exploitation (c) Co-extinction (d) Mass extinction
19. According to IUCN, number of described species on earth are :
(a) 10 lakh (b) 1.5 million (c) 7 million (d) 20-50 million
20. According to Robert May, possible number of species on earth might be about:
(a) 3 million (b) 5 million (c) 7 million (d) 20 million or more
21. In global species diversity, India‟s share is :
(a) 2.4% (b) 8.1% (c) 12.2% (d) 15%
22. Which of the following species have become extinct due to over-exploitation by human?
(a) Steller’s sea cow (b) Passenger’s pigeon (c) Cichlidfish (d) 2 of the above
23. Introduction of this species in lake Victoria resulted in extinction of cichlid fish species:
(a) Gavials (b) Nile Perch (c) Crocodiles (d) Water Hyacinth
24. Co-extinction can be observed in case of:
(a) Host and parasite relation (b) Amensalism
(c) Predation (d) 2 of the above
25. Biodiversity should be conserved because :
(a) It is economically beneficial for human (b) It is ecologically beneficial
(c) Its our ethical responsibility (d) All of these
26. In situ mode of conservation is :
(a) Biospheres (b) National Parks (c) Wild life sanctuaries (d) All of these
27. Species diversity is expected to:
(a) Increase towards equator
(b) Increase towards higher altitude
(c) Less in tropical forests in comparison to temperate forests
(d) High in deserts and deep lakes
28. Which of the following is expected to have highest biodiversity?
(a) Amazonian rain forest (b) Sea coast of Australia
(c) Rain forest in India (d) Savannah grasslands in Africa
29. Which of the following reason does not justify the abundance of species in tropical areas?
(a) They have remain relatively undisturbed for millions of years
(b) Absence of seasonal variations
(c) Migration of species from temperate areas
(d) More availability of sunlight
30. Ex situ mode of conservation is :
(a) Botanical gardens (b) National parks (c) Sacred grooves (d) All of these
31. Seed banks and cryopreservation techniques are respectively:
(a) Ex situ and in site mode of conservation (b) In situ and in situ mode of conservation
(c) Ex situ and ex situ mode of conservation (d) In situ and ex situ mode of conservation
32. "The Earth Summit'fconversion on biodiversity) was held in Rio de Janeiro in :
(a) 1992 (b) 1996 (c) 2002 (d) 2005
33. Which animal is recently extinct from Bali?
(a) Steller’s Sea cow (b) Dodo (c) Quagga (d) Subspecies of tiger
34. Recently which of the following species has become extinct from Africa?
(a) Thylacine (b) Dodo (c) Steller’s sea cow (d) Quagga
35. Which of the following is not the result of loss of biodiversity?
(a) Decrease in plant production
(b) Increase in resistance against draught
(c) Variability in disease or pest cycle increases
(d) Variability in water use increases
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36. It can be said that the present rate of extinction of species on earth is times then previous 5 mass
extinctions.
(a) 2-20, slower (b) 100-1000, slower (c) 2-20, faster (d) 100-1000, faster
37. According to most of biologists, most of the species waiting to be discovered are in :
(a) Tropical climate (b) Temperate climate (c) Subtropical climate (d) Tundra climate
38. At present how many genetically different strains of rice are found in India?
(a) 1000 (b) 5000 (c) 10000 (d) 50000
39. Diversity within a single species is known as diversity.
(a) Species (b) Genetic (c) Ecosystem (d) Biological
40. Which of the following is the most important cause for the extinction of plant and animals species?
(a) Habitat loss and fragmentation (b) Over-exploitation
(c) Alien species invasion (d) Co-extinctions
41. 'The Evil Quartet' refers to :
(a) 4 mass extinctions
(b) 4 reasons behind evolution
(c) 4 reasons behind biodiversity losses
(d) 4 most important chlorofluorocarbons (CFCs) destroying ozone layer
42. Which of the following is not the member of The Evil Quartet'?
(a) Over-exploitation (b) Co-extinction (c) Alien species invasion (d) Pollution
43. Which set of reasons is the most likely root cause of cutting of Amazon rain forests?
(A) Introduction of goats (B) Use of DDT
(C) Cultivation of soyabean (D) Cultivation of Cocoa plants
(E) Crowing of grasslands for beef cattle (F) Pollution
(a) A and C (b) C and E (c) B, C and F (d) A, D and F
44. A medicinal plant—Rauwolfia vomitoria, growing in different Himalayan ranges show genetic variations
in terms of potency of reserpine. This indicates:
(a) Genetic diversity (b) Ecosystem diversity (c) Species diversity (d) Biological diversity
45. Of the total known species on earth, insects constitutes :
(a) 30% (b) 50% (c) 70% (d) 80%
46. There are about megadiversity countries in the world.
(a) 5 (b) 8 (c) 12 (d) 18
47. According to biologists, how many prokaryote species might be on earth?
(a) 0.5 million (b) 1 million (c) 2 million (d) Not sure
48. Select the incorrect statement:
(a) Ecological diversity in India is more diverse than Norway
(b) In India about 5000 varieties of mangoes are found
(c) Among vertebrates, more than half of the species belong to fishes
(d) India is one of the 12 mega diversity countries of the world
49. Half of the vertebrate species belong to :
(a) Fishes (b) Reptilia (c) Aves (d) Mammalia
50. Which of the following group/set will be having more number of living species on earth?
(a) Fungi + Amphibians + Reptiles (b) Reptiles + Fishes + Mammalia
(c) Angiosperms (d) Fishes + Amphibians + Reptiles
51. More number of living species belong to :
(a) Fishes (b) Reptiles (c) Mammalia (d) Angiosperms
52. Uptil now about species of plants and species of animals have been recorded from India.
(a) 100000, 300000 (b) 90000, 45000 (c) 45000, 300000 (d) 45000, 90000
53. Which set of given statements is incorrect?
(A) Global species diversity of India is 2.4%.
(B) At present, about 90,000 species of animals are known in India.
(C) Known species of prokaryotes and protists are about 15% of total known species on earth.
(a) Only A (b) B and C (c) Only B (d) A and C
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54. Incorrect about patterns of biodiversity is :
(a) Biodiversity increases when we move from poles to equators
(b) Biodiversity is more rich in tropics in comparison to temperate areas
(c) Amazonian rain forest is having richest biodiversity on earth
(d) Biodiversity increases with increase in altitude
55. Select the correct arrangement of countries in sequence of biodiversity of bird species:
[(A) India, (B) Greenland, (C) Columbia, (D) New York]
(a) D > C > B > A (b) A > C > D > B (c) C > A > D > B (d) C > D > B > D
56. "Within a region, species richness increases with increasing explored area, but only upto a limit." This
was the observation of:
(a) Paul Ehrlich (b) Robert May
(c) Kofi Annan (d) Alexander von Humboldt
57. According to scientists, most of the undiscovered insect species might be in :
(a) Coral reefs (b) Rain forests (c) Grass lands (d) Coniferous forests
58. Incorrect about Amazonian rain forests :
(a) Lungs of earth (b) Richest biodiversity on earth
(c) Highest plankton diversity (d) Highest insect diversity
59. Statement A: Forests in 1 regions like Equador have upto 10 times as many species of vascular plants in
comparison to forests of 2 regions like Midwest of USA.
Statement B : German naturalist, 3 ; while working in 4 jungles, observed that — 'Within a region,
species richness 5 with increasing explored area, but only upto a limit.'
(a) 2-Tropical, 5-Increases
(b) 3-Alexander von Humboldt, 4-South American
(c) 1-Tropical, 4-South African
(d) 2-Temperate, 5-Decreases
60. Graph between species richness and area is drawn. Result is :
(a) Parabola (b) Rectangular hyperbola (c) Sigmoid (d) Straight line
61. All of the following hypothesis support the existence of greater biological diversity in tropics than
temperates, except:
(a) Absence of frequent glaciations in tropics
(b) Presence of seasonal variation in tropics
(c) Receiving more solar energy by tropics
(d) More predictable environment promoting greater niche specialization
62. Long-term ecosystem experiments using outdoor plots was done by :
(a) David Tilman (b) Paul Ehrlich (c) Humboldt (d) May
63. Statement A : Forests in tropical regions like Equador have upto 10 times as many species of vascular
plants in comparison to same in temperate regions like Midwest of the USA.
Statement B : Seasonal variations are nil in temperate regions.
(a) Only statement A is correct
(b) Only statement B is correct
(c) Statements A and B, both are correct
(d) Statements A and B, both are incorrect
64. Read the statement given and select the correct option :
Statement A : According to David Tilman's long term ecosystem experiments, it can be said that
variations in biomes are very little in a stable ecosystem.
Statement B: Aravali Hills in Rajasthan are declared as "Hot Spots".
(a) Only statement A is correct. (b) Only statement B is correct
(c) Statements A and B, both are correct. (d) Statements A and B, both are incorrect
65. "Rivet Popper hypothesis" was proposed by :
(a) Robert May (b) Paul Ehrlich
(c) Alexander von Humboldt (d) David Tilman

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66. Global biodiversity is shown in terms of species in the given groups. Identify the groups —A, B and C.

A B C
(a) Angiosperms Algae Molluscs
(b) Angiosperms Algae Echinoderms
(c) Algae Angiosperms Echinoderms
(d) Algae Angiosperms Molluscs
67. Rivet popper hypothesis explains:
(a) Species area relationships (b) Importance of biodiversity on earth
(c) Mars extinctions (d) Concept of species
68. According to 'Rivet Popper Hypothesis', which of the following is not comparable?
(a) Rivets-Species (b) Airplane-Ecosystem
(c) Safety of flight-Stability of ecosystem (d) Popping-Origin of species
69. How many hot spots are found in world?
(a) 3 (b) 25 (c) 34 (d) 48
70. Incorrect data about India is:
(a) Biosphere Reserves = 14+ (b) Hot-spots = 20+
(c) National parks = 90+ (d) Wild of sanctuaries = 448+
71. Which of the following is not considered as sacred groove?
(a) Khasi and Jaintia Hills in Meghalaya. (b) Western Ghats in Karnataka and Maharashtra
(c) Paudi and Gadhwal areas of Uttarakhand. (d) Aravali Hills in Rajastan
72. In Rivet Popper Hypothesis' of Paul Ehrlich, loss of key species driving an ecosystem is indicated by:
(a) Adding the rivets on seats (b) Removing the rivets from seats
(c) Removing the rivets from windows (d) Removing the rivets from wings
73. From the list of following, how many are presently living?
[Quagga, Siberian tiger, Javan tiger, Thylacine, Balenoptera, Corvus, Phrynosoma]
(a) 2 (b) 3 (c) 4 (d) 5
74. Select the incorrect match :
(a) Dodo — Mauritius (b) Paul Ehrlich — Rivet Popper Hypothesis
(c) Amazonian rain forests — Lungs of earth (d) David Tilman — Term Biodiversity
75. Statement A : In the last 500 years, 3 subspecies of tigers have became extinct — Bali, Javan and Siberian.
Statement B: Tropics have greater biological diversity in comparison to temperates.
(a) Only Statement A is correct (b) Only Statement B is correct
(c) Both Statements A and B are correct (d) Both Statements A and B are incorrect
76. On a logarithmic scale, the relationship between species richness and area is a straight line described by
the equation — [S = Species richness, A = Area, Z = Slope of line and C = Y-intercept ]
(a) log S = log C + A log Z (b) log C = log S + A log Z
(c) log S = log C + Z log A (d) log S = log A + Z log C
77. The relationship between species richness and area is a straight line on a logarithmic scale. It is described
by the equation :
Log S = log C + z log A in which Z is Y-intercept having value :
(a) In range of 0.1 to 0.2, irrespective of taxonomic group
(b) Variable depending upon the taxonomic group
(c) Static —0.5
(d) In range of 0.5 to 1

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78. Log S = Log C + Z log A
Above equation is derived from the relationship between species richness and area, on a logarithmic scale,
which is a straight line. Value of z if we analyse in very large areas (like continents) will be between :
(a) 0.1 to 0.2 (b) 0.6 to 1.2 (c) 2-4 (d) 5-10
79. According to 'Rivet Popper Hypothesis', the airplane will become dangerously weak if:
(a) More rivets are added to the air plane (b) Popping of rivets continue
(c) Passengers start moving (d) Few rivets exchange their positions
80. According to Paul Ehrlich‟s "Rivet Popper Hypothesis" removing of rivets from wings of plane is:
(a) Less serious than removing rivets from seats
(b) Less serious than removing rivets from windows
(c) Less serious than removing rivets from seats and windows both
(d) Most serious
81. Which of the following 'hot spot‟ is not found in India?
(a) Western Ghats and Sri Lanka (b) Indo-Burma (c) South central China (d) Himalaya
82. Which animal is recently extinct from Australia?
(a) Quagga (b) Thylacine (c) Dodo (d) Steller’s sea cow
83. If the present rate of extinction of species continues, almost half of the species on earth will be lost in next:
(a) 10 years (b) 100 years (c) 500 years (d) 1000 years
84. Statement A: Human activities result in fragmentation of large habitats. Statement B: Fragmentation
mainly affects birds and mammals.
(a) Only statement A is correct. (b) Only statement B is correct
(c) Both statements A and B are correct. (d) Both statements A and B are incorrect
85. Large habitats are broken to small habitats by the human activities. This is:
(a) Fragmentation (b) Urbanization (c) Niche specialization (d) Overexploitation
86. Uptil now, how many mass extinctions have already occurred?
(a) 4 (b) 5 (c) 6 (d) 7
87. Present scenario can be considered as mass extinction.
(a) 3rd (b) 4th (c) 5th (d) 6th
88. Match the Column-A with those in Column-B :
Column A : (Extinction animal species) Column B : (Country)
A. Quagga 1. Australia
B. Steller's Sea cow 2. Russia
C. Dodo 3. Africa
D. Thylacine 4. Mauritius
(a) A-3.B-2.C-4.D-1 (b) A- 3. B-2, C-1, D-4
(c) A-2, B-1.C-4, D-3 (d) A-3, B-1, C-4, D-2
89. Which of the following vertebrate group appears to be more vulnerable to extinction than remaining
others?
(a) Amphibians (b) Reptiles (c) Aves (d) Pisces
90. Allow many species of plants and animals are facing threat of extinction in India?
(a) 250 (b) 650 (c) 1200 (d) 2000
91. Every mammalian species and every amphibian species are facing threat of extinction.
(a) 2nd ,3rd (b) 3rd, 4th (c) 4th ,3rd (d) 5th, 4th
92. Passenger Pigeon became extinct due to:
(a) Overexploitation (b) Parasitism (c) DDT poisoning (d) Co-extinction
93. Over exploitation has resulted in extinction of:
(a) Passenger pigeon (b) Cichlid fish species (c) African cat fish (d) Thylacine
94. If a fish species become extinct then its parasites undergo:
(a) Overexploitation (b) Co-extinction (c) Habitat loss (d) Bio-magnification
95. Which of the following genus is not of an invasive weed?
(a) Parthenium (b) Lantana (c) Clarias (d) Eicchornia
96. How much of total 02 in earth s atmosphere is contributed by Amazon forests?
(a) 1-2% (b) 5% (c) 10% (d) 20%
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97. Which of the following term refers to the exploration of molecular, genetic and species level diversity so
that the quantity of products can be increased?
(a) Bio-magnification (b) Over-exploitation (c) Bio-prospecting (d) Bio-remediation
98. A and C are those vertebrate groups that are having maximum number of species globally. Select the
correct option:

A C
(a) Fishes Birds
(b) Birds Mammals
(c) Reptiles Birds
(d) Fishes Mammals
99. Approximately, how many species of native birds became extinct after the colonization of tropical Pacific
Islands by human?
(a) 200 (b) 500 (c) 1000 (d) 2000
100. Out of the following, how many are in situ modes of conservation?
(1) Biodiversity hotspots (2) National parks
(3) Botanical gardens (4) Sacred grooves
(5) Herbarium
(a) 1 (b) 2 (c) 3 (d) 4
101. How many “biodiversity hotspots” are found in India?
(a) 1 (b) 3 (c) 8 (d) 4
102. Convention on biological biodiversity is also known as:
(a) Ramsar Convention (b) The Earth Summit
(c) Montreal Protocol (d) Kyoto Protocol
103. How many national parks have been established till now in India?
(a) 38 (b) 54 (c) 90 (d) 142
104. In Madhya Pradesh—Sarguja, Chanda and Bastar are meant for conservation of biodiversity. These
areas are:
(a) National Parks (b) Sacred Grooves (c) Sanctuaries (d) Biosphere Reserves
105. In 1992, the Earth summit was held in :
(a) Rio de Janerio (b) New York (c) Paris (d) Montreal
106. Select the correct statement:
(a) Aravali Hills in Rajasthan are sacred
(b) Zoological parks are in situ modes of conservation
(c) In India, 34 hotspots are found
(d) Uptil now, more than 90 biosphere reserves have been established
107. Which set of species got extinct due to over exploitation?
(a) Passenger pigeon and Steller’s sea cow (b) Cichlid fish species and Steller’s sea cow
(c) Cichlid fish species and Passenger pigeon (d) African Cat fish and Cichlid fish species
108. Introduction of an 1 fresh water fish species— 2 , has resulted in extinction of many 3 species of 4 fishes in
lake Victoria.
(a) 1-Indigenous, 3-African Catfish
(b) 1-Alien, 4-Cichlid fish
(c) 2-Nile perch, 4-African Catfish
(d) 1-Indigenous, 2-Cichlid fish

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109. In lake Victoria in East Africa introduction of which species has resulted in loss of many species of
Cichlid fish species?
(a) African Cat fish (b) Water hyacinth (c) Nile perch (d) Steller’s Sea Cow
110. If A — Species richness and B — Endemism, then biodiversity hotspots have:
(a) Low degree of A and low degree of B
(b) Low degree of A and high degree of B
(c) High degree of A and low degree of B
(d) High degree of A and high degree of B
111. Wildlife safari parks are:
(a) Sacred grooves
(b) In situ mode of conservation
(c) Ex situ mode of conservation
(d) A type of museum
112. World summit on sustainable development held in :
(a) Rio de Janerio (b) Johannesberg (c) Paris (d) London
113. Read the following statements and answer the question following them :
(A) Western Ghat regions are in Karnatakaa
(B) Eggs of organisms are fertilized in vitro and the plants can be propagated using tissue culture
methods.
(C) World summit on sustainable development held in 2002.
(D) All the biodiversity hotspots cover about 2% of earth s land area.
(E) Nature also provides some intangible benefits to human.
(F) in the last 500 years, IUCN Red list (2004) indicates the extinction of 784 species worldwide.
How many of the above statements are incorrect?
(a) None (b) One (c) Two (d) Three
114. Greatest Biodiversity is observed in :
(a) Tropics (b) Temperate (c) Sub-tropical (d) Poles
115. Match the columns :
Column I Column II
A. Khasi and Jaintia Hills 1. Conserving seeds
B. Western Ghats and Sri Lanka 2. Hot spot
C. Zoological parks 3. Sacred grooves
D. Seed Banks 4. Ex situ mode of conservation
(a) A-3.B-2.C-4.D-1 (b) A-3, B-4, C-2, D-1
(c) A-2, B-4, C-3, D-1 (d) A-4, B-1, C-3, D-2
116. Read the following statements (A-E) and answer the question following them :
(A) Hotspots are also the regions of accelerated habitat loss.
(B) Introduction of African catfish (Clarius gariepinus) has resulted in extinction of many indigenous
Cichlid fish species in Indian rivers.
(C) In India 34 biodiversity hot spots are present.
(D) In World summit on sustainable development held in 2002, member countries decided to significantly
reduce the biodiversity loss by 2012.
(E) Khasi and Jaintia Hills of Mizoram are sacred grooves.
How many of the above statements are true?
(a) None (b) One (c) Two (d) Three
117. Select the incorrect pair?
(a) Megadiversity countries in world-12
(b) Genetically different strains of rice-1000
(c) May’s estimates on global species diversity-7 million species worldwide
(d) National parks in India-90
118. According to the May ‟s global estimates, how many of the species have been recorded so far?
(a) 15% (b) 22% (c) 35% (d) 45%

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119. Global diversity is shown in terms of species in plant groups. A and B are expected to be:

(a) Mosses and fungi (b) Algae and fungi

(c) Angiosperms and ferns (d) Fungi and angiosperms

ANSWER KEY

1. (d) 2. (c) 3. (a) 4. (d) 5. (a) 6. (d) 7. (c) 8. (b) 9. (a) 10. (b)
11. (d) 12. (a) 13. (d) 14. (a) 15. (b) 16. (b) 17. (a) 18. (b) 19. (b) 20. (c)
21. (b) 22. (d) 23. (b) 24. (a) 25. (d) 26. (d) 27. (a) 28. (a) 29. (c) 30. (a)
31. (c) 32. (a) 33. (d) 34. (d) 35. (b) 36. (d) 37. (a) 38. (d) 39. (b) 40. (a)
41. (c) 42. (d) 43. (b) 44. (a) 45. (b) 46. (c) 47. (b) 48. (b) 49. (a) 50. (a)
51. (d) 52. (d) 53. (d) 54. (d) 55. (c) 56. (d) 57. (b) 58. (c) 59. (b) 60. (b)
61. (b) 62. (a) 63. (a) 64. (a) 65. (b) 66. (d) 67. (b) 68. (d) 69. (c) 70. (b)
71. (c) 72. (d) 73. (c) 74. (d) 75. (b) 76. (c) 77. (a) 78. (b) 79. (b) 80. (d)
81. (c) 82. (b) 83. (b) 84. (c) 85. (a) 86. (b) 87. (d) 88. (a) 89. (a) 90. (b)
91. (c) 92. (a) 93. (a) 94. (b) 95. (c) 96. (d) 97. (c) 98. (a) 99. (d) 100. (c)
101. (b) 102. (b) 103. (c) 104. (b) 105. (a) 106. (a) 107. (a) 108. (b) 109. (c) 110. (d)
111. (c) 112. (b) 113. (a) 114. (a) 115. (a) 116. (b) 117. (b) 118. (b) 119. (d)
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