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#	Question	Answer
1	What is described as a unifying principle that gives a holistic perspective to biology?	Ecology.
2	According to the text, biology may be presented in which forms?	As botany, zoology and microbiology, or as classical and modern biology.
3	What does modern biology mainly refer to in the text?	Molecular aspects of biology.
4	What is the essence of biological understanding according to ecology?	Understanding how organisms interact with other organisms and physical habitats as organised wholes.
5	Name the organised wholes mentioned in ecology.	Population, community, ecosystem and biosphere.
6	Which environmental issue is highlighted as an important aspect of ecology?	Anthropogenic environmental degradation and related socio-political issues.
7	Who is revered as the Father of Ecology in India?	Ramdeo Misra.
8	Which ministry was later established as a result of environmental planning efforts mentioned in the text?	Ministry of Environment and Forests (1984).
9	According to the example in the text, why does a bird sing during the breeding season?	To communicate with its mate.
10	What are the four levels of biological organisation with which ecology is concerned?	Organisms, populations, communities and biomes.
11	What is a population?	A group of individuals of a species living in a well-defined geographical area, sharing or competing for similar resources and potentially interbreeding.
12	Can organisms produced by asexual reproduction also be considered a population?	Yes, for ecological studies they are generally considered a population.
13	Give examples of populations mentioned in the text.	Cormorants in a wetland, rats in an abandoned dwelling, teakwood trees in a forest tract, bacteria in a culture plate, and lotus plants in a pond.
14	At which level does natural selection operate to evolve desired traits?	At the population level.
15	Why is population ecology considered important?	Because it links ecology to population genetics and evolution.
16	What population attributes are not possessed by individual organisms?	Birth rates, death rates, sex ratio and age distribution.
17	In population studies, what do birth rates and death rates refer to?	Per capita births and deaths.
18	A pond had 20 lotus plants and 8 new plants were added. What is the birth rate?	0.4 offspring per lotus per year.
19	If 4 fruitflies die in a population of 40 in one week, what is the death rate?	0.1 individuals per fruitfly per week.
20	What is sex ratio in a population?	The proportion of males and females in a population.
21	What is an age pyramid?	A graphical representation of the age distribution of individuals in a population.
22	What does the shape of an age pyramid indicate?	Whether the population is growing, stable or declining.
23	What does the size of a population indicate about its habitat status?	It tells us a lot about the status of the population in the habitat.
24	Ecological processes are evaluated in terms of changes in what factor?	Population size.
25	What is the technical term for population size?	Population density (N).
26	Give an example of a very small population size mentioned in the text.	Siberian cranes at Bharatpur wetlands with population size less than 10.
27	Give an example of a very large population size mentioned in the text.	Chlamydomonas in a pond.
28	Why is total number not always the best measure of population density?	Because in some cases it is meaningless or difficult to determine.
29	Which measures may be more meaningful than numbers for some populations?	Per cent cover or biomass.
30	Which plant example is used to explain meaningful population measures?	Carrot grass (Parthenium hysterophorus) and a huge banyan tree.
31	Why is counting sometimes not a practical method of estimating population density?	Because populations may be huge and counting may be impossible or very time-consuming.
32	What is an example of relative density given in the text?	Number of fish caught per trap in a lake.
33	How is tiger census often estimated in national parks and tiger reserves?	By using pug marks and fecal pellets.
34	Is population size a static parameter?	No, it changes with time.
35	Name factors that affect population size.	Food availability, predation pressure and adverse weather.
36	What do changes in population density indicate?	Whether a population is flourishing or declining.
37	Population density fluctuates due to how many basic processes?	Four basic processes.
38	Which two processes increase population density?	Natality and immigration.
39	Which two processes decrease population density?	Mortality and emigration.
40	Define natality.	Natality refers to the number of births during a given period added to the initial population density.
41	Define mortality.	Mortality is the number of deaths in the population during a given period.
42	Define immigration.	Immigration is the number of individuals of the same species entering a habitat from elsewhere.
43	Define emigration.	Emigration is the number of individuals leaving a habitat and going elsewhere.
44	Write the equation for population density at time t + 1.	Nt+1 = Nt + [(B + I) – (D + E)]
45	Under what condition will population density increase?	When births plus immigrants (B + I) exceed deaths plus emigrants (D + E).
46	Under normal conditions, which factors mainly influence population density?	Births and deaths.
47	In which situation can immigration contribute significantly to population growth?	When a new habitat is being colonised.
48	What do growth models study in population ecology?	Whether population growth with time shows a specific and predictable pattern.
49	Which two major types of population growth are described in the text?	Exponential growth and logistic growth.
50	What is essential for the unimpeded growth of a population?	Availability of resources such as food and space.
51	Under what condition does exponential growth occur?	When resources in the habitat are unlimited.
52	What kind of growth pattern occurs when resources are unlimited?	Exponential or geometric growth.
53	According to Darwin, what ability does each species possess under unlimited resources?	The ability to fully realise its innate potential to grow in number.
54	Write the equation for exponential population growth.	dN/dt = rN
55	Why is the intrinsic rate of natural increase (r) important?	It is used to assess impacts of biotic and abiotic factors on population growth.
56	What is the r value for the Norway rat?	0.015.
57	What is the r value for the flour beetle?	0.12.
58	What was the r value for the human population in India in 1981?	0.0205.
59	What type of curve is produced by exponential growth?	J-shaped curve.
60	Write the integral form of the exponential growth equation.	Nt = N0ert
61	What does Nt represent in the exponential growth equation?	Population density after time t.
62	What does N0 represent in the exponential growth equation?	Population density at time zero.
63	What is the value of e in the exponential growth equation?	2.71828.
64	What can happen to species growing exponentially under unlimited resources?	They can reach enormous population densities in a short time.
65	Which anecdote is used to explain rapid exponential growth?	The wheat grains on the chessboard story.
66	Which organism is used as an example of rapid doubling through binary fission?	Paramecium.
67	Why can exponential growth not continue indefinitely in nature?	Because resources are limited.
68	What does limited availability of resources lead to?	Competition between individuals.
69	What is carrying capacity (K)?	The maximum possible number of individuals that a habitat can support.
70	What type of growth occurs when resources become limited?	Logistic growth.
71	What phases are observed in logistic growth?	Lag phase, acceleration phase, deceleration phase and asymptote.
72	What happens when population density reaches carrying capacity?	Growth becomes asymptotic.
73	What type of curve is formed in logistic growth?	Sigmoid curve.
74	What is another name for logistic growth?	Verhulst-Pearl Logistic Growth.
75	Which growth model is considered more realistic for animal populations?	Logistic growth model.
76	What is Darwinian fitness in population ecology?	Reproductive fitness represented by a high r value.
77	Why do populations evolve different life history traits?	To maximise reproductive fitness in their habitat.
78	What do ecologists suggest about life history traits?	They evolve in relation to abiotic and biotic constraints of the habitat.
79	Give examples of organisms that breed only once in their lifetime.	Pacific salmon fish and bamboo.
80	Give examples of organisms that breed many times during their lifetime.	Most birds and mammals.
81	Which organisms produce a large number of small-sized offspring?	Oysters and pelagic fishes.
82	Which organisms produce a small number of large-sized offspring?	Birds and mammals.
83	What is currently an important area of ecological research?	Evolution of life history traits in different species.
84	Can a natural habitat be inhabited by only a single species?	No, such a situation is inconceivable.
85	Why can even plant species not survive alone?	They require soil microbes for nutrient recycling and animals for pollination.
86	What do animals, plants and microbes together form through interactions?	A biological community.
87	What are interspecific interactions?	Interactions between populations of two different species.
88	What can be the outcomes of interspecific interactions?	Beneficial, detrimental or neutral.
89	Which interaction benefits both species?	Mutualism.
90	Which interaction harms both species?	Competition.
91	In predation, which organisms benefit and suffer?	Predator benefits and prey suffers.
92	In parasitism, which organisms benefit and suffer?	Parasite benefits and host suffers.
93	What is commensalism?	One species benefits while the other is neither harmed nor benefited.
94	What is amensalism?	One species is harmed while the other remains unaffected.
95	What common feature is shared by predation, parasitism and commensalism?	The interacting species live closely together.
96	What is the ecological significance of predation?	It transfers energy fixed by plants to higher trophic levels.
97	Why are herbivores considered predators in a broad ecological context?	Because they feed on plants.
98	Besides energy transfer, what role do predators play in ecosystems?	They keep prey populations under control.
99	What can happen if predators are absent from an ecosystem?	Prey populations may grow excessively and cause ecosystem instability.
100	Why do introduced exotic species often spread rapidly?	Because the invaded area lacks their natural predators.
101	Which invasive plant spread rapidly in Australia in the early 1920s?	Prickly pear cactus.
102	Which organism was introduced in Australia to control prickly pear cactus?	A cactus-feeding moth.
103	On what principle are biological control methods in agriculture based?	The ability of predators to regulate prey populations.
104	What interaction symbols are used for mutualism?	+ +
105	What interaction symbols are used for competition?	– –
106	What interaction symbols are used for predation?	+ –
107	What interaction symbols are used for parasitism?	+ –
108	What interaction symbols are used for commensalism?	+ 0
109	What interaction symbols are used for amensalism?	– 0
110	How do predators help maintain species diversity in a community?	By reducing the intensity of competition among competing prey species.
111	Which predator is important in the rocky intertidal communities of the American Pacific Coast?	Starfish Pisaster.
112	What happened when starfish were removed from an enclosed intertidal area?	More than 10 species of invertebrates became extinct within a year.
113	What is camouflage?	Cryptic coloration that helps prey avoid detection by predators.
114	Why is the Monarch butterfly avoided by predators?	It is highly distasteful due to a special chemical present in its body.
115	How does the Monarch butterfly acquire its defensive chemical?	By feeding on a poisonous weed during the caterpillar stage.
116	For plants, who are considered predators?	Herbivores.
117	Approximately what percentage of insects are phytophagous?	Nearly 25 per cent.
118	Why is herbivory particularly severe for plants?	Because plants cannot run away from predators.
119	What are common morphological defenses in plants against herbivores?	Thorns in Acacia and Cactus.
120	What effects can plant chemicals have on herbivores?	They can make herbivores sick, inhibit feeding or digestion, disrupt reproduction, or kill them.
121	Which plant produces poisonous cardiac glycosides?	Calotropis.
122	Why do cattle and goats avoid browsing on Calotropis?	Because it contains highly poisonous cardiac glycosides.
123	Name some chemical substances produced by plants as defenses against grazers and browsers.	Nicotine, caffeine, quinine, strychnine and opium.
124	According to Darwin, what is a potent force in organic evolution?	Interspecific competition.
125	Does competition occur only between closely related species?	No, unrelated species can also compete for the same resources.
126	Give an example of competition between unrelated species.	Flamingoes and resident fishes competing for zooplankton in shallow South American lakes.
127	What is interference competition?	Competition where one species reduces the feeding efficiency of another even when resources are abundant.
128	How is competition best defined in ecology?	A process in which the fitness of one species (measured in terms of its ‘r’ the intrinsic rate of increase) is significantly lower in the presence of another species.
129	Which tortoise became extinct after goats were introduced in the Galapagos Islands?	Abingdon tortoise.
130	Which organisms are generally more adversely affected by competition?	Herbivores and plants.
131	What mechanism promotes coexistence between competing species?	Resource partitioning.
132	How can species avoid competition through resource partitioning?	By choosing different feeding times or different foraging patterns.
133	Which scientist showed coexistence among five closely related warbler species?	MacArthur.
134	How did the warbler species avoid competition?	Through behavioural differences in foraging activities.
135	Why has parasitism evolved widely among organisms?	Because the parasitic mode of life ensures free lodging and meals.
136	What is host specificity in parasites?	The ability of parasites to parasitise only a single species of host.
137	Name some adaptations evolved by parasites.	Loss of unnecessary sense organs, adhesive organs or suckers, loss of digestive system, and high reproductive capacity.
138	Why do parasites often have complex life cycles?	To involve intermediate hosts or vectors that facilitate parasitisation of the primary host.
139	Which intermediate hosts are involved in the life cycle of the human liver fluke?	A snail and a fish.
140	Which vector spreads the malarial parasite?	Mosquito.
141	How do parasites generally affect their hosts?	They reduce survival, growth, reproduction and population density of the host.
142	What are ectoparasites?	Parasites that feed on the external surface of the host organism.
143	Give examples of ectoparasites mentioned in the text.	Lice on humans, ticks on dogs, and ectoparasitic copepods on marine fish.
144	Why is Cuscuta considered a parasitic plant?	It derives nutrition from the host plant it parasitises.
145	What evolutionary changes are seen in Cuscuta?	Loss of chlorophyll and leaves.
146	Why is the female mosquito not considered a parasite?	Because it only needs blood for reproduction and does not live parasitically on the host.
147	What are endoparasites?	Parasites that live inside the host body.
148	Name some sites where endoparasites may live in the host body.	Liver, kidney, lungs and red blood cells.
149	Why are endoparasite life cycles more complex?	Due to their extreme specialisation.
150	What features are simplified in endoparasites?	Morphological and anatomical features.
151	Which feature is emphasised in endoparasites?	Reproductive potential.
152	What is brood parasitism?	A form of parasitism where a bird lays eggs in the nest of another bird and lets the host incubate them.
153	Which birds are suggested for observing brood parasitism in nature?	Koel (cuckoo) and crow.
154	Define commensalism.	An interaction where one species benefits while the other is neither harmed nor benefited.
155	Give an example of commensalism involving plants.	Orchid growing as an epiphyte on a mango branch.
156	Give an example of commensalism involving marine organisms.	Barnacles growing on the back of a whale.
157	Why do cattle egrets stay close to grazing cattle?	Cattle stir up insects that the egrets can catch easily.
158	What benefit does the sea anemone get from clown fish?	No apparent benefit.
159	What is mutualism?	An interaction in which both species benefit.
160	What are lichens?	Mutualistic associations between fungi and photosynthesising algae or cyanobacteria.
161	What are mycorrhizae?	Associations between fungi and roots of higher plants.
162	How do fungi benefit plants in mycorrhizae?	By helping in absorption of essential nutrients from the soil.
163	What do plants provide fungi in mycorrhizae?	Energy-yielding carbohydrates.
164	What do plants require animals for in mutualistic relationships?	Pollination of flowers and dispersal of seeds.
165	What rewards do plants offer pollinators?	Pollen and nectar.
166	What rewards do plants offer seed dispersers?	Juicy and nutritious fruits.
167	What does co-evolution mean in plant-animal interactions?	Evolution of the flower and its pollinator species in close association with each other.
168	What type of relationship exists between many fig trees and wasps?	Tight one-to-one mutualistic relationship.
169	How many wasp species generally pollinate a given fig species?	Only one specific partner wasp species.
170	What does the female wasp use the fig fruit for?	As an oviposition (egg-laying) site.
171	What nourishes the larvae of the fig wasp?	Developing seeds within the fig fruit.
172	How does the fig wasp help the fig plant?	By pollinating the fig inflorescence while searching for egg-laying sites.
173	What does the fig provide to the wasp in return for pollination?	Some developing seeds as food for wasp larvae.
174	Why are orchids considered evolutionarily fascinating?	Because they show diverse floral patterns adapted to attract specific pollinators.
175	Which pollinators are commonly attracted by orchids?	Bees and bumblebees.
176	Do all orchids provide rewards to pollinators?	No, not all orchids offer rewards.
177	How does Ophrys attract its pollinator?	One petal resembles the female bee in size, colour and markings.
178	What is pseudocopulation in Ophrys pollination?	The male bee attempts mating with the flower, mistaking it for a female bee.
179	How is pollen transferred in Ophrys orchids?	The bee gets dusted with pollen during pseudocopulation and transfers it to another flower.
180	Define ecology as given in the summary.	Ecology is the study of relationships of living organisms with abiotic and biotic components of their environment.
181	What are the four levels of biological organisation in ecology?	Organisms, populations, communities and biomes.
182	Why is population ecology considered important?	Because evolutionary changes through natural selection occur at the population level.
183	What is a population according to the summary?	A group of individuals of a species sharing or competing for similar resources in a defined geographical area.
184	Name population attributes absent in individuals.	Birth rates, death rates, sex ratio and age distribution.
185	What is an age pyramid?	A graphical representation of age distribution in a population.
186	What can population density be expressed as?	Numbers, biomass or per cent cover.
187	What type of growth occurs under unlimited resources?	Exponential growth.
188	What type of growth occurs when resources become limiting?	Logistic growth.
189	What limits population growth ultimately?	Carrying capacity of the environment.
190	What does intrinsic rate of natural increase (r) measure?	The inherent potential of a population to grow.
191	Name the types of interspecific interactions listed in the summary.	Competition, predation, parasitism, commensalism, amensalism and mutualism.
192	What is the Competitive Exclusion Principle?	The superior competitor eliminates the inferior competitor.
193	What helps closely related species coexist despite competition?	Evolved mechanisms such as resource partitioning.
194	What attributes do populations possess that individuals do not?	Birth rates, death rates, sex ratio and age distribution.
195	What happens to a population growing exponentially if it doubles in size in 3 years?	The intrinsic rate of increase (r) can be calculated from the growth equation.
196	Name important defence mechanisms in plants against herbivory.	Morphological defenses like thorns and chemical defenses like toxic substances.
197	What type of interaction exists between an orchid growing on a mango tree branch and the mango tree?	Commensalism.
198	What ecological principle forms the basis of biological control of pest insects?	Predation.
199	Define population.	A group of individuals of a species sharing or competing for similar resources in a defined geographical area.
200	Define community.	A group of interacting populations of different species living in a habitat.
201	Define commensalism.	An interaction in which one species benefits while the other is neither harmed nor benefited.
202	Define parasitism.	An interaction in which one organism benefits while the other is harmed.
203	Define camouflage.	Cryptic coloration that helps organisms avoid detection by predators.
204	Define mutualism.	An interaction in which both interacting species benefit.
205	Define interspecific competition.	Competition between individuals of different species for shared resources.
206	What type of curve is shown by logistic population growth?	Sigmoid curve.
207	What limits logistic population growth?	Carrying capacity (K).
208	Which statement best explains parasitism?	One organism is benefited (parasite), and the other is harmed or detrimental (host).
209	Name any three important characteristics of a population.	Birth rate, death rate and sex ratio.