Nootan solutions for बायोलॉजी [अंग्रेजी] कक्षा १२ आयसीएसई chapter 15 - Organisms and Populations [Latest edition]

Eichhornia is a ______.

Which of the following factors is least likely to affect the type of organism colonizing a pond?

Identify the odd member in the following:

If in a geographic region, rainfall is low, temperatures are high, the soil is loose and sandy, with a low water table, it is not reasonable to expect there ______.

Which of the following is not a climatic factor?

Climate represents ______.

Soil is ______.

Which of the following results in air pollution?

Plants adapted to grow in open sun are ______.

A population is a group of ______.

Which of the following forest plants controls the light conditions at the ground?

In a population of predators and prey, it was seen that when the prey population was numerically high, the predator population consumed more and more prey. This is because the predator population ______.

Amensalism is a type of interspecific relationship in which ______.

In commensalism interspecific relationship:

A biotic community is an assemblage of ______.

An animal that uses camouflage to avoid detection must also have ______.

A number of populations of different species interacting with one another is called:

Community diversity is made of ______.

Interaction between two species in which one feeds on the other is ______.

Which of the following is correct in a predator-prey cycle?

An intimate relationship between two species in which co-evolution and adaptation occur is ______.

Interaction between two species as both attempt to use the same environmental resources is ______.

A form of symbiosis in which one participant benefits and the other apparently is not benefited or harmed is ______.

Which of the following statements is not true about parasitism?

A form of symbiosis in which both participants benefit is ______.

A probable example of commensalism is ______.

Plant prey defense includes which one of the following?

Animal prey defense includes all of the following except:

Which of the following is a commensalistic relationship?

A two-way flow of benefits in mutualistic interactions between species is an outcome of ______.

Two species in the same habitat can coexist when they:

Which one of the following levels of ecology most considers the effects of predation and interspecific competition on the distribution and abundance of organisms?

According to the principle of competitive exclusion, ______.

______ is an interspecific association in which all species involved benefit.

A population is made up of ______.

Which one of the following is a total parasite?

Which one of the following is an example of mutualism?

Orchids, which grow on trees, are the examples of ______.

All organisms living together and interacting with one another in a common environment or natural habitat in a local area are known as a ______.

Plants that grow in nitrogen-deficient soils and swampy and boggy places are called ______.

Small herbaceous plants that grow on higher plants but do not obtain their nourishment from them are called ______.

No predator can become proficient at acquiring prey because ______.

Parasitism is an interaction between two species in which ______.

Mutualism is an interaction between two species in which ______.

Hyena that lives on left over food of the lion is called a ______.

A stronger species being benefited at the cost of weak species is an example of ______.

A population is a group of ______.

Dominance hierarchies are most common when ______.

Altruistic behaviours between closely related animals are selected for because they ______.

Intraspecific competition is competition among ______.

Intraspecific competition is strongest when the ______.

Demography is the study of statistics that affects ______.

Members of biologic species are potentially able to ______.

Which one of the following is not true of singing in male birds?

Lichens are association of ______.

Type of Interaction where an individual sacrifices its own welfare (life) for the benefit of another animal of its own species is ______.

Amensalism is an association between two species where ______.

Nostoc keeps a symbiotic relation ______.

A population is a group of ______.

Exponential growth occurs when there is ______.

The carrying capacity of a population is determined by its ______.

Demography is the study of statistics that affects ______.

When a population is small, there is a greater chance of ______.

The rate at which a population grows or declines depends upon the rate of ______.

Which of the following factors does not affect sustainable population size?

Human population growth curve is a ______.

Consider five human populations that differ demographically only in their age structures. The population that will grow the most in the next 30 years is the one with the greatest fraction of people in which of the following age group?

Which of the following would necessarily decrease the density of a population in a given habitat?

Epiphytes ______ obtain nutrition from the supporting plant.

Nepenthes (pitcher plant) is an example of ______ plants.

The total physical environment of an organism is known as ______.

The alpine plants are ______ gregarious in habit and with beautiful colour flowers.

Edaphic factor is related with conditions of ______.

Presence of high concentration of cell sap, development of water storage tissue, underground perennating organs, lignified and cutinised tissue, well-developed root system, and reduction in leaf size, are characteristic feature of ______.

Root is feebly developed, and stem is soft with a large number of air cavities in ______.

Xerophytes are the plants which normally grow in ______ conditions.

Organisms which have wide tolerance limits for various environmental factors are called as ______ species.

Buoyancy in Eichhornia results from spongy enlargements of the ______.

If the soil particles are loose and could be identified individually, the soil is called as ______.

The place where an organism lives is known as ______.

According to Allen’s Rule, the mammals from colder climates have ______ ears and ______ limbs.

Nepenthes (pitcher plant) is an example of ______ plants.

An association which is not harmful to both the parties is known as ______.

Epiphytes ______ obtain nutrition from the supporting plant.

Chemicals that are released by individuals and serve to influence the behaviour of other members of their own species are called ______.

A limited area that an animal defends is its ______, whereas an area that an animal moves through regularly but does not defend is its ______.

When in some bird species, one member of a flock gives a warning cry upon sighting a predator and thus allows the flock to escape but draws the predator’s attention to itself, the behaviour can be considered to be an example of ______.

The more ______ two organisms are, the more intense the competition between them. Intraspecific competition is ______ intense than interspecific competition.

Evolved features that make organisms better suited to live and reproduce in their environments are called ______.

At carrying capacity, the population growth rate is ______.

The maximum number of individuals that an environment can support is determined by its ______.

State whether the following statement is true or false:

Everything which influences the life activities of an organism constitute its environment.

State whether the following statement is true or false:

The xerophytes are plants which require minimum amount of water supply and therefore to be placed midway between hydrophytes and mesophytes.

State whether the following statement is true or false:

In deserts, the velocity of the wind is high, and yet the leaves do not get torn into bits.

State whether the following statement is true or false:

Two different regions having the same amount of annual rainfall can exhibit different vegetational constituents.

State whether the following statement is true or false:

Plants developing under the influence of drying winds are abnormally short.

State whether the following statement is true or false:

The plants of high mountains show xeromorphic characters.

State whether the following statement is true or false:

Fire is an ecological factor.

State whether the following statement is true or false:

Soils having very fine particles and give smooth feeling is clay.

State whether the following statement is true or false:

The universal feature of xerophytic plants is selective absorption and tolerance of high concentrations of salt.

State whether the following statement is true or false:

The layers of air nearer the earth are richer in CO₂ than those above.

State whether the following statement is true or false:

A population consists of the number of individuals in a given area at a particular time.

State whether the following statement is true or false:

An ecological community is an assemblage of interacting populations.

State whether the following statement is true or false:

Species that tolerate narrow range temperature are called stenothermic.

State whether the following statement is true or false:

Species that tolerate a wide range of salinity are called euryhaline.

State whether the following statement is true or false:

A food relation in which an animal feeds on a dead animal or one killed by another animal is known as predation.

State whether the following statement is true or false:

Human intervention in natural community interactions usually makes the community more stable.

State whether the following statement is true or false:

All the physiological requirements and activities of a species in its normal surroundings make up its habitat.

State whether the following statement is true or false:

One of the effects of predation is the stabilization of the predator-prey relationship when there is not too much predatory pressure on the prey population.

State whether the following statement is true or false:

Plants use spines and chemical poisons to prevent predation by animals, especially insects.

State whether the following statement is true or false:

Bacteria living in the human digestive tract and producing vitamins used by the human are best described as parasitic organisms.

State whether the following statement is true or false:

In commensalism, one partner derives benefit from the other and adversely affects the benefactor.

State whether the following statement is true or false:

An epiphyte is a plant that grows on other plants, using them for support but not for nutrition.

State whether the following statement is true or false:

The territory of an animal is larger than its home range.

State whether the following statement is true or false:

The dominant individual in a herd is always a male.

State whether the following statement is true or false:

Pheromones are chemical substances meant for communication and coordination of organs in an individual.

State whether the following statement is true or false:

In commensalism, one partner derives benefit from the other and adversely affects the benefactor.

State whether the following statement is true or false:

A population consists of the number of individuals in a given area at a particular time.

State whether the following statement is true or false:

Demography deals with family pedigrees.

State whether the following statement is true or false:

The population growth rate is inversely related to generation time.

State whether the following statement is true or false:

An ecological community is an assemblage of interacting populations.

Which one of the following is not a part of the biotic environment:

insects, air, plants, birds?

Name a succulent xerophyte.

Name a free-floating hydrophyte.

Name an emergent hydrophyte.

Name a heterophyllous hydrophyte.

State any four alternatives by which organisms can overcome stressful external conditions.

Which one of the two, stenothermals or eurythermals, shows a wide range of distribution on Earth?

How do herbs and shrubs survive under the shadow of big canopied trees in forests?

Give an example where percentage cover is a more meaningful measure of the population size.

Mention any two activities of animals which get cues from diurnal and seasonal variation in light intensity.

In xerophytic plants, the thorns are a modification of which organ?

What are the main functions of air-chambers in hydrophytic plants?

Give the scientific term for a parasite living on other parasite.

Name a species which is both a prey and a predator.

Give two examples of commensal species.

Give two examples of mimicry.

Give one example each of mutualism and proto-cooperation.

Name the two components of lichens.

Which organism was used to control Opuntia in Australia?

Which one of the following is not a part of the biotic environment:

insects, air, plants, birds?

What do you understand by the term competition?

What is a ‘biotic community’?

Name an ecto- and an endoparasite.

Name the three types of mimicry.

Give the scientific term for the symbiotic relationship between fungi and the roots of higher plants.

Name a carnivorous (insectivorous) plant.

Name an epiphytic plant.

Scientific term for an animal behaviour which benefits others but is of no advantage to itself.

How does the Monarch butterfly defend itself from predators? Explain.

What is Commensalism? Explain it with a suitable example.

State Gause’s Competitive Exclusion Principle.

Name the type of association that the genus Glomus exhibits with higher plants.

Predation is usually referred to as a detrimental association. Mention any two significant roles predation plays in nature.

List two advantages that a mycorrhizal association provides to the plant.

Name the interspecific interaction in which one is detrimental while the other is neutral.

How are closely related species of warblers able to co-exist in a competitive environment?

An orchid plant is growing on the branch of a mango tree. What type of interaction do you observe between the orchid and the mango tree?

Write what do phytophagous insects feed on.

Name the two intermediate hosts which the human liver fluke depends on to complete its life cycle, so as to facilitate parasitization of its primary host.

What is an amensalism?

Among the crustose, foliose, and fruticose lichens, which one is a pioneer species?

What is symbiosis?

Write the name of a bacterium which is found in root modules of leguminous plants.

Name the scientist associated with human population growth.

Name the best-known contribution of T. R. Malthus.

Define zero population growth.

Explain the term:

Carrying capacity

What does the following term mean?

Biotic potential

What does the following term mean?

Environmental resistance

Explain the term natality.

Name the type of growth curve that characterises most populations growing in a favourable environment.

The rate at which a population grows or declines depends upon what?

Name the factors which do not affect sustainable population size.

What type of age pyramid reflects an expanding growth status of the human population?

State any four alternatives by which organisms can overcome stressful external conditions.

List the different attributes that a population has, and not an individual organism.

Which one of the two, stenothermals or eurythermals, shows a wide range of distribution on Earth?

In a pond, there were 40 lotus plants. After a year, the number rose to 56. Calculate the birth rate of a lotus plant.

If 8 individuals in a laboratory population of 80 fruit flies died in a week, then what would be the death rate for the population for the said period?

A forest hardly has any carnivores. A census of herbivorous mammals was taken and plotted as a graph, shown below. Identify the curve that will explain the population growth of herbivores. Give a reason to your answer.

Plot a logistic growth curve.

How do herbs and shrubs survive under the shadow of big canopied trees in forests?

Give an example where percentage cover is a more meaningful measure of the population size.

Mention any two activities of animals which get cues from diurnal and seasonal variation in light intensity.

Give the scientific term for the statistical study of the human population.

What does nature’s carrying capacity for a species indicate?

What parameters are used for tiger census in our country’s national parks and sanctuaries?

Give a scientific term for the study of human population covering all aspects and parameters.

State how the constant internal environment is beneficial to organisms.

What are stenothermal organisms?

Name the various environmental factors that affect plant life. Describe how any one of these factors influences plants?

Write a short note on various ecological factors which influence the distribution of plants.

What is an environment?

How do climatic factors affect the vegetation?

Write an essay on ‘light as an ecological factor’.

With the help of suitable examples, show how the environment influences the behaviour of organisms and also how the organisms influence the environment of their surroundings.

What do you mean by edaphic factor?

Discuss those physical, chemical, and biological properties of soil which affect plant growth.

Explain how the structure and composition of the soil surface affect the vegetation of any area.

Lichen is considered a good example of obligate mutualism. Explain.

In theory, populations of organisms can increase exponentially. What does this mean?

In theory, populations of organisms can increase exponentially. Why is it rarely seen in nature?

Describe a biotic community of your nearby place stating the relationships that exist between the common species comprising it.

Write a short note on predation.

Write a short note on mimicry.

Write a short note on mutualism.

Write a short note on antibiosis.

Write a short note on competition.

Describe how human intervention with a community can interfere with normal competition, and give two examples.

Describe how human intervention with a community can interfere with normal predation, and give two examples.

Give an example of parasitism, commensalism, and mutualism, and show that it is not always easy to distinguish between these relationships.

Is competition more acute between the individuals of the same species or those of different species? Explain.

What is symbiosis?

Give a broad outline of various types of positive interactions among organisms.

Population growth is determined by the interaction of biotic potential and environmental resistance. Comment on the statement.

Give an account of the population growth curves.

What is reproductive fitness? Explain it with the help of an example.

Define Allen’s rule.

The following diagram represents the population growth curves of two different species, A and B, living together in an area. Answer the following questions based on it.

1. What type of growth patterns are exhibited by the species A and B?
2. Give mathematically equations to represent the growth curves of species A and species B separately.
3. In the diagram, what does the horizontal line K represent?

What are the key elements that lead to so much variation in the physical and chemical conditions of different habitats?

What will happen to a well-growing herbaceous plant in the forest if it is transplanted outside the forest in a park?

What would happen to all the energy fixed by autotrophic organisms if the community has no animals to eat the plants?

The weed Calotropis usually grows in abandoned fields.

Study the table given below in regard to population interactions. Identify the interactions (a) to (e).

Note: (+) plus = beneficial interaction; (−) minus = deterimental interaction; (0) zero = neutral interaction.

Name the interaction in the following:

Cuckoo lays her eggs in the crow’s nest.

Name the interaction in the following:

Orchid grows on a mango tree.

Name the interaction in the following :

Ticks live on the skin of dogs.

Name the interaction in the following:

Sea anemone is often found on the shell of a hermit crab.

Name the interaction in the following:

Cuscuta growing on a shoe flower plant.

Name the interaction in the following:

Mycorrhizae living on the roots of higher plants.

Name the interaction in the following:

Clown fish living among the tentacles of sea anemone.

Name the interaction in the following:

Ascaris worms living in the intestine of human.

Name the interaction in the following:

Sucker fish attached to the shark.

Name the interaction in the following:

Smaller barnacles disappeared when Balanus dominated in the coast of Scotland.

Name the interaction in the following:

Wasp pollinating fig inflorescence.

Name the interaction in the following:

Whale and the barnacles growing on its back.

Name the interaction in the following:

Bumblebee and its favourite orchid, Ophrys.

Egrets are often seen along with grazing cattle. How do you refer to this interaction? Give a reason for this association.

What are the key elements that lead to so much variation in the physical and chemical conditions of different habitats?

Study the population growth curves in the graph given ahead and answer the questions which follow:

1. Identify the growth curves ‘a’ and ‘b’.
2. Which one of them is considered a more realistic one, and why?
3. If `(dN)/dt = rN ((K - N)/K)` is the equation of the logistic growth curve, what does K stand for?
4. What is symbolised by N?
5. Mention the conditions responsible for the curves ‘a’ and ‘b’ respectively.

Explain the equation:

N_{t + 1} = N_t + [(B + I) − (D + E)]

On the basis of the flow chart given below.

How is diapause different from hibernation?

If a marine fish is placed in a freshwater aquarium, will the fish be able to survive? Why or why not?

Define phenotypic adaptation.

Give one example of phenotype adaptation.

Most living organisms cannot survive at temperatures above 45°C.

How are some microbes able to live in habitats with temperatures exceeding 100°C?

Distinguish between the following:

Hibernation and Aestivation

Distinguish between the following:

Ectotherms and Endotherms.

Write a short note on adaptations of desert plants.

Write a short note on adaptations of desert animals.

Write a short note on adaptations of plants to water scarcity.

Write a short note on behavioural adaptations in animals.

Write a short note on the importance of light to plants.

Write a short note on the effect of temperature or water scarcity and the adaptations of animals.

List the various abiotic environmental factors.

Give an example of an endothermic animal.

Give an example of an ectothermic animal.

Give an example of an organism of benthic zone.

Name important defence mechanisms in plants against herbivory.

An orchid plant is growing on the branch of a mango tree. How do you describe this interaction between the orchid and the mango tree?

What is the ecological principle behind the biological control method of managing with pest insects?

Define Population.

Define Community.

Define the following term:

Commensalism

Give one example of commensalism.

Define the following term:

Parasitism

Give one example of parasitism.

Define the following term:

Camouflage

Give one example of Camouflage.

Define mutualism.

Give one example of Mutualism.

Define the following term:

Interspecific competition

Give one example of Interspecific competition.

Select the statement which explains best parasitism.

1. One organism is benefited
2. Both the organisms arc benefited
3. One organ is benefitted, other is affected.
4. One organism is benefited, other is affected

List the attributes that populations but not individuals possess.

If a population growing exponentially double in size in 3 years, what is the intrinsic rate of increase (r) of the population?

With the help of a suitable diagram, describe the logistic population growth curve.

List any three important characteristics of a population and explain.

If you had ever been to any high altitude place, you must have experienced what is called ‘altitude sickness’. But gradually you get acclimatised and stop experiencing altitude sickness.

Can you think of any natural habitat on Earth that is inhabited just by a single species?

My friend Prakash has a beautiful garden in his house with a lot of ornamental plants, including a section of rose plants and cacti growing in it. On a morning walk, Prakash tried to pluck a rose flower and got hurt by a thorn present on the twig of the plant. He soon started thinking about the beauty of rose flowers, but was not able to understand the presence of thorns over them. He soon approached his father (who is a horticulturist) to resolve his curiosity. Can you feel how his father explained and solved his curiosity?

Is it possible to achieve ‘zero population growth rate’? If yes, what kind of age pyramid is obtained?

Differentiate between biotic potential and carrying capacity.

Differentiate between commensalism and amensalism.

Differentiate between commensalism and mutualism.

Differentiate between euryhaline and stenohaline.

Differentiate between intraspecific and interspecific competition.

Differentiate between mutualism and competition.

Differentiate between natality and mortality.

Differentiate between parasitism and predation.

Differentiate between population and community.

Differentiate between predation and cannibalism.

Differentiate between predation and scavenging.