Thinking Process

Ecology is study of the relationship of living organisms with their abiotic and biotic components. It consists of two branches. (i) Autecology (ii) Synecology

Answer

(b) Autecology is the study of relationship of an individual other options are irrelevant to its environment. So, the relation of a population or community to its environment is called synecology.

• Option (a) is incorrect because the relation of a population to its environment is studied under synecology, not autecology.
• Option (c) is incorrect because the relation of a community to its environment is also studied under synecology, not autecology.
• Option (d) is incorrect because the relation of a biome to its environment is a broader ecological study and does not fall under autecology, which focuses on individual organisms.

Answer

(c) The adjacent biotic (natural) communities, generally do not posses a fine demarcation edge or line between them. The adjacent of two communities is represented by population of both the communities, and this transition zone between two communities is referred as ecotone.

Rest of the options do not define ecotone (zone of transition).

• (a) A polluted area does not describe a transition zone between two natural communities; it refers to an area contaminated by pollutants.
• (b) The bottom of a lake is a specific aquatic environment and does not represent a transition zone between two different communities.
• (d) A zone of developing community refers to an area where a new community is forming or growing, not a transition zone between two existing communities.

Answer

(d) Biosphere is composed of all living organisms present on earth which interact with their physical environment. In other words a biosphere or ecosphere term is collectively used for all the ecosystems of world.

Ecosphere or biosphere can not be defind by other three options, as they represent only a part of ecosystem.

• Option (a) is incorrect because the biosphere is not just a component in the ecosystem; it encompasses all ecosystems on Earth, including all living organisms and their interactions with the physical environment.

• Option (b) is incorrect because the biosphere is not limited to the plants present in the soil; it includes all living organisms, such as animals, plants, microorganisms, and their interactions with the physical environment.

• Option (c) is incorrect because the biosphere refers to life on Earth, not life in outer space. The term specifically pertains to the regions of Earth where life exists.

Answer

(c) Ecological niche is ecologically adapted zone, i.e., the specific place of habitat occupied by individual of a species. It in turn is determined by factors such as by its range of tolerance. i.e., the physical position and functional role of a species within the community, etc.

Rest of the options are incorrect.

• (a) The surface area of the ocean is incorrect because an ecological niche refers to the role and position a species has in its environment, not a specific physical area like the surface of the ocean.

• (b) An ecologically adapted zone is incorrect because it is a broader term that can refer to any area adapted to by various species, whereas an ecological niche is specific to the role and position of a particular species within a community.

• (d) Formed of all plants and animals living at the bottom of a lake is incorrect because an ecological niche is specific to the role and position of a single species, not a collective group of all organisms in a particular habitat.

Answer

(d) According to Allen’s rule, the mammals (endothermal animals) from colder climates or areas show shorter extremities like ears and limbs as compared to the mammals of warm region. The shorter extermise of mammals in colder region help to minimise heat loss and maintian homestatis.

Rest of the other options does not stand true for Allen’s rule.

• (a) Shorter ears and longer limbs: This option is incorrect because Allen’s rule states that mammals in colder climates have shorter extremities, including both ears and limbs, to minimize heat loss. Longer limbs would increase the surface area for heat loss, which is not advantageous in cold climates.

• (b) Longer ears and shorter limbs: This option is incorrect because Allen’s rule emphasizes that both ears and limbs are shorter in mammals from colder climates. Longer ears would increase the surface area for heat loss, which is not beneficial in cold environments.

• (c) Longer ears and longer limbs: This option is incorrect because Allen’s rule indicates that mammals in colder climates have shorter extremities, including both ears and limbs, to reduce heat loss. Longer ears and limbs would increase the surface area for heat loss, which is contrary to the adaptations described by Allen’s rule.

Thinking Process

Habitat of an organism is characterised by both abiotic component and biotic component. Abiotic components consists of temperature, water, light and soil.

Ans (d) Next to temprature water is an important abiotic component influencing the life of an organism/organisms. In an oceanic ecosystem, the organisms face water related problems like $\mathrm{pH}$, salinity of water. The salt concentration (salinity) of sea measured in parts per thousand is $30-35$

The other three options are incorrect.

Note The salinity (measured in parts per thousand) is less than 5 in land water, 30-35 in sea water and $>100$ do in some hypersaline water bodies like lagons.

• Option (a) $10-15$: This range is incorrect because it is too low for typical sea water salinity. Sea water generally has a higher salinity, around $30-35$ parts per thousand.

• Option (b) $30-70$: This range is incorrect because it is too broad and includes values that are much higher than typical sea water salinity. Typical sea water salinity is around $30-35$ parts per thousand, and values above $35$ are not common in standard sea water.

• Option (c) $0-5$: This range is incorrect because it is too low and corresponds to fresh water or land water, not sea water. Sea water has a significantly higher salinity, around $30-35$ parts per thousand.

Answer

(a) Formation of that tropical forest need annual temperature $18-25^{\circ} \mathrm{C}$ and annual rainfall (precipitation) above $140 \mathrm{~cm}$, usually between $150-400 \mathrm{~cm}$ and reach upto $1000 \mathrm{~cm} /$ year. Tropical forest (tropical rain or evergreen forest mainly occurs in equatorial or subequatorial region like Amazon, Central America and Orinco and Congo river basins of South America and Africa respectively.

The other options are incorrect.

Note The average mean temperature to form a tropical/subtropical rain forest is $17^{\circ} \mathrm{C}$ $25^{\circ} \mathrm{C}$ and climate is characterised by mild winter.

• Option (b) is incorrect because the mean annual temperature range of $5-15^{\circ} \mathrm{C}$ is too low for the formation of tropical forests, which require a warmer climate. Additionally, the mean annual precipitation of $50-100 \mathrm{~cm}$ is insufficient, as tropical forests need significantly higher rainfall.

• Option (c) is incorrect because the mean annual temperature range of $30-50^{\circ} \mathrm{C}$ is too high for the formation of tropical forests. Tropical forests typically form in regions with a mean annual temperature of $18-25^{\circ} \mathrm{C}$. The mean annual precipitation of $100-150 \mathrm{~cm}$ is also on the lower end of the required range, which is usually between $150-400 \mathrm{~cm}$.

• Option (d) is incorrect because the mean annual temperature range of $5-15^{\circ} \mathrm{C}$ is too low for the formation of tropical forests. Tropical forests require a warmer climate with a mean annual temperature of $18-25^{\circ} \mathrm{C}$. The mean annual precipitation of $100-200 \mathrm{~cm}$ is also on the lower end of the required range, which is usually between $150-400 \mathrm{~cm}$.

Answer

(c) In a forest ecosystem, light is an important abiotic component that controls a number of life processes in organism. In forest, its intensity, duration and quality at ground is controlled by tall trees, which have higher productivity than shrubs and herbs growing underneath. Lianas and climber are woody vines which make commensalism association with tall trees. Herbs and shrubs occupies lower strata of forest.

• (a) Lianas and climbers: Lianas and climbers are woody vines that rely on tall trees for support to reach sunlight. They do not control light conditions at the ground level but rather depend on the structure provided by tall trees to access light.

• (b) Shrubs: Shrubs are shorter plants that grow beneath the canopy of tall trees. They do not have the height or density to significantly control light conditions at the ground level.

• (d) Herbs: Herbs are the lowest strata of plants in a forest ecosystem. They grow close to the ground and are shaded by taller plants like shrubs and trees. Therefore, they do not control the light conditions at the ground level.

Answer

(c) In a forest ecosystem tall trees of forest plants controls the light condition, i.e., intensity, duration and quality of light at the ground. A well growing herbaceous plant in forest receive less intensity, duration and quality of light, but when it is transplanted in a park outside its natural habitat, the light will be received uninterrupted.

So due to change in its microclimate, it may not survive. Rest of the other options are incorrect to depict the fate of plant.

• (a) It will grow normally: This option is incorrect because the plant is being moved from its natural habitat in the forest to a different environment in the park. The change in microclimate, including factors like light intensity, humidity, and soil composition, can affect its growth and survival.

• (b) It will grow well because it is planted in the same locality: This option is incorrect because even though the park may be in the same general locality, the specific microclimate conditions in the park can be significantly different from those in the forest. These differences can impact the plant’s ability to thrive.

• (d) It grows very well because the plant gets more sunlight: This option is incorrect because while more sunlight might seem beneficial, the herbaceous plant is adapted to the lower light conditions of the forest floor. Excessive sunlight can lead to stress, dehydration, and other issues that can hinder its growth or even cause it to die.

Thinking Process

Population growth is the important characteristic of population, which is determined by addition and loss of individual. In case of higher addition of organisms/individual than lost, population show positive growth, i.e., vital index is more than 100. But when vital index is less than 100, population show negative growth.

Population growth is controlled by interaction between three factors naturally; biotic potential, standing state and environmental resistance.

Answer

(d) Biotic potential is the natural capacity of a population to multiply/increase at its maximum rate under favourable environmental conditions. Population of Paramecium show 100 per hour growth, i.e., two individuals are produced by one.

• Option (a) 50 per hour: This option is incorrect because the population increased by 100 individuals in one hour (from 50 to 150), not by 50 individuals. Therefore, the growth rate cannot be 50 per hour.

• Option (b) 200 per hour: This option is incorrect because the population increased by 100 individuals in one hour, not by 200 individuals. Therefore, the growth rate cannot be 200 per hour.

• Option (c) 5 per hour: This option is incorrect because the population increased by 100 individuals in one hour, not by 5 individuals. Therefore, the growth rate cannot be 5 per hour.

Answer

(b) Growth rate is $200 \%$ as one organism is producing two individuals at a time. (Refer to Question number-10).

• Option (a) 100: This option is incorrect because a 100% growth rate would imply that each organism is producing one additional individual, resulting in a doubling of the population. However, the given scenario states that one organism is producing two individuals, which corresponds to a 200% growth rate.

• Option (c) 50: This option is incorrect because a 50% growth rate would imply that each organism is producing half an additional individual, which is not possible in this context. The scenario specifies that each organism produces two individuals, leading to a 200% growth rate.

• Option (d) 150: This option is incorrect because a 150% growth rate would imply that each organism is producing 1.5 additional individuals. However, the scenario clearly states that each organism produces two individuals, resulting in a 200% growth rate.

Answer

(c) Variation in number of individuals in a population is expressed as population density and population size. A population of more young individual than older individuals, will show positive growth in future (after some yrs), i.e., it will increase after some time.

Rest of the options do not represent the correct status of population.

• (a) It will decline: This option is incorrect because a population with more young individuals is likely to grow as these young individuals mature and reproduce, leading to an increase in population size rather than a decline.

• (b) It will stabilise: This option is incorrect because a population with a higher proportion of young individuals is expected to grow as these individuals reach reproductive age, leading to an increase in population size rather than immediate stabilization.

• (d) It will first decline and then stabilise: This option is incorrect because there is no reason to expect an initial decline in a population with more young individuals. The population is more likely to increase as the young individuals mature and reproduce, leading to growth rather than an initial decline.

Answer

(b) The parameters used for tiger census in our country’s national park and sanctuaries are foot prints (pug marks) and faecal pallets of conserved animals.

• (a) Pug marks only: This option is incorrect because relying solely on pug marks (footprints) can lead to inaccurate counts due to overlapping tracks, misidentification, and the inability to distinguish between individual tigers.

• (c) Faecal pellets only: This option is incorrect because faecal pellets alone do not provide enough information to accurately count tigers. They can help in identifying the presence of tigers but are insufficient for a precise census without additional data like pug marks.

• (d) Actual head counts: This option is incorrect because actual head counts are impractical and nearly impossible in dense forests and large sanctuaries. Tigers are elusive and solitary animals, making it extremely difficult to spot and count each individual directly.

Answer

(c) Population growth means increase in its size and is determined by addition and loss of individual in a population. Population density is the number of individuals present per unit volume/area at given time.

Thus, mortality and emigration would necessarily decrease the density of a population in a given habitat due to loss of individual result from mortality (deaths) and emigration.

When natality rate will be more than mortality rate and increased immigration rate mould necessarily increase the density of a population.

• (a) Natality > mortality: This would increase the density of a population because the birth rate (natality) is higher than the death rate (mortality), leading to a net gain in the number of individuals.

• (b) Immigration > emigration: This would also increase the density of a population because more individuals are entering the population (immigration) than leaving it (emigration), resulting in a net increase in population size.

• (d) Natality and immigration: Both natality (births) and immigration (incoming individuals) contribute to an increase in population density, as they add more individuals to the population.

Answer

(c) Binary fission, a mode of asexual reproduction in protozoan produce two offsprings from parent individual. So

Thus, the population of protozoan will be 64 , after six generations.

• Option (a) 128: This option is incorrect because after six generations of binary fission, the number of protozoans will be (2^6 = 64), not 128. The calculation for 128 would require seven generations, not six.

• Option (b) 24: This option is incorrect because the number of protozoans after six generations of binary fission follows the pattern (2^n), where (n) is the number of generations. (2^6 = 64), not 24. The number 24 does not fit the exponential growth pattern of binary fission.

• Option (d) 32: This option is incorrect because 32 is the number of protozoans after five generations, not six. After six generations, the number of protozoans will be (2^6 = 64).

Answer

(b) Exponential equation

$$ \begin{aligned} d N / d t & =(b-d) \times N \\ d N / 10 & =(0.028-0.008) \times 14(0.020) \times 14 \\ d N / 10 & =.28 \\ d N & =.28 \times 10 \\ d N & =2.8 \\ & =14 \text { million }+2.8 \text { million } \\ & =16.8 \text { million }=17 \text { million } \end{aligned} $$

So, the number of people present in 2015 is predicted as 17 millions.

• Option (a) 25 millions: This option is incorrect because the exponential growth rate calculated from the given birth and death rates does not support such a high population increase. The net growth rate is 0.02 per year, which over 10 years results in a population increase to approximately 17 million, not 25 million.

• Option (c) 20 millions: This option is incorrect because the exponential growth rate of 0.02 per year over 10 years does not result in a population increase to 20 million. The calculated population increase leads to approximately 17 million, not 20 million.

• Option (d) 18 millions: This option is incorrect because the exponential growth rate of 0.02 per year over 10 years results in a population increase to approximately 17 million, not 18 million. The calculation shows that the population would be closer to 17 million.

Thinking Process

Interspecific interactions in population arise from the interaction of populations of two different species. This could be beneficial, neutral or detrimental to one or both of the species.

Answer

(b) When one species is benefitted and other is harmed, in an association between two species, it is called amensalism. In commensalism one species is benefitted and other is unaffected.

The other options are in correct because While in when one species is harmed and other is benefitted, the relationship is termed as parasitism.

• Option (a) is incorrect because when one species is harmed and the other is benefitted, the relationship is termed as parasitism, not amensalism.
• Option (c) is incorrect because when one species is benefitted and the other is unaffected, the relationship is termed as commensalism, not amensalism.
• Option (d) is incorrect because when both species are harmed, the relationship does not fit the definition of amensalism.

Answer

(c) Lichens represent a positive (beneficial) interaction between two different species, one fungus and another algae.

Rest of the species combination or associations are not true for lichens.

Note Algal species is called as phycobiont while fungal species is referred to as mycobiont. The fungal species comes from two classes Ascomycetes (ascolichen) and Basidiomycetes (basidiolichen).

• (a) bacteria and fungus: Lichens are not formed by the association of bacteria and fungus. The symbiotic relationship in lichens specifically involves a fungus and an algae or cyanobacterium, not bacteria.

• (b) algae and bacterium: Lichens do not consist of an algae and a bacterium. The correct association is between a fungus and an algae or cyanobacterium, not a bacterium.

• (d) fungus and virus: Lichens are not formed by the association of a fungus and a virus. The symbiotic relationship in lichens involves a fungus and an algae or cyanobacterium, not a virus.

Answer

(a) Sandal wood (Santalum album) is partial root parasite.

Mistletoe (Viscum) is considered as hemiparasite which derive a part of nourishment from host plant. Orobanche is a holo parasite which infects species from favciae i.e., beans, loranthus, Ganoderma are parasite, basidiocarpic mushrooms.

• Mistletoe (Viscum) is considered a hemiparasite, which means it derives part of its nourishment from the host plant but can also perform photosynthesis to some extent.

• Orobanche is a holoparasite, meaning it completely relies on the host plant for its nourishment and does not perform photosynthesis.

• Ganoderma is a parasitic basidiocarpic mushroom, which means it is a fungal parasite and not a plant parasite.

Thinking Process

Reproductive phase in higher plants is characterised by appearance of flowers. Sexually there are two types of flowering plants: monocarpic and polycarpic.

Answer

(a) Monocarpic plants are those plants which flower once in their life e.g., all annuals (wheat, rice), biennials like carrot and radish, perennial like bamboo. Banana is a monocarpic plant, so reproduces sexually once in its lifetime.

Rest of the options are incorrect.

• Mango: Mango trees are polycarpic, meaning they can flower and fruit multiple times throughout their lifespan.

• Tomato: Tomato plants are also polycarpic, capable of producing flowers and fruits multiple times during their growing season.

• Eucalyptus: Eucalyptus trees are polycarpic as well, flowering and producing seeds many times over their long lifespan.

Answer

Stenothermal Organisms

Temperature, a major abiotic factor affects the metabolism, activity and so many other physiological functions of the organism

On the basis of temperature tolerance, organism can be classified as eurythermal and stenothermal.

(i) Eurythermal organisms can tolerate and thrive in a wide range of temperatures.

(ii) Stenothermal organisms tolerate only a narrow range of temperatures.

Answer

Eurythermic species are those species which possess or show a wide range of temperature tolerance.

Answer

Euryhaline species

Water, another major abiotic component affects the life of organism. The quality of water like $\mathrm{pH}$, salinity (salt concentration) are water related problems faced by aquatic organisms, organisms or species that can tolerate wide range of salinity are regarded as euryhaline Species.

Answer

Stenohaline species are those species which show a narrow range of salinity tolerance.

Answer

Interaction between two species is called interspecific interaction. These could be beneficial, detrimental or neutral to one of the species or both.

Answer

Commensalism is an interaction where one species is benefitted and the other is unaffected. e.g., an orchid growing as an epiphyte on a mango branch.

Answer

Parasitism is the association in which one species produces poisonous substance or a change in environmental conditions that is harmful to another species. Examples are protozoans such as Amoeba and Plasmodium vivax that lives in human body and cause diseases.

Answer

Mycorrhiza is a symbiotic association between a fungus and the root of higher plants like conifers i.e., Pinus and leguminous plants.

Note Fungal hyphae get protection and nourishment from its symbiont, while in turn helps in absorption of organic solutes to higher plants.

Answer

Halophytes emergent land plants that can tolerate the salinities of sea and are even able to maintain their water supply from the same are called as halophytes.

Answer

At high altitude the sun light is brighter as compared to plains, it is because of reduced distance from the sun and particles free air. Similarly lower temperatures are because of lower atmospheric pressure which is more in plains as compared to high altitude.

Answer

Homeostasis is the tendency of the organism to maintain a constant internal environment despite varying external environmental conditions like temperature.

Answer

Aestivation is a behavioural adaptation to avoid extreme heat and dessication in summer season. In which the organism slows down its metabolic activities.

It is also known as summer sleep.

Answer

It is a stage of suspended development that some organisms like zooplanktons in lakes and ponds, adopt to survive under unfavourable conditions.

Answer

In case of unlimited resources, the pattern of growth rate is exponential.

Answer

The organism that feed on plant sap and other parts of plants are termed as phytophagous.

Answer

High altitude sickness is experienced by the people going to high altitudes, where oxygen concentrations are low and the body system reacts by developing the symptoms like nausea, headache and heart palpitations.

Answer

An interaction between blue whale and the barancle growing on its back is an example of commensalism (interspecific relation) between them.

Answer

Ectoparasite feeds on the external surface of the host organism, e.g., Lice on humans and ticks on dogs. Many marine fish are infested with ectoparasitic copepods.

Endoparasites live inside the host body at different sites (liver, kidney, lungs, red blood cells, etc.). Such as malarial parasites $P$. vivax, gut parasites, i.e., tapeworm.

Their morphological and anatomical features of endoparasites are greatly simplified while emphasising their reproductive potential.

Answer

Brood parasitism is the phenomenon in which an organism (parasite) lays eggs on the nest of other organism (host).

e.g., Cuckoo (koel) bird lays its eggs in the nest of its host and lets the host incubate them. The eggs of the parasitic bird resemble the host’s egg in size and colour to reduce the chances of the host bird detecting the foreign eggs and ejecting them from the nest.

Short Answer Type Questions

Answer

Coral reefs are found in zone with high salt concentration (salinity), optimal temperature and with a less siltation condition which fairly facilitate to colonise corals. In case of high siltation and water flow, coral reef do not colonise.

Answer

No, a freshwater fish placed in the aquarium containing sea water, will not be able to survive. Because, its body system is adapted to function normally in a narrow range of salinity and it cannot survive in the high salinity of sea water.

Answer

Contractile vacuole helps in osmoregulation. Because of the cellular environment of a freshwater organism being hypertonic, the water diffuses inside the cell constantly and gets collected in the contractile vacuole, which squeezes the extra water out of the cell periodically.

Thus, keeping the internal environment constant. While in case of marine organisms, this does not occur due to high salinity, therefore no need of contractile vacuole.

Thinking Process

On the basis of light tolerance or adaptation, plants may be heliophytes and sciophytes.

Answer

Plants growing well in bright sunlight or favour bright light are called heliophytes or sun plants. While those plants which require low intensity of light or partial shade for growing are termed as shade loving plants or sciophytes.

Answer

Submerged plants receive weaker illumination than exposed floating plants in a lake because all colours of the visible components of the spectrum of light do not enter or penetrate in the depths of water.

Answer

In a sea shore, water current restrict distribution of organisms. In streamed areas of ocean, animals are strong swimmer or possess attaching organs such as peduncle, or live under stone, in burrows etc.

Burrowing animals like tubeworm, Nerlies are strong swimmer. Burrowing, building cubes and holdfast or penduncle adaptation are found in sandy, muddy and rocky substratum respectively.

Answer

(a) Salvinia is a hydrophytes - Partially or completly submerged in water.

(b) Opuntia is a xerophyte - Dry habitat succulent leaves.

(c) Rhizophora is a halophyte - Saline habitat

(d) Mangifera is a mesophyte - Terrestrial habitat.

Answer

(a) Hydrilla is submerged hydrophyte

(b) Typha is rooted emergent

(c) Nymphaea is rooted with floating leaves

(d) Lemna is free floating hydrophyte

(e) Vallisnaria is rooted submerged hydrophytes.

Answer

The density of population per unit area is measured in following units

(a) The density of a bacterial population in a habitat per unit area is measured in volume/number unit.

(b) Biomass/area/region is measuring unit for density of population of banyan.

(c) Number/area is measuring unit for the density of population of deer.

(d) Weight/area is measuring unit for density of population of fish.

Answer

(a) The three tiers are to be labelled as (i) Pre-reproductive phase (iii) Post-reproductive phase (ii) Reproductive phase

(b) The given age pyramid represents the expanding type of population growth.

Answer

The termite provides shelter and space for the protozoan Trichonympha to live. The Protozoa present in gut digests the wood, which termite feeds upon. In the absence of Trichonympha the termite is unable to digest wood and hence dies. Thus, the association of two given animal species represent mutualism.

Answer

The type of association, the lianas have with the trees is commensalism because the plant gets the support of the tree without affecting harming or providing any benefit to the tree.

Answer

The scientific names of two microorganisms inhabiting the human intestine are Escherichia coli and Lactobacillus.

Answer

Tree line is the edge of the habitat where trees are capable of growing. Due to environmental conditions such as cold temperature, high altitude or lack of moisture the trees are not found beyond this line and if found show stunted growth or form low dense matted bushes.

Answer

When the pre-reproductive age group individuals are comparatively fewer and both reproductive and post-reproductive stages are almost in equal stage, i.e., at same level. It is zero population growth rate.

An inverted bell shaped age pyramid is obtained for zero population growth rate.

Answer

A population has the following characterstics that are employed in human population census. (i) Natality and mortality (ii) Sex ratio (iii) Population density (iv) Age distribution (v) Population growth

Answer

(a) Migratory animal-American buffalo and dolphin.

(b) Camouflaged animal-Grasshopper and chameleon.

(c) Predatoranimal-Lion.

(d) Biological control agent-Myxoma virus to kill European rabbit and Gambusia fish to check growth of mosquito larvae.

(e) Phytophagous animal-Insects (beetle, butterfly, etc.).

(f) Chemical defense agent-Cardiac glycosides.

Answer

Answer

I. Figure A show a pollinator (bee) on a flower. The association between pollinator insect and plant is termed as mutulalism.

II. Predation.

III. Egrets and grazing cattle is good example of commensalism.

IV. Scavenging- The insect is playing the role of an scavenger.

Long Answer Type Questions

Answer

Figure $I$ It is a single population and all individuals are of the same species, i.e., a individuals interact among themselves and their environment intraspecific interaction.

Figure II It is a community and it contains three populations of species A, B and C. They interact with each other and their environment and is called interspecific interaction.

Figure III It is a biome. It contains three communities of which one is in climax and other two are in different stages of development. All three communities are in the same environment and they interact with each other and their environment.

Answer

An individual and a population has following certain attributes like pattern of distribution. dispersal biotic potential and gene pool. Phenomenon of distribution of individual within geographical boundaries of the population is termed as interapopulation dispersion or internal distribution patterns or dispersion

Dispersal an individual is dispersed at one or another time during their life in a population which is revealed by immigration or emigration.

(i) Immigration is the number of individuals of the same species that have come into the habitat from elsewhere during a specified time period.

(ii) Emigration is the number of individuals of the population who exit or leave the habitat and go elsewhere during a specified time period.

Biotic Potential Biotic potential is the natural capacity of a population to increase its size under ideal environmental conditions.

Gene pool All the genotypes of all individuals in a breeding population is referred to as gene pool.

Answer

Figure A It is a ‘pyramid’ shaped age pyramid. In this figure, the base, i.e., pre-reproductive stage is very large as compared with the reproductive and post-reproductive stages of the population. This type of age structure indicate that the population would increase rapidly.

Figure $\mathbf{B}$ It is an ‘inverted bell’ shaped pyramid. In this figure, the pre-reproductive and reproductive stages are same. This type of age structure indicates that the population is stable.

Figure $\mathbf{C}$ It is ‘urn’ shaped pyramid. In this figure, the pre-reproductive and reproductive stages are less than the post-reproductive stages of this population. In this population more older people are present. This type of age structure indicates that the population definitely is declining.

Answer

The growth curve shown above is logistic growth curve or S-shaped curve.

Logistic growth curve is considered more realistic because unlimited resources are not available in an ecosystem or in a habitat, where

$K$-stands for carrying capacity.

$\mathrm{N}$-indicates population density, which is the number of species of a population per unit area.

$r$-is for intrinsic rate of natural increase.

Answer

Initially, after a lag phase, the population will grow in an exponential manner as the nutrients and space will be abundant.

When the food sources get depleted, the population density starts decreasing and ends in an asymptote phase, then the population density reaches the carrying capacity (maximum number of individuals of a population or species that a given environment can sustain indefinitely).

The population shows a pattern of logistic growth giving an S-shaped curve.

Where $K=$ carrying capacity

$N=$ population density at time ’ $t$ '

$r=$ Intrinsic rate of natural increase

Answer

The interspecific interaction are of three types positive or beneficial, negative or antagonistic and last neutral interaction.

Some positive interactions are scavenging, commensalism, protocooperation and mutualism.

Mutualism This interaction confers benefits on both the interacting species, e.g.,

(i) Lichens represent an intimate mutualistic relationship between a fungus and photosynthesising algae or cyanobacteria.

(ii) The mycorrhizae are associations between fungi and the roots of higher plants. The fungi help the plant in the absorption of essential nutrients from the soil while the plant in turn provides the fungi with energy-yielding carbohydrates.

(iii) Plants offer nectar, juicy and nutritious fruits to animals that help pollinate their flowers and disperse their seeds.

Commensalism This is the interaction in which one species benefits without affecting the other, e.g.,

(i) An orchid growing as an epiphyte on a mango branch.

(ii) Barnacles growing on the back of a whale.

(iii) The cattle egret foraging close to the cattle that stir up and flush out insects from the vegetation.

(iv) Sea anemone that has stinging tentacles and the clown fish that lives among them to get protection from predators.

Scavenging is the act of feeding by scavenger like bacteria, fungi on the remain of dead animals.

Protocooperation in the type of relationship in which both partners mutually obtain benefits. But they associate purely to benefit from each other and can live without each other.

Answer

Competition is a rivalry relationship between two or more organisms. A competition between individual of same species (intraspecific) is more acute than the competition between individual of different species as all the members in a intraspecific competition have same basic requirements like food, water, light, space, mating and shelter.

But this is true only when resources are limited. According to Gause’s principle, one of the species is to be eliminated.

But studies recently have revealed that species facing intraspecific competition may evolve mechanism to pencourage co-existence rather than exclusion. This can also be done by a method known as ’ resource partitioning'.

Answer

Parasites have evolved special adaptations such as

(i) The loss of unnecessary sense organs as in lice, mites and fleas don’t have wings.

(ii) Presence of adhesive organs or suckers to cling on to the host-in tapeworms and leeches.

(iii) Loss of digestive system i.e., tapeworm.

(iv) High reproductive capacity i.e., roundworm produces large progeny.

Answer

A biome can be define as the large communities of the world and shows that area with similar climate have communities of same type. Climate is the main factor that determine the type of soil which in turn determines the type of vegetation. The type of vegetation and climate together determine the kind of microorganisms and animals.

The other determining factors are latitude and altitude, intensity and duration of winter and summer days, water mass and topography. The main biome of the world does not show boundary of any country and regional and local variations exist in each biome.

e.g., temperate deciduous forest receive an annual precipitation between 75-150 cm and tropical rain forest show a rainfall above $140 \mathrm{~cm} / \mathrm{yr}$ which may reach upto $400 \mathrm{~cm} / \mathrm{yr}$.

Answer

Soil salinity is the salt content in soil, which is caused by improper irrigation. The process of increasing salt content is termed as salinisation.

Causes of Soil Salinity The high salt concentration of soil is caused by improper irrigation method from a salt laden water table. When salt concentration in soil is increased, than it get accumulated due to evaporation.

Human activities like fertilising crop is also responsible for salinity of soil. As fertiliser contain potassium, which can form a naturally occuring salt-sylvite. Salinity of soil degrades soil and vegetation. Normally the $\mathrm{pH}$ value of soil comprises between 2.2-9.7, while above which the soil is degrading by salt content.

Answer

Plants require sunlight for photosynthesis. Therefore, light is an important factor that affects the distribution of plants. e.g.,

(i) Many species of small plants (herbs and shrubs) growing in forests are adapted to photosynthesise optimally under very low light conditions so they will be seen distributed in shady areas under tall, canopied trees.

(ii) Many plants in the shade will grow vertically to gain access to light. These plants will appear to have smaller leafs and smaller than others of the same species of the same age found in conditions with better sunlight.

(iii) Large sized trees will be present in areas that get abundant sunlight.

(iv) Plants dependent on sunlight to meet their photoperiodic requirements for flowering, will try to be distributed in area, where this requirement is being met for their reproductive success.

Answer

I. Mango, Acacia

II. Archaebacteria

III. Jelly fishes

IV. Earthworm

V. Cuscuta

VI. Cocos nucifera

VII. Bacteria

VIII. Octopus

IX. Salt content (osmotic regulation)

X. All plant and fish like large mouth bass (temperature conformer)