Additional Questions - Chapter 6 Principles of Ecology 12th Biology Botany Guide Samacheer Kalvi Solutions - SaraNextGen [2024-2025]

Updated By SaraNextGen

On April 24, 2024, 11:35 AM

Additional Questions and Answers

1 - Mark Questions
Question 1.
Who is called as the father of Modem Ecology?
Answer:
Eugene P. Odum
Question 2.
Autoecology deals with the study of
(a) Community
(b) Population
(c) Individual species
(d) Niche of species
Answer:
(c) Individual species
Question 3.
Environment of any community is called
(a) Paratope
(d) Biotope
(c) Opitope
(d) Biotope
Answer:
(d) Biotope
Question 4.
Match Coloumn I with Column II

Answer:
(a) -111
(b) $-i$
(c) $-\mathrm{iv}$
(d) - ii
Question 5.
The study of soil is called as
(a) Lithotripsy
(b) Lithosphere
(c) Pedology
(d) Pedology analysis
Answer:
(c) Pedology
Question 6.
Identify the indicators of fire.
(a) Pucinia
(b) Pyricularia
(c) Pyronema
Answer:
(c) Pyronema
Question 7.
The surface features of earth are called .................
Answer:
Topography
Question 8 .
Amensalism is called as .....................
Answer:
Antibiosis
Question 9.
......................... is the transition zone between two ecosystems.
Answer:
Ecotone

Question 10 .
Match the type of species interaction with correct combination. Interaction Type Combination

Answer:
(a) $-i i i$ (b) $-i$ (c) $-i v(d)-i i$
Question 11.
Wasps is the fruits of fig is an example for type of species interaction.
Answer:
Mutualism
Question 12 .
Statement 1: Latitudes represent distance from the equator.
Statement 2: Height above the seal level from longitude.
(a) Statement 1 is correct. Statement 2 is incorrect.
(b) Statement 1 is incorrect. Statement 2 is correct.
(c) Both the statements are correct.
(d) Both the statements are incorrect.
Answer:
(a) Statement 1 is correct. Statement 2 is incorrect.
Question 13.
Statement 1: Holoparsites depend totally on other organisms for nutrition.
Statement 2: Dumta is holoparasite.
(a) Statement 1 is correct. Statement 2 is incorrect.
(b) Statement 1 is incorrect. Statement 2 is correct.
(c) Both the statements are correct.
(d) Both the statements are incorrect.
Answer:
(c) Both the statements are correct.
Question 14.
Statement 1: Ephemerals are drought evaders.
Statement 2: They are not true xerophytes.
(a) Statement 1 is correct. Statement 2 is incorrect.
(b) Statement 1 is incorrect. Statement 2 is correct.
(c) Both the statements are correct.
(d) Both the statements are incorrect.
Answer:
(c) Both the statements are correct.

Question 15 .
Assertion (A) : Plains and valleys are rich in vegetation Reason (R): Slow drain of surface water and better water retention is noticed.
(a) $A$ is true $R$ is false
(b) R explains $A$
(c) $A$ and $R$ are false
(d) $\mathrm{A}$ and $\mathrm{R}$ are true. But $\mathrm{R}$ doesnot explains $\mathrm{A}$ Answer:
(b) R explains A
Question 16.
Utricularia is a
(a) Rooted floating hydrophyte
(b) Submerged floating hydrophyte
(c) Rooted submerged hydrophyte
(d) Amphibious hydrophyte
Answer:
(b) Submerged floating hydrophyte
Question 17.
Earth day is observed on
(a) April 22nd
(b) March 21st
(c) July 07th
(d) September 16th
Answer:
(a) April 22nd
Question 18.
Plants in sandy soils are commonly called as
Answer:
Psammophytes
2 - Mark Questions

Question 1.
How Earnest Haeckel defined ecology?
Answer:
Earnest Haeckel defined "Ecology is the study of the reciprocal relationship between living organisms and their environment."
Question 2.
What is ecological hierarchy?
Answer:
The interaction of organisms with their environment results in the establishment of grouping of organisms which is called ecological hierarchy.
Question 3.
Sequentially arrange the different units of ecological hierarchy.
Answer:

Question 4.
Define
1. Autecology
2. Synecology.
Answer:
1. Autecology is the ecology of an individual species and is also called species ecology.
2. Synecology is the ecology of a population or community with one or more species and also called as community ecology.
Question 5 .
What is Niche?
Answer:
An ecological niche refers to an organism's place in the biotic environment and its functional role in an ecosystem.
Question 6.
What are ecological factors?
Answer:
The environment (surrounding) includes physical, chemical and biological components. When a component surrounding an organism affects the life of an organism, it becomes a factor. All such factors together are called environmental factors or ecological factors.
Question 7.
Name the climatic factors that affect plant life.
Answer:
Light, Temperature, Water, Wind and Fire.
Question 8 .
Name any four physiological processes in plants, where the light plays a crucial role.
Answer:
1. Photosynthesis
2. Transpiration
3. Seed germination
4. Flowering

Question 9.
Heliophytes differ from Sciophytes. How?
Answer:
Heliophytes - Light loving plants. Example: Angiosperms.
Sciophytes - Shade loving plants. Example: Bryophytes and Pteridophytes.
Question 10.
Based on temperature prevalence, Raunkiaer classified world's vegetation into four types. Name them.
Answer:
Raunkiaer classified the world's vegetation into the following four types. They are megatherms, mesotherms, microtherms and hekistotherms.
Question 11.
Distinguish between evergreen forests and sclerophyllous forests.
Answer:
Evergreen Forests: Found where heavy rainfall occurs throughout the year.
Sclerophyllous Forests: Found where heavy rainfall occurs during winter and low rainfall during summer.
Question 12.
What does the term 'Timber line' refers to?
Answer:
Timber line is an imaginary line in a mountain or higher areas of land that marks the level above which trees do not grow. The altitudinal limit of normal tree growth is about 3000 to $4000 \mathrm{~m}$.
Question 13.
Compare Euryhaline organisms with stenohaline organisms.
Answer:
1. Euryhaline: Organisms which can live in water with wide range of salinity. Examples: Marine algae and marina angiosperms.
2. Stenohaline: Organisms which can withstand only small range of salinity. Example: Plants of estuaries.
Question 14.
Write the composition of gases in atmosphere.
Answer:
Nitrogen $-78 \%$, Oxygen $-21 \%$, Carbon-di-oxide $-0.03 \%$, Argon and other gases $-0.93 \%$.
Question 15.
What is Albedo effect?

Answer:
Gases let out to atmosphere causes climatic change. Emission of dust and aerosols from industries, automobiles, forest fire, S02 and DMS (dimethyl sulphur) play an important role in disturbing the temperature level of any region. Aerosols with small particles is reflecting the solar radiation entering the atmosphere. This is known as Albedo effect.
Question 16.
Point any two adverse effects of fire in an environment.
Answer:
1. Fire has a direct lethal effect on plants.
2. It brings out the alteration of light, rainfall, nutrient cycle, fertility of soil, $\mathrm{pH}$, soil flora and fauna
Question 17.
Pyronema confluens is the indicator of fire - comment.
Answer:
Pyronema confluens is a fungus which grow on the soil of burnt or fire disturbed areas. Hence it is called as indicator of fire.
Question 18 .
What are edaphic factors?
Answer:
Edaphic factors are the abiotic factors related to soil, include the physical and chemical composition of the soil formed in a particular area.
Question 19.
Name the study that deals with soil factors. Also mention the optimal soil $\mathrm{pH}$ for crop cultivation.
Answer:
The study of soil is called pedology. The best $\mathrm{pH}$ of soil for crop cultivation is 5.5 to 6.8 .
Question 20.
Define soil profile.
Answer:
Soil is commonly stratified into horizons at different depth. These layers differ in their physical, chemical and biological properties. This succession of super-imposed horizons is called soil profile.
Question 21.
Given below are few types of plants. Mention their habitats.
1. Halophytes
2. Chasmophytes
3. Cryophytes

4. Psammophytes.
Answer:
1. Halophytes: Plants living in saline soils.
2. Chasmophytes: Plants living in rocky crevices.
3. Cryophytes: Plants living in ice surface.
4. Psammophytes: Plants living in sandy soils.
Question 22.
Mention any four topographic factors that affect vegetation.
Answer:
1. Latitude
2. Altitude
3. Direction of mountain and
4. Steepness of mountain.
Question 23.
How the steepness of mountain affects the vegetation?
Answer:
The steepness of the mountain or hill allows the rain to run off. As a result the loss of water causes water deficit and quick erosion of the top soil resulting in poor vegetation. On the other hand, the plains and valley are rich in vegetation due to the slow drain of surface water and better retention of water in the soil.
Question 24 .
Name any two positive interactions with an example for each.
Answer:
1. Mutualism - E.g: Lichen
2. Commensalism - E.g: Orchids.
Question 25.
Define mutualism with an example.
Answer:
Mutualism is an interaction between two species of organisms in which both are benefitted from the obligate association. E.g. Lichens (alga with fungus).
Question 26.
What is the principle of commensalism?
Answer:
Commensalism is an interaction between two organisms in which one is benefitted and the other is neither benefitted nor harmed. The species that derives benefit is called the commensal, while the other species is called the host.

Question 27.
Specify the type of interactions between the given pair of species.
1. Spanish moss and Oak tree
2. Cuscuta and Acacia
3. Nepenthes and Ants
4. Alga and fungus
Answer:
1. Commensalism
2. Parasitism
3. Predation
4. Mutualism
Question 28.
Explain the concept of proto co-operation.
Answer:
Proto Co-operation is an interaction between organisms of different species in which both organisms benefit but neither is dependent on the relationship. Example: Soil bacteria / fungi and plants growing in the soil.
Question 29.
What are Holoparasites? Give example.
Answer:
The organisms which are dependent upon the host plants for their entire nutrition are called Holoparasites. They are also called total parasites.
Example: Cuscuta is a total stem parasite of the host plant Acacia.
Question 30.
What are hemiparasites? Give example.
Answer:
Hemiparasites is the organisms which derive only water and minerals from their host plant while synthesizing their own food by photosynthesis are called Hemiparasites. They are also called partial parasites.
Example: Viscum.
Question 31.
Cite an example for partial stem parasite and partial root parasite.
Answer:

1. Partial stem parasite - E.g: Loranthus.
2. Partial root parasite-E.g: Santalum.
Question 32.
Define Amensalism.
Answer:
Amensalism is an interspecific interaction in which one species is inhibited while the other species is neither benefitted nor harmed. The inhibition is achieved by the secretion of certain chemicals called allelopathic substances. Amensalism is also called antibiosis.
Question 33.
Point out any two morphological adaptations noticed in the roots of hydrophytes.
Answer:
1. Roots are totally absent in Wolffia and Salvinia or poorly developed in Hydrilla or well developed in Ranunculus.
2. The root caps are replaced by root pockets.
Example: Eichhomia.
Question 34.
What are hygrophytes? Give example.
Answer:
The plants which can grow in moist damp and shady places are called hygrophytes. Examples: Habenaria (Orchid) and Mosses (Bryophytes), etc.
Question 35.
What are trichophyllous plants? Give example.
Answer:
In xerophytic plants, with the leaves and stem are covered with hairs are called trichophyllous plants.
Example: Cucurbits (Melothria and Mukia)
Question 36.
Give an example for following type of adaptations.
1. Phyllode
2. Cladode
Answer:
1. Phyllode-E.g: Acacia.
2. Cladode-E.g: Asparagus.

Question 37.
Write a brief note on pneumatophores. Give an example.
Answer:
Pneumatophores are the special type of negatively geotropic roots developed by halophytes. It possess pneumathodes to get sufficient aeration. They are also called breathing roots.
Example: Avicennia.
3 - Mark Questions
Question 38.
Differentiate habitat from niche.
Answer:
Habitat:
1. A specific physical space occupied by an organism (species).
2. Same habitat may be shared by many organisms (species).
3. Habitat specificity is exhibited by organism.
Niche:
1. A functional space occupied by an organism in the same eco-system.
2. A single niche is occupied by a single species.
3. Organisms may change their niche with time and season.
Question 39.
What is thermal stratification? Explain its types.
Answer:
Thermal stratification is usually found in aquatic habitat. The change in the temperature profile with
increasing depth in a water body is called thermal stratification. There are three kinds of thermal stratifications.
1. Epilimnion - The upper layer of warmer water.
2. Metalimnion - The middle layer with a zone of gradual decrease in temperature.
3. Hypolimnion - The bottom layer of colder water.
Question 40.
What are the adverse effects of temperature on plant?
Answer:
1. Temperature affects the enzymatic action of all the bio-chemical reactions in a plant body.

2. Low temperature with high humidity can spread diseases to plants.
3. The varying temperature with moisture determines the distribution of the vegetation types.
Question 41.
Explain briefly about the three types of fire.
Answer:
1. Ground fire - Which is flameless and subterranean.
2. Surface fire - Which consumes the herbs and shrubs.
3. Crown fire - Which bums the forest canopy.
Question 42.
Classify soil based on its formation.
Answer:
Based on soil formation (pedogenesis), the soils are divided into:
1. Residual soils -These are soils formed by weathering and pedogenesis of the rock.
2. Transported soils - These are transported by various agencies.
Question 43.
Loamy soil is ideal for crop cultivation - Justify.
Answer:
Loamy soil is ideal soil for cultivation, since it consists of $70 \%$ sand and $30 \%$ clay or silt or both. It ensures good retention and proper drainage of water. The porosity of soil provides adequate aeration and allows the penetration of roots.
Question 44.
Direction of mountain determines the richness of vegetation - Justify.
Answer:
North and south faces of mountain or hill possess different types of flora and fauna because they differ in their humidity, rainfall, light intensity, light duration and temperature regions. The two faces of the mountain or hill receive different amount of solar radiation, wind action and rain. Of these two faces, the windward region possesses good vegetation due to heavy rains and die leeward region possesses poor vegetation due to rain shadows (rain deficit).
Question 45.
What are epiphytes? Explain their characteristic features.
Answer:
The plants which are found growing on other plants without harming them are called epiphytes. They are commonly found in tropical rain forest The epiphytic higher plant (Orchids) gets its nutrients and water
from the atmosphere with the help of their hygroscopic roots which contain special type of spongy tissue called Velamen. So it prepares its own food and does not depend on the host. They use the host plant only for support and does not harm.
Question 46 .
Discuss on predator - prey interaction with example.
Answer:
Predation: It is an interaction between two species, one of which captures, kills and eats up the other. The species which kills is called a predator and the species which is killed is called a prey. The predator is benefitted while the prey is harmed. Many herbivores are predators. Cattles, Camels and Goats etc., frequently browse on the tender shoots of herbs, shrubs and trees.
Question 47.
Give an account of Mimicry.
Answer:
Mimicry is a phenomenon in which living organism modifies its form, appearance, structure or behavior and looks like another living organism as a self defence and increases the chance of their survival. Floral mimicry is for usually inviting pollinators but animal mimicry is often protective. Mimicry is a result of evolutionary significance due to shape and sudden heritable mutation and preservation of natural selection.
Question 48
Mention any two species that exhibits protective mimicry.
Answer:
1. Carausium morosus (Stick insect)
2. PhyIlium frondosum (Leaf insect).
Question 49.
What is co-evolution? Explain with example.
Answer:
The interaction between organisms, when continues for generations, involves reciprocal changes in genetic and morphological characters of both organisms. This type of evolution is called Co-evolution. It is a kind of co-adaptation and mutual change among interactive species.
Examples:
- Corolla length and proboscis length of butterflies and moths (Habenaria and Moth).
- Bird's beak shape and flower shape and size.
Question 50 .
How physical dryness differ from physiological dryness?
Answer:
1. Physical dryness: In these habitats, soil has a little amount of water due to the inability of the soil to hold water because of low rainfall.
2. Physiological dryness: In these habitats, water is sufficiently present but plants are unable to absorb it because of the absence of capillary spaces.

Example: Plants in salty and acidic soil.
Question 51.
Point out the Anatomical adaptations exhibited by the Halophytes.
Answer:
Anatomical adaptations:
1. Epidermal cells of stem is heavily cutinized, almost squarish and are filled with oil and tannins.
2. Star' shaped sclereids and ' $H$ ' shaped heavy thickened spicules that provide mechanical strength to cortex are present in the stem.
3. The leaves may be dorsiventral or isobilateral with salt secreting glands.
5-Mark Question
Question 52.
Explain various edaphic factors that affect vegetation.
Answer:
The important edaphic factors which affect vegetation are as follows:
1. Soil moisture: Plants absorbs rain water and moisture directly from the air.
2. Soil water: Soil water is more important than any other ecological factors affecting the distribution of plants. Rain is the main source of soil water. Capillary water held between pore spaces of soil particles and angles between them is the most important form of water available to the plants.
3. Soil reactions: Soil may be acidic or alkaline or neutral in their reaction. $\mathrm{pH}$ value of the . soil solution determines the availability of plant nutrients. The best $\mathrm{pH}$ range of the soil for cultivation of crop plants is 5.5 to 6.8 .
4. Soil nutrients: Soil fertility and productivity is the ability of soil to provide all essential plant nutrients such as minerals and organic nutrients in the form of ions.
5. Soil temperature: Soil temperature of an area plays an'important role in determining the geographical distribution of plants. Low temperature reduces use of water and solute absorption by roots. .
6. Soil atmosphere: The spaces left between soil particles are called pore spaces which contains oxygen and carbon-di-oxide.
7. Soil organisms: Many organisms existing in the soil like bacteria, fungi, algae, protozoans, nematodes, insects and earthworms, etc. are called soil organisms.
Question 53.
What does competition refers to? Classify and describe it.
Answer:
1.Competition: It is an interaction between two organisms or species in which both the organisms or species are harmed. Competition is the severest in population that has irregular distribution. Competition is classified into intraspecific and interspecific.
2. Intraspecific competition: It is an interaction between individuals of the same species. This competition is very severe because all the members of species have similar requirements of food, habitat and pollination etc., and they also have similar adaptations to fulfill their needs.
3. Interspecific competition: It is an interaction between individuals of different species. In grassland, many species of grasses grow well as there is little competition when enough nutrients and water is available. During drought Shortage of water occurs. A life and death competition starts among the different species of grass lands.
Survival in both these competitions is determined by the quantity of nutrients, availability of water and migration to new areas. Different species of herbivores, larvae and grass hopper competing for fodder or forage plants. Trees, shrubs and herbs in a forest struggle for sunlight, water and nutrients and also for
pollination and dispersal of fruits and seeds, The Utricularia (Bladderwort) competes with tiny fishes for small crustaceans and insects.
Question 54.
Point out any five morphological adaptations of epiphytes.
Answer:
Morphological adaptations:
1. Root system is extensively developed. These roots may be of two types. They are Clinging roots and Aerial roots. Clinging roots fix the epiphytes firmly on the surface of the supporting objects. Aerial roots are green coloured roots which may hang downwardly and absorb moisture from the atmosphere with the help of a spongy tissue called velamen.
2. Stem of some epiphytes are succulent and develop pseudo bulb or tuber.
3. Generally the leaves are lesser in number and may be fleshy and leathery.
4. Myrmecophily is a common occurrence in the epiphytic vegetation to prevent the predators.
5. The fruits and seeds are very small and usually dispersed by wind, insects and birds.
Higher Order Thinking Skills (HOTs) Questions
Question 1.
Being a tropical country, India is the largest producer of delicious mangoes. These mango tree don't grow in temperate countries. Give reason.
Answer:
Mango tree show very narrow range of thermal tolerance. Hence they cannot grow in temperate countries.

Question 2.
What is cause of flag forms in trees?
Answer:
Unidirectional wind stimulates the development of flag forms in trees.
Question 3.
In the picture given below, $\mathrm{A}$ and B represents the two different biomes. What does the letter $\mathrm{C}$ denotes?
What will be its impact on the organisms in C Explain with example.
Answer:

The letter $\mathrm{C}$ denotes Ecotone - a transition zone between two different ecosystem. Those species found in the ecotone will have impact of environment of two habitats.
E.g. Owl in the ecotone area between forest and grassland.
Question 4.
Observe the tabular column and complete it using proper terms.

Answer:
$
\begin{aligned}
& \mathrm{A}=+ \\
& \mathrm{B}=\text { Commensalism } \\
& \mathrm{C}=- \\
& \mathrm{D}=\text { Parasitism } \\
& \mathrm{E}=-
\end{aligned}
$