NEET BIOLOGY UNIT25 ORGANISMS AND POPULATIONS

NEET BIOLOGY

UNIT25 ORGANISMS AND POPULATIONS

At various level of biological organisation macromolecules, cells,tissues, organs, individual organisms, population,communities and scosystems and biomes, complexity by investigating processes can be understood. Ecology deals with the study of interactions and interrelationships between organisms and thir environment.It is concerned with the four level of biological organisations-organisms, populations, communities and biomes. The essence of ecological understanding is to know how organisms interact with other organisms and physical environment as a group and hance behave like organised wholes i.e., population, community, ecosystem or even as the whole biosphere. This topic emphasize more on organismic and population level.

BIOLOGY FOR NEET & AIIMS

Introduction

 The term ecology was coined and described by E.Haeckel. The term ecology was first authentically used by

Reiter.

 Father of ecology – Reiter

 The term Ethology for ecology was used by – Geoffroy Hilaire

 The term Hexicology for ecology was used by – G.H. Mivart

 Study of ecology was initiated in India by – W. Dudgeon

 Father of Indian Ecology – Prof. Ram Deo Misra

 First of all term ecology was employed for study of plants – Warming

 The study of interaction or inter-relationship of organism with their environment is called ecology.

Organism Environment

 Organism and environment are always interdependent, inter related or mutually reactive.

Branches of Ecology – It is based on organism level

1. Autecology or species ecology – Study of the relation of a species with its environment is known as autecology

2. Synecology or Biocoenology or Community ecology – Study of the relation of the group of different species with their environment. Ex. Population, community, ecosystem, biome ecology.

Aims & Scope

 The main aim of ecology is to study the interrelationship between organisms. i.e., Plants, animals and environment..

 Studies like pollution, soil conservation, soil erosion, proper use of land, afforestation, control on deforestation, regulation of overgrazing, flood control, maintenance of soil fertility etc., are also done in the ecology.

 Thus, the scope of this science is very vast.

 The living world can be dealt at different level of complexities. A molecular biologists restricts itself to the level of genes & cells whereas a development biologist deals at the level of tissues, organs & organisms. Whereas an ecologist treats the living organisms largely at the level of population, community & ecosystem.

 A population is defined as a group of individuals of a species growing in a given area.

 A community, on the other hand, is collection of populations of different species growing in a given area.  The transition zone between two different communities is known as ecotone.

 A species may be defined as a uniformly inbreeding population spread over a time. Ecologically, a species is sub-divided into ecotype and the ecotypes into ecads.

Ecotype/Ecological Race/Ecospecies :

 Formed due to genotypical responce to a particular habitat.

 Genetically different but interfertile.

 Adaptations are genetically fixed and irreversible.

 Variations are not changed if different ecotypes are grown in same habitat

 Ecospecies with one or more ecotypes.

Physchrophytes :

 They are also known as hekistotherms. These plants are grown in cold soil (land). Psychrophytes are found in north and south polar regions. The plants grown at 11000 feet or above are only psychrophytes. They known as Alpines. Such plants are grown on Himalaya.

 Cold lands are physiologically dry. Plants are unable to absorb water because temperature of soil is very less, reasons are as follows -

 The viscosity of the water increase due to decrease in temperature.

 Water potential of water decreases due to low temperature.

 The permeability of plasma membrane decreases at low temperature.

 The true characters of xerophytes are found in these plants, such as small leaves, thick cuticle and very deep root system.

e.g. Rhododendron, Delphinium, Anemone, Primula, Sexifraga.

Adaptation against High pressure  In hydrothermal vents :

 No excess body cavities (swim bladder)  provide bouyancy.

 Flesh and bones are Flubby

 T.M.O-Tri methylineoxide. Binds with pressure sensitive protiens and protects their pressure inhibition.

 Serine phosphaethanol amine - protects protiens from pressure effect.

Adaptation of plants against predators :

Thorns, Hairs, Thick stem, Nectorless. Silica in grasses.

Chemicals : Cafin, Tannin, Quinin, Opium, Glycosides, Pyrethrin.

Adaptation of Animals against predators :

(i) Cryptic appearence/Camouflage.

Grass hopper-Look like green leaf.

Preying Mantis-Look like dead leaf.

 Best pH of the soil for cultivation of plant is 5.5 - 6.5

 Excess water produces salinity problem in soil.

 Calcifuge Plants  Those plants which can grow in little amount of calcium in soil (pH - 3.8 to 4.0) eg., Rhododendron, Rumax etc.

 Calcarious soil  Soil having excess of calcium carbonate.

 Alkaline soil can be corrected by adding gypsum (CaCO4) and heavy irrigation whereas acidic soil can be corrected by adding lime Ca(OH)2

 Availability of nutrients from the soil is related with pH of soil.

Literization :

In the tropical area due to high temperature, high rainfall, litter is decomposed very rapidly in A-layer. Due to

mineralization of Al and Fe are liberated in the upper layer (A-layer) of soil, colour of this soil becomes redishbrown,

this process is known as laterization and soil is literite.

Podsolization :

In temperate area temperature is low and high humidity occurs. Humus and minerals contents dissolve and

percolate with water and are leached from A layer to B layer. Due to loss of chemicals the colour of soil of Alayer

(horizon) turns to light ash colour. This process is known as podosolization and soil is known as podosols.

Gleization :

In tundra region due to low temperature and humid condition humus is formed in less quantity and moves slowly

in B-layer. So colour of B-layer becomes blue-grey due to deposition of Fe salt. This process is known as

gleization and soil is known as gleys.

BIOLOGY FOR NEET & AIIMS

 An isolated, biological entity (e.g., unicellular or multicellular) which is able to perform biological process independently

called as organism. Individual organism is the basic unit of ecological hierarchy.

Organism and its Environment

 Organism’s life exists not just in a few, favourable habitats, but even in extreme and harsh conditions, e.g., desert,

rainforests, deep ocean and other unieque habitats.

 The suitability of environment directly affect the growth of residing population and manifested in from of various

biological communities.

 Following diagrammatic representation clearly indicates the relationship between environmental conditions and its impact on population which ultimately results into different types of communities.

Responses to Abiotic Factors

 Organism cope up with the stressful conditions or possibilities to manage with the adverse situation. With following set of modification, an organism can stabilised its relationship with environment.

Regulate

 Some organisms are able to maintain a constant body temperature and constant osmotic concentration despite changes in the external environment. e.g., Thermoregulation, as human is an isothermic organism, it regulate the temperature, in summer by sweating and in winter by shivering. The proces of regulation mostly occurs in birds and higher animals.

Conform

 It is the strategy to adjustment of organisms towards environmental conditions. In this an organism control their physiology in the tune of environmental conditions. e.g., poikilotherms (i.e., an organism which fails to maintain their body temperature constant) changes their body temperature with environment e.g., fishes.

BIOLOGY FOR NEET & AIIMS

Ex.1 Plant species having a wide range of genetical distribution evolve into a local population known

(A) Ecotype (B) Biome

(E) Ephemerals

Sol. (A)

Ex.2 Biogenetic law was put forward by

The term ecology was coind by

(A) E. Haeckel (B) Charles Darwins

Sol. (A)

Ex.3 The term ‘niche’ of a species refers to

(A) Specific and habitual function

(B) Specific place where an organism lives and

perform its duty

(D) Specific function of organism

Sol. (B) : Ecological niche is specific habitat where a

specific species lives.

Ex.4 The figure given below is a diagrammatic

representation of response of organism to abiotic

factors. What do a, b and c represent respectively.

Sol. (A)

External level

Internal level

(a) (b) (c)

(A) Regulator Conformer Partial regulator

(B) Conformer Regulator Partial regulator

(D) Partial

regulator

Regulator Conformer

Sol. (A)

Ex.5 The plant of this group are adapted to live partly in

water and partly above substratum and free from

water.

Pnenumatophore roots are present in

(A) Xerophytes (B) Thalophytes

Sol. (C)

Ex.6 Population density of terrestrial organisms is

measured in terms of individual per

(A) Meter3 (B) Meter4

Sol. (D) : Population density is the total population within

a geographic entity divided by the number of square

miles of land area of that entity measured in square

kilometers square meters or square miles.

Ex.7 The concept that “Population tends to increase

geometrically while food supply increases

arithmetically” was put forward by

(A) Thomas Malthus (B) Adam Smith

Sol. (A) : It was an essay on the principles of population

by R.T. Malthus which made Darwins realise that

under intense competition, natural seletion operates.

Ex.8 Autecology is the

(A) Relation of heterogenous population to its

environment

(B) Relation of an individual to its environement

(D) Relation of a biome to its environement

Sol. (B)

Ex.9 Ecological niche is

(A) The surface area of the ocean

(B) Composed of the plants present in the soil

(D) Formed of all plants and animals living at the

bottom of a lake

Sol. (C)

SOLVED EXAMPLE

ORGANISMS AND POPULATIONS

1. The term ecology was coined by

(A) Linnaeus (B) William

2. Number of endangered species of angiosperms in

India is

(A) 487 (B) 3000

3. The carrying capacity of a population is determined

by its

(A) Birth rate (B) Death rate

4. Tetonic is the study of

(A) Earthquakes (B) Earth's crust

5. A community is defined as

(A) A group of birds

(B) A collection of species

(D) An interactive ecosystem

6. Distribution of different plant geographically is

called

(A) Allopatric (B) Sympatric

7. Group of two or more than two plant species is called

(A) Plant community (B) Animal ecosystem

8. Study of environment and animals relation

(A) Ecosystem (B) Phytosociology

9. Which of the following statements is true regarding

individuals of same species

(A) They are interbreeding

(B) They live in same niche

(D) They live in different habitate

10. Which of the following isolation is important for

speciation

(A) Seasonal (B) Tropical

11. Species are considered as

(A) Real units of classification devised by

taxonomists

(B) Real basic units of classification

(D) Artificial concept of human mind which cannot

be defined in abosolute terms

12. "Exobiology" refers to the study of

(A) Exodermis (B) Terrestrial organism

13. Y-shaped energy flow model was given by

(A) H.T. Odum (B) E.P. Odum

14. The ecological niche of population is a

(A) Geographical area that it covers

(B) Place where it lives

(D) None of these

15. Biological concept of species is mainly based on

(A) Reproductive isolation

(B)Morphological features only

(D) Morphology and methods of reproduction

16. Territoriality occurs as a result of

(A) Parasitism (B) Predation

17. In an aqueous environment, the microscopic animals

are collectively called

(A) Herbivores (B) Carnivores

18. Soil is a mixture of

(A) Sand and clay

(B) Sand and humus

(D) Sand, clay and humus

19. Clay soil is obtained

(A) In desert (B) Around ponds

20. A bird enters the mouth of crocodile and feed on

parasitic leeches. The bird gets food and crocodile

gets ribs of blood sucking leeches. Both the partners

can live independently. Such an association is

(A) Mutualism (B) Amensalism

SINGLE Exercise # 1 OBJECTIVE NEET LEVEL

BIOLOGY FOR NEET & AIIMS

1. Ruthless exploitation and pollution of the

environment has increased the magnitude of waste

materials which has disturbed the operations of all

important

(A) Biomes

(B) Ecosystems

(D) All above

2. The study of inter-relationship between living

organisms and their environment is called

(A) Ecosystem (B) Phytogeography

3. Term 'ecology' was proposed by

(A) William (B) Odum

4. Biotic potential refers to

(A) Increase of population under optimum

conditions

(B) Increase of population under given conditions

conditions

(D) Increase of population under climatic

conditions

5. E.P. Odum is a leading

(A) Bryologist (B) Physiologist

6. The term 'biocoenosis' was proposed by

(A) Tansley (B) Carl Mobious

7. Ecology takes into account only

(A) Environmental factors only

(B) Plant adaptations only

(D) All of the above

8. World environment day is celeberated on

(A) 15th March (B) 15th April

9. Ecological factors which prevent a species from

producing at its maximum rate is termed as

(A) Survival curve (B) Ecological drift

(D) None of these

10. The ecologically fixed and genetically irreversed

species are called

(A) Ecotone

(B) Ecological equivalents

(D) None of these

11. Biogenetic law was putforward by

(A) E. Haeckel (B) Charles Darwins

12. Agrostology is related with the study of

(A) Agricultural growth (B) Epiphytes

13. The plants and animals living in a given area form

(A) Biological community (B) Ecotone

14. Phytotron is a device by which

(A)Mutations are produced in plants

(B) Plants are grown in controlled environment

(D) Leaf fall occurs on abscission layer

15. Name the famous plants ecologist

(A) Jagdish Chandra Bose (B) Birbal Sahani

16. 'Eco' term refers as

(A) Biosphere (B) Environment

17. The major characteristics of the vegetation of a

locality are controlled by

(A) Man only

(B) Mainly by climate

(D) Altitude of place only

18. Ozone layer depletion or hole in ozone layer is being

found in

(A) North pole (B) South pole

19. The resource which regulates the flow of energy in

desert ecosystem is the availability of

(A) Light (B) Water

20. Which of the following ecological factor exerts a

direct effect

(A) pH (B) Topography

Exercise # 2 SINGLE OBJECTIVE AIIMS LEVEL

ORGANISMS AND POPULATIONS

1. Match the following with correct combination

Column - I Column - II

(A) Mutualism (i) Tiger and deer

(B) Commensalism (ii) Cuscuta on Cissus

(D) Predation (iv) Crab and sea anemone

(A) A - (i), B - (ii), C - (iii), D - (iv) (B) A - (iv), B - (iii), C - (ii), D - (i)

(E) A - (iv), B - (ii), C - (iii), D - (i)

2. Match the following and choose the correct combination from the options given below.

Column - I Column - II

(Population interaction) (Examples)

(A) Mutualism (1) Ticks on dogs

(B) Commensalism (2) Balanus and Chathamalus

(D) Competition (4) Epiphyte on a mango branch

(E) Predation (5) Orchid Ophrys and bee

(A) A-1, B-5, C-4, D-3, E-2 (B) A-2, B-1, C-5, D-4, E-3

(E) A-5, B-4, C-1, D-2, E-3

3. Column I represent the size of the soil particles and Column II represents type of solid components. Which of the

following is correct match for the Column I and Column IL

Column - I Column - II

(A) 0.2 to 2.00 mm (i) Slit

(B) Less than 0.002 mm (ii) Clay

(D) 0.002 to 0.02 mm (iv) Fine sand particle

(A) A - (ii), B - (iii), C - (iv), D - (i)

(B) A - (iv), B - (i), C - (iii), D - (ii)

(D) None of the above

4. Match list I with list II and choose the correct option

Column - I Column - II

(A) Pacific salmon fish (1) Verhulst-Pearl Logistic growth

(B) Nt =Noert (2) Breeds only once in lifetime

(D) dN/dt = rN (K – N/K) (4) A large number of small sized offsprings

(A) A-4, B-3, C-1, D-2 (B) A-3, B-4, C-1, D-2

(E) A-2, B-4, C-3, D-1

Exercise # 3 PART - 1 MATRIX MATCH COLUMN

BIOLOGY FOR NEET & AIIMS

1. Special kinds of roots called pneumatophores are

characteristics of the plants growing in

(A) sandy soils

(B) saline soils

(D) dryland regions

2. What is true for individuals of same species?

(A) Live in same niche

(B) Live in same habitat

(D)Live in different habitats

3. Two different species cannot live for long duration

in the same niche or habitat. This law is

(A) Allen’s law

(B) Mendel’s law

(D) Weismann’s theory

4. Which of the following is a correct pair?

(A) Cuscuta - Parasite

(B) Dischidia - Insectivorous

(D) Capsella - Hydrophyte

5. Which type of association is found in between

entomophilous flower and pollinating agent

(A) Mutualism (B) Commensalism

6. Choose the correct sequence of stages of growth

curve for bacteria

(A) lag, log, stationary, decline phase

(B) lag, log, stationary phase

(D) decline, lag log phase

7. The semilog of per minute growing bacteria is plotted

against time. What will be the shape of graph?

(A) Sigmoid

(B) Hyperbola

(D) Descending straight line

8. Mycorrhiza is an example of

(A) endoparasitism (B) decomposers

9. Diffuse porous woods are characteristic of plants

growing in

(A) temperate climate (B) tropics

10. In which one of the following habitats does the

diurnal temperature of soil surface vary most ?

(A) Shrubland (B) Forest

11. What is a keystone species?

(A) A species which makes up only a small

proportion of the total biomass of a community,

yet has a huge impact on the communitys

organisation and survival

(B) A common species that has plenty of biomass,

yet has a fairly low impact on the community’s

organisation

biomass and on other species in the community

(D) A dominant species that constitutes a large

proportion of the biomass and which affects

many other species.

12. In which one of the following pair is the specific

characteristic of soil not correctly matched ?

(A) Laterite - Contains aluminium compound

(B) Terra rossa - Most suitable for roses

(D) Black soil - Rich in calcium carbonate

13. Which one of the following pairs is mismatched ?

(A) Savanna - Acacia trees

(B) Prairie - Epiphytes

(D) Coniferous - Evergreen trees

14. Animals have the innate ability to escape from

predation. Examples for the same are given below.

Select the incorrect example

(A) enlargement of body size by swallowing air in

puffer fish

(B) melanism in moths

(D) colour change in Chamaeleon

Exercise # 4 PART - 1 PREVIOUS YEAR (NEET/AIPMT)

ORGANISMS AND POPULATIONS

1. Match mean annual precipitation in column I with the biome in column II and choose the right option.

Column I Coumn II

(i) 0-50 cm (A) Tropical forest

(ii) 50-100cm (B) Coniferous forest

(iii) 150-100 cm (C) Grassland

(iv) 50-250 cm (D) Desert

(A) (i)-D,(ii)-C,(iii)-A, (iv)-B (B) (i)-C,(ii)-A,(iii)-B, (iv)-D

(E) (i)-D,(ii)-A,(iii)-C, (iv)-B

2. Benthic organisms are affected the most by

(A) Light reaching the forest floor (B) Surface turbulence of water

3. Large woody vines are more commonly found in

(A) Temperate forests (B) Mangroves (C) Tropical rainforests (D) Alpine forests

4. Major ecological community of plants and animals extending over large natural areas is known as

(A) Bioregion (B) Biosphere (C) Biota (D) Biome

5. Which one of the following is not a method of soil conservation?

(A) Mulching (B) Overgrazing (C) Strip cropping (D) Crop rotation

6. Many fresh water animals cannot live for long in sea water mainly because of the

(A) Change in the atmosphere (B) Change in the levels of thermal tolerance

(E) Change of temperature and light

7. Some desert beetles can survive on “metabolic water”,without ever drinking liquid water which

(A) Is a breakdonw product of pyruvate inside the mitochondria, along with carbon dioxide

(B) was produced as water in the organisms they eat

(D) is absorbed from the air along with respiratory oxygen

8. Which of the following statements regarding responses of organisms to abiotic factors is false ?

(A) All birds and mammals are capable of thermoregulation.

(B) Majority of animals and nearly all plants cannot maintain a constant internal environment.

(D) Very small animals are commonly found in polar regions ar they have to spend less energy to generate body

heat.

(E) Diapause is a stage of suspended development seen in zooplanktons.

9. The animals that rely on the heat from environment than metabolism to raise their body temperature are, in strict

sense, called

(A) Ectothermic (B) Poikilithermic (C) Homeothermic (D) endothermic

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