Environmental Biology

Question 1

What is environment

Answer 1

The environment is the complex of physical, chemical, and biotic factors that act upon an organism or an ecological community and ultimately determine its form and survival

Question 2

Environmental biology

Answer 2

Is the study of biological components of the environment and its relationship with each other and with abiotic components.

Question 3

Organisational levels of the environment and definitions

Answer 3

Individual(organism) - Any organism or living thing which has its own characters in physiology, evolution and behaviour in relation to environmental factors

Population - Group of individuals of the same species, living in the same area and producing fertile offsprings through interbreeding.

Community - collection of populations of different species living in the same area
interacting with each other.

Ecosystem - collection of communities as well as the abiotic factors with
which they interact.

Biosphere - entire portion of Earth that is inhabited by life.

Question 4

Components of the environment

Answer 4

Abiotic components - non-living components. e.g: water, air, light, temperature, nutrients, sunlight, soil. usually resources are obtained from lithosphere, atmosphere and hydrosphere.

Biotic components - primary producers, consumers and decomposers

Question 5

Niche and habitat

Answer 5

Niche is the role that a particular organism plays in the ecosystem

Habitat is the physical area where a species lives

Question 6

Interactions between abiotic and biotic components of the environment

Answer 6

 Biotic-biotic interactions- e.g. competition, feeding relationships, symbiotic relationships
between individuals and species.
 Biotic-abiotic interactions- e.g. water uptake of plants from soil
 Abiotic-abiotic interactions-e.g. chemical reactions occurring in the soil.

Question 7

What are trophic levels

Answer 7

The producers and consumers in ecosystem can be arranged into several feeding groups, each known as trophic level (feeding level).

producers represent the first trophic level, herbivores represent the second trophic level, primary carnivores represent the third trophic level and top carnivores represent other levels.

Question 8

Food chain

Answer 8

A food chain is a linear sequence of organisms through which nutrients and energy pass from one trophic level to another trophic level of an ecosystem beginning with a primary producer.

Question 9

Primary production

Answer 9

is the amount of organic matter produced by autotrophs in a given area during a given period of time. (Unit: gm-2day -1or kg ha-1year -1)
ha = hectare

Question 10

3 types of food chains

Answer 10

Grazing food chains - starts with a primary producer
Detritus food chain - Starts with detritus (dead remains of an organism)
Parasitic food chains - Starts with a host organism

In a forest ecosystem, most of the energy is transmitted in detritus food chains whereas the most amount of energy is transmitted in ocean ecosystems through grazing food chains

Question 11

Food web

Answer 11

In a natural ecosystem isolated food chains does not exist

The food web is an interconnected feeding relationships in an ecosystem.

Question 12

Energy loss along food chains

Answer 12

The flow of energy along a food chain is always unidirectional.

At each trophic level in the food chain, a considerable fraction (about 90 %) of the potential energy is lost as heat and respiration. As a result, organisms in each trophic level pass on lesser energy (about 10 %) to the next trophic level than they actually receive.

This limits the number of trophic levels in any food chain to four or five.

The most ecologically efficient food chain is the shortest one.

Question 13

Ecological pyramids

Answer 13

The pyramids are a graphical representation which depicts the number of organisms, biomass and productivity at each trophic level.

The higher the steps in the ecological pyramid the lower will be the number of individuals and the larger their size.

The concept of ecological pyramid was developed by Charles Elton; these pyramids are also known as Eltonian pyramids.

Question 14

Types of ecological pyramids

Answer 14

 Pyramid of energy - represents the amount of energy at different trophic levels. As there is considerable loss of energy during the flow of energy from organism to other, the energy pyramid
always upright and vertical.

 Pyramid of numbers - The pyramid of numbers depicts the relationship in terms of the number of producers, herbivores and the carnivores at their successive trophic levels. 2 types as upright (producer, herbivore, carnivore) and inverted (host, parasites)

 Pyramid of biomass - n this pyramid there is a gradual decrease in the biomass from the producers to the higher trophic levels. 2 types as upright and inverted.

Question 15

Biome

Answer 15

A biome is a large geographical area which is classified based on the predominant vegetation adapted to that particular environment.

Question 16

Tropical forests

Answer 16

This biome is distributed close to the equator and extends to the sub equatorial areas

The average annual rainfall in tropical rain forests is about 2000 -4000 mm and in tropical dry forests it is about 1500- 2000 mm. Seasonal rainfall with a dry season of 6-7 months is prominent in the dry forests and a fairly constant rainy season is prominent in the rainforests.

average temperature of 25 -29 °C, whereas in the tropical dry forests it may reach up to 33 °C.

In tropical rainforests an emergent layer, canopy and sub canopy layers are visible. Evergreens are prominent in tropical rain forests whereas in dry forests leaves of deciduous species fall in the dry season. Epiphytes are common in this biome.

Question 17

Highest diversity of plants and animals out of all terrestrial biomes

Answer 17

Tropical forests

Question 18

Savana

Answer 18

Savanna is spread close to the equator and subequatorial areas.

The average annual rainfall in this biome is around 300-500 mm. A prolonged dry season of approximately 8-9 months is prominent. The average temperature range is 24- 29 °C. However in subequatorial areas seasonal variations may occur. Many insects (termites), lions and zebras are the common animals which are adapted with long range vision and long distance migration. Tall grass cover with scattered trees.

Question 19

Desert

Answer 19

Desert is a temperate or tropical biome

annual average rainfall is less than 3000 mm per year.The temperature varies seasonally and daily and exceeds 50 °C in hot deserts while in cold deserts it drops below -30° C. Water conservation is a prominent feature and contains many nocturnal animal species

Question 20

Adaptations of desert plants

Answer 20

Succulent plant body
Most plants have C4 pathway of photosynthesis
Deep roots in shrubs
Presence of spines and thorns
Presence of toxins in leaves

Question 21

Chaparral

Answer 21

Chaparral occurs in mid latitude coastal regions

Chaparrals receive an average annual rainfall of 300-500 mm. They experience rainy winters and dry summer. The average temperature is between 10 to 12 °C but can reach up to 40 °C.

Chaparral is vulnerable to fire caused by human activities.

Question 22

Adaptations of plants found in chaparral

Answer 22

 Seed germination occurring only after a hot fire.
 fire resistant roots.
 Uses of food stored in the fire resistant roots for resprouting after a fire.
 Quick re -sprouting enables usage of nutrients released by the fire.
 Tough evergreen leaves in woody plants to survive in droughts.

Question 23

Temperate grasslands

Answer 23

These grasslands occur under temperate climatic regimes that are intermediate to those that support forest and desert.

The average rainfall is 300 to 1000 mm per year.
During winter seasons the average temperature falls below -10 °C and in summer it is about 30 °C.

The prairie is often divided into three types according to height of the dominant vegetation—tall-grass, mixed-grass, and short-grass.

The tall-grass prairie is now an endangered natural ecosystem

Question 24

Temperate broadleaf forests

Answer 24

Distribution of temperate broadleaf forests are at mid latitudes in the northern hemisphere. The average annual precipitation is between 700 to 2000 mm.

Average temperature during winter is zero while in summer it is up to 35 °C

The dominant trees are mostly deciduous. A vertical layering (stratification) can be seen in temperate broadleaf forests. They are closed canopy layer, one or two strata of understory trees, shrub layer and herb layer. There are only few epiphytes can be found.

Question 25

Northern coniferous forests

Answer 25

Precipitation: Annual average precipitation is around 300- 700 mm and a periodic drought is also common. The temperature is -50 C in winter and 20 C0 in summer.

The northern forest is dominated by coniferous trees. They have needle like leaves that prevent high transpiration.

Question 26

Largest biome on earth

Answer 26

Northern coniferous forest

Question 27

Tundra

Answer 27

Amounting 20% of earths land surface. Alpine tundra occurs at high altitudes on mountains, while arctic tundra occurs at low latitudes.

average precipitation around 200 to 600 mm and the alpine tundra receives > 1000 mm precipitation respectively. During the winter time temperature falls below -30 C and during the summer temperature it is always less than 10 C.

A layer of permafrost which is a permanently frozen layer of soil can be seen. This permafrost layer restrict the growth of the roots of plants.

Question 28

Sri Lanka is situated in which zone

Answer 28

North-equatorial tropical zone

Question 29

Groups of ecosystems of Sri Lanka

Answer 29

Terrestrial ecosystem
Inland wetland ecosystem
Ecosystems with coastal regions

Question 30

Tropical wet low land rainforests

Answer 30

Found below 900m elevation
Annual temperature is 28 C
Annual rainfall is 2000mm-5000mm
Vegetation is filled with woody lianas .
Sinharaja, Kanneliya, Nakiyadeniya.
Animal species are Purple faces langur, Sri Lankan slender loris, Golden wet zone palm civet.
Plant species are Hora, Naa and Hal.

Question 31

Tropical montane forests

Answer 31

Elevation 1500m above sea level
Temperature is 16 C and rainfall is 2000mm.
Characterised by the short canopy of 13m. Trees with umbrella shaped rounded crowns, twisted branches and small leathery leaves which accommodates strong winds prevailing in the region.
Plant species are Keena, Walkurudu, Gal weralu.
Animal species are Sri Lankan yellow eared bulbul, Sri Lankan highland shrew, Sambar
Knuckles range, Piduruthalagala and Hakgala

Question 32

Tropical dry mixed evergreen forests / Dry monsoon forests

Answer 32

Distributed in areas below 300m altitude. Annual temperature is 29 C while rainfall is 1000mm - 1500mm. Plant species are Weera, Palu, Kaluwara. Animal species are leopard, bear and deer.
Wilpattu, Yala, Wasgamuwa, Maduru-oya, Ritigala Strict Nature reserve

Question 33

Tropical thorn shrubs

Answer 33

Found in arid lowlands. Annual temperature is 31 C while rainfall is 1000mm. Plant species are Gini, Ranawara and Heeressa. Animal species are leopard, elephant and deer. Hambantota, Mannar, Puttalam

Question 34

Savanna (Sri Lanka)

Answer 34

Periodic fires are common in this ecosystem. Plant species are Nelli, aralu, mana, iluk. Bibile, Monaragala, Mahiyanganaya, Wellawaya.

Question 35

Extensive wet patana are only found in

Answer 35

Hortan plains

Question 36

What are tussock grasses

Answer 36

Grasses found within wet patana which does not reach uptown 1m in height. e.g: Arundinella villosa, Chrysopogan nodulibarbis

Question 37

Patana

Answer 37

Wet patana are found 1500m from sea level. Rainfall is 2000mm and temperature ranges from 5-18 C. Grasses do not reach more than 1m in height and are known as tussock grasses.

Dry patana are found 500m - 1600m. Average rainfall is 1400mm - 2000mm. Temperature is 18-24 C. Grasses grow unto 1-2m in height such as Pangiri mana. Hantana, Gampola, Welimada and Haputale.

Question 38

Definition of wetlands

Answer 38

According to Ramsar Convention, wetlands are defined as areas of marsh, fen, peatland or water, whether natural or artificial, permanent or temporary with water that is static or flowing, fresh, brackish or salt, including areas of marine water the depth of which at low tide not exceed six metres.

Question 39

Sri Lanka has how many river basins

Answer 39

103 natural river basins

Question 40

Marshes and swamp forests

Answer 40

Marshes are lying low lands filled with water of surface run-off, seepage of ground water and flood of rivers. Plant species are habarala, Colocasia, Kekatiya and Pan

Swamp forest are forest vegetation inundated with water for a short amount of time. Wathurana swamp at Bulathsinhala located in the Kalu ganga basin.

Question 41

Villus

Answer 41

Flood plains of reservoirs. Vegetation contains grasses and sedges. Mahawelli flood plain, Wilpaththu national park

Question 42

Lagoons and estuaries

Answer 42

Lagoons are coastal wetlands generally separated from the sea by a sand barrier. Negambo and Bundala lagoons

Estuaries are formed in places where rivers enter the sea and does not contain a sand barrier. Maduganga, Benthota.

Question 43

Mangroves

Answer 43

Characteristics are saline/brackish water, loose soil and anoxic (low O2) conditions. Plant species are Kadol and Mas athu gas, Karan Koku and Katy-ikili
They have a thick cuticle to reflect Sunrays, Some have salt glands to secrete excess salt, They have special roots to intake atmospheric O2, They germinate while attached to the mother plant (viviparous)

Question 44

Salt marshes

Answer 44

Marshlands of arid coastal areas where soil dries up forming crystals of salts during the dry period. characterised by high wind, high temperature, low rainfall and sand blowing with salts. Plant species are Saliconia sp. Manner, Puttalum, Hambantota

Question 45

Sea grass beds

Answer 45

In large lagoons where wave action is low, shallow sea bed is accompanied by sea grasses. These are not actually glasses but called as grasses due to their shape of the leaves (Halophyla Sp, Halodule Sp). Provides breeding sites for many fish species.

Question 46

Coral reefs

Answer 46

Known as rainforests of the sea which contains calcareous structures secreted by a group of marine invertebrates. High productivity and high biodiversity of organisms which inhabit these areas. Sea turtles and dolphins often accommodate these areas. Gulf of manner, Southern cost from akurala to tangalle.

Question 47

Reservoirs

Answer 47

There are no natural lakes in Sri Lanka.
Plant species are nelum, manel and kekatiya. In addition invasive species such as japan jabara and salvinia are found as well.

Question 48

Sea shore

Answer 48

Long sea shore of Sri Lanka varies in nature. Most common is the sandy sea shore which includes high temperature throughout the year, salt spray and high winds are characteristics features. Plant species are maha rawana rewula and muhudu binthmburu

Question 49

Sand dunes

Answer 49

Characterized by the stunted and sparse vegetation found in large masses of sand. Shapes of sand dunes are determined by wind speed and direction. They are raised beaches of sand. Mullativu

Question 50

Definitions of climate change and global warming

Answer 50

Climate changes are significant long-term changes of the climate attributed directly or indirectly to human activities in addition to natural climatic variability observed over comparable time periods.

Global warming is the increase in the average temperature of the earth’s surface due to enhanced green house effect of green house gases

Question 51

Contributing factors on global warming and climate change

Answer 51

1. Increase of the emission of CO2 and other greenhouse gasses (GHG) due to human activities
   2.Deforestation and decrease of the vegetation cover of the world
   3.Destroying the large quantity of phytoplankton by UV radiation due to the deple tion of the ozone layer.

Question 52

Green house gases and method of emission

Answer 52

CO2 is the most common GHG emitted due to the burning of organic matter such as fossil fuels, burning of forests and solid waste.

CH4 is a GHG with a higher GWP. Emitted by anaerobic decomposition, enteric fermentation, cattle farming and paddy cultivation. Less abundant than CO2

N2O is a GHG with a high GWP. Emitted as a by product in fertiliser use and production, in internal combustion engines, nitric acid production and other industrial processes. Can remain in the atmosphere for a longer time period.

Manmade industrial gases, namely, Perfluorocarbons (PFCs), Hydrofluorocarbons (HFCs) and Sulfur Hexafluoride (SF6) are also considered as greenhouse gases with a very high global warming potential.

Black carbon or the carbon particles which are suspended in lower atmosphere emitted due to incomplete combustion of fossil fuels, and other organic matters. These particles are extremely small, ranging from 10 μm 2.5 μm. These Black Carbon have an enormous ability to absorb heart and it cause to increase the air temperature

Question 53

Enteric fermentation

Answer 53

natural part of the digestive process in ruminant animals such as cattle, sheep, goats, and buffalo

Question 54

Carbon sequestration

Answer 54

Forests remove carbon dioxide from the atmosphere and fix through photosynthesis (carbon sequestration). Deforestation reduce the carbon sequestration capacity, carbon capture on the planet (i.e soil carbon) and increase the atmospheric CO2 concentration.

Due to the conversion of forests lands into agricultural or farming lands such as palm oil.

Question 55

Phytoplanktons and how they contribute to prevent global warming

Answer 55

Normally the carbon absorption capacity of phytoplankton are higher than terrestrial plants. Though the phytoplankton are unicellular microscopic organism they have been distributed in large area and they were responsible for the 60%-70% of absorption of atmospheric carbon

Question 56

Effects of global warming and climate change

Answer 56

Sea level rising
Extreme weather events
Less production of foods (threat to food security)
Degradation of coral reefs
Increase in the insect population
Loos of biodiversity

Question 57

Ozone layer depletion

Answer 57

Most ozone particles are concentrated in the region of stratosphere in between 10-50 km of the atmosphere,

Naturally, the total concentration of ozone in the stratosphere remains relatively constant with the concentration of 300 to 350 Dobson Units (D.U). Ozone depletion is described when levels fall below 200 D.U
This thinning of the ozone layer refers as Ozone hole due to CFCs, MeBr, Helene and HCFC.

Effects of the Ozone Layer depletion include eye diseases, skin cancer and infectious diseases.
It is a known fact that the physiological and developmental processes of plants are affected by UV-B radiation, It directly destroyed phytoplankton which form the foundation of aquatic food webs in the sea and it cause to reduce the composition of food web in the sea ecosystem. UV-B can also cause damage to early development stages of fish, shrimp, crab, amphibians and other animals.

Question 58

Desertification

Answer 58

process of land degradation in arid, semi-arid and dry sub-humid areas resulting from various factors, including climatic variations and human activities

The main driving forces of desertification can be separated into climate variations and human activities,
Deforestation is another main factor to decertification because of it is directly influencing to reduce the rainfall, precipitation, soil humidity and water recharge of underground reservoirs

Over-exploitation of water and soil, uncontrolled mining and excessive use of agro-chemical products and as well as poor land management practices also caused to desertification.

Question 59

Effects of desertification

Answer 59

water scarcity, destroys habitats of animal and plant species and reduces agricultural activities mainly the growth of crop species., food security of the people as well as for the animals and carbon storage capacity of plants and soils will also be reduced in the long run.

Question 60

The Convention on International Trade in Endangered Species of Wild Fauna and Flora

Answer 60

CITES

The aim of CITES is to ensure that international trade of specimens such as horns and skins of wild animals and whole plant or parts of plants does not threaten their survival. e.g: skin of Sri Lankan Leopard and cycas plants

Question 61

Convention on biological diversity

Answer 61

CBD

goals include the conservation of biological diversity, sustainable use of components of biological diversity, fair and equitable sharing of benefits arising from genetic resources

Question 62

Convention on wetlands

Answer 62

Ramsar convention

Question 63

Wetlands of Sri Lanka declared as ramsar sites

Answer 63

Anawilundawa, Bundala, Kumana, Maduganga, Vankalai and Wilpattu

Question 64

International convention for the prevention of pollution from ships

Answer 64

MARPOL

Question 65

International convention for the protection of the ozone layer

Answer 65

Montreal protocol

Question 66

Convention on climatic change

Answer 66

Kyoto protocol

Question 67

Basel convention

Answer 67

The Basel Convention on the Control of trans boundary movements of hazardous wastes and their Disposal intends to protect human health and the environment against the adverse effects of hazardous wastes.

two types of wastes defined as “other wastes” such as waste containing heavy metals such as Lead (Pb) and Mercury (Hg) and wastes from hospitals which contains contaminants.

Question 68

Environmental Legislation and Policies in Sri Lanka

Answer 68

Fauna and Flora Protection Ordinance and National Environmental Act

Question 69

Biodiversity

Answer 69

Includes all forms of life on earth. Biodiversity is the variability seen among individual of all sources including terrestrial, marine and other aquatic ecosystems and its relationship with the environment. Explained under 3 levels genetic, species and ecosystems

Question 70

Basic component of biological diversity and largest scale of biodiversity

Answer 70

Genetic and ecosystems

Question 71

Values of biodiversity

Answer 71

Environmental service value - CO2 fixation through photosynthesis, nutritional cycles, water cycle, purification of water, erosion prevention and flood control

Recreational value - source of revenue (national parks, zoological gardens and botanical gardens), develops of creativity

Ethical value - right of all species live on this planet

Educational value - through the study of nematodes, rats and primates, functions of the human body has been understood and certain medicines has been devoloped. Disaster management

Socio, cultural and economic value - wetlands are sacred for aborigines of Australia, 28 species if trees are sacred for buddhists and bulls are sacred for hindus

Question 72

Threats of loss of biodiversity

Answer 72

Scientists have predicted that we are in the midst of the 6th mass extension ( most recent 1 been occurred 65 million years ago) . Extinction rate is 1000 times faster at present. Many mangroves and coral reefs has been lost and upto 50% species of cycads, conifers, mammals, birds and amphibians are facing extinction according to the IUCN red list.

Question 73

Threats to biodiversity

Answer 73

Habitat loss/ fragmentation. e.g: mass scale destruction of mangroves in lagoons of Negambo and Puttalam

Overexploitation - Kotalahimbutu, sea cucumber and fish species such as tuna and cod

Pollution - Eutrophication and acid rains

Introduction of invasive alien species - Gandapana does not allow germination and seedling growth of other plants as it produces toxins which are added to the soil through leaf litter, Gini-thana in dry pathana causes wild fires due to its dry biomass.

Climate change

Question 74

Invasive alien species

Answer 74

Invasive alien species are alien (exotic) plants and/or animals whose introduction and spread outside their natural geographic range threaten native biodiversity. Alien invasive species compete against or prey on native species which can make them extinct

Question 75

Biodiversity hot spots

Answer 75

Areas with a high concentration of endemic species facing exceptional levels of threats have been described by Myers as biodiversity hotspots. Sri Lanka together with western Ghats of India have been identified ad biodiversity hotspots of South Asian region.

Question 76

Extinction rate within the next 30 years

Answer 76

5-10%

Question 77

Extinct

Answer 77

A taxon is Extinct when there is no reasonable doubt that the last individual has died. E.g. Dodo ( Lived in Mauritius), Wooly Mammoth (Lived in North America), Legume (Crudia zeylanica)

Question 78

Extinct in the wild

Answer 78

A taxon is extinct in the wild when it is known only to survive in cultivation, in captivity or as a naturalized population (populations) well outside its natural habitat. E.g; Giant tortoise of Seychelles

Question 79

Critically endangered

Answer 79

A taxon is critically endangered when the best available evidence indicates that it is facing an extremely high risk of extinction in the wild. Marbled rock frog and maha madu

Question 80

Endangered

Answer 80

A taxon is endangered when the best available evidence indicates that it is facing a very high risk of extinction in the wild. Eg: Etha, wesak orchid

Question 81

Vulnerable

Answer 81

A taxon is vulnerable when the best available evidence indicates that it is facing a high risk of extinction in the wild. Punchi Leena and buttercup

Question 82

Endemic species

Answer 82

An endemic species is a species that is confined to a particular area or country, and not found growing naturally anywhere else in the world.
Plant species are hora and goraka
Animal species are the black ruby barb and the slender loris

Question 83

Indigenous species

Answer 83

A plant or animal species that occurs in its historically known natural
range and that forms part of the natural biological diversity of a particular geographic area.
Snake head and kithul

Question 84

Exotic (alien) species

Answer 84

A species that has been introduced from another geographic region to an area outside its natural range due to human activities. Tilapia and rubber

Question 85

Migratory species

Answer 85

Migration refers to the act of moving from one place to another in a manner that is seasonally determined and predictable.
Indian fly Cather and Indian pitta

Question 86

Relict species

Answer 86

The remnants of a once widespread species, which are now found in very restricted or isolated areas, due to fact that areas in which these species are found is lost in many parts of the world.
The Tuatara living only on a few small islands of New Zealand, Ichthyophis and Lingula found in Thambalagamuwa bay in Trincomalee

Question 87

Flagship species

Answer 87

Flagship species is a species chosen as a symbol or icon to represent an ecosystem in need for conservation. These species are chosen for their vulnerability, attractiveness or distinctiveness in order to bring about support and acknowledgement from the public at large.
Bengal tiger of India, Giant panda of china and the blue magpie of Sri Lanka

Question 88

Keystone species

Answer 88

These are species that play a very important role in the stability and functioning of a system. If that species is removed the system tends to collapse. e.g. Planktons of a pond

Question 89

Basis of conservation

Answer 89

A principal goal of conservation is to ensure the long term survival of as many species as possible. Species that are in danger of extinction have to be specially protected and steps should be taken to ensure their continued reproduction and survival. Conservation can be done in two ways.
In-situ and Ex-situ

Question 90

In-situ conservation

Answer 90

The species is protected and its reproduction facilitated in its natural habitat. Basically a large enough population and adequate, appropriate, habitat space has to be ensured. E.g. National parks such as Yala and Minneriya national parks, Forest reserves such as Kanneliya, Piduruthalagala

Question 91

Ex-situ conservation

Answer 91

The species is taken out of its natural habitats, and looked after in places where its survival and reproduction are ensured.
Zoological gardens and Botanical gardens of a country play a key role in ex-situ conservation.