The 6 The 6 th th International International Junior Science Olympiad Junior Science Olympiad Training Programme Training Programme

SURVIVAL IN THE ENVIRONMENT

Dr. K.M. Leung

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Notes to Teachers Notes to Teachers

• Adaptation ­ physical, behavioural and physiological adaptation (0.5 hr)

• How adaptation helps animals survive (0.5 hr) • Examples of adaptations of different animals in harsh

environments (e.g. desert, polar region) • Defences against predators • Osmoregulation in freshwater and marine fish

• Environment (1 hr) • Habitat • Effects of physical environment on organisms (light,

temperature, gases, water, wind, topographical factors and edaphic factors)

• Effects of living environment on organisms (species, population, community, niche, biome, biosphere, symbiosis)

Learning Objectives: Learning Objectives:

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Notes to Teachers Notes to Teachers

• Physical conditions affecting aquatic animals • Dissolved oxygen, temperature salinity, acidity, turbidity,

water current, substrate (0.5 hr) • Method of study of a particular environment

• Line and belt transect method (0.5 hr)

Learning Objectives (cont’d) Learning Objectives (cont’d)

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Learning Outcomes Learning Outcomes

• Describe the cell theory • Appreciate the advances in technology contribute to the development of the cell theory

• Relate the significance of different chemicals found in a cell to life

• Explain the properties and functions of the cell membrane using the fluid mosaic model

• Identify different organelles and describe their functions • Compare the structure between plant and animal cell • Compare the structure between prokaryotic and eukaryotic cells

• Arrange the levels of organization in a living organism in the correct order

After learning the topics students will be After learning the topics students will be able to: able to:

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ECOLOGY ECOLOGY the study of the inter­relationship of organisms and their environment

ECOSYSTEM ECOSYSTEM a stable, self­perpetuating dynamic system formed by interaction among living and non­living components through which energy flows and

nutrients cycle 5

A. ADAPTATION Adaptation is the modification of an organism in its anatomical structure, physiological process or behavioural trait through the process of natural selection (evolution) such that it increases the chances of survival and reproductive success of the organism.

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ancestral amphibian

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Limbs for flight

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1. Physical Adaptation nCertain body parts of an organism become modified to help it to survive in its habitat, e.g. skin color, shape, body covering.

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2. Behavioural Adaptation n It is the special ways that an organism behaves to survive in its habitat, e.g. cryptic hehaviour.

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3. Physiological Adaptation n It is the biochemical reactions or processes performed by the systems in an organism, e.g. making venom, secreting slime, being able to keep a constant body temperature.

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B. B. HOW ADAPTATION HOW ADAPTATION HELPS ANIMALS HELPS ANIMALS SURVIVE SURVIVE

1. Adaptations of Desert Animals nProblems faced in a desert: desiccation high temperature

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a) Camels a) Camels

• kidneys produce very concentrated urine

• humps store fatty tissue • metabolic water produced during respiration

• woolly coat reduces heat gain

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b) Other desert animals b) Other desert animals

• long appendages to dissipate body heat

• active only at dusk and at dawn

• hide in burrows or caves during day time

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2. Adaptations of Animals in 2. Adaptations of Animals in Polar Regions Polar Regions

nProblems faced in the polar region: the temperature is too low (both on land and in the sea)

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a) Polar bears a) Polar bears • thick layer of fur for insulation • white fur as camouflage • blubber (thick fat layer) for insulation and energy reserve

b) Polar fish, e.g. Arctic cod b) Polar fish, e.g. Arctic cod • antifreeze proteins and glycoproteins lower the freezing point of water to prevent the formation of ice crystals in the bodies of polar organisms

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3. Defences against Predators a) Camouflage / Cryptic coloration n body colours and patterns that allow them to blend into the background

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b) Warning coloration nAnimals that are toxic to predators have colours patterns that serve as warning to would­be predators.

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c) Protective armour

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4. Osmoregulation a) Freshwater fish n The salt concentration of freshwater is lower

than that of the fish body fluid.

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b) Marine fish n The salt concentration of seawater is higher than that of the fish body fluid.

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C. ENVIRONMENT n Environment is all the external conditions and factors, living and nonliving (chemical and energy), that affect an organism.

n Habitat is a place with a particular set of abiotic factors (physical factors) in which organisms live.

e.g. oceans, freshwater stream, estuary, woodland, grassland. A habitat can be subdivided into numerous microhabitats, each with its own particular conditions (micro­climate), e.g. wood crevices, rock pools.

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1. Physical Environment n physical and chemical factors (abiotic factors) affecting an organism

a) Climatic factors i) Light 1) Light intensity – varies with seasons, latitude and weather conditions § Effects on plants ~ necessary for photosynthesis. ~ shady plants with larger leaves sunny plants ~ High intensity of ultra­violet light may kill phytoplankton near the water surface.

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u Effects on animals l High intensity of ultra­violet light may cause skin cancer in animals.

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2)Photoperiod – the duration of daily exposure to light § Effects on plants ~ flowering and fruiting of some plants. ~ breaks seed dormancy

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u Effects on animals l Change in photoperiod indicates the change of season. Photoperiod getting shorter and shorted means the coming of winter.

l It affects the reproduction, migration and seasonal colour change of birds and hibernation of animals since these activities in animals may follow the change of season.

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3) Presence of light § Effects on plants ~phototropism in root and shoot.

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u Effects on animals l Some animals are active under dim light condition, i.e. at night. They are called nocturnal animals, e.g. many mammals.

l Some animals are active in day time. They are called diurnal animals, e.g. birds.

l Some animals are active at twilight (during dusk and dawn), they are called crepuscular animals, e.g. bats. 28

ii)Temperature – affects the enzyme activities and thus the metabolic activities of organisms.

1) Effects on plants ~ temperature decreases from the equator towards the North and South Pole

~ Together with different amount of rainfall, different biomes will be formed at different latitudes.

~ Temperature also falls with increase in altitude.

~ The same trend of change in biomes along the latitudes may also be observed with increase in altitude.

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BIOMES OF THE WORLD

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l Temperature falls with increase in altitude. l The same trend of change in biomes along the latitudes may also be observed with increase in altitude.

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2) Effects on poikilotherms ~ Within 5 – 35 o C, metabolic rate increase with increase in temperature

~ At higher temperature, the poikilotherms will hide in burrows or under shady area to prevent overheating. Some poikilotherms may undergo aestivation.

~ At low temperature, some poikilotherms need to hibernate.

3) Effects on homoiotherms ~ Some homoiotherms living in hot area are very small and have large surface area to volume ratio for promoting heat loss, e.g. kangaroo rat.

~ Some mammals may have a pair of large ears for greater heat loss.

~ Some mammals may hibernation in winter while birds migrate to warmer area to breed and feed.

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iii) Gases 1) Carbon dioxide ~ dissolves in water affecting the pH of soil water and in turn affects plant growth

~ combines with calcium to form bones and shells of some animals

2) Oxygen ~ essential in aerobic respiration of organisms ~ Terrestrial organisms will not be affected since the atmosphere has a high concentration of oxygen (21%).

~ Aquatic animals may suffocate or need to escape if the dissolved oxygen content of water is too low.

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iv) Water 1) Effects on the distribution of plants § Algae are restricted in water because they lack cuticle.

§ Mosses and ferns are restricted in moist area because they need water for transferring gametes.

§ Gymnosperms and Angiosperms are fully adapted to the terrestrial environment because both of them can transfer their gametes without using water. The gametes are transferred via wind or insects.

§ Availability of water can affect the type of dominant vegetation in a place.

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l Availability can affect the type of dominants vegetation in a place.

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2) Effects on the distribution of animals ~ Animals must require a water source for survival. ~ Animals that not well adapted to dry condition on land are restricted to moist areas (e.g. near water, in damp place, in damp burrows)

e.g. earthworms, woodlice, amphibians

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~ Some desert animals can still survive without drinking water for a long period of time because they can use the metabolic water obtained from the oxidation of fats stored inside their bodies, e.g. camels.

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v) Wind ­ Wind affects transpiration of plants by removing moist air from around the leaves,

­ Trees in persistently windy positions may grow poorly as a result of high transpiration.

­ Strong wind may break branches of trees.

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b) Topographical factors (altitude, slope and aspect)

i) Altitude ­ Temperature decreases with higher altitude.

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Mount Kilimanjaro Mount Kilimanjaro

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ii) Slope l influences water movement and the amount of erosion l Trees are more difficult to establish on slope that are too steep.

l Water drains away more quickly on steep slope, thus reduces the water availability of soil.

l Soil erosion is more serious on steep slope, plants of large size cannot grow on thin layer of soil.

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c) Edaphic factors (soil & its texture, nutrient status, acidity and moisture content)

Soil provides food and shelter for bacteria, fungi, many invertebrates (e.g. worms, insects, mites).

Soil provides anchorage, water, mineral salts for plants

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2. Living Environment a) Species is a group of organisms that are capable of interbreeding to produce fertile offspring.

b) Population is a group of individuals of the same species living together in a particular area at the same time and interbreeding among themselves.

c) Community consists of all the organisms (plants and animals) living within a defined area or habitat interacting with one another.

e.g. forest community – dominant trees, shrubs, herbaceous plants, climbers and creepers and a variety of animals (squirrels, caterpillars, plant bugs, etc.)

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d) Niche Niche refers to the way of life of an organism in its natural surroundings, including its feeding habit and functional role in the ecosystem.

e.g. detritivores, herbivores, carnivores (different stages of an organism may have different niche.)

Horses, cows, and giraffes are herbivores. Horses and cows have similar niches in their natural habitats and would compete with the other. Cows and giraffes occupy different niches.

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e) Biosphere is the part of the Earth and its atmosphere in which organisms live and interact with one another and with their nonliving environment.

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f) Biome is the terrestrial portion of the biosphere which are large regions characterized by distinct climate and specific life­forms (especially vegetation) adapted to it.

e.g. tropical rain forest, savannah, desert

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nQ. Construct a concept map to illustrate the interrelationship among biosphere, biome, ecosystem, community and population.

Biosphere

Biomes Ecosystems Communities

Populations

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g) Symbiosis is any intimate relationship or association between members of 2 or more species. Each of the two interacting species either benefited or harmed.

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i) Competition ­ 2 or more individual organisms of the same species or from different species attempting to use the same scarce resource in the same ecosystem.

n Plants: compete for light, water, minerals, spaces

n Animals: compete for food, shelters, mates

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1)Intraspecific competition competition between members of the same species for the same resources

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2)Interspecific competition n Competition between members of 2 or more different species for any limited resources

n commonly used resource abundant Æ share

n resources limited Æ the more the niches of 2 species overlap, the more they compete with one another

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n With significant overlapping of niches, one of the competing species must migrate to another place if possible shift its feeding habits or behaviour through natural selection and evolution suffer a sharp population decline become extinct in that area

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Paramecium

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ii) Predation n Predator attacks and kills prey for food. n feeding relationship between two organisms n natural method of quality control, diseased / less fit individuals are killed out

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Predator­prey interaction between a lynx and a snowshoe hare

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iii) Commensalism n interaction between organisms of different species in which one type of organisms benefits and the other type is neither having benefits nor harmed

n e.g. epiphyte

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iv) Mutualism is the type of species interaction in which both participating species benefit from each other.

e.g. lichen – an association of algae and fungi

Fungi

provides a habitat for algae; provides moisture, mineral nutrients; protects against desiccation

provides sugars as food

Algae

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v) Parasitism is the interaction between species in which one organism (parasite) getting benefits from the other organism (host) and causing harmful effects to the host, e.g. tapeworm.

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D. PHYSICAL CONDITIONS AFFECTING AQUATIC ANIMALS

1.Dissolved Oxygen (DO) n fast running stream – high DO content n stagnant water – low DO content

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n Some species must need plenty supply of dissolved oxygen while some species can tolerate a highly anaerobic condition.

n Some animals may be able to extract enough oxygen in water even though the DO level is low.

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2. Temperature n Temperature affects the enzyme activities and thus the metabolic activities of organisms.

n water temperature increases, metabolic rates of aquatic animals increase; hence their oxygen demands also increase

n water temperature increases, solubility of oxygen in water decreases; hence less dissolved oxygen in water

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3. Salinity n Salinity is the concentration of halides (fluoride F­, chloride Cl­, bromide Br­, iodide I­) in water.

n Freshwater < 0.05% n Brackish water 0.05 – 3% n Saline water 3 – 5% n Brine > 5%

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4. Acidity (pH) n If the water is too acidic (too much carbon dioxide is present), the growth rate of molluscs will be retarded because the formation of shells of them is more difficult.

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5. Turbidity n Turbidity is high if the amount of suspended solid in water is large. The suspended solid may clog the gills of aquatic animals making them difficult to breathe.

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6. Water Current n Water current brings along oxygen, food particles, minerals, and carries away wastes.

n Strong water current may cause dislodgement of some organisms from their habitats and prevent the settlement of planktonic larvae onto suitable substratum.

n Water current may help the migration of fish and dispersal of gametes and larvae.

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7. Substrate a) Soft substrate e.g. mud, sand n Animals may burrow into mud or sand to get shelter so as to stay away from enemies. They may avoid desiccation when the tide is out, e.g. clams, crabs.

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b) Hard substrate e.g. rocks, boulders n Animals can find shelters in the crevices of rocks. n Some animals have special means to attach themselves onto the rock surface.

n Examples: Barnacles and oyster cement themselves onto the rock surface.

n Chitons, limpets, snails have sucker­like foot to attach onto the rock surface and move around to feed.

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E. E. METHOD OF STUDY OF A METHOD OF STUDY OF A PARTICULAR ENVIRONMENT PARTICULAR ENVIRONMENT

1.Studying the Distribution of Organisms a) Line transect method n A transect line is laid on the study site. n Organisms touching the line along each ½ m or 1 m interval are recorded.

n This method only shows the distribution of the organisms without knowing their abundance but it gives a quick impression of the dominant species.

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n n Transect Transect – a line chosen for study n n Quadrat Quadrat – a square frame made of wood or metal of size ½ m x ½ m or 1 m x 1 m to enclose a sampling area

b) Belt transect method This is a quantitative account of the This is a quantitative account of the organisms present along the transect line organisms present along the transect line to examine the distribution and abundance to examine the distribution and abundance of organisms. of organisms.

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1 2 3 4 5 6 7 8 9 10 11 12

X 4 8 15 14 13 12 10 6 4 4 4 0

Y 10 13 4 20 0 10 4 0 16 12 2 10

•y­axis divided into sections for each organism

•frequency (no.) of each organism is plotted along its own x­axis

•frequency is divided by 2, half of it is plotted above the x­ axis and half below it

•the points are jointed together to form a polygon symmetrical about the x­axis 76

c) Measurement of animal populations i) Direct counting n useful for sedentary animals n numbers of animals present are count directly

n Usually a small sample is counted and multiply up to give the full number.

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ii) Mark­release­capture n useful for active animals n large number of the animals are captured and marked

n then released back into their habitats n second capture carried out later n recordtotal number of animals captured and the number of animals that are marked are ed

n estimate the population using the Lincoln index:

no. marked in whole population size of whole population

No. of marked in the second capture Total no. of animals caught in the

second capture

=

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2. Measuring the Physical Factors a) Temperature n Record with a thermometer. n Allow the thermometer to stabilize before taking the temperature.

n b) pH of water n Record with pH paper or pH meter.

n c) Salinity of water n Collect a water sample and measure the salinity with a refractometer.

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d) Relative humidity nMeasure relative humidity with the whirling hygrometer (wet bulb and dry bulb thermometers). nRecord temperatures of the wet and dry bulb thermometers. n Calculate the difference and read against the scale to get the relative humidity.

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e)Wind speed n Measure wind speed by holding the hand­held wind­meter against the wind.

f) Wind direction n Measure wind direction with a wind gauge.

8)Light intensity n Measure the light intensities of different micro­habitat with a light probe.

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Report writing Report writing nAbstract n Introduction nMaterials & Methods nResults nDiscussion nConclusion nReferences

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References for further study: References for further study:

n Biology (6th ed.); EP Solomon, LR Berg & DW Martin; Thomas Learning Inc.; 2002

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