class: name: date: 20 ecosystems - shared learning resources -...

Class: Name: ( ) Date:

New Senior Secondary Mastering Biology Oxford University Press 2014 (Second Edition)

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20 Ecosystems

20.1 Basic concepts of ecology (Book 3, p. 20-3)

A What is ecology? (Book 3, p. 20-3)

� Ecology (生態學) is the study of the interrelationships between (1) _______________ and

those between organisms and the (2) _______________ _______________.

B Levels of organization in ecological studies (Book 3, p. 20-3)

� Ecological studies can be carried out at different levels:

Level of organization Description

(3) _______________ (種) It is the basic unit of classification of organisms. Individuals of

the same species can interbreed to reproduce fertile offspring.

(4) _______________ (種群) It refers to a group of organisms of the same species living in

the same habitat.

(5) _______________ (群落) It refers to all the populations of different species living in the

same habitat.

(6) _______________ (生態系)

It is a natural unit of all the organisms in a community and the

physical environment. Their interactions make the unit

self-supporting, stable, and yet dynamic.

Biome (生物群系)

It is a complex of communities that occupy a large

geographical area, and is characterized by a dominant type of

(7) _______________.

Biosphere (生物圈) It refers to the entire space on the earth’s surface where

organisms exist.

� The (8) _______________ is the basic unit in ecological study as it includes communities of

organisms interacting with their physical environment.


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C Basic features of an ecosystem (Book 3, p. 20-5)

� Ecosystems have the following three basic features:

Feature Description

Interactions of organisms

with one another and with

the physical environment

Organisms interact with one another (e.g. through feeding), and

show different (9) _______________ in order to live in specific

environments.

Flow of energy

Energy flows from one organism to another in the form of

(10) _____________, and is eventually lost as (11) ____________.

Energy cannot be cycled. The (12) _______________ provides a

constant supply of energy into the ecosystem.

Cycling of materials

Useful elements such as carbon are not lost from an ecosystem.

They are (13) _______________ between organisms and their

physical environment through different processes.

D Major types of ecosystems in Hong Kong (Book 3, p. 20-6)

▲ (14) _______________ _______________ ▲ (15) _______________ _______________

▲ (16) _______________ ▲ (17) _______________ ▲ (18) _______________

energy flow

cycling of materials

sun

light energy materials

organisms

heat energy

physical environment

▲ Flow of energy and cycling of material in an ecosystem

Key:


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20.2 Abiotic factors of an ecosystem (Book 3, p. 20-9)

� Organisms make up (1) _______________ (生物的) components of ecosystems. The organisms

are affected by (2) _______________ _______________ (非生物因子), which are the non-living

components of the ecosystem.

1 Temperature

� (3) _______________, such as mammals and birds, can maintain a relatively constant body

temperature. They can remain active in a (4) _______________ (wider / narrower)

temperature range.

▲ The ears of the African Elephant provides a

large (5) ______________ ____________

to promote heat loss.

▲ Seals have a thick layer of

(6) ______________ _____________ to

reduce heat loss.

� (7) _______________, such as reptiles, amphibians and fish, cannot maintain a relatively

constant body temperature. They are restricted to areas with a (8) _______________ (wider /

narrower) temperature range.

� Some mammals, reptiles and amphibians (9) _______________ during the winter to slow

down their metabolism. Some animals like butterflies may (10) _______________ to warm

places during the winter.

� Many plants can only grow within a certain range of temperature.

� Temperature affects flowering.

2 Light

� (11) _______________ (晝行的) are active during the day and rest at night.

(12) _______________ (夜出的) animals are active at night and rest during the day.

◄ Bushbabies (灌叢嬰猴)

are nocturnal. They have good night vision.

◄ Bats determine the position of obstacles or prey by locating the echoes of their sounds.


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� Some animals living in total darkness may be able to emit light to help them see or attract their

prey.

� Light intensity affects the rate of (13) _______________ in plants.

� Day-length affects the flowering of plants.

3 Rainfall and humidity

� Animals living in dry areas develop various mechanisms to retain

or obtain water.

� Kangaroo rats stay in underground holes during the day to

minimize the evaporation of water by (14) _______________.

� Leaves of some (15) _______________ (旱生植物) are modified to

form (16) _______________ to reduce water loss by transpiration.

▲ Cacti have spine-like leaves

4 Wind speed

� On rocky shores, strong winds may generate strong

(17) _______________ that can wash organisms away. Some

organisms have muscular feet that attach them firmly onto rocks.

� Wind is a medium for (18) _______________ of flowers and

(19) _______________ of seeds.

� In windy conditions, the rate of transpiration of plants

(20) _______________ (increases / decreases).

▲ Limpets (帽貝) have

muscular feet

5 Water current

� Strong water currents may wash organisms away. Organisms may have a (21) _____________

body or have their fins developed into suckers to avoid them from being washed away.

6 Salinity

� Salinity (鹽度) refers to the concentration of dissolved salts or ions in water. It directly

determines the (22) _______________ _______________ and hence the availability of water

and minerals to organisms.

◄ Certain mangrove plants possess

(23) ____________ _____________ to

remove excess salt.

salt crystals


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7 Oxygen concentration

� The concentration of oxygen in aquatic habitats depends on a number of factors:

Factor Effect on oxygen concentration Reason

Temperature Oxygen concentration (24) ____________

when temperature increases.

Increase in temperature

(25) ____________ the solubility

of oxygen in water.

Water

current

Oxygen concentration (26) ____________

when water flows more quickly.

Splashes increase the contact of

oxygen in the air with water.

Organic

matter

Oxygen concentration (27) ____________

in the presence of organic matter.

The decomposition of organic

matter uses oxygen.

� The concentration of oxygen in soil air depends on the (28) _______________ of the soil

particles. In soil with small particles, the air spaces among the particles are

(29) _______________ and the concentration of oxygen is (30) _______________.

� Organisms living in habitats of low oxygen concentration show different adaptations so that

they can obtain sufficient oxygen.

◄ Some mangrove trees have (31) _______________ roots

which grow above the water-logged soil to obtain oxygen. There

are also many (32) _______________ on the roots that allow

gas exchange to take place.

8 Soil properties

� Soil properties affect the types of plants present, and hence the types of animals living in the

soil.

� Soil pH: Most plants prefer soil of pH 5.5 to 7.

� Soil particle size: In silt (粉砂土) and clay (黏土), soil particles are (33) _______________

than those in sand. They can hold (34) _______________ better and contain more

(35) _______________. Different types of plants require soil of different composition to grow.

� Amount of humus (腐殖質): Humus is formed from the (36) _______________ of organic

matter. It is the major source of nutrients in soil. It can also hold a large amount of

moisture.


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20.3 Biotic community of an ecosystem (Book 3, p. 20-15)

A Common terms used to describe the biotic community (Book 3, p. 20-15)

1 Niche and habitat

� A (1) _______________ is the place where an organism lives.

� A (2) _______________ (生態位) is the role that an organism plays in its environment. It is

determined by the (3) _______________ range in which the organisms live, the type of food

they eat, and the (4) _______________ they occupy.

2 Species diversity

� (5) _______________ _______________ (物種多樣性) refers to the variety of organisms that

make up a community. It is determined by the (6) _______________ _______________

(i.e. the number of species in the community) and the (7) ______________ _______________

of different species (i.e. the proportion of different species within the community).

� Example:

community 1 community 2

Both communities have the same species richness because they are both made up of four

different species (A, B, C and D). However, the four species are present in similar

(8) _______________ in community 1 and we can easily notice the four different species.

Therefore, the species diversity of community 1 is (9) _______________ (higher / lower)

than that of community 2.

3 Dominant species

� Among the different species in a community, usually a few species exert a strong influence on

the composition and diversity of the community. These species are called the

(10) _______________ _______________ (優勢種).

� In terrestrial ecosystems, the dominant species are usually the commonest types of plants.

A

B

C

D


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� Organisms in a community interact with one another in different ways. They may gain benefit

(+), be harmed (–) or not be affected (0).

1 Predation (+ , –)

� In (11) _______________ (捕食), the predator (捕食者) gains benefit (+) while the

(12) _______________ (獵物) is harmed (–).

� The change in the population of the predator is always (13) _______________ behind that

of the prey.

popu

latio

n s

ize prey

predator

I II III

Period I:

An increase in the population of the prey results

in a corresponding increase in the population of

the predator because more food is available for

the predator.

Period II:

The population of the predator increases rapidly

because of an abundant food supply. The

predators eat up the prey so quickly that the

population of the prey decreases.

Period III:

The population of the predator decreases

because its food supply becomes limited. This allows the population of the prey to recover.

time

2 Competition (– , –)

� All organisms involved in (14) _______________ (競爭) are harmed (–).

� Two major types of competition:

- (15) _______________ competition (種內競爭) among organisms of the same species

- (16) _______________ competition (種間競爭) among organisms of different species.

� Intraspecific competition is usually (17) ______________ (more / less) intense because

individuals of the same species have the same (18) _______________.

3 Symbiosis

� Three common types of (19) _____________ (共生):

- (20) _______________ (偏利共棲) (+ , 0)

- (21) _______________ (互利共生) (+ , +)

- (22) _______________ (寄生) (+ , –).

� In parasitism, the (23) ____________ (寄生物) lives

on or inside the (24) ___________ (寄主), obtaining

benefits from the host and causing it harm.

▲ Mutualism between algae and fungi in lichens

▲ Dodder (parasite) winding around its host plant

B How do organisms in a community interact with one another?

(Book 3, p. 20-16)


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� The series of changes in the composition of a community over a period of time is called

(25) _______________ _______________ (生態演替).

� During the process, organisms modify their environment in ways that allow other species to

come in and (26) _______________ them. The process repeats and species diversity

progressively (27) _______________ (increases / decreases) to a maximum, when a

(28) _______________ _______________ (頂級群落) is reached.

1 Primary succession

� Primary succession (原生演替) starts with the colonization of a (29) _______________ (光禿)

area where there were no soil or organisms before.

� The process of primary succession:

i Barren rocks are formed from cooled lava after a

volcanic eruption. Lichens first colonize the area and

form the (30) _______________ _______________

(先鋒群落). Organic matter accumulates and the rocks are

broken up into smaller pieces, forming

(31) _______________.

ii Mosses, ferns and grass start to grow. They become

established over most part of the rocks and become the

(32) _______________ species. They provide food and

shelter for plant-eating animals.

iii Dead, decaying plants and animals, as well as animal

waste form (33) ______________ which further enriches

the soil. The soil becomes thick enough for the growth of

(34) ______________ (灌木) which grow over the grass

and ferns. More animals are attracted to the habitat.

iv Finally, the soil becomes thick and rich in

(35) _______________. It can support the growth of

(36) _______________ which grow over the shrubs. The

habitat becomes a woodland that attracts increasing

number of animals. A (37) _______________

_______________ is reached.

C What is ecological succession? (Book 3, p. 20-20)

lichens barren rock

mosses grass and ferns

thin layer of soil

shrub grass thicker layer of soil

tree


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2 Secondary succession

� (38) _______________ _______________ (次生演替) takes place in areas that once supported

life but are now barren.

� As (39) _______________ is already present, secondary succession does not need the pioneer

community of lichens.

� Secondary succession usually develops more quickly because (40) _______________, roots

and underground vegetative organs of plants may still survive in the soil.

▲ Secondary succession on a hillside after a hill fire

20.4 Energy flow in an ecosystem (Book 3, p. 20-25)

A How does energy flow in an ecosystem? (Book 3, p. 20-25)

○1 In most ecosystems, energy

ultimately comes from the

(1) _______________.

○2 Light energy is captured by plants through

(2) _______________, and is then converted to

(3) _______________ energy in plants.

○4 Energy is lost through (5) _______________ (排泄),

egestion, and in the form of (6) _______________

body parts. It is also lost in the form of heat during

(7) _______________.

○1

○2

○3 ○3

○4 ○4

○4 ○4

○3 Energy flows in the form of

(4) _______________ in an

ecosystem.


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B What are food chains and food webs? (Book 3, p. 20-26)

1 Food chain

� A (8) _______________ _______________ (食物鏈) shows the sequence of organisms in a

particular feeding relationship. It also shows the direction of (9) _______________ and

(10) _______________ flow from one organism to another.

� Organisms may act as (11) _______________ (生產者), (12) _______________ (消費者) or

(13) _______________ (分解者), depending on their roles in energy flow.

Role of organism Description

Producers � Can make their own food (i.e. (14) ______________ (自養生物))

� Most of them are photosynthetic

Consumers

� Feed on other living organisms (i.e. (15) ______________ (異養生物))

� Consumers feeding on plants are called (16) _______________

(草食性動物). Those feeding on animals are called (17) ____________

(肉食性動物)

� Can be classified into three types depending on their positions in the

food chain:

- (18) _______________ consumers (初級消費者): feed on producers

- secondary consumers (次級消費者): feed on primary consumers

- (19) _______________ consumers (三級消費者): feed on secondary

consumers

Decomposers

� Feed on dead, non-living organic matter (i.e. (20) _______________

(腐生生物))

� Break down (21) ______________ matter into (22) ______________

nutrients

� Important in material (23) _______________

� Usually not shown in food chains

grass

(24) ___________

rabbit

(25) ____________

consumer

fox

(26) ____________

consumer

tiger

(27) ____________

consumer

▲ An example of a food chain and the role of organisms in the food chain

role:


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2 Food web

� A (28) ______________ ______________ (食物網) shows all the possible (29) _____________

relationships among selected organisms in an ecosystem.

▲ A food web in a forest

C Trophic levels and energy flow (Book 3, p. 20-29)

� A (30) _____________ _____________ (營養級) is the feeding level of an organism, depending

on its position in a food chain. Energy flows from lower to higher trophic levels.

Organisms in a food chain

Role in food chain Trophic level Direction of energy flow

Tiger (31) _______________ consumer

(carnivore)

Fourth

Fox Secondary consumer

(carnivore)

Third

Rabbit Primary consumer

(herbivore)

Second

Grass (32) _______________

(usually a plant or an alga)

First


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� Energy is (33) _______________ in several ways when it is transferred from one trophic level

to another. Therefore, (34) ______________ (more / less) energy is available to organisms at a

higher trophic level.

� With fewer trophic levels, less energy is lost. Therefore, a shorter food chain can support

(35) _____________ (more / less) consumers at higher trophic levels than a longer food chain.

1 Only a small proportion of grass is eaten.

2 About 30% of energy obtained from grass is lost when undigested and unabsorbed materials are

passed out as (36) _____________.

3 About 60% is lost as

(37) ____________

during respiration or when it is used to support body functions.

4 Some energy is lost through

(38) _____________

products, e.g. urea.

Less than 10% of the energy obtained from grass is used to make body material, which can be transferred to the next trophic level.

▲ The ways of energy loss from one trophic level to another

▲ Energy flow along trophic levels in an ecosystem


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D What are ecological pyramids? (Book 3, p. 20-31)

� Ecological pyramids (生態錐體) are graphical representations showing the amount of energy

flowing within ecosystems.

1 Pyramid of numbers

� A (39) _____________ _____________ _____________ (數量錐體) is a bar diagram showing

the number of organisms at each trophic level. The (40) _______________ of each bar is

proportional to the number of organisms at that trophic level.

� In some cases, an inverted pyramid of numbers is observed:

Example 1:

In a food chain starting with a tree, the tree

can support a large number of herbivores

(e.g. caterpillars).

Example 2:

For parasites living on the body surface of an

organism, the parasites (e.g. fleas) are often

much smaller than the host and the host can

support the lives of many parasites.

▲ An inverted pyramid of numbers for organisms living on an oak tree

▲ An inverted pyramid of numbers for fleas living on a dog

parasites

host

1200 fleas

1 dog

tertiary consumer

secondary consumers

primary consumers

producers

1 eagle

3500 toads

70 000 grasshoppers

5 800 000 grass plants

▲ An pyramid of numbers on a grassland

primary consumers

secondary consumers

producer 1 oak tree

10 000 caterpillars

6 birds


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2 Pyramid of biomass

� A pyramid of biomass (生物量錐體) is a bar diagram showing the total (41) _______________

_______________ of organisms at each trophic level in a given unit area at a particular

point of time.

� The case of an inverted pyramid of numbers can be presented as a normal pyramid if a

pyramid of biomass is used.

� A pyramid of biomass may become inverted when organisms at a lower trophic level have a

much higher (42) _______________ rate than organisms at a higher trophic level.

3 Limitations of ecological pyramids

� The (43) _______________ _______________ of an organism may vary with the type of food

eaten. Some organisms may also change their (44) _______________ as they grow.

� The energy flow to (45) _______________ is not considered.

20.5 Material cycling in an ecosystem (Book 3, p. 20-35)

A The carbon cycle (Book 3, p. 20-35)

� Carbon in producers is transferred to consumers in the form of (1) _______________ matter

by (2) _______________.

� Organic matter in dead bodies or waste material of organisms is used as food by

(3) _______________.

� Carbon dioxide is released into the atmosphere and oceans through:

� (4) _______________ of organisms,

� decomposition of organic matter by (5) _______________,

� combustion of (6) _______________ _______________, and

� reactions of carbonates in (7) _______________ (石灰石) with acids in water.

� Carbon dioxide in the atmosphere and oceans is returned to the bodies of producers when

the producers carry out (8) _______________.

primary consumers

producers

birds (20 g/m2)

caterpillar (80 g/m2)

oak tree (1600 g/m2)

▲ An upright pyramid of biomass

secondary consumers primary consumer

producer photosynthetic phytoplankton (4 g/m

2)

zooplankton (21 g/m2)

▲ An inverted pyramid of biomass


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▲ The carbon cycle (碳循環)

B The nitrogen cycle (Book 3, p. 20-37)

� Nitrogen in producers is transferred to consumers in the form of (9) _______________

matter by feeding.

� Decomposers break down organic waste and dead bodies. The nitrogen inside them is

converted to (10) _______________ compounds. These compounds are eventually turned into

(11) ______________ through (12) _______________ (硝化) by nitrifying bacteria (硝化細菌).

� Nitrogen is also added to the soil through (13) _______________ (閃電).

nitrogen (in atmosphere)

nitrogen oxides

nitrates (in soil)

lightning dissolve in rainwater

organic waste and dead bodies

ammonium compounds

nitrites nitrates (in soil)

decomposition

by decomposers

nitrifying bacteria

nitrifying bacteria

nitrification


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� (14) _____________ _____________ _____________ (固氮細菌) in the soil convert nitrogen

in soil air to ammonium compounds by (15) _______________ _______________ (固氮).

The ammonium compounds are stored in their body. When they die, they are decomposed by

decomposers. The ammonium compounds in them are released into the soil and converted to

nitrates by (16) _______________.

� Nitrogen fixing bacteria are also present in the (17) ______________ ______________ (根瘤)

of (18) _______________ plants (豆科植物). They convert nitrogen gas in the soil air to

ammonium compounds for the growth of the plants.

� Nitrogen is removed from the soil when (19) _______________ take up the nitrate ions for

(20) _______________ synthesis.

� In poorly aerated soil, (21) _______________ _______________ (反硝化細菌) change nitrates

in the soil into (22) _______________ gas by denitrification (反硝化).

nitrates (in soil)

nitrogen (in atmosphere)

denitrification

by denitrifying bacteria

nitrogen (in soil air)

ammonium compounds (in bacteria)

ammonium compounds

(in soil)

nitrates (in soil)

nitrogen fixation

by free-living nitrogen fixing

bacteria

decomposition

by decomposers

nitrification

by nitrifying bacteria

▲ The nitrogen cycle (氮循環)


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20.6 Conservation of ecosystems (Book 3, p. 20-42)

A The impact of human activities on ecosystems (Book 3, p. 20-42)

� Human activities have brought undesirable impacts on ecosystems:

Impact Description

Habitat destruction � The loss of habitats dramatically reduces biodiversity.

Overexploitation of

resources

� Over-hunting of many species leads to a rapid drop in the number of

individuals, or even put them in danger of (1) _______________ (滅絕).

Pollution

� Sulphur dioxide and nitrogen oxides cause respiratory diseases and

(2) _____________ _____________ (酸雨).

� Industrial sewage (污水) may cause poisoning.

Global warming

(全球暖化)

� As carbon dioxide and other (3) ____________ _________ (溫室氣體)

accumulate in the atmosphere, more (4) _______________ is trapped

on earth. This may speed up the melting of icebergs in polar regions.

Polar organisms may therefore lose their habitats.

▲ Rhinos are in danger of extinction because they are overhunted

▲ Burning fossil fuels releases a lot of air pollutants

B How can we conserve ecosystems? (Book 3, p. 20-43)

� (5) ______________ (保育) is necessary for maintaining a sustainable (可持續的) environment.

� Some principles in conservation:

- protection of natural habitat

- protection of (6) _______________ species

- use of (7) _______________ energy sources

- good management of the use of natural resources

- reduction in the use of natural resources and waste production


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20.7 Ecological study (Book 3, p. 20-45)

A How do we find out the distribution and abundance of organisms

in a habitat? (Book 3, p. 20-45)

1 Quadrat

� A (1) _______________ (樣方) is a square frame of fixed area.

� It is thrown randomly onto the ground. The number of different kinds of organisms in the

area enclosed by the quadrat is recorded.

� (2) _______________ sampling and calculating a mean value are necessary to make the

estimation more reliable.

2 Line transect

� A (3) _______________ (樣條) is a piece of inelastic string with markings at 1-m intervals.

� In the (4) _______________ _______________ (樣線) method, a transect is placed along a

specific direction.

� A distribution graph can be drawn to show the individuals touching the transect.

▲ The line transect method

▲ A distribution graph drawn according to the distribution of plants in the above diagram


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3 Belt transect

� In the belt transect (樣帶) method, a (5) _______________ is laid down along the area to be

studied, and (6) _______________ are placed continuously or at fixed intervals on one side

of the transect.

� The positions of the quadrats and the organisms enclosed by the quadrats are recorded. The

data can be presented using a (7) _______________ _______________ (鳶形圖).

▲ The belt transect method

▲ A kite diagram drawn according to the data in the table on the left


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� Comparison of sampling methods:

Quadrat Line transect Belt transect

Kind of habitat

studied

Fairly (8) _____________

habitats

Habitats that show (9) _____________ in

environmental conditions

Choice of area of

study

Random (10) _____________, i.e. carefully chosen for

specific environmental conditions of interest

Target type of

organisms studied Plants, (11) _____________ or fairly slow-moving organisms

Information

obtained

Range of

(12) _____________ of

the species in a habitat

Presence or absence

of the species along

the line

(13) _____________

of the species at

different positions

along the line, and the

range of distribution

of the species

B How do we measure abiotic factors in a habitat? (Book 3, p. 20-48)

� Various instruments can be used to collect data about abiotic factors in ecological studies.

� With advances in technology, (14) _______________ _______________ have been developed.

They can log data with different sensors to collect data about abiotic factors in ecological

studies.

▲ A data logger

Go to

Practical 20.1 Conducting an ecological study of a local habitat

(Book 3, p. 20-49; Practical Workbook for SBA 3 • 4, p. 20-1)


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Answers

Ch 20 Ecosystems

20.1 1 organisms 2 physical environment 3 Species 4 Population

5 Community 6 Ecosystem 7 plant 8 ecosystem 9 adaptations

10 food 11 heat 12 sun 13 cycled 14 freshwater stream

15 rocky shore 16 mangrove 17 woodland 18 grassland

20.2 1 biotic 2 abiotic factors 3 Homoiotherms 4 wider 5 surface area

6 subcutaneous fat 7 Poikilotherms 8 narrower 9 hibernate 10 migrate

11 Diurnal 12 Nocturnal 13 photosynthesis 14 sweating 15 xerophytes

16 spines 17 waves 18 pollination 19 dispersal 20 increases

21 flattened 22 water potential 23 salt glands 24 decreases 25 reduces

26 increases 27 decreases 28 size 29 small 30 lower

31 aerial 32 lenticels 33 smaller 34 moisture 35 nutrients

36 decomposition

20.3 1 habitat 2 niche 3 temperature 4 space 5 Species diversity

6 species richness 7 relative abundance 8 proportions 9 higher 10 dominant species

11 predation 12 prey 13 lagging 14 competition 15 intraspecific

16 interspecific 17 more 18 needs 19 symbiosis 20 commensalism

21 mutualism 22 parasitism 23 parasite 24 host

25 ecological succession 26 replace 27 increases 28 climax community

29 barren 30 pioneer community 31 soil 32 dominant 33 humus

34 shrubs 35 nutrients 36 trees 37 climax community

38 Secondary succession 39 soil 40 seeds


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20.4 1 sun 2 photosynthesis 3 chemical 4 food 5 excretion

6 uneaten 7 respiration 8 food chain 9 energy / material 10 material / energy

11 producers 12 consumers 13 decomposers 14 autotrophs 15 heterotrophs

16 herbivores 17 carnivores 18 primary 19 tertiary 20 saprophytes

21 organic 22 inorganic 23 cycling 24 producer 25 primary

26 secondary 27 tertiary 28 food web 29 feeding 30 trophic level

31 Tertiary 32 Producer 33 lost 34 less 35 more

36 faeces 37 heat 38 excretory 39 pyramid of numbers

40 area 41 dry mass 42 reproduction 43 trophic level 44 diet

45 decomposers

20.5 1 organic 2 feeding 3 decomposers 4 respiration 5 decomposers

6 fossil fuels 7 limestone 8 photosynthesis 9 organic 10 ammonium

11 nitrates 12 nitrification 13 lightning 14 Nitrogen fixing bacteria

15 nitrogen fixation 16 nitrification 17 root nodules 18 leguminous 19 plants

20 protein 21 denitrifying bacteria 22 nitrogen

20.6

1 extinction 2 acid rain 3 greenhouse gases 4 heat 5 Conservation

6 endangered 7 alternative

20.7

1 quadrat 2 Repeated 3 transect 4 line transect 5 transect

6 quadrats 7 kite diagram 8 uniform 9 transitions 10 Systematic

11 immobile 12 distribution 13 Abundance 14 data loggers

class: name: date: 20 ecosystems - shared learning resources -...

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