Module Question

CHAPTER 7 : DYNAMIC ECOSYSTEM 1

7.1 THE ABIOTIC AND BIOTIC COMPONENTS OF THE ENVIRONMENT

The abiotic and biotic components of an ecosystem Fill in the blank / (FITB) The biotic components consists of

-------------------- : Autotrophs, Example: -------------------

------------------- Heterotrophs Example: --------------------

Secondary consumers Example: --------------------

Tertiary consumers Example: --------------------

Decomposers Example: --------------------

Food Chain , Food webs and Trophic level

Trophic level Functional group Food chain 1 Food chain 2

1

2

3

4

Producers

Primary consumers

Secondary consumers

Tertiary consumers

Grass

Rats

Snakes

Hawks

Water plants

Tadpoles

Dragonfly nymphs

Frogs

Pyramid of numbers

Represents the number of individuals at each trophic level of food chain at a

particular time. The number of organisms decreases up the trophic levels.

Hawks

Snakes

Rats

Grass

secondary consumers

primary consumers

trophic level 4

trophic level 3

trophic level 2

tertiary consumers

producerstrophic level 1


QUESTION TO ANSWER / QTA 1

Figure 1 shows a terrestrial ecocystem.

(a) Abiotic and biotic components influence the lives of organism. Fill in the boxes in Figure

1 to show two more abiotic components and two more biotic components. [2 marks]

(b) On Figure 2, mark and label one example off the following organisms.

(i) (i) Producer (ii) Consumer (iii) Decomposer [2 marks]

(c) Based on figure 2 , construct one food chain consisting of four trophic level.

1st trophic level 2nd trophic level 3rd trophic level 4 th

trophic level [2 marks] (d) An organism in the 3rd trophic level in Figure 1 has decreased in number.

(i) Based on the food chain you have constructed in (c), suggest a way to increase

the numbers of this organism again.

…………………………………………………………………………………….

….………………………………………………………………………………..

[1mark]

(ii) Explain your suggestion in (d)(i)

………………………………………………………………………………………….

………………………………………………………………………………………….

………………………………………………………………………………………….

…………………………………………………………………………………………

[2 marks]

( e )The organisms in the trophic level in Figure 1 absorbs 15 000 kJ solar energy. Energy

loss at each trophic level is 90%. Calculate the total every transferred to the organisms

in the 3rd trophic level.

= -------------------------kJ

Figure 1


[2 marks]

Energy Flow

i The producers absorb -------------------energy from the sun and convert it

into ------------------- stored in organic molecules during -------------------.

ii When a carnivore eats a -------------------, the herbivore’s available energy

is transferred on to the carnivore. The carnivore also loses energy

through respiration, ------------------- and -------------------.

iii About -------------------of the energy lost to the environment, only

------------------- is converted into new tissue and storage material (bio

mass).

QTA 2

Figure 2 represents the energy flow through a food chain consisting of four organisms.

The total energy in the tissue of the green plant is shown in the box.

Figure 2

(a) Complete the other boxes to show the total energy in the tissues of each of

the consumer, assuming 90% loss of energy at each of the stage in the

food chain.

[1 mark]

(b) State one process is likely to be responsible for the loses of energy from

one stage to another

Green plant

Primary consumer

Tertiaryconsumer

Secondaryconsumer

500 kJ

90% energy

loss

90% energy

loss

90% energy

loss


…..………………………………………………………………………………………

…………………………………………………………………………………………..

[1 mark]

(c)(i) What is meant by the term producer in the food chain?

…….……………………………………………………………………………………

…..……………………………………………………………………………………..

[2 marks]

(ii) State the source from which the producer obtains its energy

………..………………………………………………………………………………..

[1 mark]

(a) (d) Explain why there are rarely more than four or five trophic levels in a food chain.

…………………..……………………………………………………………………….

………………..………………………………………………………………………….

…………………….……………………………………………………………………..

[2 marks]

(e) Paddy caterpillar sparrow eagle

Based on the above food chain, explain how the practice of spraying crops with

insecticides, for example DDT can lead the predator being harmed.

…………………………………………………………………………………………..

…………..………………………………………………………………………………

………………………………………………………………………………………….

………………………..……………………………………………………………………

[2 marks]

(f) Construct a food web involving the following organisms found in a freshwater pond.

Start with producers at the bottom of your web.

Green algae, large carnivorous fish, water beetle, tadpoles,

water fleas, water snails, small fish, mosquito larvae


[3 marks]

Interaction between biotic components

(a) Symbiosis

Water beetles

T large carnivorous fish

Small fish

Water fleas mosquito larvae water snails

Green algae

Interactions between organisms

--------------------------------------Symbiosis

--------------------------------------

Competition

-----------------


A close interaction between different species which ------------------- -------------------

and ------------------- with each other for an extended period of time.

(i) Commensalisms

One partner benefits (commensal) while the other (-------------------) derives neither

------------------- nor -------------------.

Epiphytes

plants which grow on other plants to obtain ------------------- and support.

example: pigeon orchids, staghorn ferns and bird’s nest ferns.

Epizoics

• animals which live on the body of other animals

• a -------------------gets free transportation and feeds on food scraps left behind by the -------------------

(ii) Mutualism • A relationship between two species of organisms in which ------------------- . • Example 1: Association of leguminious plants and -------------------.

(iii) Parasitism One organism ------------------- (parasite) while the other is harmed (---------------).

Types : a. Ectoparasites

b.Endoparasites

(b)Saprophytism

Living organisms obtain food from ------------------- and ------------------- organic matter

Example : Saprophytic bacteria, ------------------- and -------------------

(c )Prey-predator

An organism (prey) is haunted and ------------------- by a stronger and bigger organism

(predator).


------------------- by the predator

------------------- in size compared

to the predator

The prey population is ---------------

than the predator population

The prey relies on speed or

------------------- to avoid being

caught by the predators.

Predators usually have long canine

teeth, ------------------- vision and sharp

claws to capture and kill their prey.

Have hooked ------------------- to tear

the flesh of their prey.

The prey – predator relationship between a rat and an owl.

The rat is the ------------------- of the owl. The owl is the -------------------.

An increase in the ------------------- population followed by an ------------------- in the

------------- population.

When the rat population ------------------- due to increasing predation or other factors

such as the spread of diseases, the owl’s ------------------- ------------------- becomes

limited and this leads to a ------------------- in the population of predators.

The prey–predators regulate each other’s population in a cyclical manner which

maintains the populations of both organisms in a ------------------- -------------------

The interactions between biotic components in relation to feeding.

P

Q

PredatorPrey


Figure 3

Figure 3 shows a plant species P with green leaves on a tree trunk.

The interaction between species P and the host plant, Q is ------------------- Species P is

a type of ------------------- which is able to synthesize their own food by -------------------

process. It grows on the tree trunk to achieve a greater height so that it can receive more

------------------- for photosynthesis process. It does not absorb nutrients from the host

tree. The host tree neither gains nor loses

How species P obtains their needs and adapted to the environment

• Roots system

Occupied by -------------------.

The ants bring all kinds of rubbish and remnants of food to the roots.

These materials gradually ------------------- into humus.

• Leaf

Arrangement in the form of a -------------------

It can collect falling ------------------- which then decomposes into humus

Corrugated leaves with ------------------- can direct rainwater and dew to the roots

Leaf with thick cuticle to reduce -------------------

QTA 3

Interdependence between organisms is a phenomenon that is always operating between

in a community of organisms.

Figure 4

(a) Name the type of relationship between the mushroom and the decaying branch.


………………………………………………………………….. [ 1 mark ]

(b) What is the benefit gained by the mushroom through this association in (a)? ……………………………………………………………………………………………….. ……………………………………………………………………………………………….. [ 1 mark ]

( c) State the function of the parts labeled X and Y X : ….………………………………………………………………………………………….. Y :……………………………………………………………………………………………. [ 1 mark ]

(d) Give two important contributions of mushrooms to man.

(i) ………………………………………………………………………………………….

(ii) …………………………………………………………………………………………. [ 2 marks]

(e) (i) Suggest one example of an organism that shares the same method of nutrition as in Figure 4. ………………………………………………………… [ 1 marks](e) (i) Explain the role of this organism in the ecosystem ………………………………………………………………………………………………. ………………………………………………………………………………………………… [ 2 marks]

Competition

An interaction between organisms to get the same resources that is in

------------------- supply.

------------------- organisms will migrate or die

Animals compete for shelter, ------------------- and breeding mates.

Plants compete for water, nutrients, light and space.


8.2 COLONISATION AND SUCCESSION IN AN ECOSYSTEM Ecosystem

TERM MEANING

Species A group of organisms that look alike and have

------------------- characteristics, share the same ecological

niche and are capable of inter ------------------- and producing

fertile ----------

Types of competition

-------------------

competition

* Members of the

------------- species

compete for the same

resources.

* Examples:

1. Paramecium

--------------aurelia

among themselves.

2. maize plants among

themselves.

-------------------

competition

* Competition between

------------------- species

* Examples:

1. Paramecium

-------------- aurelia and

Paramecium

-------------------

2. maize plants and

paddy plants.

CommunitySpecies


For example, ------------------- and water lilies are two

different species of water plants.

Population A group of organisms of the ------------------- species living in

the same ------------------- at the same time.

For example, a population of elephants living in a jungle.

Community Several ------------------- of different species living in the

same habitat in an ecosystem.

For example, a freshwater pond community.

Ecosystem A community of ------------------- organisms -------------------

with each other and with the ------------------- environment.

Examples : -------------------, a wetland and a pond

Niche The ------------------- of an organism in the ecosystem.

Organisms that undergo metamorphosis in their life cycles

occupy different niches.

For example, a ------------------- lives entirely in ------------------

and utilizes different resources from those of an adult frog

which lives mainly on -------------------.

Habitat A natural environment where organisms -------------------

Example, a single tree can be a habitat for caterpillars and

-------------------.

COLONISATION AND SUCCESSION IN MANGROVE SWAMPQTA 4 : Figure 5 shows the geographical distribution of mangrove trees along the east coast.


Figure 5

1

(a) (i) Name the mangrove trees in zone A to D. A : ………………………… B : ……………………

C : ………………………… D : …………………… [4 marks]

(ii) Among the mangrove trees stated in (a) (i), which is the pioneer species?

……………………………………………………………………… [2 marks]

(b) State two problems faced by the pioneer species in the colonization of

swampy area.

.………………………………………………………………………………………………..

… ......................................................................................................................................

[2 marks ]

(c) Explain two adaptive characteristics that enable the pioneer species to survive in the swamp area.………………………………………………………………………………………………..…..

………………………………………………………………………………………. ……….. …

………………………………………………………………………………………...................

…………………………………………………………………………………… [2 marks]

(d) (i) What is meant by viviparous seedlings?

……………………………………………………………………………………[ 1 mark ]

(d) (ii) What is the benefit of this to the mangrove plant?

…………………………………………………………………………………………………….

…………………………………………………………………………………… [1 mark]

A. SUCCESSION IN A MANGROVE SWAMP

Avicennia sp. and ------------------- zone (----------------

species )

Extensive ------------------- systems ------------------- and

collect sediments.

The ------------------- becomes more compact and

-------------------

The ground becomes higher

Rhizophora sp. zone (successor species)

Replace the pioneer species

The ------------------- roots trap silt and ---------------.

The soil firmer, ------------------- and

-------------------------------------- submerged by sea water

Bruguiera sp. zone

Replace the Rhizophora sp.

The roots ------------------- more silt and mud.

Modify the ------------------- structure.

Terrestrial plants like the nipah palm and -------------------

then ------------------- the bruguiera sp.

Terrestrial forest and then a -------------------rainforest is

formed after hundred years

C

AE D B


(B) Colonisation and succession in a pond8.3 POPULATION ECOLOGYTHE SAMPLING TECHNIQUE TO STUDY THE POPULATION SIZE OF ORGANISM

Sampling techniques

Quadrat sampling technique

to study and estimate the population size of ------------------

Capture, mark, release and recapture

To estimate the population size of ------------------

to estimate the ------------------- and ------------------ of organisms.


QTA 5

Figure 6Figure 6, show an oil palm estate. An oil palm estate is identified as a habitat for owls and rats. The manager of oil palm estate plans to use biology control to control the population size of rats which are damaging the oil palm in the estate.

Based on ecological studies, some students have carried out a study to estimate the size of the rats population between the area of estate. The result obtained are recorded in Table 1

Steps in the collection of samples

Station X Station Y

Number of rats captured, marked and released 110 70

Number of rats recaptured 3 days later

130 50

Number of marked rats 60 25

1 (a) What technique is used for estimating the population of the rat?

………………………………………………………………………………..

[1 mark]

(b) (i) Give two characteristics of the material used for marking the rat.


……………………………………………………………………………..

……………………………………………………………………………..

…………………………………………………………………………….

[2 marks]

( b)(ii) Where will you release the rat after they are marked?

………………………………………………………………………………..

………………………………………………………………………………..

[1 mark]

(c) Why are the rat caught again after three days?

…………………………………………………………………………………

[1 mark]

(b) (d) Estimate the population of the rat in station X and station Y.

(c) ………………………………………………………………………………………….

…………………..………………………………………………………………………

………………..……………………………………………………………………......

…………………….……………………………………………………………………

[2 marks]

(e) Give three reasons for the difference in the population of the rat in two stations.

………………………………………………….…………..

……………………………………………………………………………………………………

..

……………………………………………………………………………………………………

.………………………………

[3 marks]

CAPTURE, MARK, RELEASE AND RECAPTURE TECHNIQUE

THE EFFECT OF THE ABIOTIC FACTORS ON THE POPULATION GROWTH RATE OF AN ORGANISMpH value

- the population distribution of

Pleurococcus sp. is higher at a neutral

pH

An experiment to

investigate the effect

of the abiotic factors

on the population

growth rate of an

organism. (investigate

the population

distribution of

Pleurococcus sp.)

Temperature

the population distribution of Pleurococcus sp. is

------------------- at a mild temperatures.

temperatures

Humidity

- a -------------------

humidity

is more suitable

for the growth of

Pleurococcus sp

Light intensity

- -------------------

light Intensity is

more favourable for

Pleurococcus sp.

Aspects- the aspects such as lower temperatures and low

light intensities are ------------------- for the growth of Pleurococcus sp.

Formula : (number of individuals in the first sample) x

Population (number of individuals in the second

sample)size number of marked individuals recaptured

=


8.4 BIODIVERSITY

Classification of organisms into the five kingdoms

Protista - -------------------, algae, protozoa- membrane-bound nuclei and organelles.- -------------------, heterotrophic or both- examples : spirogyra sp. amoeba sp. paramecium sp.

Monera- composed of ------------------- organisms

- -------------------, have cell walls, no ------------------- bound nuclei and organelles.

- photosynthetic and non- photosynthetic

- typical shapes: rod, round,spiral

- examples : Cyanobacteria,


________________ __________________ system.

Kingdom

Organisms Human Wolf Frog

Genus Canus Rana

Species lupis pipiens

Scientific name

-------------------

Plantae - all -------------- plants

- ------------------- autotrophic eukaryotes, immobile

photosynthetic

- have ------------------- cell walls

- examples :

flowering plants fern

Fungi- multicellular eukaryotes- -------------------, have hyphae called ---------------- they have no ------------------ examples : yeast

mucor sp. mushrooms

Animalia - ---------------- ------------------- eukaryotes- well-------------------- tissues- examples : mammals, fish reptiles


QUESTION TO ANSWER

Explain how a classification is use to name Panthera leo and Panthera tigris

The naming of organisms is based on the ------------- ------------ -------------

Each organism has ------------------- name in latin.

First name begin with capital letters refers to the -------------------, second refers to

-------------------, written in Italic

-------------------I s the genus in which the lion and tiger are placed.

However, they are of a different -------------------.

The lion belongs to the species ------------------- while the tiger belongs to the species

-------------------.

8.5 THE IMPACT OF MICROORGANISMS ON LIFE

Types of microorganisms

To which organisms do the following descriptions apply?

W Tobacco mosaic virus

X Yeast

Y Bread mould

Z Bacillus

1. Parasite

2. Saprophyte

3. Form spores

4. A multicellular organism

5. Genetic material is a single strand of RNA

6. Reproduces by binary fission

THE EFFECTS OF ABIOTIC COMPONENTS ON THE ACTIVITY OF MICROORGANISMS

ABIOTIC COMPONENT

EFFECTS


Temperature - ------------------- at low temperature

- the optimum temperature is between -------------------

- beyond ------------ the growth of microorganisms is inhibited

- microorganisms and their spores can be ------------------- at

a temperature of about 121°C

The activity of yeast is optimal at a temperature of --------.

Light intensity - prefer ------------------- or low light intensities

- ------------------- intensities of sunlight or ultraviolet rays can

------------------- microorganisms

- ------------------- and photosynthetic bacteria need light to

photosynthesize

The activity of yeast is higher at a ------------------- intensity of light.

pH value - most bacteria prefer slightly ------------------- conditions .

pH ------

- moulds, yeast and protozoans prefer acidic conditions

(pH 4.5 – pH 5.0)

- extreme pH can kill the microorganisms

The activity of yeast is optimum in the ------------------- medium.

Nutrient - all microorganisms except ------------------- need nutrients and

water for reproduction and growth

- without nutrients or water, microorganisms will die or

form -----------------

The higher the concentration of nutrients, the ---------------

the activity of yeast.

QTA 6 :THE IMPACT OF MICROORGANISMS ON LIFE


Figure 7 : The impact of microorganisms on life

Microorganisms are found everywhere on the surface of the earth. Many types of

microorganisms are harmless and are actually quite beneficial to humans.

(a) State 5 types of microorganisms found on earth.

1.…………………… 2. …………………… 3.………………… 4.……………………… 5…………………… [2 marks]

th e (b) With example, explain the importance of any 3 types of microorganisms.

…………………………………………………………………………………………………….

……………………………………………………………………………………………….

……………………………………………………………………………………………….

……………………………………………………………………………………………….

[3 marks]

(c)(i) From Figure 7 name 2 groups of nitrogen fixing bacteria and state briefly their

way of life.

……………………………………………………………………………………….

[3 marks]

(c)(ii) What is the meaning of nitrogen fixing bacteria?

………………………………………………………………………………………

………………………………………………………………………………………

………………………………………………………………………… [2 marks]


(d) What is compound x ?

………………………………………. [ 1 marks]

(e) What is the use of microorganisms in biotechnology ?

………………………………………………………………………………….

…………………………………………………………………………………

………………………………………………………………………………..

[ 2 marks]

(e) What is the importance of preservation and conservation of biodiversity ?

………………………………………………………………………………….

…………………………………………………………………………………

………………………………………………………………………………..

[ 2 marks]

GUIDED ESSAY :THE ROLE OF USEFUL MICROORGANISMS

1. Decomposition

a. Carried out by a group of ------------------- bacteria and fungi, called ---------------

b. Secrete ------------------- that break down complex organic nutrients into

------------------- inorganic substances such as carbon dioxide, water and

----------------- this reduces pollution by preventing the accumulation of the

remains of decaying organisms.

c. Maintain life on earth by recycling and ------------------- nutrients into the soil.

2. Digestive system in human

Symbiotic bacteria in human ------------------- synthesise vitamin B12

and -------------------

Deficiency in vitamin B12 lead to anaemia, ------------------- needed for

blood clotting.

3. Alimentary canal of termites

Termites feed on ------------------- which contains cellulose, they do not

have the enzymes (-------------------) to digest the cellulose.

Trichonympha sp. is a mutualistic protozoans present in the alimentary

canal of termites and secrete -------------------

4 Nitrogen cycle


a. The nitrogen cycle allows nitrogen to be utilized by organisms and ---------------

to the physical environment.

b. Plants can only ------------------- nitrogen in the form of -------------------, nitrite or

nitrate ions.

c. Nitrogen fixing bacteria such as -------------------. (lives in the soil) and

------------------- (lives in the root nodules of leguminous plants) can convert

atmospheric nitrogen into ------------------- compounds (NH3 and NH4) through a

process called -------------------.

d. Nitrates are taken up by the roots of plants and converted into plant -------------

When the animals eat the plants, the organic nitrogen is transferred into the

body of animals and becomes animal protein

e. Waste matter, ------------------- and animals which die and decompose are

converted into ammonium compounds.

f. Ammonium compounds are converted into -------------------and nitrates by

------------------- through a process called -------------------.

g. Ammonia converted into nitrites (NO2-) by -------------------

h. Nitrites converted into nitrates (NO3¯) by -------------------.

i. The cycle is balanced by a continuous return of nitrogen to the atmosphere by

-------------------which break down nitrates and release nitrogen back into the

atmosphere.


The effect of harmful microorganisms1. Harmful microorganisms can ------------------- the food and substances.

2. Microorganisms that cause diseases are called -------------------.

3. Organisms that transmit the pathogens are called --------------------------------------.

How the diseases spreadi) Direct contact- a contagious disease can be spread by ---------------- with an infected person or

using their personal items such as ---------------- clothing.

ii) Airborne and droplet transmission

- airborne transmission is a method where the pathogens can change into -------------

and then transmitted by ---------------- droplet transmission is a method where

liquid

Airborne and droplet transmission

- airborne transmission is a method where the pathogens can change into --------------

and then transmitted by -------------- droplet transmission is a method where

liquid

Food and water

- microorganisms enter the alimentary canal through contaminated food and water,

------------- hands

Disinfectants

- solutions used to -------------------

surgical equipment, kill

microorganisms on the floor.

Examples : phenol, formaldehyde

Vaccines

- a suspension of -------------------

or

------------------- bacteria or

viruses

which is inoculated into the body

to induce the production of

-------------------. Example : BCGAntiseptics

- used on cuts and ------------------- to

kill and inhibit the growth of

microorganisms. Examples :

acriflavin, -------------------

Antibiotics

- Penicillin and streptomycin are

produced by microorganisms

which inhibit the growth or

------------

other microorganisms, esp.

bacteria

Methods of controlling pathogens


GUIDED QUESTION PAPER 3 :QTA 7: Complete the report below

Objective: Estimating the percentage coverage of plants using the quadrat

sampling technique.

Problem statement: What is the percentage coverage for plant species P and Q

in the selected sample?

Hypothesis : ……………………………………………………..

Variables

i. manipulated: …………………………………………………..

ii.responding: …………………………………………………….

iii. constant: ……………………………………………………..

Apparatus: 1m X 1m quadrat

Technique: To estimate …………………………………………..

Procedure:

1. Survey and select a suitable sampling area.

2. Identify two plant species, P and Q to be sampled in the area.

3.Place ten square quadrats, each 1m2 on the sampling area randomly.

4. Divide each quadrat into ………. small quadrat using nails and strings.

5. Each small quadrat measures ……………. (The size of each small quadrat is

…………….)

6. Count the number of small quadrats for the plant species P. (Count only the

small quadrats that are covered ………. or more by the species.)

7. Count the total area covered by the plant species P by multiplying total number

of ……………………… covered with the area of one small quadrat (0.01 m2).

8. Repeat ………………………………………………………………….

9. Record the observation in the table below.

10. ……………….. the percentage coverage of species P and Q using the

formula below

Percentage coverage = Total area covered by the species X 100%


Number of quadrats X area of one quadrat

Result.

Species Area covered by the species in each

quadrat (1m2))

Total area

covered by

the species

(m2)

Percentage

coverage %

P

1 2 3 4 5 6 7 8 9 10

Q

Conclusion: ………………………………………………………………………………

……………………………………………………………………………………………..

Figure 2 represents the energy flow through a food chain consisting of four organisms.

The total energy in the tissue of the green plant is shown in the box.

Green plant

Primary consumer

Tertiaryconsumer

Secondaryconsumer

500 kJ

90% energy

loss

90% energy

loss

90% energy

loss


Figure 2

(a) Complete the other boxes to show the total energy in the tissues of each of

the consumer, assuming 90% loss of energy at each of the stage in the

food chain.

[1 mark]

(b) State one process is likely to be responsible for the loses of energy from

one stage to another

…..………………………………………………………………………………………

…………………………………………………………………………………………..

[1 mark]

(c)(i) What is meant by the term producer in the food chain?

…….……………………………………………………………………………………

…..……………………………………………………………………………………..

[2 marks]

(ii) State the source from which the producer obtains its energy

………..………………………………………………………………………………..

[1 mark]

(d) (d) Explain why there are rarely more than four or five trophic levels in a food chain.

…………………..……………………………………………………………………….

………………..………………………………………………………………………….

…………………….……………………………………………………………………..

[2 marks]

(e) Paddy caterpillar sparrow eagle

Based on the above food chain, explain how the practice of spraying crops with

insecticides, for example DDT can lead the predator being harmed.

…………………………………………………………………………………………..

…………..………………………………………………………………………………

………………………………………………………………………………………….


………………………..……………………………………………………………………

[2 marks]

(g) Construct a food web involving the following organisms found in a freshwater pond.

Start with producers at the bottom of your web )

[3 marks]

Interaction between biotic components

Symbiosis

A close interaction between different species which live together and interact with each

other for an extended period of time.

Commensalisms

One partner benefits (commensal) while the other (host) derives neither

benefit nor harm.

Epiphytes

plants which grow on other plants to obtain sunlight and support.

example: pigeon orchids, staghorn ferns and bird’s nest ferns.

Epizoics

• animals which live on the body of other animals

• a remora fish gets free transportation and feeds on food scraps left behind by the sharkMutualism • A relationship between two species of organisms in which both benefit . • Example 1: Association of leguminious plants and Rhizobium.Parasitism

Green algae, large carnivorous fish, water beetle, tadpoles,

water fleas, water snails, small fish, mosquito larvae

Water beetles

T large carnivorous fish

Small fish

Water fleas mosquito larvae water snails

Green algae


One organism benefits (parasite) while the other is harmed (host).

Types : a. Ectoparasites

b. Endoparasites

Saprophytism

Living organisms obtain food from dead and decaying organic matter

Prey-predator

An organism (prey) is haunted and eaten by a stronger and bigger organism (predator).

An increase in prey population followed by an increase in the predator

population.

When the prey population decreases due to increasing predation or other factors

such as the spread of diseases, the predator’s food supply becomes limited and

this leads to a decline in the population of predators.

The prey–predators regulate each other’s population in a cyclical manner which

maintains the populations of both organisms in a dynamic equiblibrium

Haunted by the predator

Smaller in size compared to the predator

The prey population is bigger than the

predator population

The prey relies on speed or camouflage

to avoid being caught by the predators.

Predators usually have long

canine teeth, sharp vision

and sharp claws to capture

and kill their prey.

Have hooked beaks to tear

the flesh of their prey.

Prey Predator


Interactions between organisms

Prey-predatorSaprophytismSymbiosis

MutualismCommensalisms

Competition

Parasitism


Questions to answer

Figure 3

Interaction between organism

Fiigure 3 shows a plant species P with green leaves on a tree trunk.

The interaction between species P and the host plant, Q is commensalisms

Species P is a type of epiphyte which is able to synthesise their own food by

photosynthesis process.It grows on the tree trunk to achieve a greater height so that it

can receive more sunlight for photosynthesis process. It does not absorb nutrients from

the host tree .The host tree neither gains nor loses

How species P obtains their needs and adapted to the environment

• Roots system

Occupied by ants.

The ants bring all kinds of rubbish and remnants of food to the roots.

These materials gradually decompose into humus.

• Leaf

Arrangement in the form of a basket.

It can collect falling leaves which then decomposes into humus

Corrugated leaves with grooves can direct rainwater and dew to the roots

Leaf with thick cuticle to reduce transpiration.

P

Q


Questions to answer

Interdependence between organisms is a phenomenon that is always operating between

in a community of organisms.

Figure 4

( a) Name the type of relationship between the mushroom and the decaying branch.………………………………………………………………………………………………………. [ 1 mark ]

( b) What is the benefit gained by the mushroom through this association in (a)?………………………………………………………………………………………………………. [ 1 mark ]

( c) State the function of the parts labeled X and Y X : ….………………………………………………………………………………………….. Y :……………………………………………………………………………………………. [ 1 mark ]

( d) Give two important contributions of mushrooms to Man.

(iii) ………………………………………………………………………………………….

(iv) …………………………………………………………………………………………. [ 2 marks]


Competition

An interaction between organisms to get the same resources that is in

limited supply.

Weaker organisms will migrate or die

Animals compete for shelter, food and breeding mates.

Plants compete for water, nutrients, light and space.

Types of competition

Intraspecific competition

* Members of the same

species compete for the

same resources.

* Examples:

1. Paramecium aurelia

among themselves.

2. maize plants among

themselves.

Interspecific competition

* Competition between

different species

* Examples:

1. Paramecium aurelia

and Paramecium

caudatum

2. maize plants and

paddy plants.


Figure 4Figure 4, show an oil palm estate. An oil palm estate is identified as a habitat for owls and rats. The manager of oil palm estate plans to use biology control to control the population size of rats which are damaging the oil palm in the estate.

Based on ecological studies, some students have carried out a study to estimate the size of the rats population between the area of estate. The result obtained are recorded in Table 1

Steps in the collection of samples

Station X Station Y

Number of rats captured, markes and released

110

70

Number of rats recaptured 3 days later

130 50

Number of marked rats 60 25

1 (a) What technique is used for estimating the population of the rat?

………………………………………………………………………………..

1 mark]

(b) (i) Give two characteristics of the material used for marking the rat.

……………………………………………………………………………..

……………………………………………………………………………..

…………………………………………………………………………….

[2 marks]

( b )(ii) Where will you release the rat after they are marked?

………………………………………………………………………………..


………………………………………………………………………………..

[1 mark]

(c) Why are the rat caught again after three days?

…………………………………………………………………………………

[1 mark]

(e)

(d) Estimate the population of the rat in station X and station Y.

(g) ………………………………………………………………………………………….

…………………..………………………………………………………………………

………………..……………………………………………………………………......

…………………….……………………………………………………………………

[2 marks]

(e) Give three reasons for the difference in the population of the rat in two

stations.

………………………………………………………………………………….…………..

……………………………………………………………………………………………………..

…………………………………………………………………………………………………….

……………..……………………………………………………………………………………

[3 marks]


8.6 THE PROCESS OF COLONISATION AND SUCCESSION IN AN ECOSYSTEM Ecosystem

TERM MEANING

Species A group of organisms that look alike and have similar

characteristics, share the same ecological niche and are

capable of interbreeding and producing fertile offspring.

For example, duckweeds and water lilies are two different

species of water plants.

Population A group of organisms of the same species living in the

same habitat at the same time.

For example, a population of elephants living in a jungle.

Community Several populations of different species living in the same

habitat in an ecosystem.

For example, a freshwater pond community.

Ecosystem A community of living organisms interacting with each

other and with the non-living environment.

Examples : a rainforest, a wetland and a pond

Niche The role of an organism in the ecosystem. Organisms that

undergo metamorphosis in their life cycles occupy different

niches.

Population Community EcosystemSpecies


For example, a tadpole lives entirely in water and utilizes

different resources from those of an adult frog which lives

mainly on land.

Habitat A natural environment where organisms live.

For example, a single tree can be a habitat for caterpillars

and birds.

Colonisation and succession

Mangrove swamp

Figure 5 shows the geographical distribution of mangrove trees along the east coast.

Figure 5

1

(a) (i) Name the mangrove trees in zone A to D. A : …………………………………………………

B : …………………………………..………………

C : …………………………………………………..

D : ……………………………………………………

[4 marks]

(ii) Among the mangrove trees stated in (a) (i), which is the pioneer species?

………………………………………………………………………………………

A

C

BDE


[2 marks]

(b) State two problems faced by the pioneer species in the colonization of

swampy area.

.………………………………………………………………………………………………..

… ......................................................................................................................................

[2 marks ]

(d) Explain two adaptive characteristics that enable the pioneer species to survive in the swamp area.………………………………………………………………………………………………..…..

………………………………………………………………………………………. ……….. …

………………………………………………………………………………………...................

……………………………………………………………………………………………………

[4 marks]

(d) (i) What is meant by viviparous seedlings? …

…………………………………………………………………………………………………..

…………………………………………………………………………………………………

[ 1 mark ]

(d) (ii) What is the benefit of this to the mangrove plant?

…………………………………………………………………………………………………….

……………………………………………………………………………………………………

[1 mark]


( A ) Colonisation and succession in a mangrove swamp


(B) Colonisation and succession in a pond

Colonisation by pioneer species- disused pond, pioneer species (phytoplankton, algae) and submerged plant (Hydrilla sp.,Cabomba sp.,elodea sp.) begin to grow and carry out photosynthesis.- when they die and decompose, organic matter converted into humus at the pond base, the pond become shallow.


8.3 Population Ecology

Succession by floating plants- the condition becomes favourable for floating plants such as water hyacinths (Eichornia sp.) and duckweeds (Lemna sp.)- they spread covering water surface and prevent sunlight from reaching the submerged plant causing these plants to die since they cannot photosynthesise.- the decomposed plants add more organic matter and the pond becomes more shallow

Succession by emergent plants- the emergent plants (sedges, cattails) replace the floating plants.- they grow from the edge of the pond towards the middle of the pond as the pond becomes more shallow.- when these plants die, their decomposed remains are added as sediments to the base of the pond thus reduces the depth of the pond.

Succession by land plants- the condition becomes suitable for land plants like small herbaceous weeds.- gradually, the land becomes much drier- more land plants (shrubs,herbs and large woody plant) start to grow.

Climax community- a jungle emerges and turns into a tropical rainforest which form a climax community.


GUIDED QUESTION PAPER 3: QTA 8

Lemna minor is a species of free-floating aquatic plants from the duckweed family Lemnaceae. The plants grow mainly by vegetative reproduction: two daughter plants bud off from the adult plant.

An experiment is carried out to investigate the effect of abiotic factor such as pH on Lemna sp. growth. Experiment is done under controlled conditions: 12 hours a day light exposure and using the same Knop’s solution. Petri dish is filled with 20 ml Knop’s solution with different pH value and 5 Lemna sp. each.The Knop’s solution is treated by adding acid or alkali to achieve the pH value needed.


** Knop’s solution is a solution which contains essential nutrient for plants growth.

Figure 1

After 7 days, the observation is made and the result shown in Table 1..

Figure x : The impact of microorganisms on life

Microorganisms are found everywhere on the surface of the earth. Many types of microorganisms

are harmless and are actually quite beneficial to humans.

(a) State 5 types of microorganisms found on earth.

…………………………………………………………………………………………………………………………………………………………………………………………………………………… [2 marks]

th e (b) With example, explain the importance of any 3 types of microorganisms.

…………………………………………………………………………………………………….

……………………………………………………………………………………………….

……………………………………………………………………………………………….

Lemna minor

Petri dish

Knop’s solution


……………………………………………………………………………………………….

[3 marks]

(c)(i) From Figure x name 2 groups of nitrogen fixing bacteria and state briefly their

way of life.

……………………………………………………………………………………….

(c)(ii) What is the meaning of nitrogen fixing bacteria?

………………………………………………………………………………………

(d) What is compound x ?

……………………………………….

Table 1

pH value

Petri dish Number of Lemna sp.

2


4

6

8


10

12

Based on the experiment, answer all questions below.

(a) State the number of Lemna sp. in the spaces provided in Table 1. [3 marks]

(b) (i) Based on Table 1, state two observations that can be made in this experiment.

Observation 1: ……………………………………………………………..


………………………………………………………………………………

………………………………………………………………………………

………………………………………………………………………………

Observation 2: ……………………………………………………………..

………………………………………………………………………………

………………………………………………………………………………

………………………………………………………………………………

[3 marks](ii) State the inference for each observation made in (b) (i).

Inference for observation 1:………………………………………………

………………………………………………………………………………

………………………………………………………………………………

………………………………………………………………………………

Inference for observation 2: :……………………………………………

………………………………………………………………………………

………………………………………………………………………………

………………………………………………………………………………

[3 marks]

2. Based on the experiment, define operationally the abiotic factor in an ecosystem.

………………………………………………………………………………

………………………………………………………………………………

………………………………………………………………………………

………………………………………………………………………………

[3 marks]


Module Question

Documents

trophic level of food

trophic levels

total energy

energy loss

loss of energy

marks energy flowi

food webs

kj solar energy