Ecosystems

Question 1

What is an ecosystem?

Answer 1

An area where organisms present are affected by and interacts with biotic and abiotic factors

Question 2

State the different examples of an ecosystem

Answer 2

Rock pools
Playing field
Large tree

Question 3

State the biotic factors of a rock pool

Answer 3

producers are seaweeds which can be eaten by herbivores like limpets

There exists strong competition for food (e.g. seaweed)

This can decline the population or organisms present in small rock pool ecosystem

Question 4

State the abiotic factors of a rock pool

Answer 4

High and low tides affect rock pools heavily.

During high tide these pools become completely submerged by seawater.

Therefore, organisms experience some abiotic factors such as pH, salinity, temperature like that of marine organisms.

But during low tide, these organisms face more adverse abiotic conditions such as high salinity and temperatures .

These conditions are tolerable by organisms who have a wide range of tolerance.

Question 5

State the biotic factors of a playing field

Answer 5

Grasses , daisies, clover and dandelions form the producer level.

Large number of animals (such as caterpillars and rabbits act as consumers

Question 6

State the abiotic factors of a playing field

Answer 6

Excessive precipitation leads to very wet year - facillitates water logging of soil

Making it unsuitable of growth of plants

Due to less numbers of producers,decline in population of consumers takes place

Question 7

State the biotic factors of a large tree

Answer 7

Leaves of a large tree can become food for caterpillars

Excessive consumption of tree leaves will lead to defoilation, slow growth and eventual death of the tree

Question 8

State the abiotic factors affecting a large tree

Answer 8

Prolonged exposure to harsh environments such as drought has negative impact on the growth of a tree.

Due to these factors, death of plant parts or death of whole tree may occur

Question 9

What is biomass?

Answer 9

Mass of a living organism

Question 10

How is biomass used?

Answer 10

Energy is stored in the form of biomass and it is transferred through the ecosystem between trophic levels

Question 11

What does the transfer of energy show?

Answer 11

The transfer of biomass

Question 12

How does the transfer of biomass/energy occur?

Answer 12

Transfer of biomass occurs due to presence of food chain and food web

Question 13

Define what is meant by a food chain

Answer 13

Simple linear chain of different trophic levels where organism of one trophic level eats organism of another trophic level

Question 14

Define what is meant by a food web

Answer 14

network of multiple food chains.

Due to this network, now it is no more simple and linear, rather it has become complex and web-like

Question 15

between what type of trophic level does the transfer of biomass take place?

Answer 15

From producers to consumers

Question 16

What cannot be transferred further in the food chain?

Answer 16

All the energy transferred to next trophic level from previous trophic level cannot be transferred further

Question 17

Give examples of how energy is lost?

Answer 17

In the process of respiration and other metabolic activities

Question 18

Define Gross Productivity

Answer 18

The absorbed energy at a certain trophic level

Question 19

Define Net Productivity

Answer 19

The actual energy available for next trophic level

Question 20

How do you calculate net productivity?

Answer 20

Gross productivity - Respiratory loss

Question 21

How do you calculate efficient energy transfer

Answer 21

(Net productivity/ energy recieved) * 100

Question 22

Outline the energy transfer between trophic levels can be measured by following steps

Answer 22

1) Calculation of amount of biomass seperately in both trophic levels
2) Multiplication of size of population with amount of biomass in both trophic levels
3) This provides total amount of energy in the organisms at that trophic level
4) Difference between the amount of energy from both trophic level will be the amount of energy transferred

Question 23

Outline the human activities that can manipulate the transfer of biomass through ecosystems

Answer 23

Herbicides
Fungicides
Insecticides
Intro of natural predators
Fertilisers
Livestock

Question 24

How do herbicides manipulate the transfer of biomass

Answer 24

Use of herbicides to kill weeds for reducing competitiion with agricultural crops for sunlight leads to faster growth, larger size and increased productivity

Question 25

How does the use of fungicides manipulate the transfer of biomass through ecosystems?

Answer 25

To kill fungi for stopping damage of agricultural crops has resulted in faster growth, larger crops and increased productivity as the plants are now able to use ther maximum enrgy for production rather than fighting against diseases.

Question 26

How does the use of insecticides manipulate the transfer of biomass through ecosystems?

Answer 26

Use of insecticides to kill pests (insects) for stopiing damage to crops has resulted in faster growth, larger crops and increased productivity as the plants are now able to use their maximum energy for production rather than fightiing against diseases.

Question 27

How does the introduction of natural predators manipulate the transfer of biomass through ecosystems?

Answer 27

Such as ladyirds, which predate on greenfly has lead to reduction of biomass from crops because of pest attack

Question 28

How can fertilisers manipulate the transfer of biomass through ecosystems

Answer 28

Fertilisers are used in crop fields to replenish the limited minerals and thus increasing the rate of growth as more energy from the ecosystem can be utilised

Question 29

How can livestock manipulate the transfer of biomass through ecosystems?

Answer 29

Livestock are provided with such fodder, which will increase their biomass production and hence productivity is increased.

Question 30

What happens to the parts of foods which can not be eaten up by organisms?

Answer 30

Passed onto another group of organisms known as decomposers

Question 31

What do decomposers do?

Answer 31

Take up waste materials such as faeces of other organisms and clean the environment

Question 32

How do decomposers consume dead and decaying organisms?

Answer 32

Saprotrophic mode of nutrition

Question 33

How does the recycling of nutrients take place?

Answer 33

Through various biogeochemical cycles

Question 34

Give examples of various biogeochemical cycles

Answer 34

Carbon cycle
Nitrogen cycle
Phosphorous cycle

Question 35

Which cycle is the most important?

Answer 35

Nitrogen is the most abundant gas present in our atmosphere.

Question 36

What does the nitrogen cycle represent?

Answer 36

Represents how gaseous nitrogen is converted from usable form and again converted back to atmospheric nitrogen.

Question 37

Outline the four different steps in the nitrogen cycle

Answer 37

Nitrogen fixation
Ammonification
Nitr