ecology

Question 1

What are producers?

Answer 1

Organisms that trap light energy and convert it into chemical energy during photosynthesis

Examples include green plants and green algae.

Question 2

What is the role of producers in a food chain?

Answer 2

They start all food chains.

Question 3

Define consumers.

Answer 3

Organisms that cannot make their own food and obtain energy by feeding on other organisms.

Question 4

What are primary consumers?

Answer 4

Herbivores/omnivores that feed directly on plants.

Question 5

What are secondary consumers?

Answer 5

Carnivores/omnivores that feed on primary consumers.

Question 6

What are tertiary consumers?

Answer 6

Carnivores/omnivores that feed on secondary consumers.

Question 7

What are decomposers?

Answer 7

Organisms that break down dead organisms, faeces, and excretory products to obtain energy.

Question 8

What is the significance of decomposers in an ecosystem?

Answer 8

They release inorganic nutrients back to the environment for nutrient cycling.

Question 9

Give examples of decomposers.

Answer 9

Fungi, bacteria, and earthworms.

Question 10

Define a food chain.

Answer 10

A sequence showing the transfer of energy from one organism to another along a feeding pathway.

Question 11

What do arrows represent in a food chain?

Answer 11

The direction in which energy flows.

Question 12

What is a food web?

Answer 12

A series of related food chains interlinked together.

Question 13

Can organisms occupy more than one trophic level in a food web?

Answer 13

Yes, due to various food sources.

Question 14

How much energy is typically lost when transferred from each trophic level?

Answer 14

About 90%.

Question 15

Is energy flow in a food chain cyclic or non-cyclic?

Answer 15

Non-cyclic.

Question 16

What is the ultimate source of energy in an ecosystem?

Answer 16

The sun.

Question 17

What is light energy converted into during photosynthesis?

Answer 17

Chemical energy.

Question 18

How is energy passed from producers to consumers?

Answer 18

Via feeding.

Question 19

List the ways energy is lost to the environment along the food chain.

Answer 19

• As heat energy during respiration
• As chemical energy in uneaten body parts
• As chemical energy through undigested matter in faeces
• As chemical energy through excretion of waste products

Question 20

What happens to total energy in each trophic level as you go down a food chain?

Answer 20

It decreases progressively.

Question 21

Why do food chains rarely consist of more than four trophic levels?

Answer 21

Due to energy loss at each trophic level.

Question 22

Are short food chains more or less efficient than long food chains?

Answer 22

More efficient.

Question 23

What is the relationship between the length of a food chain and the energy available to the final consumer?

Answer 23

The shorter the food chain, the greater the amount of energy available to the final consumer.

Question 24

What is the Pyramid of Numbers?

Answer 24

A representation that allows the comparison of the number of organisms present in each trophic level at a particular time.

The width of the rectangle is proportional to the number of individuals at each trophic level.

Question 25

What are the trophic levels in a Pyramid of Numbers?

Answer 25

1. Producer: Grass 2. Primary consumer: Rabbits 3. Secondary consumer: Snakes 4. Tertiary consumer: Hawks ## Footnote Most pyramids of numbers are usually pyramid shaped but there are exceptions.

Question 26

Under what conditions can a Pyramid of Numbers be inverted?

Answer 26

1. Organisms in one trophic level are parasitic on organisms of another trophic level 2. Many small organisms feed on a large organism ## Footnote Example: primary producer is a large plant.

Question 27

What is the Pyramid of Biomass?

Answer 27

A representation that allows the comparison of the mass of organisms present in each trophic level at a particular time. ## Footnote Constructed based on the dry mass of organisms in each trophic level.

Question 28

What is dry mass?

Answer 28

Mass of organism when all its water is removed. ## Footnote The width of the rectangle in a pyramid of biomass is proportional to the total biomass of all individuals in that trophic level.

Question 29

What is an advantage of the Pyramid of Biomass?

Answer 29

Better than pyramid of numbers because it takes into account both the number as well as the body mass of the organisms.

Question 30

What is a disadvantage of the Pyramid of Biomass?

Answer 30

Organisms have to be killed to measure mass.

Question 31

What is the carbon cycle?

Answer 31

In a balanced ecosystem, nutrients are not lost but continually recycled, with carbon being one of the many nutrients cycled in the environment.

Question 32

How is carbon dioxide removed from the atmosphere?

Answer 32

1. Photosynthesis 2. Feeding 3. Fossilisation ## Footnote Green plants absorb carbon dioxide for manufacturing carbon compounds.

Question 33

How is carbon dioxide released into the environment?

Answer 33

1. Respiration 2. Combustion 3. Decomposition ## Footnote Organic compounds in dead organisms are broken down into simpler components by decomposers.

Question 34

What is a carbon sink?

Answer 34

An area that stores carbon compounds for an indefinite period and stores more carbon than it releases. ## Footnote Examples: Oceans, forests, soil.

Question 35

What is a carbon source?

Answer 35

A process/area that releases more carbon than it stores. ## Footnote Examples: burning of fossil fuels, respiration, fires, volcanoes.

Question 36

Why are oceans considered the largest carbon sinks?

Answer 36

1. Dissolved carbon dioxide is absorbed by phytoplankton and algae in photosynthesis 2. Carbon compounds are buried in the seabed 3. Calcification of shelled marine organisms stores carbon in shells. ## Footnote Feeding by large predators also contributes to carbon storage.

Question 37

How do forests act as carbon sinks?

Answer 37

1. Absorb atmospheric carbon dioxide for photosynthesis 2. Store carbon compounds as starch, cellulose, or bark 3. Remains of dead trees can be buried and stored as coal. ## Footnote Increase in soil carbon through decay and decomposition of organisms.

Question 38

What is biomagnification?

Answer 38

Occurs when certain chemicals (e.g., insecticides) are passed along the food chain, increasing in concentration in the bodies of organisms along trophic levels.