Ecosystems

Question 1

Define an ecosystem?

Answer 1

All the living organisms that interact with one another in a defined area

Question 2

Two factors that affect an ecosystem?

Answer 2

Abiotic and Biotic

Question 3

Examples of biotic factors?

Answer 3

Competition, disease, food availability, territory

Question 4

Examples of abiotic factors?

Answer 4

Light intensity, temperature, water availability, oxygen availability, soil mineral concentration

Question 5

What produces the most energy for ecosystems?

Answer 5

The Sun

Question 6

What is a trophic level?

Answer 6

Each stage in the food chain

Question 7

The first trophic level is called what?

Answer 7

A producer

Question 8

What is a producer?

Answer 8

An organism that converts light energy into chemical energy by the process of photosynthesis

Question 9

What is a consumer?

Answer 9

Organisms that obtain their energy by feeding on other organisms

Question 10

Why don’t food chains have more than 4 trophic levels?

Answer 10

Not sufficient biomass and stored energy left to support any further organisms

Question 11

What is biomass?

Answer 11

The mass of living material present in a particular place of an organism

Question 12

How do you calculate biomass?

Answer 12

Net production of biomass = gross production (initial energy) subtracted by the respiratory loss

Question 13

What is the measurement for biomass?

Answer 13

gm-2yr-1
(grams per meter squared per year)

Question 14

In a food chain diagram where are the producers always placed?

Answer 14

At the bottom of the pyramid

Question 15

How much of biomass is consumed by an organism passed onto the next trophic level?

Answer 15

10 percent !!

Question 16

Equation for the efficiency of trophic levels?

Answer 16

energy available after transfer/ energy available before transfer x 100

Question 17

Where does the biomass go once entered into an organism?

Answer 17

The environment, lost in urine/excretion, movement, respiration

Question 18

The unit for the efficiency of energy transfers between trophic levels?

Answer 18

kJm-2year-1

Question 19

How much sun energy is captured by organic material?

Answer 19

1-3 percent

Question 20

Why do organisms capture so little sun radiation?

Answer 20

Most hits the Earth and bounces back by clouds, dust and the atmospher

Question 21

Ways that humans can manipulate biomass through an ecosystem?

Answer 21

Reducing competition by feeding them, using pesticides or fertilizers, destruction of habitat eg:deforestation, routine antibiotic application or heating

Question 22

Name and describe what a scavenger is?

Answer 22

An organism that breaks/opens up the carcass. An example is hyenas or vultures

Question 23

What is a decomposer?

Answer 23

An organism that feeds on and breaks down dead plant or animal matter by external digestion

Question 24

An example of a decomposer?

Answer 24

Fungi or bacteria

Question 25

Detritivores are what?

Answer 25

Break down organic material by internal digestion, increases the SA for the decomposers

Question 26

Examples of detritivores?

Answer 26

Woodlice, maggots, worms

Question 27

Conditions needed for decomposition?

Answer 27

Optimum temperature for digestive enzymes, high oxygen availability, moist water availability

Question 28

Examples of habitats with no decomposition?

Answer 28

Mountains, volcanoes, amber, peat bogs

Question 29

How much of the atmosphere is nitrogen?

Answer 29

78%

Question 30

Why is nitrogen essential?

Answer 30

Essential element for making amino acids and proteins

Question 31

Why is the nitrogen cycle needed?

Answer 31

The nitrogen in the atmosphere cannot be taken up by plants. It needs to be combined with other elements such as oxygen and hydrogen

Question 32

4 processes involved in the nitrogen cycle?

Answer 32

Nitrogen fixation, Ammonification, Nitrification and Denitrification

Question 33

What is involved in nitrogen fixation?

Answer 33

Bacteria such as Rhizobium and Azotobacter combine Nitrogen with Hydrogen to make Ammonia

Question 34

Where is Rhizobium found?

Answer 34

In the root nodules of leguminous plants, the bacteria has a mutualistic relationship with the plants

Question 35

Describe ammonification?

Answer 35

Its the process of decomposers converting nitrogen-containing compounds into ammonium ions

Question 36

Nitrification?

Answer 36

The ammonium ions from ammonification are converted into NITRITES and then become NITRATES used in plants

Question 37

What is the name of the bacteria involved in nitrification?

Answer 37

Nitrosomonas

Question 38

When and why does denitrification occur?

Answer 38

In the absence of oxygen (anaerobic conditions) Denitrifying bacteria uses the nitrates as a source of energy for respiration and nitrogen gas is released

Question 39

What is succession?

Answer 39

The process in an ecosystem where abiotic factors change, causing the biotic factors to change

Question 40

Primary succession?

Answer 40

Occurs in a newly found area of land, bare rock, no soil or organic matter

Question 41

Secondary succession?

Answer 41

In areas of land where soil is present but has no plant or animal species (the bare earth after a forest fire)

Question 42

Examples of primary succession occuring?

Answer 42

Volcano eruptions, sand blown by the wind, glaciers retreating