Section 8 Ecology And Environment

Question 1

What is a population?

Answer 1

A group of organisms of the same species

Question 2

What is a community?

Answer 2

Several different populations living in a habitat

Question 3

What is an ecosystem?

Answer 3

An ecosystem is made up of a number of different habitats sharing the same environment, and consists of all the living and non living elements interacting together e.g. a rainforest

Question 4

What can you use to estimate a population size?

Answer 4

Quadrat

Question 5

What is a transect?

Answer 5

A line of quadrats

Question 6

What is a trophic level?

Answer 6

Each stage of the food chain

Question 7

What eventually happens to organisms?

Answer 7

Die and get eaten by decomposers

Question 8

What is a pyramid of numbers?

Answer 8

Represents the number of organisms at each stage of the food chain

Question 9

What is a pyramid of biomass?

Answer 9

Each bar shows the mass of living material in that stage

Question 10

What is a pyramid of energy transfer?

Answer 10

Show the energy transferred to each trophic level in a food chain
Always gets smaller

Question 11

How much energy is passed on to each tropic level?

Answer 11

10 percent

Question 12

Explain why only about 10% of energy is transferred from one tropic level to the next?

Answer 12

• used in respiration (lost as heat)
• used in movement
• maintaining constant body temperature
• some material not eaten by the consumer

Question 13

What brings carbon down to the atmosphere?

Answer 13

Photosynthesis in plants

Question 14

What releases CO2 into the atmosphere?

Answer 14

From decomposition

Combustion and respiration

Question 15

Why is carbon monoxide poisonous?

Answer 15

It combines with red blood cells and prevent it from carrying oxygen

Question 16

What causes acid rain?

Answer 16

Sulfur dioxide comes from sulfur impurities in fossil fuels

When mixes with rain clouds it forms dilute sulfuric acid and falls as acid rain

Question 17

What does acid rain do?

Answer 17

Lakes become more acidic killing the ecosystems

Kills trees

Question 18

How does the greenhouse effect work?

Answer 18

Greenhouse gases trap heat from the sun

Question 19

Name some greenhouse gases?

Answer 19

Carbon dioxide
Methane
CFCs

Question 20

What is a habitat?

Answer 20

A place where a living organism lives e.g. a pond or garden

Question 21

What is nitrogen fixation?

Answer 21

Process of turning N2 from the air into nitrogen compounds in the soil which plants can use.
Can be done by:
Lightning - energy makes nitrogen react with oxygen giving nitrates
Nitrogen- nitrogen fixing bacteria in roots and plant nodules

Question 22

What are the four different types of bacteria involved in the nitrogen cycle?

Answer 22

Decomposers - break down proteins and urea and turn them into ammonia
Nitrifying bacteria - turn ammonia into nitrates
Nitrogen-fixing bacteria- turns atmospheric N2 into nitrogen compounds
Denitrifying- turn nitrates back into N2 gas

Question 23

How does sewage cause eutrophication?

Answer 23

Phosphates in the sewage, from detergents, and nitrates, from urine
These extra nutrients cause plants in the river to grow, eutrophication

Question 24

Describe the use of quadrats as a technique for sampling the distribution of organisms in their habitats.

Answer 24

• select at least three quadrats, count how many organisms are in each e.g. Daisies
• add no of organisms in all three together to get a total and divide by no of quadrats to find the mean no per quadrat
• multiply mean by no of total quadrats on that field or grid to get estimate for no of daisies or organisms in that field or area

Question 25

How can you find a trend using a quadrat?

Answer 25

Place one quadrat each metre along a straight line, you can find the percentage cover for diff distances. This is called sampling along a transect.

Question 26

Describe the trophic level of a producer.

Answer 26

- they are plants - anything able to get their food from photosynthesising - anything made up of H, C, O

Question 27

Describe the trophic level of a primary consumer.

Answer 27

Organisms that eat the producers and are eaten by the secondary consumers

Question 28

Describe the trophic level of a secondary consumer.

Answer 28

Organisms that eat primary consumers and are eaten by tertiary consumers

Question 29

What are decomposers?

Answer 29

Either insects, worms, fungi or bacteria Organisms that break down dead material and waste, which releases elements it contained back into the system e.g. carbon and nitrogen

Question 30

What are food chains?

Answer 30

Food chains show what's eaten by what in an ecosystem

Question 31

What are food webs?

Answer 31

Food webs show how food chains are linked

Question 32

What are pyramids of numbers?

Answer 32

Pyramids of numbers are used to show the number of organisms at each tropic level in a food chain

Question 33

What are pyramids of biomass?

Answer 33

Pyramids of biomass take into account the mass of living material in each tropic level of a food chain

Question 34

What are pyramids of energy transfer?

Answer 34

Pyramids of energy transfer show the energy transferred to each tropic level in a food chain. They are always the right shape for a pyramid as there is always going to be energy lost at each level.

Question 35

Describe the stages in the water cycle.

Answer 35

- heat from the sun makes water evaporate from land and sea, whilst water also evaporates from plants (transpiration) - warm water vapour produced by these processes rises and when it gets higher it cools down and condenses to form clouds - water falls from these clouds as precipitation (rain / snow / hail) and surface water run off occurs down the sides of mountains and structures, returning the water to the land or sea, and the cycle continues.

Question 36

Describe the stages in the carbon cycle.

Answer 36

- CO2 in air - used in green plants for carbon compounds in photosynthesis - when animals feed on plants, carbon compounds pass from plant to them - respiration from plants and animals passes CO2 back into the air, but if animals are dead, they are decomposed, meaning decomposers feed on the carbon compounds from dead waste - decomposers then release CO2 back into air by their respiration - once decomposers have broken down dead material, fossilisation occurs, making fossil fuels, which then when are burned for energy in combustion release CO2 back into the air.

Question 37

Describe the stages in the nitrogen cycle.

Answer 37

- nitrogen in the air (is inert so can't be used in this form by organisms) - so nitrogen fixation occurs by either lightning or by nitrogen fixing bacteria in soil and nodules on a plant, turning nitrogen in the air into nitrogen compounds in the soil (nitrates) - nitrogen compounds in the soil (nitrates) pass into plants as this is where they get their nitrogen from - nitrogen compounds (nitrates) then pass into animals when they eat plants and / or are lost by plants and animals in their death and excretion, and form ammonia - nitrifying bacteria then turn ammonia from decaying matter into nitrites, then back into nitrates - denitrifying bacteria then turn these nitrates back into nitrogen gas in the air and the cycle continues

Question 38

Why do living organisms need nitrogen?

Answer 38

To make proteins and DNA.