4. ecology and the environment

Question 0

how can quadrats be used to estimate the population size of an organism in two different areas?

Answer 0

A square of around a meter (a quadrat) takes a sample from a area and the populations are counted. This can be repeated many times before being multiplyed out as if it were the complete area of the land. Two different samples can be put in two separate areas and the sampling done for both will estimate population for both areas.

Question 1

Define:

population
community
habitat
ecosystem

Answer 1

Population:
Number of individuals in a particular species.

Community:
Populations of different species interacting.

Habitat:
The area where a population lives.

Ecosystem:
A community in a particular habitat made up of different populations interacting with in the habitat.

Question 2

how can quadrats be used to sample the distribution of organisms in their habitats?

Answer 2

A sample square (a quadrat) is taken at random.

The number of a population in that square is taken. This is repeated in different areas and compared to show where populations are dense and not.

Question 3

explain the names given to different trophic levels to include producers, primary, secondary and tertiary consumers and decomposers

Answer 3

Different trophic levels= different feeding levels

Producer (turns light energy into chemical energy)

Primary consumer (eats the producer and gains its energy)

Secondary consumers

Tertiary consumers

When these organism die they are broken down by decomposers- fungi and bacteria.

Question 4

Describe the transfer of substances and of energy along a food chain

Answer 4

As one thing consumes another the energy and other things inside it- for example fat and vitamins- get transferred to the consumer. If you eat a fatty piece of beef you get the fat from the cow.

Question 5

why does only about 10% of energy get transferred from one trophic level to the next?

Answer 5

The reason why not all of the energy will make it to the next tropic level is that some of it will be used up on the level it is at. The energy is used for the life processes of the animal that it is in.

e.g If a bunny rabbit eats a cabbage, it will use some of the energy to keep warm, some to move e.c.t so fox only gets some of the original energy from the cabbage.

Question 6

describe the stages in the water cycle - (define evaporation, transpiration, condensation and precipitation)

Answer 6

Evaporation is when water turns into steam due to being heated

Transpiration is when water is evaporated from leaves

Condensation is when water vapour turns into water due to being cooled, this forms clouds

Precipitation is when water is released from a cloud, e.g. rain, snow, hail

Question 7

What are the stages of the carbon cycle?

Answer 7

respiration
photosynthesis
decomposition
combustion

Question 9

What is respiration?
What is the respiration equation?

What is Photosynthesis?
What is the photosynthesis equation?

Answer 9

Respiration is carried out by animals and plants to release energy from glucose, the equation is:
C6H12O6 + 6O2 → 6CO2 + 6H2O . This means carbon is produced.

Photosynthesis is what plants do to create glucose the equation is:
6 CO2 + 12 H2O → C6H12O6 + 6 O2 + 6 H2O. This means carbon is used.

Question 10

What is decomposition?

What is combustion?

Answer 10

Decomposition is happens when an animal dies, it is then eaten by a decomposer which releases the carbon in it back into the atmosphere.

Combustion is burning, if something with carbon is burnt it will release it into the atmosphere, e.g. a tree, fossil fuel.

Question 11

What are the biological consequences of pollution of air by sulfur dioxide and by carbon monoxide?

Answer 11

Sulfur dioxide and carbon monoxide are created by many processes we use in factories and homes.

When in the atmosphere they can dissolve in rain water to create rain the is acidic. Acid rain corrodes metals and rocks like limestone which can damage buildings and statues. Acid rain can also change the PH in soil or rivers, this can mean that some species can not survive in that area.

Question 12

What is a ‘greenhouse gas’?

Name some greenhouses gases:

Answer 12

water vapour
carbon dioxide
nitrous oxide
methane
CFC (a compound that contains only carbon, chlorine, hydrogen and fluorine)

A green house gas is one that absorbs heat reflected by the earth, this heat is then trapped in the earth’s atmosphere warming the earth. In large quantities these gasses can change the climate by keeping in too much heat. Gasses that do this include: water vapour, carbon dioxide, nitrous oxide, methane and CFCs.

Question 13

how do human activities contribute to greenhouse gases?

Which processes produce greenhouse gases?

Answer 13

Many of the processes that we carry out in homes and factories produce or release gasses with the greenhouse effect. Many things release greenhouse gasses when they are burned; reactions can create greenhouse gasses; some plants and animals that we keep a lot of naturally release greenhouse gasses.

Processes that produce greenhouse gasses include burning fossil fuels and keeping large amounts of live stock.

Question 14

how does an increase in greenhouse gases results in an enhanced greenhouse effect?

This may lead to global warming. What are the consequences of global warming?

Answer 14

The sun heats up the earth with infra-red waves that it emits, these waves travel from the sun through the earth atmosphere and warm it up. The earth emits its own rays so that it maintains its heat instead of just warming up forever! Many of these rays escape the earth’s atmosphere- revealing it of heat- but some are absorbed by certain gasses- Greenhouse gasses- this means the heat is trapped within the earth’s atmosphere. On a large scale this heats the earth, which we call global warming, and this can lead to climate change: the expected weather patterns reverse or exaggerate: this is thought to result in natural disaster (drought, floods).

Question 15

Eutrophication can result from leached minerals from fertiliser.

What is eutrophication?

Answer 15

Eutrophication is when there are excessive amounts of nutrients in a lake. The effects of this are that algae will bloom (grow quickly). Having a lot of algae will mean that there is not enough oxygen for other organisms, they will also struggle to find enough light as algae covers the surface. More organisms will die then usual- more algae to die/ less oxygen and light so fish die- so decomposers will thrive; these decomposers will also use a lot of oxygen from the water. In the end there will not be enough oxygen for fish.

Nutrients get leached into rivers from soil as rain water runs off land into rivers and lakes taking nutrient with it. If fertiliser has been put in the soil then the soil will be rich in certain nutrient, especially nitrogen: so rain water runs off fertilised soil it will bring high amounts of nutrient into surrounding rivers or lakes causing eutrophication.

Question 16

What are the effects of deforestation?

Answer 16

Leeching: loss of nutrient from soil.
Normally nutrient is rained into the soil; absorbed by plants; shed in their leaves/when they die; digested by decomposers so its back in the soil. If you take away the vegetation you remove nutrients from the cycle. In addition to this the soil is not protected by plants and so when it rains there will be a higher rate of surface run off, this will take the nutrients from the soil with it.

Soil erosion is also caused by the fact that without plants to protect the soil there is more surface run off, because soil is taken with it.

Plants absorb water from the soil and lose water from their leaves (through transpiration) in to the atmosphere which goes on to make clouds. If there are less plants then less water is evaporated into the atmosphere, this means there are less clouds; less clouds means less rain, which can mean drought.

Plants also convert carbon dioxide into oxygen when they photosynthesise. Forests carbon sinks, they use more carbon than they release: this means they help to make sure there aren’t too high levels of CO2 in the atmosphere. When forests are cut down this process is lost and additionally the trees are usually burnt which releases CO2 into the atmosphere.

Question 17

What are the biological consequences of pollution of water by sewage?

Answer 17

Basically its the same process as eutrophication. (increases in the number of micro-organisms causing depletion of oxygen)

Sewage contains nutrient which enable algae to flourish. They take up sunlight and oxygen. Many fish die and other organisms die. Decomposers thrive on there dead bodies; meaning even more oxygen is taken up by microorganisms.

Question 18

describe the stages in the nitrogen cycle, including the roles of nitrogen fixing bacteria, decomposers, nitrifying bacteria and denitrifying bacteria (specific names of bacteria are not required).

Answer 18

Nitrogen fixing bacteria turn nitrogen from N2 into ammonia.
Decomposers break down dead animals, urea and egested materials which releases nitrogen into the soil as ammonia.
Nitrifying bacteria convert nitrates into nitrogen.
Denitrifying bacteria break down nitrates into nitrogen which is then released into the atmosphere.