Topic 2: Ecosystems
Question 1
Read the paragraph below and fill in the missing words using these words:
trophic transfers bar numbers productivity levels balance mass measure population energy inverted
Pyramids
Pyramids of number
A diagram that indicates the relative numbers of organisms at each level in a food chain. The length of each bar gives a measure of the relative . Pyramids begin with producers, usually the greatest number at the bottom decreasing upwards.
Advantages
This is a simple easy method of giving an overview and is good at comparing changes in numbers with time or season.
Disadvantages
All organisms are included regardless of their size, therefore a system say based on an oak tree would be (have a small bottom and get larger as it goes up trophic ). Also they do not allow for juvenilles or immature forms. Numbers can be to great to represent accurately.
Pyramids of biomass
As pyramids of number but uses dry of all organisms at each trophic level.
Advantages
Overcomes the problems of pyramids of number.
Disadvantages
Only uses samples from populations, so it is impossible to biomass exactly.also the time of the year that biomass is measured affects the result.
Pyramids of energy
The bars are drawn in proportion to the total utilised at each trophic level. Also the of producers in a given area measured for a standard time, and the proportion utilised by consumers can be calculated.
Advantages
Most accurate system shows the actual energy transferred and allows for rate of production.
Disadvantages
It is very difficult and complex to to collect energy data.
Why use ecological pyramids.
Ecological pyramids allow you to examine easily energy and losses. They give an idea of what feed s on what and what organisms exist at the different trophic levels. They also help to demonstrate that ecosystems are unified systems,that they are in .
A diagram that indicates the relative numbers of organisms at each level in a food chain. The length of each bar gives a measure of the relative . Pyramids begin with producers, usually the greatest number at the bottom decreasing upwards.
Advantages
This is a simple easy method of giving an overview and is good at comparing changes in numbers with time or season.
Disadvantages
All organisms are included regardless of their size, therefore a system say based on an oak tree would be (have a small bottom and get larger as it goes up trophic ). Also they do not allow for juvenilles or immature forms. Numbers can be to great to represent accurately.
Pyramids of biomass
As pyramids of number but uses dry of all organisms at each trophic level.
Advantages
Overcomes the problems of pyramids of number.
Disadvantages
Only uses samples from populations, so it is impossible to biomass exactly.also the time of the year that biomass is measured affects the result.
Pyramids of energy
The bars are drawn in proportion to the total utilised at each trophic level. Also the of producers in a given area measured for a standard time, and the proportion utilised by consumers can be calculated.
Advantages
Most accurate system shows the actual energy transferred and allows for rate of production.
Disadvantages
It is very difficult and complex to to collect energy data.
Why use ecological pyramids.
Ecological pyramids allow you to examine easily energy and losses. They give an idea of what feed s on what and what organisms exist at the different trophic levels. They also help to demonstrate that ecosystems are unified systems,that they are in .
Question 2
Choose the answers that match the facts by ticking the boxes
Minimata Bay
Story of Minamata Bay.
Minamata is a small factory town in Japan, dominated by one factory, The Chisso Factory. Chisso make petrochemical based substances from fertiliser to plastics. Between 1932 and 1968 Chisso dumped an estimated 27 tons of mercury into Minamata Bay.
Begining in the 1950’s, thousands of people started to suffer from mercury poisoning.
What had happened?
Some bacteria can change mercury to a modified form called methylmercury. Methylmercury is easily absorbed into the bodies of small organisms such as shrimp. When the shrimp are eaten by fish, the methylmercury enter the fish. The methylmercury does not break down easily and can stay in the fish bodies for a long time. As the fish eat more and more shrimp, the amount of methylmercury increases. The same increase in concentration happens when people then eat the fish. Fish are a major part of the diet of people around Minamata bay.
There is a slow magnitude build up along the food chain: Very many bacteria absorb very small amounts of mercury - many shrimp eat a lot of bacteria building up the mercury concentration - lots of fish eat lots of shrimp again building up the concentration and finally a small number of humans at the top of the food chain eventually eat a lot of fish and absorb high levels of methylmercury.
Minamata is a small factory town in Japan, dominated by one factory, The Chisso Factory. Chisso make petrochemical based substances from fertiliser to plastics. Between 1932 and 1968 Chisso dumped an estimated 27 tons of mercury into Minamata Bay.
Begining in the 1950’s, thousands of people started to suffer from mercury poisoning.
What had happened?
Some bacteria can change mercury to a modified form called methylmercury. Methylmercury is easily absorbed into the bodies of small organisms such as shrimp. When the shrimp are eaten by fish, the methylmercury enter the fish. The methylmercury does not break down easily and can stay in the fish bodies for a long time. As the fish eat more and more shrimp, the amount of methylmercury increases. The same increase in concentration happens when people then eat the fish. Fish are a major part of the diet of people around Minamata bay.
There is a slow magnitude build up along the food chain: Very many bacteria absorb very small amounts of mercury - many shrimp eat a lot of bacteria building up the mercury concentration - lots of fish eat lots of shrimp again building up the concentration and finally a small number of humans at the top of the food chain eventually eat a lot of fish and absorb high levels of methylmercury.
This process is known as bioaccumulation.
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The shrimp did not suffer because they are immune to mercury poisoning
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The lag between the time the first mercury was dumped and the first effects in humans was because it was only after the 1950s that the amount of dumping was high enough to affect humans
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The mercury eventually disappeared from the bay because it was released to the atmosphere during decomposer respiration
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Question 3
Choose the answers that match the facts by ticking the boxes
Biomes
Examine the map below
Tropical rainforests generally have only one season
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Deserts are generally more productive than tundra
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In Europe the gulf stream exerts a moderating effect on climet which allows decidous forest to stretch further North than in North America
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Temperate grassland forms away from prevailing oceanic air flows
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There is less conifer forest in the S hemisphere because conifer seeds do not migrate easily
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