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KS4 Biology B17a / Side 1

The Carbon Cycle

The words and pictures shown below are needed to complete the carbon cycle on the next sheet. Cut out the pieces and decide where they fit best on sheet Side 2. Stick them in position once it has been checked by your teacher.

Sha Tin College Science Department - May 23

KS4 Biology B17a / Side 2Complete this diagram using the shapes you have cut from the previous page.

Use your textbook and visit the following website to answer the questions below.http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/C/CarbonCycle.htmlA. List 4 sources of Carbon that exist in the non-living environment.1. 2. 3. 4.


http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/C/CarbonCycle.html


B. What process coverts carbon dioxide gas into organic (living) matter? C. How does Carbon from the living organism return to the atmosphere and

water? D. The uptake and return of carbon dioxide to and from the atmosphere are

not balanced. What has the trend been in recent decades? E. Using the website information, when did atmospheric levels of carbon

dioxide begin to rise? F. The changes in atmospheric carbon dioxide have been caused by human

activities. Name and explain the two major causes. G. What is a carbon sink? H. Explain what is meant by the, “Greenhouse Effect”. The website diagram

will be useful.



I. Demonstrate the Greenhouse effect with a plastic bottle. Use a nail to make a hole in the bottle and insert a thermometer. Place a second thermometer next to the bottle. Ensure the same amount of sunlight reaches both. Take the temperature and compare every ten minutes. What do you notice? Explain.

J. The diagram below shows the carbon cycle. Write down the correct words

in boxes 1-5.



Practise questions

1. The diagram shows part of the carbon cycle.

(a)Name process A. [1]

(b)What type of organisms is responsible for process B? [1]

(c) Write the word equation for process C. [3]

(d)On the diagram, draw an arrow labelled X to show how animals obtain carbon. [1]


Carbon dioxide in the air

Dead remains

Animals

Green plants

A

B

C D


2. Diagram below shows part of the carbon cycle.

(a)Fill in the three spaces on the diagram. [3]

(b)Use the information in the diagram, and your own knowledge, to explain how deforestation and the burning of fossil fuels can affect the concentration of carbon dioxide in the air. [3]


KS4 Biology B17a / Side 73.

(a)With reference to the diagram, state, in each case, one letter which represents [3]i. The process of respiration; ii. The process of photosynthesis; iii. A process which depends on the activity of fungi and bacteria.

(b)i. Deforestation affects the carbon cycle and the water cycle. Suggest

and explain one effect of deforestation on the water cycle. [2]

ii. Describe three other undesirable effects of deforestation on the environment, apart from the effect on the water cycle. [3]1.

2.

3.



E

D

C

B

A

Carbon dioxide in the air

Fuels

Carbon compounds in plants

Carbon compounds in dead material

Carbon compounds in animals

death

feedingdeath

4. A farmer sprayed fertilisers containing ammonium nitrate onto a field in which young wheat seedlings were growing.(a) Explain why farmers often add nitrogen-containing fertilisers to the soil where

crops are growing. [2]

(b)i. Describe how the ammonium and nitrate ions would be absorbed by the

wheat plants. [2]

ii. Name the tissue that would transport the ammonium and nitrate ions through the plant. [1]

(c) Some of the fertiliser was washed into a river which ran alongside the wheat field.Diagram below shows how this affected the numbers of bacteria, algae and fish in the river, downstream from the wheat field. It also shows how it affected the oxygen concentration.

i. Explain the shape of the curve for the numbers of algae. [2]

ii. With reference to the curves for bacteria and oxygen in the diagram, explain the shape of the curve for fish. [4]


KS4 Biology B17a / Side 9Extension5. A farmer wanted to know how to get the best yield from a variety of maize. He

measured out ten plots, each 5m x 5m, in the same field. He added nitrate fertiliser to the plots, but not to the other five plots.He then sowed maize seed in each of the plots. He sowed different numbers of seeds in each of the five plots with nitrate fertiliser, and also in each of the five plots with no nitrate fertiliser. All the seeds germinated.The graph shows the yield of maize he obtained from each of the ten plots.

(a)i. Suggest why curve A is above curve B. [3]

ii. Suggest why both curves rise as the number of seeds per plot increases from 100 to 300. [1]

iii. Suggest why both curves fall as the number of seeds per plot increases from 400 to 500. [2]


KS4 Biology B17a / Side 10(b) Next year, the farmer is going to sow maize in a field which measures 50m x

25m. He will add nitrate fertiliser to the field.The mass of 100 maize seeds is approximately 50 grams.Calculate the mass of seed the farmer should sow in the field, to get the maximum yield. Show your working. [3]

6. Average global temperatures have increased in recent decades. Many scientists believe that this is due to deforestation and the burning of fossil fuels. However some scientists argue that the burning of fossil fuel does not account for this increase. Explain this viewpoint.

7. Name two other Greenhouse gases other than carbon dioxide.

8. How does deforestation of Tropical rain forest produce a double whammy as far as contributing to an increase in global temperature?


KS4 Biology B17b / Side 1

The Nitrogen Cycle

Use the following words to complete the above diagram: Dead matter & waste matter fed off by decomposers Denitrifying bacteria Free living nitrifying bacteria in the soil Nitrogen fixing bacteria within root nodules of legumes Ammonia Nitrate

Look at your text book and visit the following website in order to answer the following questions:http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/N/NitrogenCycle.htmlThere are 4 key processes that participate in this cycling of Nitrogen.

Nitrogen Fixation (Biological Fixation). Decay. Nitrification. Denitrification.

All 4 processes involve microbes. Explain what each process involves and name the microbes involved.1. Nitrogen Fixation


http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/N/NitrogenCycle.html

KS4 Biology B17b / Side 22. Decay

3. Nitrification

4. Denitrification

The following diagram summarises the Nitrogen Cycle.

A. What processes are represented by the following numbers on the cycle?1. 2. 3. 4. 5. 6.


KS4 Biology B17b / Side 3B. State why process 1 can occur in clover but does not occur in grass

C. State the importance of adding humus to the soil.

D. Name 2 compounds containing Nitrogen that is involved in process 5.

E. The flow diagram represents part of the Nitrogen cycle. At points A, B and C, insert the name of the correct bacteria from the following list:

Decomposing

Denitrifying Nitrifying

F. Name 2 biological and one abiotic-non living- way of adding nitrate to soil.

G. What can farmers do to replace nitrate in the soil other than by using artificial fertilizer?


A ______________ Free Nitrogen

Nitrates

Plant protein Animal protein

Ammonium saltsNitrates

Nitrates

B _______________

C ______________


The Pros and cons of Fertilizers

Fertilizers illustrate the conflict between having to feed a large population whilst conserving the environment. You need to know the advantages and disadvantages of using nitrogen fertilizers.

Advantages1. Fertilizers give nitrates to the soil to help plants produce protein and

grow healthily. Wheat for example will produce more grain in a fertilized field compared fairly with an unfertilized field.

2. Fertilizers allow farmers to grow their crop close together. This improves productivity. The land is being used intensively.

3. Intensive farming means that less land used for farming and more is left in its natural state.

Disadvantages1. Approximately only half the fertilizer put on land is taken up by plants.

The rest runs off the surface and leaches into the ground water and eventually rivers, ponds and lakes. Fertilizers in rivers etc causes eutrophication. Severe eutrophication kills aquatic life.

2. Fertilizer gets into our drinking water. Nitrate in drinking water can cause, “blue baby syndrome” and possibly cancer of the stomach. High nitrate levels can also occur in certain foods, especially vegetables. Nitrate moves down through the soil very slowly so the present nitrate problem is a result of fertilizer use some 20 years ago.

3. Manufacturing fertilizers requires energy from fossil fuels. As well as using up precious fuels, this adds to the pollution of the atmosphere.

For each of the words in bold above write a sentence to explain the meaning. You may need to write more to explain eutrophication.

Visit the website below shows eutrophication in Lake Erie in Hawaiiwww.umanitoba.ca/institutes/fisheries/eutr.html

There is a lot of discussion about pollution levels in the waters of Hong Kong. Find and keep a log of information regarding eutrophication in Tolo Harbour and the Pearl River.


http://www.umanitoba.ca/institutes/fisheries/eutr.html

KS4 Biology B17b / Side 5Practise questions1. Diagram below shows a nitrogen cycle for open grassland.

(a)i. Name one nitrogen compound found in plants. [1]

ii. Name an example of a nitrogen compound which is excreted by

mammals. [1]


nitrogen compounds in dead plant and

animal matter

nitrogen compounds in

animals

ammonium compounds in

the soilnitrogen

compounds in plants

nitrates in the soil

nitrogen gas in the

air

death

death

excretion

X


iii. Process X can only occur in certain plants. Which group of organisms carry out this process and where in a plant are they found? [2]Organism Where found

(b)The grassland is ploughed up and turned into farmland. Crops of maize are grown on it year after year.i. Predict and explain the effect of this change on the nitrogen cycle and

on the crop yield. [4]Effect on the nitrogen cycle

Effect on crop yield

ii. Suggest one way in which the farmer could prevent the effect on crop yield. [1]


KS4 Biology B17b / Side 72. Diagram below shows the nitrogen cycle.

(a)i. Name the main nitrogen-containing compound found both in plants

and in animals. [1]

ii. Name one nitrogen-containing compound that is present in urine. [1]

iii. Name the type of organism that causes the changes at A. [1]

iv. What atmospheric conditions bring about the change at B? [1]

(b)Using the diagram, explain why it is an advantage to have good drainage in most agricultural land. [4]

KS4 Biology B17c / Side 1

The Water Cycle


nitrogen-containing compounds in animals

nitrogen-containing compound in urine

decaying remainsnitrates

fertilisers

nitrites

ammonia and ammonium compounds

nitrogen gas in atmosphere

nitrogen-containing compounds in green

plants

denitrifying bacteria in waterlogged soils

in aereated soil

in aerated soil

legumes e.g. beans

B

A

A

1. Fill in the missing words:The Word

Starts With this

LetterHint Answer

WA substance that is very important to us. We need it to live, and it covers two thirds of the surface of the Earth

O A large body of water on the surface of the earth.

E A process in which liquid water turns into water vapour (a gas).

PIn transpiration, water from these objects evaporates into the atmosphere.

CA fluffy-looking object in the sky that contains tiny water droplets or ice particles. It is formed when water vapour condenses.



R This type of precipitation is water that falls from clouds in a liquid state.

SThis type of precipitation is water that falls from clouds in a fluffy, frozen state.

G A large, slowly-moving river of ice.

R A large, flowing body of water that usually empties into a sea or ocean.

WThe process in which water circulates from the oceans to the clouds to the land to the rivers, and then accumulates back into the oceans.

2. State three ways in which animals can lose water:

3. How do plants use water?

The great proportion of water is recycled without the intervention of animals or plants. The sun shining and the wind blowing over the oceans evaporate water from their vase exposed surfaces. The water vapour produced in this way enters the atmosphere and eventually forms clouds. The clouds release their water in the form of rain or snow (precipitation). The rain collects in streams, rivers and lakes and eventually flows back into the oceans. The human population diverts some of this water for drinking, washing, cooking, irrigation, hydro-electric schemes and other industrial purposes, before allowing it to return to the sea.

4. Name the main reservoir for water on the earth’s surface.

5. Name the main reservoirs for fresh water.


KS4 Biology B17c / Side 3Affects of Deforestation on the Water Cycle

Forests have a profound effect on climate, water supply and soil maintenance. They have been described as environmental buffers. For example, they intercept heavy rainfall and release the water steadily and slowly to the soil beneath and into the streams and rivers that start in and flow through them. The tree roots hold the soil in place. At present we are destroying forests at an alarming rate.

6. List some of the reasons why this is happening:

Removal of forests allows soil erosion, silting up of lakes and rivers, floods and loss for ever of thousands of species of plants and animals. Heavy rainfall washes the soil off hillsides and leaves them bare and unable to sustain further pant life. Sedimentation builds up in rivers and cause rivers to burst their banks. Sedimentation has also shortened the lifespan of projects such as hydroelectric schemes and irrigation schemes.

About half the rain that falls in tropical rainforests comes from the transpiration of the trees themselves. The clouds from which form from this transpired water help to reflect sunlight and so keep the region relatively cool and humid. When areas of forest are cleared, this source of rain is removed, cloud cover is reduced and the local climate changes quite dramatically. The temperature from day and night is more extreme and the rainfall diminishes.

In North East Brazil an area that was once rainforest is now an arid wasteland. If more than 60% of a rainforest is cleared, it may cause irreversible changes in the climate of the whole region. This could turn the region into on unproductive desert.


KS4 Biology B17c / Side 4Acid Rain

Acid rain is not a new phenomenon. It was first noticed last century in regions where the industrial activity were being worn away by rain. More correctly termed acid deposition, it can fall to the Earth as rain, snow or sleet, as well as dry, sulphate-containing particles that settle out of the air. It is a problem that crosses international boundaries. Gases from coal-burning power stations in England fall as acid rain in Norway and Sweden, emissions from the United States produce acid deposition in Canada, while Japan receives acid rain from China. The effect of this fallout is to produce lakes that are so acid that they cannot support fish, and forests with sickly, stunted tree growth. Acid rain also causes the release of heavy metals (e.g. cadmium and mercury) into the food chain. Changes in species composition of aquatic communities may be used as biological indicators measuring the severity of acid deposition.

Acidity Tolerance in Lake OrganismsDifferent aquatic organisms have varying sensitivities to higher acidity (lower pH). The graph on the right shows how much acidity certain species can tolerate. The absence of certain indicator species from a waterway can provide evidence of pollution in the recent past as well as the present.

1. What is the source of sulphur dioxide?

2. What affects does it have on forests?

3. What affects does it have on organisms living in lakes?

4. How can sulphur dioxide emissions be reduced?



Acid Rain Survey in Sha Tin College

Set up the rain fall collector as shown in diagram above. You will need to first clean the funnel and bottle with distilled water. You will need to set up the apparatus away from obstructions such as buildings or trees and it should be sufficiently high off the ground. (1.5m) so that water & other contaminants cannot splash in from the surroundings.

The collection of rain should be on a regular basis at a set time of day over a period of time you decide upon. The rainfall collected should then be analysed. You need to record the volume & pH of the sample. The volume should be recorded using the following calculation:

1000 x (volume of rainfall cm3/3.14 x r2) = Rainfall in mm.(Where r is the radius of the collecting funnel.)

The pH can measured using universal indicator paper or using a pH meter.

Organise your data into a suitable tale and use the HK meteorological Society website (HK Observatory) to compare your values with these from standansed rain gauges within HK.


KS4 Biology B17d / Side 1

Controlling Pests

Read P.84-86 in Roberts

Define a pest: How do farmers usually control pests?

Pesticides and Bioaccumulation

Certain chemicals in the environment are harmful when absorbed in high concentrations. The toxicity of a pesticide is a measure of how poisonous the chemical is not only to the target organism, but to the non-target species as well. The specificity (broad or narrow) of a pesticide describes how selective it is in targeting a pest. An important issue relating to the use of a pesticide is its persistence – how long it remains in the environment. A pesticide may be biodegradable or resistant to biological breakdown. Many highly persistent pesticides get stored in fatty tissue and have the potential for bioaccumulation – the concentration increases as you pass up the trophic levels. Top consumers may ingest harmful or lethal quantities of a chemical because they eat large quantities of organisms from lower trophic levels.



Define the following terms:

Toxicity: Specificity: Biodegradable: Bioaccumulation:

Using the diagram on the side 1, calculate the increase in DDT concentration between each step in the food chain:

Between water and algae: 0.05/0.00005 = 1,000 times Between algae and plat-eating fish: Between plant eating fish and carnivorous fish: Between carnivorous birds and fish eating birds:

State briefly why top consumers are most at risk from bioaccumulation:


KS4 Biology B17d / Side 3DDT and Fish EaglesDDT situation worse in ZimbabweEight clutches of fish eagle Haliaeetus vocifer eggs collected in 1989 close to sites sampled in 1980 near Lake Kariba, Zimbabwe, showed an average increase of 60 per cent in levels of DDT. Although only 11 clutches were sampled in 1989, making it difficult to estimate the risk to the entire fish eagle population, the degree of eggshell thinning and residue levels of DDE (a DDT metabolite) were sufficient to reduce breeding success. The red-billed hoopoe Phoeniculus purpureus has suffered a serious decline in numbers in an area first sprayed against tsetse fly in 1987 and annually since. The hoopoe feeds on insects taken low down on tree trunks where DDT is applied.

1. What is DDT?

2. Explain why high levels of DDT are thought to reduce breeding success?

3. Suggest how DDT might enter the diet of a fish eagle:

4. What do fish Eagles and Peregrine falcons have in common that makes them especially susceptible to DDT poisoning?

5. You are a manufacturer and you intend to produce the perfect insecticide. Make a list of all the features which it should have and explain each:


KS4 Biology B17d / Side 4Extension

Rachel CarsonRachel Carson, the naturalist and science writer was born in Springvale, Pennsylvania in 1907. She became famous in 1951 for her book, The Sea Around Us in which she warned about the increasing danger of large-scale marine pollution.In 1962, Rachel published her well-known book, Silent Spring. This created a great deal of controversy, since it warned about the toxic build-up of synthetic pesticides in food chains.To a great extent, Rachel Carson can be credited with provoking governments into bringing in controls on pesticide usage and furthering the development of the conservationist movement.Jonathan Porritt, the well-known conservation campaigner, wrote the following about the dependence of scientific funding on government and big business (in The Guardian 31 May, 2000):

This is not a new phenomenon. At several points in Silent Spring, published in 1962, Rachel Carson comments on the complicity of so many government scientists she came into contact with, when researching the impact of pesticides on the environment and human health. She sympathised with their dilemma, but had little respect for what she saw as the dereliction of their duty as scientists, however dutiful they were as government officials. In private correspondence, she often quoted Abraham Lincoln: ‘To sin by silence when they should protest makes cowards of men’.

Questions1. Explain briefly how synthetic pesticides get into and are passed along food

chains.

2. Which trophic (feeding) level is most at threat from these chemicals?

3. Why do you think the publishing of Silent Spring provoked such a stir in the early 1960s?


KS4 Biology B17d / Side 5Read this story carefully, and then answer questionsThe Dayak people of Borneo live in large thatched huts called longhouses. At the time of this true story they suffered seriously from malaria. The World Health Organization decided to try controlling the mosquitoes which were causing the disease.Every longhouse was sprayed with DDT. Sure enough, the numbers of mosquitoes dropped dramatically. This greatly reduced the number of cases of malaria.Unfortunately, spraying with DDT interfered with other parts of the ecosystem within the Dayak longhouses. Cockroaches lived in the longhouses in large numbers, and were eaten by lizards. The cockroaches absorbed DDT, which became concentrated in the bodies of the lizards which ate them. The lizards were eaten in turn by domestic cats. By the time the food chain reached the cats, the DDT had become concentrated enough to kill them.With the death of many of the cats, the rat population of the longhouse began to increase. These rats carried parasites, such as fleas and lice, which spread a disease known as sylvatic plague. The Dayak people no longer suffered from malaria, but sylvatic plague became common. Eventually a new population of cats was brought into the Dayak community by parachute, dropped from helicopters. These helped to bring the rat population under control.But this is not the end of the sad story. Caterpillars lived in the thatched roofs of the huts, eating the thatch. If their numbers became too great they seriously damaged the roofs. Spraying with DDT killed the caterpillars, but also killed the predators and parasites which kept the caterpillars under control. Some time after the spraying, the caterpillar population began to grow again. But the populations of predators and parasites were much slower to recover. The result was a caterpillar population explosion. By the time the rainy season came, the thatched roofs of the longhouse had been so badly damaged by caterpillars that they collapsed.Questions1. Explain why DDT spraying led to the death of domestic cats in the longhouses.2. Explain why there was an outbreak of sylvatic plague following the DDT spraying.3. Why did the DDT spraying lead to the collapse of the thatched roofs?4. An ecologist has said ‘When we use insecticides, we must think of their effects on the whole ecosystem,

not just on insects.’ Why is this important?General points for discussionYou might prefer to discuss these in small groups.

Consider the benefits and drawbacks of DDT.Benefits Drawbacks

Valuable for controlling insect-spread diseases like malaria and typhus

Kills animals other than insects

Valuable for controlling insects which eat food crops

Disturbs the balance of the ecosystem

How do you think these benefits and drawbacks weigh up against each other? Was it right to ban DDT? Research in 1964-66 showed that English people had an average of 3 parts per million of DDT in their

body tissues. How did it get there? Nowadays many different kinds of insecticides are available. Many of them are designed to break down

quickly after spraying. Why is this important? Do you or your family use insecticides? If so, what for? Some plants produce their own, natural insecticide. This can be collected from the plant and used by

humans. An example is pyrethrum, which is produced by one type of chrysanthemum. Pyrethrum is widely used in parts of Africa.

Why might natural insecticides like pyrethrum be preferable to synthetic insecticides like DDT? Have a look at the labels on some insecticide packs. What is the active chemical in the insecticide?

Read the safety warning on the pack. What does the warning tell you about the insecticide?



Biological Control – An Alternative to PesticidesCaterpillar’s conquestProfessor John Lawton researches into the problem of controlling the spread of bracken. Bracken is a fern which threatens upland farms, partly because it poses a health risk to people and animals. Upland farms are artificial ecosystems, created and maintained mainly for the rearing of sheep and cattle. These farms are being threatened by the spread of bracken. Up to now the only treatment for bracken has been to use herbicides.Professor Lawton is waiting for the government permission to release the Conservular caterpillar which feeds on the bracken, using biological control as an alternative to use of herbicide. The secretary of State has to decide whether the Conservular caterpillar can be released.The article printed below describes some of the problems faced by the Secretary of State.

David the caterpillar to bracken’s Goliath

Yorkshire farmer Maurice Cottrill has just forked out $5,000 to have a helicopter hover over his land and spew out gallons of chemicals aimed at destroying one of the most pervasive and dangerous weeds known to man – bracken. In a little box in a laboratory near Ascot, Berkshire, lies a tiny caterpillar which could have done the job for nothing.Whether or not that caterpillar and thousands of its chums will ever be let loose on the massive carpet of bracken that is sweeping over Britain at the rate of 53 square kilometres a year has to be decided by the Secretary of State for the Environment.Weed control though the release of imported insects has never been tried in Britain before. If the Secretary of State permits the experiment, the caterpillar is in for

the feast of its life, because five years of painstaking research have proved that bracken is its only food. However, is that the full story? Will the beast stop there, or will it go on, wreaking unforeseen devastation. Can scientists predict what will happen when imported insects are released into the wild? Bracken is poisonous – more than 20,000 sheep and 1,000 cattle suffer poisoning each year. Its spores are carcinogenic, posing a threat to hill walkers. Bracken costs a depressing $40 million a year to control while rendering useless grazing land valued at $50 million annually. ‘Bracken is one factor which is leading to hill farming becoming uneconomic’, says the director of the Ramblers’ Association. ‘We are worried about that because, the more uneconomic hill farms become, the

more prospect there is of the forestry industry taking over.’The National Farmers Union are concerned about the consequences of the caterpillar getting out of control. What if it started consuming garden ferns? What if it loved potatoes? On the other hand, the caterpillar might help to preserve important uplands where wildlife flourishes when bracken is kept at bay. However, the experiment takes the scientists into unknown territory. World-wide, 94 species of weeds have been controlled by biological releases involving 215 types of animal in 50 countries. Professor Lawson says that approximately one-third have achieved effective control and the remainder have failed.

ActivityUse this article to compile a list of arguments for and against the use of biological control.Make a decision based on your list what advice you would give to the Secretary of State.


KS4 Biology B17d / Side 7QuestionsMelon plants grown in glasshouses are often infested with red spider mites. The red spider mites feed on the sap of them melon plants, and breed rapidly. If the grower does not control the numbers of red spider mites, then the crop may be destroyed.An experiment was carried out to compare two ways of controlling the red spider mite populations on a melon crop. Some of the melon plants were sprayed with chemical pesticides. Some of the melon plants were treated by biological control, using a larger predatory mite which preys on the red spider mites.The melons grown in three identical glasshouses.In glasshouse 1, chemical pesticides were sprayed onto the melon plants at intervals from March onwards,

In glasshouse 2, the predators were introduced in March,

In glasshouse 3, the predators were introduced in February.

The graphs show the results of the experiments, (a)

i. Suggest one other experiment which should have been done as a control, to see if either the chemical pesticide or the predatory mite had any effect on the population of red spider mites. [1]


KS4 Biology B17d / Side 8ii. Suggest one other experiment which should have been done, in order to

make a fairer comparison between the effectiveness of chemical pesticides and biological control in this situation. [1]

(b)i. By Comparing the results in glasshouse 1 and 3, outline two advantages

of using biological control rather than chemical pesticides. [2]

Advantage 1

Advantage 2

ii. By comparing the results in all three glasshouse, outline one advantage of using chemical pesticides rather than biological control. [1]

(c) Suggest why plants are not sprayed with pesticide during the four weeks before the melons are harvested for human consumption. [2]


KS4 Biology B17e / Side 1

What is Conservation?Activity 1Read the questions below as preparation. Watch the Video SB21 “Wildlife Matters” and answer the questions.1. What is the population of humans on the planet?2. Name 2 African animals that are threatened with extinction.3. How does the Oryx camouflage itself against predators?4. The Indian Tiger numbers in Ranthanbourg are increasing. How has this

been achieved?5. The money gained from donations can be used in a variety of ways to help

conservation. List as many strategies as you can that are mentioned in the video.

6. What is meant by the slogan, “When the buying stops, the killing can too!”7. Why are the following animals targeted by poachers:

a. Rhinob. Elephantc. Turtle

8. What does Minnie Driver have to say about conservation efforts in Tibet?

Activity 2Read the information sheet on Conservation. Use a coloured pen to underline the key points and complete the question.

Activity 3Read the newspaper article about conservation programmes in China to help the Bear population. Within a small group research another conservation issue that is relevant in HK, China or within SE Asia. Present to the class using PowerPoint. Use downloaded images; illustrate graphs or bullet points you wish to discuss. Look at the following websites for examples:http://www.arkive.org/http://www.worldwildlife.org/http://www.cities.org/


http://www.cities.org/

http://www.worldwildlife.org/

http://www.arkive.org/


Conservation

ExtinctionIn the course of evolution, species become extinct. After all, the fossil remains of plants and animals represent organisms that became extinct hundreds of thousands of years ago. There have been periods of mass extinction, such as what which wiped out the dinosaurs during the Cretaceous era, 65 million years ago.The ‘background’ extinction rate for, say, birds might be one species in 100-1000 years. Today, as a result of human activity, the rate of extinction has gone up by at least ten times and possibly as much as 1,000 times. Some estimates suggest that the world is losing one species every day and within 20 years at least 25 per cent of all forms of wildlife could become extinct. Reliable evidence for these figures is hard to obtain, however.A classic example is the colonization of the Pacific islands by the Polynesians. They killed and ate the larger bird species, and introduced pigs and rats which ate the eggs and young of ground-nesting species. Their goats and cattle destroyed plant species. Of about 1,000 plant species, 85 per cent has been lost since they were first discovered.This may be an example but the same sort of changes are happening all over the world. For example, only about 6,000 tigers survive in the wild. This is a mere 5 per cent of their number in 1900. (Figure 1)Humans have accelerated the rate of extinction by killing the organisms, introducing alien species and destroying habitats. Apart from the fact that we have no right to wipe out species for ever, the chances are that we will deprive ourselves not only of the beauty and diversity of species but also of potential sources of valuable products such as drugs. Many of our present-day drugs are derived from plants (e.g. quinine and aspirin) and there may be many more sources as yet undiscovered. We are also likely to deprive the world of genetic resources.

Figure 1 In 100 years the tiger population has fallen from 120,000 to 6,000

Conservation of speciesSpecies can be conserved by passing laws which make killing or collecting them an offence, by international agreements on global bans or trading restrictions, and by conserving habitats. (Figure 2)In Britain, it is an offence to capture or kill almost all species of wild birds or to take eggs from their nests; wild flowers in their natural habitats may not be uprooted; badgers, otters and bats are just three of the protected species of mammal. (Figure 3)CITES (Convention on International Trade in Endangered Species) gives protection to about 1,500 animals and thousands of plants by persuading governments to restrict or ban trade in endangered species or their products, e.g. snake skins or rhino horns. There are about 70 countries which are party to the Convention.



Figure 2 Trying to stop the trade in endangered species. A customs official checks an illegal cargo impounded at an Indian customs post

Figure 3 Badger. One of a number of species protected by law

The WWF (World Wide Fund for Nature) operates on a global scale and is represented 25 countries. The WWF raises money for conservation projects in all parts of the world, but with particular emphasis on endangered species and habitats.The IWC (International Whaling Commission) was set up to try and avoid the extinction of whales as a result of uncontrolled whaling, and has about 40 members.The IWC allocates quotas of whales that the member countries may catch but, having no powers to enforce its decisions, cannot prevent countries from exceeding their quotas.In 1985, the IWC declared a moratorium (i.e. a complete ban) on all whaling, which was reaffirmed in 2000 despite opposition from Japan and Norway. Japan continues to catch whales ‘for scientific purpose’.

Captive breeding and reintroductionsProvided a species has not become totally extinct, it may be possible to boost its numbers by breeding in captivity and releasing the animals back into the environment. In Britain, modest success has been achieved with otters. (Figure 4) It is important (a) that the animals do not become dependent on humans for food and (b) that there are suitable habitats left for them to recolonize.Sea eagles, red kites (Figure 5)and ospreys have been introduced from areas where they are plentiful to areas they had become extinct.

Figure 4 The otter has been bred successfully in captivity and released

Figure 5 Red kites from Spain and Sweden have been reintroduced to Britain

Conservation of genesIt was explained that crossing a wild grass with a strain of wheat produced an improved variety. This is only one example of many successful attempts to improve yield, drought resistance and disease resistance in food plants. Some 25,000 plant species are threatened with extinction at the moment. This could result in a devastating loss of hereditary material and a reduction of about 10 per cent in the genes available for crop improvement. ‘Gene banks’ have been set up to preserve a wide range of plants, but these banks are vulnerable to accidents, disease and human error. The only secure way of preserving the full range of genes is to keep the plants growing in their natural environments.


KS4 Biology B17e / Side 4 Conservation of habitatsIf animals and plants are to be conserved it is vital that their habitats are conserved also.Habitats are many and varied: from vast areas of tropical forest to the village pond, and including such diverse habitats as wetlands, peat bogs, coral reefs, mangrove swamps, lakes and rivers, to list but a few.

International initiativesIn the last 30 years it has been recognized that conservation of major habitats needed international agreements on strategies. In 1992, the convention on Biological Diversity was opened for signature at the ‘Earth Summit’ Conference in Rio, and 168 countries signed it. The Convention aims to preserve biological diversity (‘biodiversity’).Biodiversity encompasses the whole range of species in the world. The Convention will try to share the costs and benefits between developed and developing countries, promote ‘sustainable development’ and support local initiatives.‘Sustainable development’ implies that industry and agriculture should use natural resources sparingly and avoid damaging natural habitats and the organisms in them.The Earth Summit meeting addressed problems of population, global warming, pollution, etc., as well as biodiversity.There are several voluntary organizations which work for world-wide conservation, e.g. WWF, Friends of the Earth and Greenpeace.

Questions

1. What kinds of human activity can lead to the extinction of a species?

2. How do the roles of CITES and WWF differ? In what respects might their activities overlap?

3. How might the loss of a species affecta. Our health (indirectly) andb. The prospect of developing new varieties of crop plants resistant to

drought?



Animals Asia has freed 140 of the 500 animals it vowed to save from mainland bile farms by next year, and say attitudes to abuse are changing

Bear crusaders forging ahead

Four years after a ground breaking agreement with the central government to rescue 500 bears from bile farms b 2005, the Charity Animals Asia Foundation last week made a 3,200km journey to rescue two farmed beers in Tianjin.“They were bouncing around in their cages in rage,” said Jill Robinson, the charity’s founder, who travelled from the foundation’s animal sanctuary in Chengdu to Tianjin to pick up the bears.Ms Robinson said while the charity probably will not meet its target by the deadline, it has made a good start. The agreement aimed to rescue 500 Asiatic black bears – also known as moon bears because of the crescent-shaped mark on their chests – in Sichuan within five years, before expanding the campaign to the rest of the country.“We probably won’t get the 500 in five years but we’ve made a pretty good dent in it,” she said.Animals Asia says it has rescued almost 140 bears since the agreement was signed, causing nearly 40 bear farms to close.The most recent government figures on bear farming, released in 1999, said there were 247 farms with 7,002 bears.Farmed bears are kept in cages only slightly bigger than their own bodies and have metal or latex catheters implanted directly into their gall bladders.The catheter’s point of entry is usually infected and 10 per cent of rescued bears die in agony from chronic infection.The Tianjin bears had been fitted with “metal corsets”, which can only be removed under hospital conditions. Ms Robinson says the bears cannot be freed from their catheters immediately because

“the vest is probably keeping everything intact”.The bears were discovered by a journalist with a local newspaper in Tianjin, who passed the story on to journalists in Shanghai. The journalists raised money to compensate the farmer before handing the bears over the charity.After seven years of negotiations, Animals Asia – the first charity to campaign against the bear bile industry in China – signed an agreement with the Beijing authorities in 2000. It was the first agreement of its kind between the Chinese government and an outside animal welfare organization.Animals Asia’s last big rescue operation was in November, when it rescued 38 bears and took them to its sanctuary in Chengdu, Sichuan province. The group raises money to compensate the farmers once their farms have been closed.

“People are more and more concerned about animal welfare and that we should not base our needs on their suffering”

Wang Yee MinForestry official

Bear parts – especially the gall bladder – have been used in traditional Chinese medicine for more than 3,000 years. Bears are known for producing large quantities of bile, the active ingredient of which –ursodeoxycholic acid, or UDCA – is used for treating a range of conditions including hepatitis, cirrhosis and gallstones in humans. But artificial replacements for bear bile are readily available.

Bear farming is a lucrative business for Chinese farmers. Seven tones of dried bear bile powder was produced annually from 1994 to 1998, according to Animals Asia, of which only four tones was consumed by China’s domestic market. This over-production has led to a boom in non-therapeutic bear bile products. The farmer in Tianjin was previously making a profit of 8,000 yuan a year by selling bear bile to Koreans living in the north of China.The retail price of bear bile in Chengdu in December 2002 was US$1,000 a kilogram, according to the charity.“The market is flooded with bear bile products – used in non-essential products which have no medicinal value – we’ve even found bear bile coffee, bear bile tea and bear bile shampoo,” said Annneleise Smillie, Animals Asia’s education director.The central government signed the Convention on International Trade in Endangered Species of Wild Fauna and Flora in 1998, which outlaws bear hunting and the export of bear bile products. Still, an international black market means bear bile is illegally exported from China.Though Animals Asia still has a long way to go until the bear trade is stamped out, Ms Robinson said there were signs that attitudes in China were starting to change.“Sometimes when we stopped [on the way back to Chengdu from Tianjin], people had already read about the story of the bears and said, ‘we know about your work – you’re the people who rescue bears’,” she said. Ms Robinson said the central government had gone out of its way to assist by helping organize the rescue

despite the Sars-related ban on any transport of wild animals.“I think the government officials in Tianjin very much recognize that there is also the issue of reputation, particularly as we are coming up to the Olympics. And I think they don’t want to be aligned to this,” she said.Legislator David Chu Yu-lin, who negotiated with the central government on Animals Asia’s behalf, said: “The government has some humanitarian feelings – it’s not pure image-building.“The awareness of cruelty to animals is increasing in China. It’s a combination of awareness of animal cruelty as well as wanting to improve the image to the outside world.“When Jill found out about the bears and fell into trouble she called me.“I called the government officials, and being an NPC representative I did a little bit of threatening. I said if they don’t release the bears I will report to the highest authority in the central government, and they said okay.”A Forestry Ministry official said there was more awareness of animal welfare in china.“People are more and more concerned about animal welfare and that we should not base our needs on the suffering of animals,” said Wang Yee Min, deputy chief of forestry in Tianjin.For further information on the campaign or bear sponsorship, see Animals Asia’s website: www.animalsasia.org or 2791-2225.


http://www.animalsasia.org/

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