Helpful Bacteria

Helpful Bacteria Most bacteria are harmless to

humans, in fact some are vary useful.

Bacteria ...Aid our digestive system.Provide drugs and hormones.Produce some types of food.Provide nutrients for plants by breaking

down dead material by decomposition.

Yoghurt Yoghurt is made by

the action of a particularbacteria (lactobacillus)on milk.

It changes milk sugar (lactose) into lactic acid.

This acid gives yoghurt its sour taste.

Making Yoghurt Read the handout provided then

glue it into your notebooks.

Follow the instructions on the board for making your own yoghurt from Milk!

Pasteurization Pasteurization is the process of

heating liquids for the purpose of destroying bacteria.

Developed by French microbiologist Louis Pasteur in order to reduce sickness caused by drinking milk.

Nutrient Cycles Decomposers live off dead plant or

animal matter as well as wastes.

They break down this material into simpler chemicals and release nutrients to the soil.

Nutrient cycles show how important elements move throughout the environment.

Nitrogen Cycle Nitrogen is used for making proteins,

enzymes, antibodies, hormones, nucleic acids and cell membranes.

78% of the atmosphere is made up of nitrogen.

Plants and animals cannot directly use this nitrogen as it is very unstable.

Nitrogen Cycle Legumes (clover, lucerne, peas, etc) are

able to use atmospheric nitrogen because they have bacteria in their roots which make the nitrogen available to the plants.

This process is called nitrogen fixation.

Nitrogen is also produced by free living bacteria in the soil.

Nitrogen Cycle Other kinds of bacteria, denitrifying

bacteria, convert nitrogen compounds into nitrogen gas, completing the cycle.

Without bacteria plants would not have sufficient nitrates available to grow.

Animals must eat foods containing nitrogen.

Nitrogen in the Atmosphere

Free Living Bacteria

in Soil

Bacteria in Root Nodules of Legumes

Nitrate Compounds in Soil

Denitrifying Bacteria

Absorbed by Plants

Eaten

Decomposers

Was

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Deat

hDeat

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Carbon Cycle Plants use carbon dioxide during

photosynthesis to make sugars and starch.

Along with animals and decomposers, plants also produce carbon dioxide during respiration.

This carbon dioxide is released into the atmosphere.

Carbon Dioxide in the Atmosphere

Dead Plants and animals Acted on by Decomposers

Eaten

Death

Deat

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RespirationRespiration

Resp

iratio

n

Plants

Animals

Photosynthesis

Practice Questions1. Give 3 examples of how bacteria

are beneficial to humans.

2. Why is milk initially heated to 85°C when making yoghurt?

3. Why is yoghurt generally stored at low temperature?

Clover Weevil DamageWaikato farmers are demanding action to stop a new pest as it continues to spread through the region.

The Clover Weevil has spread steadily through the region since 1996.

The Weevil eats clover, which helps fix essential nitrogen in the soil.

Clover Weevil DamageWithout Clover, weight gain and milk yield targets are jeopardized in cattle.

Farmers can combat the effects of the Weevil by fertilizing the pastures with nitrogen but this is very expensive.

Clover Weevil Damage1. In what part of the clover is nitrogen

fixed into the soil?

2. What type of microbe fixes nitrogen?

3. What type of compounds does nitrogen help build in animals?

4. Explain how the Clover Weevil could effect the nitrogen cycle.

Clover Weevil Damage1. Root Nodules / Roots

2. Bacteria (Rhizobium)

3. Proteins / Amino Acids

4. Decrease the amount of clover in a paddock, therefore reducing the amount of available nitrogen to plants. Cattle will suffer weight gain and lower milk production as they can not create necessary proteins.