B18 - Biodiversity and Ecosystems

Question 1

What has caused a rapid increase in the human population?

Answer 1

Increased healthcare and nutrition

Question 2

What has caused waste to increase?

Answer 2

Rapid population growth and an increase in the standard of living causes resources to be used at an increasing rate. This causes waste to increase

Question 3

What environmental impacts has the human population growth caused?

Answer 3

• Land use to increase in order to build, shops, roads etc. This destroys habitats of organisms that originally lived in the area and destroys biodiversity
• Large areas of forest are cleared in order to build farmland. This destroys the natural animal and plant populations, causing biodiversity to decrease
• Large areas of land are cleared in order to mine resources such as rocks and metals, reducing habitats and biodiversity
• Waste produced by humans pollutes the environment and processing it takes up land, affecting biodiversity

Question 4

What 3 types of pollution are there?

Answer 4

• Water - sewage, fertiliser and toxic chemicals
• Air - smoke and acidic gases
• Land - landfill and toxic chemicals

Question 5

Why are peat bogs destroyed?

Answer 5

• To produce compost from peat

* To use peat as a fuel

Question 6

What are the disadvantages of peat bog destruction?

Answer 6

• It reduces the area of the peat habitat and thus the variety of different plant, animal, and microorganism species (biodiversity)
• The burning of peat releases carbon dioxide into the atmosphere
• The decay and digestion of peats to create compost releases carbon dioxide into the atmosphere

Question 7

What is incident energy?

Answer 7

light from the sun arriving at the surface of the earth

Question 8

How much incident energy is transferred by producers in photosynthesis?

Answer 8

1%

Question 9

How much energy/biomass is transferred from one trophic level to the next?

Answer 9

10%

Question 10

What is a trophic level?

Answer 10

Feeding level in an ecosystem

Question 11

Describe how biomass may be lost from one trophic level to the next:

Answer 11

Losses of biomass are due to:

• Not all ingested material is absorbed, some is egested as faeces
• Some absorbed material is lost as waste, such as glucose being broken down into carbon dioxide and water which is lost in respiration and water and urea in urine
• Energy from cellular respiration is used for movement and muscular contraction
• Energy from cellular respiration is transferred by heating the surroundings

Question 12

What is food security?

Answer 12

Having enough food to feed a population

Question 13

what 6 factors are affecting food security?

Answer 13

• The increasing birth rate may threaten the food security in some countries
• Changing diets in developed countries means that scarce food resources are transported around the world, depriving those in the area of the food
• New pests and pathogens may affect farming
• Environmental change may affect food production (i.e. famine may occur if rain fails)
• Cost of agricultural inputs
• Conflicts may affect the availability of water and food

Question 14

How can the efficiency of food production be improved

Answer 14

• The movement of animals may be restricted in order to restrict energy transfer from the food to the environment
• The temperature of the animals surroundings may be controlled in order to limit energy transfer to the environment
• Animals may be fed high protein diets to increase growth

Question 15

Explain how land pollution may occur:

Answer 15

• Human waste may not be treated properly and may cause soil pollution of chemicals and parasites
• Household and industrial waste may be sent to landfill sites which take up large areas and destroy natural habitats. Toxic chemicals may spread from the waste into the soil

Question 16

Describe how water pollution may occur:

Answer 16

• Fertilisers and minerals added to soils can easily be washed out of the soil and into local streams, ponds, and rivers. Untreated sewage may also contain high levels of nitrates. These mineral ions may stimulate the growth of algae and water plants, which grow rapidly. Some of these plants may die naturally, whereas other may die due to competition for sunlight. Microorganisms will then decompose these dead plants. This decomposition process uses a lot of oxygen which is dissolved in the water. The increased growth of plants causes increased decomposition which causes the oxygen levels in the water to fall rapidly. This may mean that there is not enough oxygen to support fish and other aerobic organisms living in the water
• Toxic chemicals, such as pesticides, may be washed into water sources. These toxic chemicals may become part of the food chain and build up at each stage through the food chain. This is known as bioaccumulation. The largest carnivores may die or fail to breed due to the build up of toxic chemicals
• Pesticides may also cause the pH levels of the water to change

Question 17

Describe how air pollution may occur:

Answer 17

• Burning fossil fuels that may contain sulphur impurities will produce sulfur dioxide. Sulfur dioxide can cause breathing difficulties if concentrations become too high
• Sulfur dioxide and nitrogen oxide may also dissolve in rainwater to produce sulfuric acid and nitric acid. acid rani may fall on trees, killing the leaves, buds, flowers, and fruit. The acid rain may soak into the soil and destroy the roots. It may also fall into bodies of water and cause the water to become acidic. It may change the soil pH and affect the enzymes in organisms.
• Smoke Pollution - particulates in the air can damage lungs and reduce the amount of light that reaches the earths surface
• Smog

Question 18

What may global warming cause?

Answer 18

• Loss of habitat - low-lying area may be flooded by rising sea levels, causes habitats and biodiversity to be lost
• Changes in distribution - Changes in temperature and rainfall patterns may cause areas to become more suitable for some animals but less suitable for other animals
• Changes in migration patterns due to changes in temperature
• Reduced biodiversity - climate change may cause some organisms to struggle to survive and may become axtinct