B18 - Biodiversity and the effect of human interaction on ecosystems

Question 1

What is biodiversity?

Answer 1

Biodiversity is the variety of all the different species of organisms on earth, or within an ecosystem.

Question 2

What defines a good biodiversity?

Answer 2

A great biodiversity ensures the stability of ecosystems by reducing the dependence of one species on another for food, shelter and the maintenance of the physical environment.

Question 3

Should we as humans maintain biodiversity? If so, has this been done well?

Answer 3

The future of the human species on Earth relies on us maintaining
a good level of biodiversity. Many human activities are reducing biodiversity and only recently have measures been taken to try to stop this reduction.

Question 4

How has rapid growth of the human population had an effect on our waste management?

Answer 4

Rapid growth in the human population and an increase in the standard of living mean that increasingly more resources are used and more waste is produced. Unless waste and chemical materials are properly handled, more pollution will be caused.

Question 5

How can pollution occur? (In what medium)

Answer 5

Pollution can occur:
• in water, from sewage, fertiliser or toxic chemicals
• in air, from smoke and acidic gases
• on land, from landfill and from toxic chemicals.

Question 6

How does pollution affect biodiversity?

Answer 6

Pollution kills plants and animals which can reduce biodiversity.

Question 7

How do humans negatively affect land use?

Answer 7

Humans reduce the amount of land available for other animals and plants by building, quarrying, farming and dumping waste.

Question 8

Why does the production of compost negatively affect biodiversity?

Answer 8

The destruction of peat bogs, and other areas of peat to produce garden compost, reduces the area of this habitat and thus the variety of different plant, animal and microorganism species that live there (biodiversity).

Question 9

Why is burning or decay of peat bad?

Answer 9

The decay or burning of the peat releases carbon dioxide into the atmosphere.

Question 10

What is peat?

Answer 10

It is a brown deposit resembling soil, formed by the partial decomposition of vegetable matter in the wet acidic conditions of bogs and fens, and often cut out and dried for use as fuel and in gardening.

Question 11

Why has deforestation in tropical areas occured?

Answer 11

Large-scale deforestation in tropical areas has occurred to:
• provide land for cattle, rice fields and palm oil.
• grow crops for biofuels.

Question 12

What are some biological consequences of global warming?

Answer 12

Changes in or loss of habitats due to these extreme weather events. Decreases in biodiversity as food chains are disrupted and extinction rates increase. Increases in migration of species to new places, including increased spread of pests and disease.

Question 13

What are the effects of CO2 and CH4 in the atmosphere?

Answer 13

Levels of carbon dioxide and methane in the atmosphere are increasing, and contribute to ‘global warming’.

Question 14

How do we attempt to have a positive effect on biodiversity?

Answer 14

Scientists and concerned citizens have put in place programmes to reduce the negative effects of humans on ecosystems and biodiversity.
These include:
• breeding programmes for endangered species
• protection and regeneration of rare habitats
• reintroduction of field margins and hedgerows in agricultural areas where farmers grow only one type of crop
• reduction of deforestation and carbon dioxide emissions by some governments
• recycling resources rather than dumping waste in landfill.

Question 15

What are trophic levels and how are they represented?

Answer 15

Trophic levels can be represented by numbers, starting at level 1 with plants and algae. Further trophic levels are numbered subsequently according to how far the organism is along the food chain.

Question 16

What are the different trophic levels?

Answer 16

Level 1: Plants and algae make their own food and are called producers.
Level 2: Herbivores eat plants/algae and are called primary consumers.
Level 3: Carnivores that eat herbivores are called secondary consumers.
Level 4: Carnivores that eat other carnivores are called tertiary consumers. Apex predators are carnivores with no predators.

Question 17

How do decomposers work?

Answer 17

Decomposers break down dead plant and animal matter by secreting enzymes into the environment. Small soluble food molecules then diffuse into the microorganism.

Question 18

How does a pyramid of biomass work?

Answer 18

Pyramids of biomass can be constructed to represent the relative amount of biomass in each level of a food chain. Trophic level 1 is at the bottom of the pyramid.

Question 19

What are producers?

Answer 19

Producers are mostly plants and algae which transfer about 1 % of the incident energy from light for photosynthesis.

Question 20

How is biomass lost?

Answer 20

Losses of biomass are due to:
• not all the ingested material is absorbed, some is egested as faeces
• some absorbed material is lost as waste, such as carbon dioxide and water in respiration and water and urea in urine.

Question 21

How much biomass is transferred from each trophic level to the next?

Answer 21

Only approximately 10 % of the biomass from each trophic level is transferred to the level above it.

Question 22

Large amounts of what are used in respiration?

Answer 22

Large amounts of glucose are used in respiration.

Question 23

What is food security?

Answer 23

Food security is having enough food to feed a population.

Question 24

What are some biological factors that threaten food security?

Answer 24

Biological factors which are threatening food security include:
• the increasing birth rate has threatened food security in some countries
• changing diets in developed countries means scarce food resources are transported around the world
• new pests and pathogens that affect farming
• environmental changes that affect food production, such as widespread famine occurring in some countries if rains fail
• the cost of agricultural inputs
• conflicts that have arisen in some parts of the world which affect the availability of water or food.

Question 25

How is efficiency of food production increased?

Answer 25

The efficiency of food production can be improved by restricting energy transfer from food animals to the environment. This can be done by limiting their movement and by controlling the temperature of their surroundings.

Question 26

What are animals fed to increase growth?

Answer 26

Some animals are fed high protein foods to increase growth.

Question 27

What is happening to fish stocks? Why should we maintain them?

Answer 27

Fish stocks in the oceans are declining. It is important to maintain fish stocks at a level where breeding continues or certain species may disappear altogether in some areas.

Question 28

How do we maintain fish stocks?

Answer 28

Control of net size and the introduction of fishing quotas play important roles in conservation of fish stocks at a sustainable level.

Question 29

What do modern biotechnology techniques enable us to do?

Answer 29

Modern biotechnology techniques enable large quantities of microorganisms to be cultured for food.

Question 30

What is the fungus Fusarium good for?

Answer 30

The fungus Fusarium is useful for producing mycoprotein, a protein-rich food suitable for vegetarians. The fungus is grown on glucose syrup, in aerobic conditions, and the biomass is harvested and purified.

Question 31

How can this biotechnology help with diabetes?

Answer 31

A genetically modified bacterium produces human insulin. When harvested and purified this is used to treat people with diabetes.

Question 32

What can GM crops provide?

Answer 32

GM crops could provide more food or food with an improved nutritional value such as golden rice.