Topic 7 - People and the Biosphere

Question 1

What is a biotic component of an ecosystem?

Answer 1

A living component

Question 2

What is an abiotic component of an ecosystem?

Answer 2

A non-living component

Question 3

Explain some of the interactions that happen within an ecosystem

Answer 3

Trees produce their own food from water, CO2, and sunlight. This is known as photosynthesis. This energy provides energy for the entire ecosystems. Organisms that create their own food via photosynthesis are known as producers. The soil is also crucial for growth as it provides minerals and nutrients for cell growth.

Primary consumers such as caterpillars eat the leaves/fruits (they are herbivores). Birds are classified as omnivores because they eat both plants and animals.

When plants and animals die they decompose due to bacteria breaking them down. This happens quickest in warm and wet conditions

Minerals from dead plants and animals are recycled and returned to the soil and can be taken up by the plants and trees for growth

Question 3

Explain some of the interactions that happen within an ecosystem

Answer 3

Trees produce their own food from water, CO2, and sunlight. This is known as photosynthesis. This energy provides energy for the entire ecosystems. Organisms that create their own food via photosynthesis are known as producers. The soil is also crucial for growth as it provides minerals and nutrients for cell growth.

Primary consumers such as caterpillars eat the leaves/fruits (they are herbivores). Birds are classified as omnivores because they eat both plants and animals.

When plants and animals die they decompose due to bacteria breaking them down. This happens quickest in warm and wet conditions

Minerals from dead plants and animals are recycled and returned to the soil and can be taken up by the plants and trees for growth

Question 4

What is an ecosystem?

Answer 4

An ecosystem is the biotic and abiotic aspects of an environment (such as a woodland) where the biotic components interact with each other and also with the abiotic environment they are found within

Question 5

What is a biome?

Answer 5

A biome is a large scale ecosystem found across the globe; each biome has its own group of plants, animals, and climate which makes it unique and distinctive

Question 6

How is an ecosystem different to a biome?

Answer 6

An ecosystem is the interaction between biotic and abiotic components. Whereas, a biome is a large region that contains similar plants, animals, and other organisms that are adapted to the area.

Question 7

Name the 7 types of biome:

Answer 7

• Tropical rainforests (Hot and wet)
• Temperate forest (Mild and wet)
• Boreal forests (Cold and dry)
• Tropical grasslands
• Temperate grasslands
• Deserts (low rainfall)
• Tundra (Cold dry)

Question 8

What is the climate of a tropical rainforest?

Answer 8

• The climate is the same all year round - there are no definite seasons
• Its hot (the temperature is generally 20-30*C and only varies by a few degrees over the year). This is because it is near the equator and the sun is overhead all year round
• Because tropical rainforests are near the equator, day length is the same (about 12 hours) all year round. This means the forests get plenty of sunshine all year.
• Rainfall is very high, around 2000 mm per year. It rains every day, usually in the afternoon

Question 9

What are the characteristics of a tropical rainforest? (plants, animals, soil)

Answer 9

• Plants - most trees are evergreen to take advantage of the continual growing season. Plants grow very quickly and are adapted to take in maximum light
• Animals - The dense vegetation provides lots of food and different habitats, so there are lots of different species of animal, for example gorillas, jaguars, anacondas, tree frogs, and sloths. There are many different species of insect and birds.
• Soil - plants grow quickly and shed leaves all year round. These decompose quickly, so there’s a constant supply of nutrients in the soil, and these nutrients are cycled quickly. However, there is a lot of leaching due to high levels of rainfall, causing nutrient poor soil (nutrients are only found near the top of the soil)

Question 10

What is the climate of a temperate forest?

Answer 10

• Temperature forests have 4 distinct seasons. The summers are warm and the winters are cool
• Rainfall is very high (up to 1500mm per year) and there’s rainfall all year round
• Days are shorter in winter and longer in summer - the hours of sunshine vary through the year

Question 11

What are the characteristics of a Temperate forest?

Answer 11

• Plants - the mild, wet climate supports fewer plant species than tropical forests, but more than boreal forests. Forests are often made up of broad-leaved trees that drop their leaves in autumn, shrubs, and undergrowth
• Animals - the mild climate and range of plants provides food and habitats for mammals, birds, and insects
• Soil - plants lose their leaves in autumn, and the leaf litter decomposes quite quickly in the moist, mild climate. This means that soils re relatively thick and nutrient-rich

Question 12

What is the climate of a Boreal forest?

Answer 12

• Boreal forests have short summers and long winters. In winter, average temperatures are below -20C and can drop much lower. In summer, average temperatures are about 10C
• Precipitation is low - generally less than 500mm a year. A lot of this falls as snow
• Boreal forests get lots of daylight during the summer months, but little or none during the winter. Skies tend to be clear, so during daylight hours there’s plenty of sunshine

Question 13

What are the characteristics of a Boreal Forest?

Answer 13

• Plants - most trees are evergreen, so they can grow whenever there’s enough light. Coniferous trees such as pine and fir are common, as are low-growing mosses and lichen.
• Animals - there are relatively few animal species in boreal forests compared to tropical forests, this is because there is less food available and animals need to be adapted to the cold climate to survive. Animals that live there include black bears, wolves, elk, and eagles
• Soil - The cool, dry climate means that needles from the trees decompose slowly, so soils are quite thin, nutrient-poor and acidic. In some areas the ground is frozen for most of the year

Question 14

What is the climate of a tropical grassland?

Answer 14

Tropical grasslands have relatively low rainfall (800-900mm a year) and distinct wet and dry seasons. Temperatures are highest (around 35C) just before the wet season and lowest (about 15C) just after it. They are found around the equator, so they get lots of sunshine all year round

Question 15

What is the climate of a temperate grassland?

Answer 15

Temperate grasslands have hot summers (up to 40C) and cold winters (down to -40C). They receive 250-500mm of precipitation a year, mostly in the late spring and early summer. Because they are further from the equator, the amount of light they receive varies through the year

Question 16

What are the characteristics of a tropical grassland?

Answer 16

Rainfall is too low to support many trees in tropical grasslands, which affects animals and soil:

• Plants - tropical grasslands consist mostly of grass, scrub, and small plants, with a few scattered trees, e.g. acacia
• Animals - They are home to many insects, including grasshoppers, beetles, and termites. Larger animals include lions, elephants, giraffes, zebras and antelope.
• Soil - Grass dies back during the dry season, forming a thin, nutrient-rich soil, but nutrients are washed out of the soil during the wet season

Question 17

What are the characteristics of a temperate grasslands?

Answer 17

Rainfall is too low to support many trees in temperate grasslands, which affects animals and soil:

• Plants - Temperate grasslands are also dominated by grasses and small plants, and have very few trees.
• Animals - Thy are home to fewer animal species than tropical grasslands - mammals include bison and wild horses, and rodents such as mole rats
• Soil - High temperatures in summer mean that decomposition is fast, so soils are relatively thick and nutrient-rich

Question 18

What is the climate of a desert?

Answer 18

• Rainfall is very low - less than 250mm per year. It might only rain once every 2 or 3 years
• Hot desert temperatures range from very hot in the day (45C) to cold at night (below 0C)
• Hot deserts get more daylight during summer than the winter. Because there is little cloud cover, they get lots of hours of sunshine every day

Question 19

What are the characteristics of a desert?

Answer 19

• Plants - Plant growth is sparse due to a lack of rainfall. A few plants do grow, e.g. cacti, thorn bushes
• Animals - relatively few animal species live in hot deserts - those that do are adapted to cope with the harsh climate. Animals that live there include lizards, snakes, insects, and scorpions
• Soil - The sparse vegetation means that there is little leaf litter, and the dry climate means that organic matter is slow to decompose. As a result, soils are mostly thin and nutrient-poor

Question 20

What is the climate of a tundra?

Answer 20

• Temperatures are low - around 5-10C during the summer and lower than -30C in the winter
• Precipitation is also very low - less than 250mm a year. Most of this falls as snow
• Tundra is found at high latitudes, so it gets near-continuous daylight in the summer and little or no daylight in the winter. There is more cloud cover in the summer

Question 21

What are the characteristics of a tundra?

Answer 21

• Plants - The cold climate and lack of light in winter makes it hard for plants to grow, and there are hardly any trees. Vegetation includes mosses, grasses and low shrubs
• Animals - the cold climate and lack of vegetation means that relatively few animal species live in the Tundra. This that do include Arctic hares, arctic foxes, mosquitoes, and lots of birds. Some animals migrate south for the winter
• Soil - The sparse vegetation produces little leaf litter, and the cold, dry climate means that organic matter decomposes slowly, so soil is thin and nutrient poor. There is a layer of permafrost below the soil surface, which can stop water from draining away.

Question 22

Describe the distribution of Tropical rainforests?

Answer 22

Tropical rainforests are found near the equator, within the tropic of Cancer and the tropic of Capricorn. They are mostly found in South America, Africa, and South East Asia in countries such as Brazil, Indonesia, and Sri Lanka. An anomaly is in Madagascar with regions of rainforest below the tropic of Capricorn.

Question 23

Describe the distribution of temperate forests

Answer 23

Temperate forests are found roughly between 25° and 50° in both hemispheres. They are mostly found in North America, Europe, and East Asia in countries such as the USA, the UK, France, and Japan. There are no anomalies

Question 24

Describe the distribution of Boreal forests:

Answer 24

The boreal forests is found north of the equator and is normally found between 50N and 60N. They are mostly found in north America and Europe in countries such as Canada, Russia, Finland, and Norway. There are no anomalies

Question 25

Describe the distribution of Tropical grasslands

Answer 25

Tropical grasslands are found near the equator, between the Tropic of Caner and the Tropic of Capricorn. They are mostly found in South America, Africa, and South Asia in countries such as Brazil and Malawi. There are no anomalies

Question 26

Describe the distribution of temperate grasslands

Answer 26

temperate grasslands are found in both hemisphere between 25* and 50*. They are found in North America, Asia, and South America in countries such as the USA, Pakistan, China, and Uruguay

Question 27

Describe the distribution of deserts

Answer 27

Deserts are usually found slightly north and south of the tropics, around 25N and 25S. They are found in North America, Africa, Asia, and Oceania in countries such as the USA, Egypt, Saudi Arabia, and Australia. An anomaly is in Somalia and Peru where deserts are located almost exactly on the equator

Question 28

Describe the distribution of Tundra

Answer 28

Tundra is found in the northern hemisphere between 60°N and 75°N. It is found in North America, Europe, and Asia in countries such as Canada, Iceland, and Russia

Question 29

What are the 4 local factors which affect biomes?

Answer 29

• Altitude
• Rock type
• Soil type
• Drainage

Question 30

How does altitude affect biomes?

Answer 30

Temperatures fall at a rate between 0.5C and 1C for every 100m in altitude, this means that the temperature is quite low in areas with high altitude. This means there is less vegetation as they are not adapted to the cold conditions, this limits the number of animals species. As a result there is not much organic matter, so soils are thin or non-existent. Additionally, there are higher levels of precipitation, due to relief rainfall. This means that the forest biome decreases and is replaced by hardier species that can survive the conditions, such as grass.

Question 31

How does rock type affect biomes?

Answer 31

Some rock types are more easily weathered to form soils, and different rock types contain different minerals. This affects how nutrient-rich the soil is. Some rocks are also permeable whereas others are impermeable. This may cause the soil to get waterlogged, meaning only plants adapted to wet conditions can grow there.

Question 32

How does soil type affect the biome?

Answer 32

More nutrient-rich soils can support more plants. The acidity and drainage of soils also varies, affecting the plants that can grow. E.g. peat soils are very acidic meaning only acid-tolerant plants can grow there.

Question 33

What would happen locally to the vegetation if water supplies were reduced?

Answer 33

There would be less vegetation as water is crucial for photosynthesis. Without water the vegetation cant grow and will become very weak / die, leaving only the plants adapted to conditions with low water levels surviving.

Question 33

What wold happen locally to the vegetation if water supplies were reduced?

Answer 33

There would be less vegetation as water is crucial for photosynthesis. Without water the vegetation cant grow and will become very weak / die, leaving only the plants adapted to conditions with low water levels surviving.

Question 34

What would happen locally to the soil type if vegetation is reduced?

Answer 34

The soil would become nutrient rich in the short term as there would be no vegetation taking up the nutrients. However in the long term, there would be no nutrients as nutrients are absorbed into the soil by litter from plants. It would also be very wet as there would be no interception or vegetation absorbing the water, as a result the soil would become nutrient-poor as the rain would leach the nutrients from the soil.

Question 35

What wold happen locally to the decomposition if temperatures and rainfall levels increase

Answer 35

An increase in temperature and rainfall would increase the amount of vegetation, therefore increasing the amount of litter from plants and therefore the amount of decomposition

Question 36

What are goods?

Answer 36

Physical materials, such as timber from trees or fish caught in a lake

Question 37

What are services?

Answer 37

Functions, e.g. how forests prevent flooding or trees add oxygen to the atmosphere

Question 38

What is indigenous?

Answer 38

Groups originating from and native to a particular place

Question 39

What are TNC’s?

Answer 39

Companies that operate in several countries, e.g. apple

Question 40

What are 4 different ecosystem services?

Answer 40

• Provision of goods
• Supporting services
• Regulating services
• Cultural services

Question 41

What is provision of goods?

Answer 41

Things that are taken from the ecosystem such as:

• Food - many indigenous people get their food directly from plants and animals, some forage for food whilst others hunt and farm
• Chemical uses - many plants have medicinal properties and are used to cure illnesses and keep people healthy. Plant species in tropical rainforests have been used to create over 7000 drugs
• Building materials - Trees and other plants are often used as building materials, e.g. pine in the taiga forest are good for construction as they grow very straight and long
• Fuel - Indigenous people rely on plants and animals for fuel for cooking and keeping warm.

Question 42

What are supporting services of an ecosystem?

Answer 42

Supporting services keep the ecosystem healthy so it can provide other services, this involves:

• Nutrient cycling
• Photosynthesis and food webs
• Soil formation

Question 43

What are regulating services?

Answer 43

Regulating services are aspects which keep the entire planet health, this involves:

• Storing carbon. and emitting oxygen, which keep the atmosphere in balance
• Purifying and regulating the flow of water within the hydrological cycle

Question 44

What are cultural services of an ecosystem?

Answer 44

Cultural services are benefits people get from visiting or being in a healthy ecosystem, this includes:

• Spiritual well-being and happiness
• Recreation and tourism

Question 45

How are humans are exploiting and destroying ecosystem services?

Answer 45

The Biosphere is also exploited by companies for commercial gain. Increasing demand and improving technology is increasing the scale of commercial exploitation, this includes:

• Energy
• Water
• Minerals

Question 46

How are humans exploiting and destroying ecosystem services for Energy?

Answer 46

Demand for energy is increasing as the world population increases and people have more electronic devices. Large areas of forest are cut down to clear land for the growing of crops that can be used to make biofuels, or to make way for coal mines or power stations. Some areas of tropical forest have been flooded by the building of hydroelectric dams. Drilling for oil and gas in the tundra is damaging the biosphere because pipelines are melting the permafrost

Question 47

How are humans exploiting and destroying ecosystem services for water?

Answer 47

Demand for water is increasing due to an increasing global population - people use water for washing, irrigating farmland etc. Water resources (lakes rivers and aquifers), can be over exploited - this is happening in arid areas like the Sahara desert. This can cause damage to the biosphere, as plants and animals no longer have enough water to survive

Question 48

What are aquifers?

Answer 48

Underground water stores

Question 49

How are humans exploiting and destroying ecosystem services for minerals?

Answer 49

Minerals such as Gold and iron are used in building, scientific instruments, electrical appliances and lots of other things - and demand for them is increasing. Minerals are often extracted by mining. Mines in tropical forests are responsible for lots of deforestation and toxic chemicals are washed into streams and rivers, killing wildlife. Open pit mining removes large areas of the land surface

Question 50

How are ecosystem services used by indigenous people?

Answer 50

Indigenous people use the ecosystem in many ways. wood and leaves from trees to build their houses, food from the forest for fuel, they hunt monkeys and antelope for meat, they use plants to make medicine.
*They also greatly appreciate the cultural services

Large scale indigenous tribes use slash and burn farming, they are called subsistence farmers

Question 51

How does the biosphere help to regulate the gases in the atmosphere

Answer 51

The biosphere helps to control the proportion of different gases in the atmosphere:
Plants take in carbon dioxide and give out oxygen during photosynthesis. Plants also act as carbon sinks. They store carbon by removing carbon dioxide from atmosphere and locking it up in biotic material. Animals take in oxygen from the air and give out carbon dioxide when they breathe

Question 52

Why is maintaining the balance of gases in the atmosphere so important?

Answer 52

• Most living organisms require oxygen to survive
• increased levels of CO2 can lead to global warming
• Increased levels of CO2 can also cause the oceans to become acidic, affecting organisms that live there
• Some CO2 is needed to keep the Earth warm enough to support life

Question 53

What is the hydrological cycle?

Answer 53

The movement of water between the land, bodies of water, and the atmosphere

Question 54

What is a Carbon Sink?

Answer 54

A natural store for carbon-containing chemical compounds, like carbon dioxide or methane

Question 55

How does the biosphere help to regulate the hydrological cycle?

Answer 55

• Water is taken up by plants, so less reaches rivers. This helps to prevent flooding and soil erosion.
• Plants also help to regulate the global water cycle by storing water and releasing it into the atmosphere slowly through transpiration. Large areas of forest can reduce the chance of drought and flooding in areas a long way away

Question 56

Explain simply the process of the hydrological cycle:

Answer 56

1) Water evaporates
2) Clouds form
3) It rains
4) Water runs to rivers and the sea
5) Repeat

Question 57

Explain how Biomass, Litter, and soil all rely on each other in the biosphere:

Answer 57

• Soil fertility depends on leaf litter as leaf litter decomposes and returns the nutrients to the soil
• Biomass depends on soil fertility as for plants to grow, they must take up nutrients from the soil
• If Biomass is removed there will be no leaf litter on the soil surface, this greatly reduces the number of nutrients returning to the soil. Without nutrients from leaf litter, the only nutrients will be from the chemical breakdown of rock and the decomposition of dead animals, this will not supply enough nutrients and therefore prevent or hinder anymore biomass growth

Question 58

Explain nutrient cycling of the biosphere in healthy soil

Answer 58

In a healthy biosphere there are many trees that offer the soil protection from rain erosion as they intercept the rain, the roots of the vegetation also helps hold the soil together. Many leaves from the trees fall to the forest floor as leaf litter. Nutrients from the litter form a layer of top soil. Soil retains water, this increases chemical weathering and the release of water from the rocks. Due to lots of interception from many trees, few nutrients are lost by leaching, leading to a very nutritious soil. As a result there is rapid vegetation growth due to nutrient-rich soil.

Question 59

Explain nutrient cycling of the biosphere in unhealthy soil

Answer 59

• There are very few trees, this means there is not much interception and few tree roots (which usually help bind the soil together).
• This results in few leaves being dropped as leaf litter. Less nutrient rich soil is produced.
• Rapid loss of nutrients by leaching (due to low interception and uptake of water by the roots) results in acidic conditions.
• Change in soil composition (mineral content and pH) renders soil infertile.
• This infertile soil results in very little vegetative growth

Question 60

What is soil composition?

Answer 60

The mineral content and pH balance of the soil

Question 61

What is carbon sequestration?

Answer 61

The absorption of carbon from the atmosphere

Question 62

Why are biomes very important carbon sinks?

Answer 62

Biomes are very important carbon sinks. They store carbon by removing carbon dioxide from the atmosphere and locking it up in biotic material. This is known as carbon sequestration.

Question 63

What are population projections?

Answer 63

Predictions of how many people there will be in the world in the future

Question 64

What is the UN high population estimation?

Answer 64

The UN high population estimation predicts that population is likely to increase exponentially from 2000 to 2100, reaching a population of 15 billion by 2100 (the current world population is ~8 billion)

Question 65

What is the UN low population prediction?

Answer 65

The UN low population estimation predicts that the world population will rise until about 2050, peaking at roughly 8 billion (the current world population is ~8 billion), then begin to decrease

Question 66

What are the 4 factors that increase demand for resources?

Answer 66

• Increasing Wealth
• Urbanisation
• Industrialisation
• Increasing population

Question 67

How does an increasing population cause demand for resources to increase?

Answer 67

As population increases, so does demand on resources. More people = more resources required

Question 68

How does increasing wealth cause demand for resources to increase?

Answer 68

Economic development means that people are getting wealthier (affluent). Wealthier people have a greater disposable income, which affects their resource consumption:

• They have more money to spend on food and therefore often buy more than they require
• They can afford cars, fridges, televisions, and other high energy consuming devices. Manufacturing and using these products requires lots of energy. This increases Energy demand
• More people can afford flushing toilets, showers, dishwashers, and other devices that use water. This increases the water demand

Question 69

How does urbanisation cause demand for resources to increase?

Answer 69

Urbanisation tends to increase resource consumption because:

• Cities tend to be more resource-intensive than rural areas - street lights and neon sign use energy, and fountains and urban parks require water
• Food and water have to be transported long distances to meet the increased demand in cities, and waste needs to be removed - this increases energy use

Question 70

How does industrialisation cause demand for resources to increase?

Answer 70

Manufacturing goods such as cars, chemicals. and electrical appliances uses a lot of energy. Manufacturing also uses a lot of water. As countries become more industrialised, their demand for energy and water increases. Industrialisation is also increasing the production of processed goods, this increases the demand for ingredients such as palm oil, which are often grown on huge plantations

Question 71

What is urbanisation?

Answer 71

Urbanisation is the growth in the proportion of a country’s population living in urban areas

Question 72

What theory does this diagram represent?

Answer 72

Malthus’s theory

Question 73

What theory does this diagram represent?

Answer 73

Boserup’s theory

Question 74

What was Malthus’s theory?

Answer 74

Malthus believed that the population was increasing faster than supply of resources, so eventually there would be too many people for the resources available. He believed that, when this happened, people would be killed by catastrophes such as famine, illness, and war, and the population would return to a level that could be supported by the resources available. The point where the population is too great for the resources available is known as the point of catastrophe - the population begins to decrease, until it is low enough that there are enough resources to support it again. Pessimistic theory, population growth is halted by crisis.

Question 75

What was Boserup’s theory?

Answer 75

Boserup believed that however big the world’s population grew, people would always produce sufficient resources to meet their needs. She though that, if resource supplies became limited, people would come up with new ways to increase production (e.g. by making technological advances) in order to avoid hardship. As population increases to be equal with resource supplies, resource supplies increase so that there are always enough resources available for the population.

Optimistic theory, technological developments will allow humans to avoid famine

Question 76

Is Boserup’s or Malthus’ theory correct?

Answer 76

Neither theory is completely right or completely wrong. There have been famines in some areas (Malthus’ theory), but not on a global scale, food production has so far kept up with population growth (Boserup’s theory). Although the Earth can provide for its current population (8 billion), it may not be able to provide for a greater population (Malthus’ theory). Some finite resources are being phased out and replaced by sustainable and renewable fuels (Boserup’s theory)