Ecology

Question 1

Factors which organisms compete for in a given habitat

Answer 1

Plants - light, space, water and mineral ions(nutrients) from the soil
Animals - Space(territory), food, water and mates

Question 2

How are organisms adapted to the conditions that they live in

Answer 2

• Features of their body structure e.g. shape or colour - A camel has a large surface area to volume ratio to help them lose heat
• Behaviour - birds migrating to warmer climates
• Functional - Desert animals conserve water by producing very little sweat

Question 3

Define an ecosystem

Answer 3

The interaction if a community if living organisms with the non living parts of their environments

Question 4

Define interdependence

Answer 4

This means that all the organisms in an ecosystem are dependent upon each other

Question 5

What is a stable community

Answer 5

A stable community is one in which the size of the populations of all species remain relatively constant over time

Question 6

Explain how a change in the abiotic factors would affect a given community

Answer 6

These changes can affect the sizes of population in a community. This means they can also affect the population sizes of other organisms that depend on them. For example, animals depend on plants for food so a decrease in a plant population could affect the animal species in a community.

Question 7

List abiotic factors

Answer 7

• Moisture levels
• Light intensity
• Temperature
• CO2 levels for plants
• O2 levels for aquatic animals

Question 8

Explain how a change in the biotic factors would affect a given community

Answer 8

A change in the environment could be the introduction of a new biotic factor .e.g. a new predator or pathogen. These changes can affect the sizes of populations in a community which can have knock on effects because of interdependence.

Question 9

List biotic factors

Answer 9

• New predators arriving
• Competition
• New pathogens
• Availability of food

Question 10

Describe an extremophile

Answer 10

An extremophile is an organism that lives in an extreme environment. An extreme environment is one in which most organisms would find it difficult or impossible to survive.

Question 11

What is a producer

Answer 11

Starting point of a food chain
Called a producer as they make their own food by photosynthesis

Question 12

What is a primary consumer

Answer 12

Herbivores that eat the plants and algae

Question 13

What is a secondary consumer

Answer 13

Carnivores that eat the primary consumers

Question 14

What is a tertiary consumer

Answer 14

Carnivores that eat other carnivores are tertiary. Carnvivore’s that have no predators are at the top of the food chain so they’re always in the highest trophic level are known as apex predators

Question 15

Explain why, in a stable community, the numbers of predators and prey rise and fall in cycles

Answer 15

The number of predators increases because there are more prey, so there is more food for them to eat. The number of prey reduces because there are more predators, so more get eaten. The number of predators reduces because there is less prey, so less food.

Question 16

Explain the role of microorganisms in cycling materials through an ecosystem

Answer 16

Microorganisms are responsible for the degradation of organic matter, which controls the release of plant nutrients, but is also important for the maintenance of soil structure and sustainability of soil quality for plant growth.

Question 17

State factors which affect the rate of decay(biology only)

Answer 17

• Temperature
• Water availability
• Oxygen availability
• Number of Decay organisms

Question 18

State the role of decomposers

Answer 18

Decomposers secrete enzymes into the environment. The enzymes digest dead animals or plant material into small, soluble molecules, The small soluble food molecules then diffuse back into the decomposer. The decomposer uses the soluble, food molecules for growth and respiration

Question 19

List the tropic levels

Answer 19

Producers, primary consumers, secondary consumers and tertiary consumers

Question 20

How much biomass gets transferred to the next level

Answer 20

Approximately 0%

Question 21

Reasons for the loss of biomass at each level

Answer 21

• Organisms don’t eat every part of the organism that they are consuming ( the bones) so not all the biomass could be passed on
• Organisms don’t absorb all the stuff in the food they ingest. The things they don’t absorb is egested as faeces
• Some of the biomass is converted into other substances that are lost as waste. For example, organisms use a lot of glucose, obtained from the biomass, in respiration to provide energy for movement and keeping warm, rather than to make more biomass. This process produces lots of waste CO2 and water as by products. Urea is another waste substance that is released in urine with water when the proteins in the biomass are broken down.

Question 22

What is the carbon cycle

Answer 22

1)Carbon enters the atmosphere as carbon dioxide from respiration and combustion.
2)Carbon dioxide is absorbed by producers to make carbohydrates in photosynthesis.
3)Animals feed on plants, passing the carbon compounds along the food chain. Most carbon they consume is exhaled as carbon dioxide during respiration. The animals and plants eventually die.
4)Dead organisms are eaten by decomposers and carbon in their bodies is returned to the atmosphere as carbon dioxide. In some conditions decomposition is blocked. The plant and animal material may then be available as fossil fuel in the future for combustion.

Question 23

What is the water cycle

Answer 23

Transpiration. We discussed the transpiration stream previously. This works to send water taken in by the roots of the plants back into the atmosphere as water vapour.
Evaporation. Water evaporates, changing state from liquid to gas, from bodies of water, such as lakes and oceans and ponds. Light energy from the sun causes this.
Condensation. After evaporation and transpiration, the water vapour cools, forming liquid clouds.
Transport. When liquid clouds are formed, they can be pushed far distances by wind.
Precipitation. Rain, snow, sleet and hail fall from the clouds into the bodies of water and the land.
Surface runoff. Sometimes, when there is a large amount of precipitation, water runs along the earth to enter bodies of water.
Infiltration. Some water that falls is absorbed into the ground. It can then be stored in aquifers. These are underground, permeable rocks.

Question 24

What is biodiversity

Answer 24

Biodiversity is a measure of the number of different species, their variety and their genetic diversity in a particular habitat

Question 25

State the benefit of ensuring a great biodiversity

Answer 25

A high biodiversity is important. It makes sure that ecosystems are stable because because different species depend on each other for things like shelter and food. Different species can also help to maintain the right physical environment for each other.

Question 26

Explain how human activities are reducing biodiversity

Answer 26

Our increasing population puts pressure on the environment as we take the resources we need to survive. But people around the world are also demanding a higher standard of living. So we use more raw materials but we also use more energy for the manufacturing processes. This all means we’re taking more and more resources from the environment more and more quickly. Unfortunately, many raw materials are being used up quicker than they’re being replaced. So if we carry on like we are, one day, we are going to run out.

Question 27

How does pollution occur in water

Answer 27

Sewage and toxic chemicals from industry can pollute lakes, rivers and oceans. affecting the plants and animals that rely on them for survival and the chemicals used on land can be washed into water like fertilisers or pesticides

Question 28

How does pollution occur in land

Answer 28

We use toxic chemicals for farming and we also bury nuclear waste underground, and we dump a lot of household waste in landfill sites

Question 29

How does pollution occur in air

Answer 29

Smoke and acidic gases released into the atmosphere can pollute the air, e.g sulphur dioxide can cause acid rain

Question 30

State how humans reduce the amount of land available for other animals

Answer 30

We use land for things like building, quarrying, farming and dumping waste. This means that there’s less land available for other organisms.

Question 31

Destruction of peat bogs

Answer 31

Bogs are areas of land that are acidic and waterlogged. Plants that live in bogs don’t fully decay when they die because there’s not enough oxygen. The partly rotted plants gradually build up to form peat. So carbon in the plants is stored in the peat instead of being released into the atmosphere. However peat bogs are often drained so that the area can be used as farmland or the peat is cut up and dried to use as fuel. Its also sold to gardeners as compost. Peat is being used faster than it is being formed. When peat is drained it comes into more contact with air and some microorganisms start to decompose it. When these microorganisms respire, they use oxygen and release carbon dioxide contributing to global warming. Carbon dioxide is also released when peat is burned as a fuel. Destroying the bogs also destroys the habitats of some animals., plants and microorganisms that live there, so reduces biodiversity

Question 32

Why is large scale deforestation done

Answer 32

It is done to clear land for farming to provide more food and to grow crops from which biofuels based on ethanol can produced

Question 33

Consequences of deforestation

Answer 33

• Less carbon dioxide is taken in, Cutting down loads of trees means that the amount of Co2 removed from the atmosphere during photosynthesis is reduced.
• More carbon dioxide in the atmosphere as Co2 is released when trees are burnt to clear land and microorganisms feeding on bits of dead wood release Co2 as a waste product of respiration
• Less biodiversity as habitats such as forest contain a huge number of different species of plants and animals, so when they are destroyed there is a danger of many species becoming extinct which means that biodiversity is reduced

Question 34

Describe global warming

Answer 34

Global warming is the unusually fast increase in the Earth’s average surface temperature and is caused by greenhouse gases like carbon dioxide and methane being released into the atmosphere. When sent out into the air, these potentially harmful gases are known as emissions.

Question 35

Consequences of global warming

Answer 35

• Sea levels are rising as the higher temperature cause seawater to expand and ice to melt causing the sea level to rise
  -Changes in species distribution - the distribution of many wild animal and plant species is changing as temperatures increase and the amount of rainfall changes in different areas. The species that need warmer temperatures are spreading further as the conditions they thrive in exist over a wider area and vice versa
  -There have been changes in migration patterns
  -Biodiversity could be reduce if some species are unable to survive a change in the climate so they become extinct

Question 36

Factors affecting food security

Answer 36

-Population
-Demand for specific foods can cause scarce food to become even more scarce
-Farming can be affected by new pests or pathogens which can result in the loss of crops and livestock
-High input costs of farming can make it too expensive for people in some countries to maintain or start food production
-There are conflicts that can affect the availability of food and water

Question 37

What is factory farming

Answer 37

Limiting the movement of livestock and keeping them in a temperature controlled environment reduces the transfer of energy from livestock to the environment. This makes farming more efficient as the animals use less energy moving around and controlling their own body temperature. This means there is more energy is available for growth, so more food can be produced from the same input of resources.

Question 38

What is sustainable fishing

Answer 38

Fish stocks are declining because we’re fishing so much. This means that there are fewer fish to eat. We need to maintain fish stocks at a level where the fish continue to breed.
-Fishing quotas is restricting the number and size of fish that can be caught in certain areas which prevents certain species from being overfished
-The net size of the fish net can reduce the number of unwanted fish. Using a bigger mesh size will let the unwanted fish escape and also so that the younger fish can slip through allowing them to reach breeding age

Question 39

What is mycoprotein

Answer 39

Using modern biotechnology, large amounts of microorganism can be cultured industrially under controlled conditions in large vats for use as a food source. Mycoprotein is used to make high protein meat substitutes for vegetarian meals like Quorn. Its made from the fungus fusarium which is grown in aerobic conditions on glucose syrup which it uses as food. The fungal biomass is harvested and purified to produce the mycoprotein