ecology

Question 1

What is a population

Answer 1

A population is defined as a group of organisms of the same species living in the same place at the same time

Question 2

What is a community

Answer 2

A community includes all of the populations living in the same area at the same time

Question 3

What is interdependence

Answer 3

If one species is removed it can affect the whole community

Question 4

What is a habitat

Answer 4

A habitat is the place where an organism lives

Question 5

What is an ecosystem

Answer 5

An ecosystem is defined as all the biotic factors and all the abiotic factors that interact within an area at one time
The term ‘biotic factors’ includes all the living components such as plants and animals
The term ‘abiotic factors’ includes all the non-living components such as light intensity, mineral ions, water availability

Question 6

Name a small and large ecosystem

Answer 6

A small ecosystem might be a garden pond
A large ecosystem might be the whole of Antarctica

Question 7

What is biodiversity

Answer 7

Biodiversity is the range and variety of different species of organisms on Earth, or within an ecosystem.
It considers not only the species richness but the variation within each species, its distribution and population size

Question 8

How do human activities reduce Biodiversity

Answer 8

Many human activities are reducing biodiversity in individual ecosystems and on a global level
E.g. waste production, deforestation and global warming

Question 9

What is the importance of biodiversity

Answer 9

Different species depend on each other for:
Food
Shelter (eg. birds nesting in trees)
Maintenance of the physical environment (eg. tree roots provide stability for soils, ensuring they do not get washed away. This in turn provides a stable habitat for other plant species)

Question 9

Why is Biodiversity good

Answer 9

High biodiversity ensures the stability of ecosystems by reducing the dependence of one species on another for these three things
Populations with high levels of diversity are also more likely to be resilient to sudden environmental impacts or disease

Question 11

What is an abiotic factor

Answer 11

An abiotic factor is a non-living factor within an environment such as temperature, light intensity and wind speed

Question 12

What are some Abiotic factors

Answer 12

Light intensity- Light is needed by plants for photosynthesis more light leads to an increase in the rate of photosynthesis and an increase in plant growth rate

Tempreture- Affects the rate of photosynthesis in plants

Moisture levels- plants and animals require water to survive

Soil pH and mineral content different species of plants are adapted o different soil pH levels and nutrient concentration levels

Question 13

What are biotic factors

Answer 13

In Biology, ‘biotic’ means living
A biotic factor is a living factor in the environment such as competition, predation and disease

Question 14

What are some Biotic factors

Answer 14

Availability of food- More food means organisms have a higher chance of surviving and reproducing this means their populations can increase

Predators- In balanced ecosystems predators catch enough prey to survive but not so many that they wipe out the population. New predators are introduced to the ecosystem could become unbalanced

New pathogens- If a new pathogens enter an ecosystem the populations living there will have no immunity or resistance to it the population may decline or wiped out

Question 15

What are trophic levels

Answer 15

Trophic levels are used to describe the feeding relationships between organisms

Question 17

What are producers

Answer 17

Produce their own organic nutrients usually using energy from sunlight

Question 18

What are primary consumers

Answer 18

Herbivores- feed on producers

Question 19

What are secondary consumers

Answer 19

Predators that feed on primary consumers

Question 20

What are tertiary consumers

Answer 20

Predators that feed on secondary consumers

Question 21

What are quaternary consumers

Answer 21

Predators that feed on tertiary consumers

Question 22

What is the difference between food webs and food chains

Answer 22

A food web is a network of interconnected food chains
A simple way to illustrate the feeding interactions between the organisms in a community is with a food chain

Question 23

Explain the transfer of energy in the trophic levels

Answer 23

Energy flows from the sun to the first trophic level (producers) in the form of light
Producers convert light energy into chemical energy
This occurs during photosynthesis, when producers convert carbon dioxide and water into glucose and oxygen
Producers use this glucose (during respiration) to produce their own biomass
Biomass is a store of chemical energy
When primary consumers consume (eat) producers, they break down the biomass of the producer (digestion) and use the chemical energy to increase or sustain their own biomass
When secondary consumers consume (eat) primary consumers, they break down the biomass of the primary consumer (digestion) and use the chemical energy to increase or sustain their own biomass, and so on
In this way, as chemical energy is transferred from one trophic level to the next, biomass is also transferred

Question 24

Why can energy be lost through trophic levels

Answer 24

Organisms rarely eat every part of the organism they are consuming – some of the biological material of plants and animals may be inedible (eg. many predators do not consume the bones of their prey)
Not all the ingested material is digested and absorbed, some is egested as faeces
Energy is used for movement
Energy is used to generate heat
Energy is used for metabolic processes
Some absorbed material is lost as waste:
Carbon dioxide and water are waste products of respiration
Water and urea are the waste products in the urine, which is produced when proteins are broken down

Question 25

What is the carbon cycle

Answer 25

Carbon is taken out of the atmosphere in the form of carbon dioxide by plants to be used for photosynthesis
It is passed on to animals (and microorganisms) by feeding
It is returned to the atmosphere in the form of carbon dioxide by plants, animals and microorganisms as a result of respiration
If animals and plants die in conditions where decomposing microorganisms are not present the carbon in their bodies can be converted, over millions of years and significant pressure, into fossil fuels
When fossil fuels are burned (the process is known as combustion), the carbon combines with oxygen and carbon dioxide is released into the atmosphere
Increased use of fossil fuels is contributing to an increase in the carbon dioxide content of the atmosphere
In addition, mass deforestation is reducing the amount of producers available to take carbon dioxide out of the atmosphere by photosynthesis

Question 26

Explain the nitrogen cycle

Answer 26

Plants absorb the nitrates they find in the soil and use the nitrogen in them to make proteins
Animals eat the plants (or other animals) and get the nitrogen they need from the proteins in the plant or animal
Waste (urine and faeces) from animals sends nitrogen back into the soil as ammonium compounds (the urea in urine contains nitrogen)
When the animals and plants die, they decay and all the proteins inside them are broken down into ammonium compounds and put back into the soil by decomposers
The plants can’t absorb ammonium compounds, so a second type of soil bacteria, nitrifying bacteria, convert the ammonium compounds to nitrites and then to nitrates, which can then be absorbed by plants – and so the cycle goes on
The conversion of ammonium compounds to nitrites and then nitrates is known as nitrification
Finally, there is a third, unhelpful type of (anaerobic) bacteria called denitrifying bacteria found in poorly aerated soil (i.e. not much oxygen)
These bacteria take the nitrates out of the soil and convert them back into N2 gas
Farmers can help reduce the amount of these unhelpful bacteria by ploughing and turning over soil