Ecology

Question 1

Population

Answer 1

A number of individuals of the same species living in the same area at the same time.

Question 2

Community

Answer 2

Multiple populations of different species living and interacting in the same area.

Question 3

Competition

Answer 3

If a group of organisms all need the same resource in order to survive and reproduce but there is a limited amount of the resource available, they are said to compete for the resource.
Competition can be between members of the same species (intraspecific competition) or between members of different species (interspecific competition).

Question 4

Adaptation

Answer 4

If an organism has certain features, behaviours or other characteristics that help it to survive and reproduce in its habitat, it is said to be adapted to its habitat.

Question 5

Ecosystems

Answer 5

An ecosystem is the interaction of a community of living organisms (biotic) with the non-living (abiotic) parts of their environment.
Ecosystems can vary greatly in size and scale. Some ecosystems are small - a single tree can be seen as an ecosystem.
Some ecosystems are very large - the whole of Antarctica can be seen as one ecosystem.

Question 6

Interaction within an ecosystem

Answer 6

In order to survive and reproduce (have offspring), organisms need certain resources from their surroundings (from the ecosystem they are living in).
This means that members of a species will often interact with members of its own species or other species.

Question 7

Competition in plants

Answer 7

Light - plants require light for photosynthesis in order to produce glucose which provides them with energy for growth.
Space - plants require space above soil so leaves can absorb maximum sunlight and below soil so roots can absorb water and mineral ions.
Water - water is essential for photosynthesis and therefore plant growth.
Mineral ions - plants require various mineral ions to make chlorophyll and protein.

Question 8

Competition in animals

Answer 8

Food - food provides animals with the energy they require for growth and reproduction.
Mates - animals require mates in order to reproduce and pass on their genes.
Territory - this is an area of habitat that provides and individual with resources such as water, food, shelter and mates.

Question 9

Interdependence

Answer 9

Within a community, each species depends on other species for food, shelter, pollination, seed dispersal etc.
If one species is removed it can affect the whole.
This is called interdependence.
A stable community is one where all the species and environmental factors are in balance so that population sizes remain fairly constant.

Question 10

Types of abiotic factors

Answer 10

Abiotic factors are non living.
Some factors are: light intensity, temperature, moisture level, soil pH, mineral content, wind intensity and direction, co2 levels, oxygen levels.

Question 11

Types of biotic factors

Answer 11

A biotic factor is a living factor.
Some examples are: availability of food, new predators, new pathogens, competition.

Question 12

Adaptations to cold regions

Answer 12

Animals here often have a small surface area: volume ratio to minimise heat loss to their surroundings (rounded shape of penguins/seals, small ears of the Arctic fox).
A thick layer of fat (seal blubber) or fur (polar bears) insulates against the cold.
These are examples of structural adaptations.

Question 13

Adaptations to hot regions

Answer 13

Some desert animals have specially adapted kidneys which produce very concentrated urine, helping the animal to retain water - this is a functional adaptation.
Some are only active in the early mornings, late evenings or at night when it is cooler - this is a behavioural adaptation.
Some animals have structures to increase their surface area: volume ratio to aid heat loss (large ears of African elephants) - these are structural adaptations.

Question 14

Extreme adaptations

Answer 14

Some organisms live in environments that are very extreme, such as at very high or low temperatures, pressures, or high salt concentration.
Organisms that can live in extreme environments are called extremophiles.
An example of habitats where extremophiles are found are deep-sea volcanic vents, where the conditions are extremely hot, under high pressure and there is no sunlight.
Bacteria called chemoautotrophs survive by using inorganic chemicals to obtain energy (rather than using sunlight in photosynthesis as photoautotrophs do).

Question 15

Producers

Answer 15

Photosynthetic organisms are the producers of biomass for life on Earth.
They produce their own food using energy from the Sun.
A producer has the following characteristics:
They are at the start of every food chain (the first trophic level, which is always the biggest).
They can photosynthesise (producers are normally green plants or algae).
They make glucose by photosynthesis.
They use this glucose to produce other biological molecules, which then make up the producer’s biomass (some of the glucose produced is also used in respiration to release energy for the cell).
In extreme environments (such as underwater volcanic vents) the producers are not photoautotrophs but chemoautotrophs who produce organic molecules without using energy from the Sun).

Question 16

Food chains

Answer 16

A simple way to show the feeding interactions between the organisms in a community is with a food chain
1. Producer: food chains always begin with a producer.
2. Primary consumer: producers are eaten by primary consumers (herbivores/omnivores).
3. Secondary consumer: primary consumers are eaten by secondary
consumers (carnivores/omnivores).
4. Tertiary consumer: secondary consumers are eaten by tertiary consumers (carnivores/omnivores).
A food chain shows the transfer of energy from one organism to the next.
The source of all energy in a food chain is light energy from the Sun.
The arrows in a food chain show the transfer of energy from one level of the food chain to the next.

Question 17

Investigating ecosystems

Answer 17

Ecology is the branch of biology that studies the distribution and abundance of species, the interactions between species, and the interactions between species and their abiotic environment.
Ecologists are biologists that study these interactions by investigating ecosystems.

Question 18

Quadrants and transects

Answer 18

They are used by ecologists to measure the distribution and abundance of species in an ecosystem.

Question 19

Recycling in an ecosystem

Answer 19

Many different materials cycle through the abiotic and biotic components of an ecosystem.
All materials in the living world are recycled to provide the building blocks for future organisms.

Question 20

Carbon cycle

Answer 20

Elements such as carbon are not endless resources.
There is a finite amount of each element on the planet.
Elements need to be recycled in order to allow new organisms to be made and grow.

Question 21

Process of carbon cycle

Answer 21

Carbon is taken out of the atmosphere in the form of carbon dioxide by plants and algae during photosynthesis (the carbon is used to make glucose, which can be turned into carbohydrates, fats and proteins - biomass - within plants and algae).
This carbon is passed on to animals (and microorganisms) when they feed on plants and algae.
It is returned to the atmosphere in the form of carbon dioxide, during respiration by plants, animals and microorganisms (that release COz during decomposition).
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 wood or fossil fuels are burned (a process is known as combusti the carbon within them combines with oxygen and carbon dioxide is released into the atmosphere.

Question 22

Water cycle

Answer 22

The water cycle provides fresh water for plants and animals on land before draining into the seas.
Water is continuously evaporated and precipitated.
Water molecules move between various locations - such as rivers, oceans and the atmosphere - by specific processes:
Water enters the atmosphere as water vapour in one of two processes.
Energy from the Sun heats the Earth’s surface and water evaporates from oceans, rivers and lakes.
Transpiration from plants releases water vapour into the air.
The warmer air of the lower atmosphere rises, taking the water vapour with it.
The moist air cools down as it rises.
Water vapour condenses back into liquid water, forming clouds.
Water returns to Earth in the form of precipitation.
As the water droplets in the cloud get bigger and heavier, they begin to fall as rain, snow and sleet.

Question 23

Role of microorganisms

Answer 23

Microorganisms play a vital role in cycling material through an
ecosystem; they return carbon to the atmosphere as carbon dioxide and mineralions to the soil.
When living organisms produce waste products or organisms die, the waste products and dead organisms are broken down (digested) by microorganisms known as decomposers.
Bacteria and fungi are the main groups of decomposers.
Decomposition (also known as decay) is the process by which waste products or dead organisms are broken down and the materials they contain (such as carbon and mineral ions such as iron, magnesium and nitrates) are returned to the environment.
When decomposing microorganisms respire, carbon is returned to the atmosphere in th form of carbon dioxide.

Question 24

Rate the of decay

Answer 24

Decomposition (also known as decay or rotting) is the breaking down and digestion of biological material (waste products and dead organisms) by organisms called decomposers.
Decomposers include microorganisms (bacteria and fungi) and detritus feeders.
Decomposition is a crucial process as it ensures that materials such as carbon and mineral ions are recycled and returned to the environment.
The rate of decay is the speed that decomposers break down biological material and is affected by three key factors.