2.2 Communities & Ecosystems

Define community

A group of populations living and interacting with each other in a common habitat

Define ecosystem

The interaction between a community and the non living parts of the environment

Define photosynthesis

The process by which plants make their own food from water and carbon dioxide using energy from sunlight

What is the equation for photosynthesis?

Carbon dioxide + water → Glucose + oxygen

What are the inputs for photosynthesis?

Sunlight as energy source, carbon dioxide and water

What are the processes for photosynthesis?

Chlorophyll in chloroplasts captures certain visible wavelengths of sunlight energy and stores this as chemical energy

What are the outputs of photosynthesis?

Glucose and oxygen

What are the transformations in photosynthesis?

LIght energy is transformed into stored chemical energy (in organic matter e.g. carbohydrates, proteins and fats).

What do the products of photosynthesis help with?

Being the raw material for producing biomass

What is glucose used for in a plant?

• Respiration: where energy is released from the breakdown of glucose

• Making celluloses to make strong cell walls, especially in a rapidly growing plant

• Combining with nitrate ones in the soil to form amino acids for protein synthesis

• Producing fats/oils for storage (in seeds)

• Converted as insoluble starch for storage in stems, leaves and roots

Define biomass

The mass of living material

Define respiration

The conversion of organic matter (glucose) into carbon dioxide and water in all organisms, releasing energy and heat

What is the equation for respiration?

Glucose + oxygen → Carbon dioxide + water

What are the inputs, processes and outputs of respiration?

• Inputs: glucose and oxygen

• Processes: oxidation inside cells

• Outputs: release of energy or work and heat

What are the transformations in respiration?

Stored chemical energy is transformed into kinetic energy and heat

What is an effect of respiration having large amounts of energy being lost as heat?

The entropy in the ecosystem increases, enabling the organisms to maintain low entropy

Define trophic levels

The position that an organism occupies in a food chain

Define food chain

The flow of energy from one organism to the next. It shows feeding relationships between species in an ecosystem

What does trophic level 1 consist of?

Producers - plants and algae that produce their own biomass using energy from sunlight

What does trophic level 2 consist of?

Primary consumers - herbivores - feed on producersW

What does trophic level 3 consist of?

Secondary consumers - predators - feed on primary consumers

What does trophic level 4 consist of?

Tertiary consumers - predators - feed on secondary consumers

What does trophic level 5 consist of?

Quaternary consumers - (apex) predators - feed on tertiary consumers

What are producers normally?

Autotrophs

Define chemosythetic organisms

Organisms that make their own food from simple compounds like ammonia, hydrogen sulphide and methane

Don’t need sunlight and are often bacteria found in deep oceans

What is the importance of producers?

• Help fix energy into the ecosystem

• Provide habitats for other organisms

• Supply nutrients (humus) to the soil

  • Bind the soil to prevent soil erosion

What are consumers?

Heterotrophs

Define heterotroph

Organisms which feed on autotrophs or other heterotrophs to obtain energy

Define decomposers

Feed on dead and decaying matter