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GCSE Biology Flash Card Questions

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B17 Organising an ecosystem

B17.1 Feeding relationships

Question	Answer
What is the original source of energy for most communities of living organisms?	light from the sun
What is the process called that captures light to make food?	photosynthesis
What organisms do photosynthesis?	plants and organisms
What is made during photosynthesis?	glucose and oxygen
Why do plants do with the glucose they produce during photosynthesis?	it is used to produce the range of chemicals that make up the cells of plants and algae
What is biomass?	the total mass of organisms in a given area
What is the impact of photosynthesis on biomass?	it increases biomass when glucose is produced
What are the producers in an ecosystem?	plants and algae
Why are plants and algae known as the producers in ecosystems?	because the produce most of the biomass for life on earth
How does the search for food connect organisms?	the members of a community depend on each other for food creating feeding relationships
How are feeding relationships represented?	by food chains
Which organisms are at the beginning of the food chain?	producers because they produce glucose by photosynthesis
Which are the main producers?	• on land - almost always plants • in fresh water - both plants and algae • in the ocean - algae and phytoplankton
What are the animals known as that eat the producers?	primary consumers
Name the primary producers.	• on land - herbivores, animals which eat plants, such as sheep, hippos, rabbits, caterpillars, hummingbirds • in the ocean - often zooplankton, shrimps, crabs, sea urchins, and some small fish
What are the animals known as that eat the primary producers?	secondary producers
What are carnivores?	animals that eat other animals for food
Where do carnivores fit in food chains?	secondary consumers mainly
Name some carnivores.	lions, foxes, blue tits, eagles and chameleons
Name some secondary consumers in the oceans?	larger fish, turtles, and seals
What are tertiary consumers?	animals that eat secondary consumers
Name some tertiary consumers.	mainly the largest animals like polar bears and eagles
What is the model for a food chain?	producer → primary consumer → secondary consumer → tertiary consumer
State an example food chain.	phytoplankton → fish → seal → killer whale
What do primary consumers eat?	plants or algae
What is the big advantage of eating plants?	they don't move around or run away
What is a disadvantage of eating plants?	cellulose is hard to digest and plant eaters have to find enough to get the nutrition they need/td>
What is a plant eater known as?	herbivores
What do secondary and tertiary consumers eat?	they eat other animals
What is an animal that eats animals called?	carnivore
What is an animal that eats animals and plants called?	omnivore
What are humans based on their food preferences?	omnivores
What is the advantage for carnivores of their diet?	their food is high in protein and fat, and relatively easy to digest
What is the disadvantage for carnivores of their diet/	animals run away and hide so need to serached for and caught, both of whih take considerable amounts of energy
What are the terms used for animals that eat other animals and the animals that are eaten when talking about their link?	predators and prey
What is a predator?	a secondary or tertiary animal that eats animals
What is prey?	an animal that is eaten by another animals, usually primary consumers and somties seondary consummers
How are the numbers of predators and prey animals linked?	when the number of prey animals increase, the number of prey animals increases and vice versa in cycles
Describe the predators-prey cycle.	• when there is plenty of food, the number of prey animals increases • the increase in prey animals leads to an increase in the number of predators • the increased number of predators means more prey animals are eaten, driving down the number of prey animals down • reduced numbers of prey animals means less food for predators forcing the number of predators down • with the number of predators down, fewer prey animals are eaten so more breed and numbers of prey animals increases • the cycle repeats again and again

B17 Organising an ecosystem

B17.2 Materials cycling

Question	Answer
Where do living organisms get materials for growth?	from the environment
State an example of organisms getting materials from the environment.	plants take mineral ions from the soil which are passed on to animals through feeding relationships
Why are the natural resources of the earth not used up by plants that keep taking materials?	because they are returned to environment - they are recycled for future organisms
Give three examples of materials being returned to the environment.	• trees shed their leaves • animals produce droppings • animals and plants die
What are the organisms called that break down waste and dead plants and animals?	decomposers
What chemicals are living organisms made up mainly of?	carbon, oxygen, hydrogen, and nitrogen
Why is the decay process important to a community?	because it means the same material can be used over and over again
What organisms are decomposers?	a group of microorganims that include bacteria and fungi
What do decomposers feed on?	waste and dead organisms
What do decomposers do?	decomposers break down dead or decaying organisms, using some of the nutrients to grow and reproduce, and release carbon dioxide, water and mineral ions as waste products
What form does carbon take when released by decomposers?	carbon dioxide
What is detritus?	a mixture of dead organic matter including decomposing plant and animal parts as well as faeces
What is the role of detritus feeders?	they often start the process of decay
What is another name for a detritus feeder?	a detrivore
Name 3 detrivores.	• beetles • worms • maggots
What is the difference between detrivores and decomposers?	• detrivores are a type of decomposer • detrivores consume material to break it down • decomposers like bacteria and fungi decompose the material externally - they don't eat it
Describe the decay process.	• decomposers return minerals including nitrates to the soil • decomposers return carbon to the atmosphere as carbon dioxide • plants take minerals up from the soil to make proteins and other chemicals • plants absorb carbon dioxde to use in photosynthesis • plants are eaten by herbivores and omnivores • herbivores are eaten by carnivores and omnivores • plants, herbivores, ominivores and carnivores die • decomposers break down dead organisms returning chemicals to the environment • the cycle repeats
Name the stages of the water cycle.	• condensation • precipitation • evaporation • transpiration • respiration
Why is the water cycle important for living organisms?	water is vital for life and the water cycle provides fresh water for plants and animals
What is precipitation?	rain, snow, hail or sleet
What makes clouds rain?	• water vapour cools to form water droplets • water droplets get heavier as more water vapour condenses • water droplets get too heavy to remain suspended in clouds and fall as rain
Where does the water vapour that rises to make clouds come from?	• plants release water in transpiration • plants and animals release water in respiration • animals release water in urine, sweat and faeces • water evaporates from the earth (land, lakes, rivers, and oceans) because the sun heats the earth's surface
How are clouds formed?	as water vapour rises, it cools and condenses forming clouds
What happens to fallen rain that is not absorbed by plants?	• lands in lakes and rivers which work their way down to the sea • surface run-off: some water washes across the surface of the land down to the sea • percolation: some water trickles through gaps in the soil and rocks then travels down to the sea

B17 Organising an ecosystem

B17.3 The carbon cycle

Question	Answer
How much carbon is cycled through the living world each year?	166 giggatonnes
Name some main chemicals in living organisms that are based on carbon structures.	DNA, fats, carbohydrates, proteins
What is a carbon sink?	a natural or artificial reservoir that accumulates and stores some carbon-containing chemical compound for an indefinite period
Name some carbon sinks.	coal, oil, gas, oceans, limestone, chalk, forests
Where is carbon found n the world?	• there is a pool of carbon in the air in the form of carbon dioxide • disolved in water including rivers, lakes, and oceans • in solid carbon sinks like coal and limestone
How is the stored carbon in sinks described?	as locked-up
What is the role of photosynthesis in the carbon cycle?	green plants and algae remove carbon dioxide from the air in photosynthesis
How is carbon removed from the environment?	by photosynthesis capturing gaseous carbon dioxide and converting it to sold chemicals
What is the carbon captured by photosynthesis used to make?	carbyhydrates, fats and proteins
What happens to the carbon once it is captured by plants?	it is passed through food chains including primary, secondary, and tertiary consumers
What is the role of respiration in the carbon cycle?	oxygen is used to break down glucose releasing carbon dioxide and water
How is carbon released back into the atmosphere by living organisms?	living organisms respire all the time producing carbon dioxide as a waste product
What part do decomposers play in the carbon cycle?	when living organisms die, they are broken down by decomposers which release carbon dioxide as they respire
Name some decomposers.	blowflies, mould, bacteria
Where is carbon stored in forests?	wood contains lots of carbon locked in by carbon dioxide during photosynthesis over years
Where does the carbon in fossil fuels come from?	fossil fuels are made from dead living organisms which locked in carbon when they were alive
What is combustion?	burning in oxygen
What happens to the carbon in fossil fuels when they combust?	the carbon they contain they release carbon dioxide
What is the modern problem with fossil fuels?	huge quantities of fossil fuels are burned worldwide releasing huge quanties back into the atmosphere changing the constitution of the atmosphere
What is the problem with using wood as a fuel?	it releases large quantities of carbon dioxide into the air
Describe the carbon cycle	• plants capture carbon from the air in photosynthesis • herbivores and omnivores acquire carbon by feeding on plants • omnivores and carnivores acquire carbong by feeding on other animals • plants and animals respire releasing carbon into the atmospher • decomposers breakdown dead plants and animals releasing carbon into the atmosphere from respiration • carbon is removed from the atmosphere when carbon dioxide disolves in water especially the oceans • wood and fossil fuels are burnt releasing carbon dioxide
What is the consequence of human use of fossil fuels?	• the carbon cycle has regulated itself for millions of years • humans are burning such large quantities of fossil fuels increasing the amount of carbon dioxide in the atmosphere • the increasing levels of carbon dioxide are causing global warming • increased temperatures are a threat to life on the planet

B17 Organising an ecosystem

B17.4 Rates of decomposition (single science only)

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