GCSE OCR Biology B3 Life on Earth

annaryann's version from 2016-05-16 20:16


Question Answer
What is a species?A group of organisms that can breed together to produce fertile offspring
What does adaptation of organisms mean?They are able to survive and reproduce successfully
What do organisms in a habitat do?Depend on other species for food and compet with each other for resources
Where are feeding relationships of organisms shown?In a food web
What is interdependence?Organisms in a habitat depending on each other other than just for food
Why might a species become extinct?If it is unable to adapt rapidly to a change in the environment
What can the introduction of a new species lead to?Extinction if the species is a competitor, predator or causes disease
How will extinction of one species affect other organisms?It will affect the food web so other organisms may become extinct
What are nearly all organisms on earth depend on?Energy from the sun
What do plants use a small amount of energy for from the sun?To produce their own food by photosynthesis
What does almost every food chain begin with? A plant or absorbing energy from the sun
How is energy transferred?From one organism to the next along a food chain
Why is some energy lost in the transfer from a plant to an animal? Some parts of the plant can't be eaten, some use energy for respiration where some is lost as heat, waste products of animal contain some energy
Why is the length of the food chains limited?Because energy is lost at each level of s food chain
What are decomposers?Microorganism such as bacteria and fungi that feed on dead or decaying organisms
What is detritus?Partly decayed material
What do detritivores do?Feed on detritus and break it down further
What is the key element of the chemicals that make up all living things?Carbon
Where is carbon continuously recycled?The carbon recycle
How does carbon enter the carbon cycle?As carbon dioxide from the air
What do plants do to carbon that enters the carbon cycle?Fix it so it can be used and stored by organisms by photosynthesis
How is carbon returned to the air in the carbon cycle?Respiration when plants and animals release energy from food, through dead organisms by soil microorganisms, combustion of organic materials
Where is nitrogen recycled?Through the nitrogen cycle
How do plants take up nitrogen in the nitrogen cycle?From the soil through their roots in the form of nitrogen compounds including nitrates
What are nitrates converted to in the nitrogen cycle?Proteins
Why is protein an important nutrient in animals diets?If passes along through food chains as animals eat plants and other animals
How are nitrates released back into the soil in the nitrogen cycle?As animal excrete waste, and as plants and animals die and are decomposed by microorganisms
How does nitrogen enter the nitrogen cycle?Nitrogen molecules in the air split by lightning- nitrogen atoms combine with oxygen to form nitrates which are washed into the soil by tain
When does nitrogen leave the nitrogen cycle?When denitrifying bacteria converts nitrates in the soil into nitrogen gas
How can environmental change be measured?Non living indicators (carbon dioxide, temp and nitrate levels) or living indicators such as phytoplankton or lichens
How do scientists monitor environmental change?From a local through to a global scale
When did life on Earth begin?Around 3500 million years ago
Where do the changes involved in evolution begin?With variation between individuals
Where can evidence of how organisms have changed be found?In fossils as they are the remains of organisms that have turned into rock
What is a mutation?.A change in the genetic information of a cell
When can mutations occur?As DNA is copied during the production of new cells
If a mutation occurs as sex cells are produced, what happens?The mutation is passed to the offspring
If a mutation is useful, what happens?It is passed on through the population
What does evolution involve?The development of a new species
What happens due to mutations in a population of organisms?The gene pool will change
What is the theory of evolution based on?Data and observations, both of organisms alive today and on the fossil record
What can influence the rate at which evolution takes place?If organisms become isolated natural selection will occur, when environmental changes occur only the best adapted organisms will survive
What was the theory of evolution based on?Darwin's observations on the Galápagos Islands which are volcanic so rganisms must have arrived from the mainland
What is biodiversity?The variety of life on Earth and in different habitats
What does intensive monoculture crop production do?Maximised crop yields but it is not sustainable

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