biology paper 2

• an ecosystem is made up of living organisms and physical conditions in a area
• the total number of organisms of each species is known as a population
• producers are organisms that make their own food by photosynthesis
• consumers are organisms that cannot make their own food so they have to eat other animals
• decomposers are consumers that feed on dead decaying material
• decomposers are microorganisms
• detrivores are small animals
• producer= grass
• consumer= animal
• biotic factors are living factors that affect the amount of organisms
• abiotic factors are the non-living factors of the environment that affect organisms
• two abiotic factors are temperature and light intensity
• mutualism is a relationship between two organisms where they both benefit.
• in parasitism relationships only one organism benefits
• carbon is cycled with nitrogen and water
• carbon dioxide can be realesed through respiration
• variation is the differnce in characteristics
• discontinuous variation is where individuals display a characteristic that falls into a distinct group
• continuous variation is a characteristic that can vary between values
• haploid cells contain half the number of chromosomes
• diploid cells contain double the amount of chromosomes
• gametes are sex cells
• fertilised eggs develop into offspring
• a genome is the entire set of genetic material
• a genotype is a type of gene
• homozygous means having two identical alleles for a gene
• heterozygous is having two different versions of a gene
• a mutations occurs when the sequence of dna bases is altered
• a phenotype is the physical characteristics of a gene
• evolution is the change in species over time
• organisms evolve through natural selection
• classification is the process of sorting living organisms into groups
• artificial classification is grouping organsims together using observable characteristics
• sampling means taking observations or measurements from a small area
• pooters are used to collect living animals
• a capture and recapture method is used to estimate a population
• plants can be sampled using a quadrat
• the removal of one species can affect others
• captive breeding means breeding animals in a human controlled environment
• ecotourism aims to ensure tourism does not have a negative impact on the environment