OCR biology paper 2 useful terms

abiotic factors

non living (physical) components of an ecosystem

biomass

the total mass of organisms in a given area

biotic factors

living components of an ecosystem

carbon cycle

process through which carbon cycles through the atmosphere, the earth and plants and animals

community

all living organisms in an area

competition

two or more organisms contesting a resource

consumers

organisms that have to eat other organisms to gain energy

decomposers

organisms that gain their energy by feed on dead or decaying material

detritivores

small animal which breaks down organic matter into small pieces

ecosystem

all the living organisms and physical conditions present in an area

egestion

removal of undigested waste from an organism

excretion

removal of waste products from an organism

habitat

the place in which an organism lives

interdependence

how different organisms depend on each other within a community

mutualism

relationship in which both organisms benefit

parasitism

relationship in which the parasite gains and the host is harmed

population

the number of organisms of a species living in an area

predation

relationship between a predator and a prey organism. predators depend on prey, normally for food

producers

organisms that make their own food through the process of photosynthesis

pyramid of biomass

diagram representing the amount biomass present at each trophic level of a food chain

trophic level

feeding level in a food chain

urine

liquid containing water, urea, and other waste substances

alleles

different versions of the same gene

asexual reproduction

resproduction which requires only one parent; results in clones

cancer

a disease which occurs as the result of cell changes that lead to uncontrolled growth and division

clone

an organism which is genetically identical to its parent

continuous variation

variation which can take any value between a miniumum and a maximum

dibloid cells

cells which contain two sets of chromosomes

discontinous variation

characteristics which fall into distinct groups

dominant allele

version of a gene whose characteristics is always expressed if present in the genotype

environmental variation

variation caused by the environment

feritilisation

joining together two gametes

gametes

sex cells

genetic cross

technique used to show the possible characteristics of an offspring

genetic variation

variation caused by an organism’s genetic material

genome

all the genetic material present in an organism

genotype

the combination of alleles present in an organism

haploid cells

cells which contain one set of chromosomes

heterozygous

organism who has different alleles of a gene

homozygous

organism who has two copies of the same allele

meiosis

cell division which produces gametes

mutation

change in the sequence of DNA bases

phenotype

characteristics which are observed in an organism

punnett square

diagram used to show the possible genetic makeup of offspring based on a mother’s and a father’s genes

recessive allele

version of a gene whose characteristic is only expressed if two copies are present in the genotype

sexual reproduction

reproduction requiring two parents, which results in variation

variation

differences within a species

zygote

fertilised egg

artificial classification

grouping of organisms based on observable characteristics

classifcation

grouping organisms who share characteristics or similarities in DNA

evolution

gradual change in a species over time

fossil

remains of a plant or animal mineralised or changed to rock

fossil record

the sequence of fossils which together show how organisms have evolved over time

natural selection

the process by which species best suited to their environment will survive and reproduce, passing on their advantageous characteristics to offspring

phlogeny

the study of evolutionary links

species

group of organisms that are able to reproduce to produce fertile offspring

biodiversity

the variety of living organisms present in an area

capture-recapture

technique used to estimate population size of animals

conservation

protecting a natural environment to ensure habitats and organisms are not lost

deforestation

removal of forest from an area

ecotourism

a form of tourism that minimises the impact of visitors on the environment

endangered species

species which have low numbers of surviving organisms left in the world

extinct

species which have no surviving organisms left in the world

identification key

chart used to identify unknown organisms

indicator species

organisms whose presence or absence can be used to indicate pollution

non-random sampling

systematically choosing where to take a sample

random sampling

position of a sample is not pre-determined; individuals are selected by chance

sample

taking observations or measurements from an area, which is representative of a larger area

seed bank

a store of seeds, conserved for future possible use

biological control

using a natural predator to control a pest population

biotechnology

the use of biological processes or organisms to produce products

donor organism

organism from which desired genes are taken

food security

the ability of human populations to access food of sufficient quality and quanitity

foreign genes

genes that are inserted into an organism from a different species

gene pool

all the genetic material present in a population

genetic engineering

altering an organism’s genome to produce an organism with desired characteristics

host organism

organism into which foreign genes are inserted

hydroponics

growing plants in water containing dissolved minerals

intensive farming

farming which uses techniques to produce maximum yield of food products from the minimum area of land. often achieved by using chemicals and machinery

ligase enzymes

enzymes which re-join DNA at sticky ends

organic farming

uses more natural methods of producing crops and rearing animals, avoiding the use of chemicals

restriction enzymes

enzymes which cut DNA at specific base sequences producing sticky ends

selective breeding

the process by which humans breed animals and plants with desired characteristics

sticky ends

exposed unpaired bases on the ends of the DNA strands produced by restriction enzymes

sustainable food production

producing food using methos that can be continued indefinitely

vector

a vehicle, such as a bacterium, used to transfer genetic material into an organism

antigens

proteins on the surface of a microorganism

antiseptic

chemicals that kill or neutralise all types of pathogen, but do not damage human tissue

antivirals

drugs that destory viruses

aseptic technique

technique used to ensure that no foreign microorganisms are introduced into a sample being tested

clinical trial

stages of testing required to approve a drug for use

communicable disease

a disease which can be transmitted between organisms

contagious

a disease which is easily transmitted

diagnosis

identifying a disease in a plant or animal

disease

a condition caused by any part of an organism not functioning properly

droplet infection

method of disease transmission; pathogens spread by airborne droplets from the nose, throat, or lungs

immunity

the ability of the body to fight off a microorganism before it has the ability to cause disease

incidence of a disease

the number of new cases of a disease, per unit population, per unit time

incubation period

the time between contracting a disease and disease symptoms showing

lymphocytes

white blood cells that make antibodies and antitoxins