Definitions from CIE 0610 Syllabus Guide

genotype

the genetic make-up of an organism in terms of the alleles present

phenotype

the observable features of an organism

homozygous

having two identical alleles of a particular gene

heterozygous

having two different alleles of a particular gene

dominant

an allele that is expressed if it is present

recessive

an allele that is only expressed when there is no dominant allele of the gene present

sex-linked characteristic

a characteristic in which the gene responsible is located on a sex chromosome and that this makes it more common in one sex than in the other

food chain

a linear sequence of organisms that shows the transfer of energy from one organism to the next, beginning with a producer

trophic level

the position of an organism in a food chain, food web, pyramid of numbers or pyramid of biomass

food web

a network of interconnected food chains

producer

an organism that makes its own organic nutrients, usually using energy from sunlight, through photosynthesis

consumer

an organism that gets its energy by feeding on other organisms

herbivore

an animal that gets its energy by eating plants

carnivore

an animal that gets its energy by eating other animals

decomposer

an organism that gets its energy from dead or waste organic material

ingestion

the taking of substances, e.g. food and drink, into the body through the mouth

mechanical digestion

the breakdown of food into smaller pieces without chemical change to the food molecules

chemical digestion

the breakdown of large, insoluble molecules into small, soluble molecules

absorption

the movement of small food molecules and ions through the wall of the intestine into the blood

assimilation

the movement of digested food molecules into the cells of the body where they are used, becoming part of the cells

egestion

the passing out of food that has not been digested or absorbed, as faeces, through the anus

haploid nucleus

a nucleus containing a single set of unpaired chromosomes, e.g. in gametes

diploid nucleus

as a nucleus containing two sets of chromosomes, e.g. in body cells

mitosis

nuclear division giving rise to genetically identical cells

meiosis (core level)

nuclear division giving rise to cells that are genetically different

meiosis (reduction d..)

reduction division in which the chromosome number is halved from diploid to haploid resulting in genetically different cells

inheritance

the transmission of genetic information from generation to generation

chromosome

a thread-like structure of DNA, carrying genetic information in the form of genes

gene

a length of DNA that codes for a protein

allele

a version of a gene

adaptive feature (core level)

an inherited feature that helps an organism to survive and reproduce in its environment

adaptive feature (extended level)

an inherited feature that helps an organism survive and reproduce in its environment

process of adaptation

the process, resulting from natural selection, by which populations become more suited to their environment over many generations

sexual reproduction

a process involving the fusion of the nuclei of two gametes (sex cells) to form a zygote and the production of offspring that are genetically different from each other

fertilisation

the fusion of gamete nuclei

pollination

the transfer of pollen grains from the anther to the stigma

self-pollination

the transfer of pollen grains from the anther of a flower to the stigma of the same flower or different flower on the same plant

cross-pollination

transfer of pollen grains from the anther of a flower to the stigma of a flower on a different plant of the same species

gravitropism

a response in which parts of a plant grow towards or away from gravity

phototropism

a response in which parts of a plant grow towards or away from the direction from which light is coming

drug

any substance taken into the body that modifies or affects chemical reactions in the body

population

a group of organisms of one species, living in the same area, at the same time

community

all of the populations of different species in an ecosystem

ecosystem

a unit containing the community of organisms and their environment, interacting together, e.g. a decomposing log, or a lake

variation

differences between individuals of the same species

mutation

genetic change

gene mutation

a change in the base sequence of DNA

tissue

a group of cells with similar structures, working together to perform a shared function

organ

a structure made up of a group of tissues, working together to perform specific functions

organ system

a group of organs with related functions, working together to perform body functions

transpiration

loss of water vapour from plant leaves by evaporation of water at the surfaces of the mesophyll cells followed by diffusion of water vapour through the stomata

translocation

the movement of sucrose and amino acids in phloem:
- from regions of production (source)
- to regions of storage OR to regions where they are used in respiration or growth (sink)

pathogen

a disease-causing organism

transmissible disease

a disease in which the pathogen can be passed from one host to another

active immunity

defence against a pathogen by antibody production in the body

sustainable resource

a resource which is produced as rapidly as it is removed from the environment so that it does not run out

sustainable development

development providing for the needs of an increasing human population without harming the environment

aerobic respiration

the chemical reactions in cells that use oxygen to break down nutrient molecules to release energy

anaerobic respiration

the chemical reactions in cells that break down nutrient molecules to release energy without using oxygen

catalyst

a substance that increases the rate of a chemical reaction and is not changed by the reaction

enzymes

proteins that function as biological catalysts

hormone

a chemical substance, produced by a gland and carried by the blood, which alters the activity of one or more specific target organs

homeostasis

the maintenance of a constant internal environment

photosynthesis

the process by which plants manufacture carbohydrates from raw materials using energy from light

limiting factor

something present in the environment in such short supply that it restricts life processes

photosynthesis chemical equation

respiration chemical equation

diffusion

the net movement of particles from a region of their higher concentration to a region of their lower concentration down a concentration gradient, as a result of their random movement

osmosis

the net movement of water molecules from a region of higher water potential (dilute solution) to a region of lower water potential (concentrated solution), through a partially permeable membrane

species

a group of organisms that can reproduce to produce fertile offspring

binomial system of naming species

an internationally agreed system in which the scientific name of an organism is made up of two parts showing the genus and species

active transport

the movement of particles through a cell membrane from a region of lower concentration to a region of higher concentration using energy from respiration

sense organs

groups of receptor cells responding to specific stimuli: light, sound, touch, temperature and chemicals

synapse

a junction between two neurones

asexual reproduction

a process resulting in the production of genetically identical offspring from one parent

deamination

the removal of the nitrogen-containing part of amino acids to form urea

sexually transmitted infection

an infection that is transmitted via body fluids through sexual contact

genetic engineering

changing the genetic material of an organism by removing, changing or inserting individual genes

reproduction (core)

the processes that make
more of the same kind of organism

nutrition (core)

taking in of materials for energy, growth and development

movement (extended)

an action by an organism or part of an organism causing a change of position or place

respiration (extended)

the chemical reactions in cells that break down nutrient molecules and release energy for metabolism

sensitivity (extended)

the ability to detect or sense stimuli in the internal or external environment and to make appropriate responses

growth (extended)

a permanent increase in size and dry mass by an increase in cell number or cell size or both

excretion (extended)

removal from organisms of the waste products of metabolism (chemical reactions in cells including respiration), toxic materials, and substances in excess of requirements