Igcse Biology Flashcards
Adaptation
Any characteristic of an organism that improves its chances of surviving in its environment.
Aerobic respiration
Respiration with oxygen. It's the oxidation of food substances in the presence of oxygen with the release of a large amount of energy. Carbon dioxide and water are released as waste products.
Anaesthetics
Drugs that make the body unable to feel pain
Arteries
Blood vessels which carry blood away from the heart.
Artificial selection
A method used by human beings to produce plants and animals with desired qualities.
Asexual reproduction
The process resulting in the production of genetically identical offspring from one parent, without the fusion of gametes.
Assimilation
The process whereby some of the absorbed food materials are converted into new protoplasm or used to provide energy.
Breathing
The process that brings about an exchange of gases between an organism and its environment.
Capillaries
Microscopic thin-walled (one cell thick) blood vessels which carry blood from a small artery (arteriole) to a small vein (venule).
Consumers
Organisms which obtain their energy by feeding on other organisms.
Decomposers
Saprotrophs and detritivores. Organisms which obtain energy by breaking down dead organisms, faeces and excretory products.
Discontinuous variation
Traits that show limited variation in their phenotypes which are easily distinguishable. It is usually controlled by only one or a few genes. It is not affected by the environment. E.g. detached earlobes-it's either yes or no.
Ecology
The study of the relationships between living organisms and the natural environment.
Endocrine glands
Ductless glands that secrete hormones into the bloodstream.
Enzymes
Biological catalysts made of protein. They alter the rate of (mostly catalyse) chemical reactions without themselves being chemically changed at the end of the reactions.
Eutrophication
The profuse growth and multiplication of algae and green plants as a result of the enrichment of nutrients in the water. Often leads to depletion of oxygen levels.
Excretion
The process by which metabolic waste products and toxic materials are removed from the body of an organism. E.g. sweating, sweat is a metabolic waste product.
Fertilisation
The process by which the male gamete fuses with the female gamete to form a zygote.
Food chain
A series of organisms through which energy is transferred in the form of food.
Food web
Two or more food chains interlinked together.
Gamete
A reproductive cell containing the haploid number of chromosomes.
Gene
A hereditary factor found on a particular locus in a chromosome. It controls a particular characteristic and codes for a specific protein.
Mutation
The sudden or spontaneous change in gene structure or a chromosome, or even the chromosome number, and may be inheritable.
Producers
Organisms which convert energy from the sun, or light energy, into chemical energy and store it as food during photosynthesis. They are the start of the food chain.
Transpiration
The loss of water vapour from aerial parts of a plant, especially through the stomata of the leaves.
Variation
The differences that can be observed within a species.
Veins
Blood vessels which carry blood towards the heart.