A2 1 Bio

Homeostasis

The maintenance of constant or steady state conditions within the body

Excretion

The removal of toxic waste of metabolism

Osmoregulation

The control of the water potential of body fluids

Ultrafiltration

The filtration of plasma and substances below a certain size into the bowman’s capsule

Reabsorption

Filtered useful products are selectively absorbed back into the blood stream from the nephron

Pathogen

Microorganism that causes disease

Antigen

Substance capable of stimulating the production of specific and complementary antibodies

Antibody

Globular proteins that are specific and complementary to particular antigens that can react with antigens leading to their destruction

Immunity

The ability of an organism to resist an infection or toxin by the action of specific antibodies or sensitised white blood cells

Passive immunity

Individual receives antibodies from another source

Active immunity

Immunity achieved through the production of antibodies by the individuals own body

Epidemic

Disease that spread rapidly through a small region (usually within one country) and affect a higher proportion of the population

Pandemic

Disease that affects many thousands of people or several countries at the same time

Antimicrobial drugs

Drugs that are effective against a broader range of microbes than antibiotics or are effective against those pathogens that antibiotics cannot combat

Action potential

The depolarisation and reversal of potential difference in neurones

Population

A group of organisms of the same species living in a particular area at the same time

Biotic potential

The maximum rate of growth of the population

Environmental resistance

The restriction by the environment on the population reaching its maximum growth rate and its biotic potential

Carrying capacity

The maximum number of a population that the ecosystem can support

Parasite

An organism that lives in or on another organism benefiting from it and causing it harm over an extended period of time

Pest

Species that damages a valuable/commercial crop species causing economic damage

Community

The biotic component of an ecosystem involving interaction between the autotrophic and heterotrophic populations present

Climax community

The stable end stage of succession which is in equilibrium with the environment

Food web

Pattern of interrelated food chains that operate in an ecosystem