A Flashcards
Absorption
The movement of digested food molecules through the wall of the intestine into the blood or lymph
Accommodation
The adjustment of the shape of the lens so as to focus light onto the retina
Acid Rain
Rain or snow which is acidic. Polluting gases such as sulfur dioxide and the oxides of nitrogen react with water in the atmosphere to form acid rain
Active Immunity
The body produces its own antibodies in response to an antigen, either on the surface of a pathogen or in a vaccine
Active Site
Part of the surface of an enzyme molecule into which the substrate fits
Active Transport
The movement of molecules or ions in or out of a cell through the cell membrane from a region of their lower concentration to a region of their higher concentration against a concentration gradient, using energy released from respiration
Adaptation
A feature that helps an organism to survive in its environment
Adaptive Feature
an inherited feature that increases an organism’s fitness.
Addiction
When a person has taken a drug so regularly that they cannot do without it
Adrenaline
A hormone produced by the adrenal glands that prepares the body for emergencies and stress, for example by increasing the glucose concentration of the blood.
Aerobic Respiration
The process that happens in cells to release a relatively large amount of energy from food substances, such as glucose, in the presence of oxygen.
AIDS
Acquired immunodeficiency syndrome - a collection of diseases that result from a weakening of the body’s immune system following infection by HIV
Allele
Any of two or more alternative forms of a gene.
Alveolus
A tiny air sac in the lungs where exchange of gases between the air and blood occurs
Amino Acid
A molecule made up of carbon, hydrogen, oxygen and nitrogen. Amino acids link together by chemical bonds to form protein molecules. Some amino acids also contain sulfur.
Amnion
the membrane that surrounds the developing fetus in the uterus.
Amnion fluid
The liquid that is contained within the amnion and which protects the fetus from mechanical damage.
Amylase
The Enzyme that breaks down starch.
Anabolic steroid
A hormone-like substance that increases the production of protein to build up muscle.
Anaerobic Respiration
The process that happens in cells to release a relatively small amount of energy from glucose in the absence of oxygen.
Anaemia
A disorder of haemoglobin in the red blood cells which means that the blood cannot carry sufficient oxygen
Antagonistic muscles
A pair of muscles which brings about movement at a joint. when one contracts, the other relaxes, e.g. the biceps and triceps which move the lower arm
Anther
The part of a flower where pollen grains are produced.
Antibiotic
A drug that is taken to kill or stop the growth of bacteria.
Antibody
A protein released by lymphocytes to protect against pathogens.
Antitoxin
A chemical released by the lymphocytes that neutralises the poisonous waste products (toxins) produced by bacteria
Arteriole
Type of blood vessel between artery and capillaries. contraction and relaxation of muscle in the wall controls flow of blood into capillaries. see vasoconstriction and vasodilation
Artery
A blood vessel through which blood travels away from the heart.
Arthropods
The phylum that consists of animals that have jointed legs and a protective exoskeleton.
Artificial Insemination (AI)
Placing semen into the uterus or oviduct as a means of treating infertility.
Artificial Selection (Selective breeding)
The selection of plants and animals for breeding because of their useful characteristics, e.g. high crop yield. also called selective breeding
ASexual Reproduction
Reproduction without the formation of gametes. New individuals are genetically identical (clones) of the parent
Assimilation
The movement of digested food molecules into the cells of the body where they are used, becoming part of the cells
Atherosclerosis
A narrowing of the arteries caused by deposits of cholesterol in the internal walls of arteries which slows down the rate of blood flow.
Atrium
A chamber of the heart that receives blood from veins and pumps it to a ventricle.
Auxin
A plant growth hormone which controls cell elongation.
