pearson textbook glossary Flashcards
abiotic factor
physical or chemical factor affecting an ecosystem e.g. light intensity or temperature
accommodation
changes taking place in the eye which allow it to focus on objects at different distances
acid rain
rain with a pH less than 5.5, caused by pollutant gases such as sulfur dioxide and nitrogen oxides
active transport
movement of molecules or ions against a concentration gradient, using energy from respiration.
adaptation
feature of an organism that suits its structure to function
active site
area on the surface of an enzyme where the substrate attaches and products are formed.
amylase
enzyme that digests starch into maltose
anaerobic respiration
reaction that releases energy from food, without using oxygen. produces lactate in mammals, carbon dioxide and ethanol in yeast.
anther
part of the stamen where pollen grains are produced
antibody
protein produced by lymphocytes that binds with foreign antigens as part of the immune response
anticodon
group of three bases on a tRNA molecule that are complementary to a codon on the mRNA
anus
outlet of the gut where faeces is expelled from the body.
antigen
chemical ‘marker’ on the surface of a cell that identifies the cell as ‘self’ or ‘non-self’
antidiuretic hormone (ADH)
hormone released from the pituitary gland. controls the water content of the blood by increasing reabsporbsion of water from the collecting ducts of the kidney into the blood.
arteriole
small artery
adenosine triphosphate (ATP)
chemical present in all cells which act as energy “currency” ATP is made by respiration and used up by any process that needs a supply of energy.
adrenaline
hormone secreted by the adrenal glands. stimulates several organs in the “fight or flight” response.
adrenal glands
pair of endocrine glands situated above the kidneys. secretes adrenaline.
agar
jelly like substance used as a culture medium for growing microorganisms.
aerobic respiration
Reaction that releases energy from food. Uses oxygen and produces carbon dioxide and water.
algae
photosynthesis protoctists. mostly unicellular, some multicellular forms (seaweeds)
algal bloom
rapid increase in numbers of algal cells in an aquatic habitat. often caused by eutrophication.
alleles
different forms of a gene
amino acid
one of about 20 different molecules that form the building blocks of proteins.
alveoli (singular = alveolus)
microscopic air sacs in the lungs where gas exchange takes place.
amnion
membrane enclosing the embryo during pregnancy.
amniotic fluid
fluid secreted by the amnion that protects the embryo by acting as a shock absorber.
axon
long extention of a neuron that carries nerve impulses in a diection away from the cell body.
bacteria (singular = bacterium)
small single-celled organisms with no necleus
auxin
plant hormone involved with tropisms and other growth responses
atria (singular = atrium)
two upper chambers of the heart where blood enters the heart from the vena cava (right atrium) and the pulmonary vein (left atrium)
assimilation
manufacture of new substances in cells using the products of digestion.
asexual reproduction
reproduction that does not involve fusion of gametes. new organisms are produced by part of an organism seperating from a single parent.
artificial insemination (AI)
method of selective breeding, where semen is used to make an animal pregnant without sexual intercourse e.g using semen from prize bulls to inseminate cows.
artery (plural =arteries)
blood vessel with a thick muscular wall and a narrow lumen, carrying blood away from the heart.
carnivore
animal that feeds on other animals
cell
basic structural unit of living organisms
bladder
mucular bag that stores urine before its removal from the body
carbohydrase
enzyme that digests carbohydrates
biotic factor
biological factor affecting an ecosystem e.g food supply, predation
bowmans capsule
structure consisiting of a hollown cup of cells at the start of a kidney tubule, the site of ultrafiltration
blind spot
area of the retina where the optic nerve leaves the eye, contains no light-sensitive cells , so an image can not be detected.
centeral nervous system (CNS)
brain and spinal cord
chlorophyll
green pigment present in chloroplasts, which absorbs light energy during photosynthesis
chitin
substance that makes up the cell wall of fungi and the outside skeleton muscles.
cellulose
polysaccharide of glucose that forms plant cell walls
clone
groups of cells, or organisms, that are genetically identical
consumer
organism that eats other organisms
coronary arteries
small arteries supplying blood to the heart muscle
cornea
transparent ‘window’ at the front of the eye that allows light to enter . also (along with the lens) refracts the light as it enters the eye.
carbon monoxide
toxic gas present in car exhast fumes and cigarette smoke
carbohydrate
organic compound composed of one or more sugar molecules
carcinogen
something that causes cancer e.g. a chemical or radiation
cardiac cycle
sequence of events taking place in the heart during one heartbeat
bile duct
tube carrying bile from the gall bladder to the duodenum
biomass
total mass of organisms, e.g in an ecosystem
coronary heart disease (CHD)
disease caused by a blockage of the coronary arteries due to a build uo of fatty material. it can cut off the blood supply to the heart and result in a heart attack.
cervix
‘the neck’ of the uterus
colon
first part of large intestine, where water is absorbed from the waste material in the gut
chloroplasts
organelle found in some plant cells, the site of the reactions of photosynthesis
cholesterol
lipid substance present in the blood and linked to coronart heart disease.
balanced diet
diet containing all of the nessecary food types and in the correct amounts and proportions to keep the body healthy
bacteriophage
virus that infects bacteria, used as a vector in genetic engineering
cell wall
non-living layer outside the cell membrane of certain types of cell. made of cellulose (plants and algae), chitin (fungi) or peptidoglycan (bacteria)
cell membrane
thin surface layer around the cytoplasm of a cell. forms a partially permeable barrier between the cell contents and the outside of the cell.
catalyst
chemical that increases the rate of reaction but remains unchanged at the end of the reaction.
cartilage
tough tissue present in several places in the body, such as rings in the trachea and between the bones at a joint
cardiac muscle
specialised muscle making up the heart wall, able to contract rythmically without fatiguing,
cardiac centre
region in the medulla of the brain that controls heart rate