BIOLOGY KEY TERMS Flashcards
abundance
a measure of how common or rare a particular type of organism is in a given environment
active site
the site on an enzyme where the reactants bind
active transport
the movement of substances from a dilute solution to a more concentrated solution against a concentration gradient, requiring energy from respiration
adaptations
special features that make an organism particularly well suited to the environment where it lives
ADH
anti-diuretic hormone helps control the water balance of the body and affects the amount of urine produced by the kidney
adrenaline
hormone that prepares the body for flight or fight
adult stem cells
stem cells that are found in adults that can differentiate and form a limited number of cells
aerobic respiration
an exothermic reaction in which glucose is broken down using oxygen to produce carbon dioxide and water and release energy for the cells
agar gel
widely used solid (gel) culture medium used for growing microorganisms
algae
simple aquatic organisms (protista) that make their own food by photosynthesis
alleles
different forms of the same gene sometimes referred to as variants
alveoli
tiny air sacs in the lungs that increase the surface area for gaseous exchange
amino acids
molecules made up of carbon, hydrogen, oxygen, and nitrogen that are the building blocks of proteins
amylase
enzyme that speeds up the digestion of starch into sugars
anaerobic respiration
an exothermic reaction in which glucose is broken down in the absence of oxygen to produce lactic acid in animals and ethanol and carbon dioxide in plants and yeast. A small amount of energy is transferred for the cells
aorta
the artery that leaves the heart from the left ventricle and carries oxygenated blood to the body
aphids
insects that penetrate the plant phloem and feed on the dissolved food. They act as vectors that carry pathogenic viruses, bacteria, and fungi into healthy plant tissue
archaea
one of the three domains, containing primitive forms of bacteria that can live in many of the extreme environments of the world.
arteries
blood vessels that carry blood away from the heart. They usually carry oxygenated blood and have a pulse
asexual reproduction
involves only one individual and the offspring is identical to the parent. There is no fusion of gametes or mixing of genetic information
atria
the upper chambers of the heart
auxin
a plant hormone that controls the responses of plants to light (phototropism) and gravity (gravitropism)
bacteria
single celled prokaryotic organisms
bases (DNA)
nitrogenous compounds that make up part of the structure of DNA and RNA. They are represented by the letters A, T, C, and G
benign tumours
growths of abnormal cells that are contained in one area, usually within a membrane, and do not invade other tissues
bile
neutralises stomach acid to give a high pH for the enzymes from the pancreas and small intestine to work well. It is not an enzyme
biodiversity
a measure of the variety of all the different species of organisms on earth
binary fission
reproduction by simple cell division, for example in bacteria
biomass
the amount of biological material in an organism
cancer
the common name for a malignant tumour, formed as a result of changes in cells that lead to uncontrolled growth and division
capillaries
the smallest blood vessels. They run between individual cells and have a wall that is only one cell thick
carbohydrase
enzymes that speed up the breakdown of carbohydrates into simple sugars
carbohydrates
molecules that contain only carbon, hydrogen, and oxygen. They provide the energy for the metabolism and are found in foods such as rice, potatoes, and bread
carbon cycle
the cycling of carbon through the living and non-living world
carcinogens
agents that cause cancer or significantly increase the risk of developing cancer
carriers
individuals who are heterozygous for a recessive allele linked to a genetic disorder. Carriers have one healthy allele so they are not affected themselves but they can pass on the affected allele to their offspring
catalyst
a substance that speeds up the rate of another reaction but is not used up or changed itself
causal mechanism
something that explains how one factor influences another
cell cycle
the three-stage process of cell division in a body cell that involves mitosis and results in the formation of two identical daughter cells.
cell membrane
the membrane around the contents of a cell that controls what moves in and out of the cell
cell wall
the rigid structure around plant and algal cells. It is made of cellulose and strengthens the cell
cellulose
the complex carbohydrate that makes up plant and algal cell walls and gives them strength.
central nervous system
the part of the nervous system where information is processed. It is made up of the brain and spinal cord
cerebral cortex
region of the brain associated with consciousness, memory, and language
cerebellum
region of the brain concerned with coordinating muscular activity and balance
chlorophyll
the green pigment contained in the chloroplasts
chloroplasts
the organelles in which photosynthesis takes place
chlorosis
the yellowing seen on the leaves of plants when they cannot make chlorophyll due to lack of magnesium ions
ciliary muscles
muscles that contract and relax to change the shape of the lens of the eye
clinical trials
test potential new drugs on healthy and patient volunteers
classification
the organisation of living organisms into groups according to their similarities
cloning
the production of identical offspring through asexual reproduction
communicable disease
disease caused by pathogens that can be passed from one organism to another
community
group of interdependent living organisms in an ecosystem
competition
the process by which living organisms compete with each other for limited resources such as food, light, or reproductive partners
contraception
methods of preventing pregnancy which usually involve preventing the sperm and egg from meeting
coordination centres
areas that receive and process information from receptors
coronary arteries
the blood vessels that supply oxygenated blood to the heart muscle
correlation
an apparent link or relationship between two factors
culture medium
a liquid or gel used to support the growth of microorganisms or other cultures, often containing specific nutrients.
cystic fibrosis
an inherited disorder that affects the lungs, digestive, and reproductive system and is inherited through a recessive allele
cytoplasm
the water-based gel in which the organelles of all living cells are suspended and most of the chemical reactions of life take place
decomposers
microorganisms that break down waste products and dead bodies
denatured
the breakdown of the molecular structure of a protein so it no longer functions
dialysis
the process of cleansing the blood through a dialysis machine when the kidneys fail
differentiate
the process where cells become specialised for a particular function
diffusion
the spreading out of the particles of any substance in a solution, or particles in a gas, resulting in a net movement of particles from an area of higher concentration to an area of lower concentration down a concentration gradient
digestive system
organ system where food is digested and absorbed
distribution
where particular types of organisms are found within an environment
domain
the highest level of classification. There are three domains – Archaea, Bacteria, and Eukaryota
dominant allele
the phenotype will be apparent in the offspring even if only one of the alleles is inherited
double circulatory system
the circulation of blood from the heart to the lungs is separate from the circulation of blood from the heart to the rest of the body
effectors
areas (usually muscles or glands) that bring about responses in the body
embryonic stem cells
stem cells from an early embryo that can differentiate to form the specialised cells of the body
endocrine system
the glands that produce the hormones that control many aspects of the development and metabolism of the body, and the hormones they produce.
endothermic reaction
a reaction that requires a transfer of energy from the environment
enzymes
biological catalysts, usually proteins
epidermal
the name given to cells that make up the epidermis or outer layer of an organism
eukaryotic cells
cells from eukaryotes that have a cell membrane, cytoplasm, and genetic material enclosed in a nucleus
evolutionary trees
models used to explain the evolutionary links between groups of organisms
exothermic reaction
a reaction that transfers energy to the environment
extinction
the permanent loss of all members of a species from an area or from the world
extremophile
an organism that can survive and reproduce in extreme conditions
fatty acids
part of the structure of a lipid molecule
follicle stimulating hormone
causes the eggs to mature in the ovary
genetic engineering
the process by which scientists can manipulate and change the genotype of an organism