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
genotype
the genetic makeup of an individual for a particular characteristic, for example hair or eye colour
gibberellins
plant hormones that are important in initiating seed germination
glucagon
hormone involved in the control of blood sugar levels
glucose
a simple sugar
glycerol
part of the structure of a lipid molecule
glycogen
carbohydrate store in animals
gravitropism
the response of a plant to gravity
guard cells
surround the stomata in the leaves of plants and control their opening and closing
haemoglobin
the red pigment that carries oxygen around the body in the red blood cells
heterozygote
individual with different alleles for a characteristic
homeostasis
the regulation of the internal conditions of a cell or organism to maintain optimum conditions for function, in response to internal and external changes
homozygote
individual with two identical alleles for a characteristic
hormones
chemicals produced in one area of the body of an organism that have an effect on the functioning of another area of the body. In animals hormones are produced in glands.
hybridomas
cells created during the production of monoclonal antibodies by the fusion of an antibody-specific lymphocyte and a tumour cell
hyperopia
long sightedness, where the rays of light from distant objects can be focused clearly on the retina but the rays of light from close objects are not focused and the objects appear blurred
hypertonic (osmosis)
a solution that is more concentrated than the cell contents
hypotonic (osmosis)
a solution that is less concentrated than the cell contents
incident energy
light from the Sun arriving at the surface of the Earth
inoculate
introducing microorganisms to a culture medium, or introducing modified microorganisms into an individual to protect them against disease
insulin
hormone involved in the control of blood sugar levels
interdependence
the network of relationships between different organisms within a community, for example each species depends on other species for food, shelter, pollination, seed dispersal, etc.
ionising radiation
has enough energy to cause ionisation in the materials it passes through, which in turn can make them biologically active and may result in mutation and cancer
isotonic (osmosis)
a solution that is the same concentration as the cell contents
lactic acid
the end product of anaerobic respiration in animal cells
limiting factors
limit the rate of a reaction, for example photosynthesis
lipase
enzymes that speed up the breakdown of lipids into fatty acids and glycerol
lipids
include fats and oils and are found in foods such as butter, olive oil, and crisps. They are made of carbon, hydrogen and oxygen
malignant tumours
invade neighbouring tissues and spread to different parts of the body in the blood where they form secondary tumours. They are also known as cancers
mean
the arithmetical average of a series of numbers
median
the middle value in a list of numbers
medulla
region of the brain concerned with unconscious activities such as controlling the heart rate and breathing rate
meiosis
two stage process of cell division that reduces the chromosome number of daughter cells. It is Involved in making gametes for sexual reproduction
metabolism
the sum of all the reactions taking place in a cell or the body of an organism
mitochondria
the site of aerobic cellular respiration in a cell
mitosis
part of the cell cycle where one set of new chromosomes is pulled to each end of the cell forming two identical nuclei during cell division
mode
the number which occurs most often in a set of data
motor neurones
carry impulses from the central nervous system to the effector organs
mutation
a change in the genetic material of an organism
myopia
short sightedness, where the rays of light from close objects are brought into focus on the retina but distant objects appear blurred as the light is focused in front of the retina
natural selection
the process by which evolution takes place. Organisms produce more offspring than the environment can support. Only those that are most suited to their environment will survive to breed and pass on their useful characteristics to their offspring.
nerve
bundle of hundreds or even thousands of neurones
neurones
basic cells of the nervous system that carry minute electrical impulses around the body
non-communicable disease
are not infectious and cannot be passed from one organism to another
nucleotide
a molecule made up of a sugar, a phosphate group, and one of four different bases. They are key units in the structure of DNA and RNA
nucleus
organelle found in many living cells containing the genetic information surrounded by the nuclear membrane
oestrogen
female sex hormone that controls the development of secondary sexual characteristics in girls at puberty, and the build-up and maintenance of the uterus lining during the menstrual cycle
organ
an aggregation (collection ) of different tissues working together to carry out specific functions
organ system
a group of organs that work together to carry out specific functions and form organisms
osmosis
the diffusion of water through a partially permeable membrane from a dilute solution (which has a high concentration of water) to a concentrated solution (with a low concentration of water|) down a concentration gradient
ovaries
female sex organs that produce eggs and sex hormones
ovulation
the release of a mature egg (ovum) from the ovary
oxygen debt
the extra oxygen that must be taken into the body after exercise has stopped to complete the aerobic respiration of lactic acid
palisade mesophyll
the upper layer of the mesophyll tissue in plant leaves made up of closely packed cells that contain many chloroplasts for photosynthesis
partially permeable membrane
a membrane that allows only certain substances to pass through
pathogens
microorganisms that cause disease
penicillium
the mould from which the antibiotic penicillin is extracted
permanent vacuole
space in the cytoplasm filled with cell sap
phenotype
the physical appearance/biochemistry of an individual for a particular characteristic
phloem
the living transport tissue in plants that carries dissolved food (sugars) around the plant
photosynthesis
the process by which plants make food using carbon dioxide, water, and light
phototropism
the response of a plant to light, controlled by auxin
pituitary gland
endocrine ‘master gland’ found in the brain that secretes a number of different hormones into the blood in response to different conditions to control other endocrine glands in the body
placebo
a medicine that does not contain the active drug being tested, used in clinical trials of new medicines
plasma
the clear yellow-liquid part of the blood that carries dissolved substances and blood cells around the body
plasmolysis
the state of plant cells when so much water is lost from the cell by osmosis that the vacuole and cytoplasm shrink and the cell membrane pulls away from the cell wall
platelets
fragments of cells in the blood that play a vital role in the clotting mechanism of the blood
polydactyly
a dominant inherited disorder that results in babies born with extra fingers and/or toes
preclinical testings
is carried out on a potential new medicine in a laboratory using cells, tissues, and live animals
primary consumers
animals that eat producers
producers
organisms such as plants and algae that can make food from raw materials such as carbon dioxide and water.
prokaryotic cells
from prokaryotic organisms have a cytoplasm surrounded by a cell membrane, and a cell wall that does not contain cellulose. The genetic material is a DNA loop that is free in the cytoplasm and not enclosed by a nucleus. Sometimes there are one or more small rings of DNA called plasmids
proteases
enzymes that speed up the breakdown of proteins into amino acids
proteins
molecules that contain carbon, hydrogen, oxygen, and nitrogen and are made of long chains of amino acids. They are used for building the cells and tissues of the body and to form enzymes
pulmonary artery
the large blood vessel that takes deoxygenated blood from the right ventricle of the heart to the lungs
pulmonary vein
the large blood vessel that carries oxygenated blood from the lungs back to the left atrium of the heart
Punnett square diagram
a way of modelling a genetic cross and predicting the outcome using probability
quadrat
a sample area used for measuring the abundance and distribution of organisms in the field
quantitative sampling
records the numbers of organisms rather than just the type
range
the maximum and minimum values for the independent or dependent variables – important in ensuring that any patterns are detected
recessive
a phenotype that will only show up in the offspring if both of the alleles coding for that characteristic are inherited.
receptors
cells that detect stimuli – changes in the internal or external environment.
red blood cells
biconcave cells that contain the red pigment haemoglobin and carry oxygen around the body in the blood
reflex arcs
bring about a reflex action. They involve the sense organ, sensory neurone, relay neurone and motor neurone
reflexes
rapid automatic responses of the nervous system that do not involve conscious thought
resolving power
a measure of the ability to distinguish between two separate points that are very close together
ribosomes
the site of protein synthesis in a cell
sample size
the size of a sample in an investigation
secondary consumer
animals that eat the primary consumers
selective breeding
speeds up natural selection by selecting animals or plants for breeding that have a required characteristic
selective reabsorption
the process in the kidney where the materials needed in the body such as glucose, some mineral ions, and water are reabsorbed back into the blood from the filtrate
sensory neurone
neurone that carries impulses from the sensory organs to the central nervous system
sex chromosome
carry the information that determines the sex of an individual
sexual reproduction
involves the joining (fusion) of male and female gametes producing genetic variation in the offspring
sexually transmitted disease
transmitted from an infected person to an uninfected person by unprotected sexual contact.
simple sugars
small carbohydrate units, for example glucose
speciation
the process by which two species evolve from a single original species by natural selection
species
the smallest group of clearly identified organisms in Linnaeus’s classification system, often described as a group of organisms that can breed together and produce fertile offspring
sperm
the male sex cells or gametes that carry the genetic material from the male parent
spongy mesophyll
the lower layer of mesophyll tissue in plant leaves that contains some chloroplasts and many large air spaces to give a big surface area for the exchange of gases
statins
drugs used to lower blood cholesterol levels and improve the balance of high- to low-density lipoproteins in the blood
stem cells
undifferentiated cells with the potential to form a wide variety of different cell types
stent
a metal mesh placed in a blocked or partially blocked artery. They are used to open up the blood vessel by the inflation of a tiny balloon
stimuli
changes in the external or internal environment that can be detected by receptors
stomata
openings in the leaves of plants, particularly on the underside and opened and closed by guard cells, allowing gases to enter and leave the leaf
suspensory ligaments
the ligaments that connect the lens of the eye to the ciliary muscles
testosterone
the main male sex hormone that controls the male secondary sexual characteristics at puberty and the production of sperm
therapeutic cloning
a process where an embryo is produced that is genetically identical to the patient so the cells can then be used in medical treatments
thermoregulatory centre
the area of the brain that is sensitive to the temperature of the blood
tissue
a group of specialised cells with a similar structure and function
tissue culture
a modern way of cloning plants that allows thousands of new plants to be created from one piece of plant tissue
transect
a measured line or area along which ecological measurements are made
translocation
the movement of sugars from the leaves to the rest of the plant through the phloem
transpiration
the loss of water vapour from the leaves of plants through the stomata when they are opened to allow gas exchange for photosynthesis. It involves evaporation from the surface of the cells and diffusion through the stomata
trophic level
feeding levels in an ecosystem
tropism
the responses of plant roots and shoots to environmental stimuli such as light or gravity
tumour
a mass of abnormally growing cells that forms when the cells do not respond to the normal mechanisms that control growth and when control of the cell cycle is lost
turgor
the pressure inside a plant cell exerted by the cell contents pressing on the cell wall
type 1 diabetes
a disorder where the pancreas fails to produce sufficient insulin
type 2 diabetes
a disorder where the body cells no longer respond to the insulin produced by the pancreas
urea
the waste product formed by the breakdown of excess amino acids in the liver
vaccine
dead or inactive pathogenic material used in vaccination to develop immunity to a disease in a healthy person
vasoconstriction
the constriction or narrowing of the blood vessels
vasodilation
the dilation or opening up of the blood vessels
veins
blood vessels that carry blood towards the heart. They usually carry deoxygenated blood and have valves to prevent the backflow of blood
vena cava
the large vein that brings deoxygenated blood from the body into the heart
ventilated
movement of air or water into and out of the gas exchange organ, for example lungs or gills
ventricles
chambers of the heart that contract to force blood out of the heart
virus
pathogens that are much smaller than bacteria and can only reproduce inside living cells of other organisms
white blood cells
blood cells involved in the immune system of the body. They engulf pathogens and make antibodies and antitoxinsx
xylem
the non-living transport tissue in plants that transports water from the roots to the leaves and shoots
zygote
the single new cell formed by the fusion of gametes in sexual reproduction
