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Complete Leaving Cert Biology Definitions
Terms in this set (217)
any measures that are taken to exclude unwanted (especially pathogenic) microorganisms, as far as is possible, from an area or object.
the ability to resist disease caused by specific pathogens by the production of antibodies or by receiving antibodies from an outside source.
a series of steps used in an investigation which strives to answer questions and explain the world around us
a possible explanation for an observation, that can be tested
the information gathered during a scientific investigation
a well-established explanation that has been repeatedly tested and confirmed in many different ways and usually over long periods of time.
Scientific Law or Principle
a statement based on repeated experimental observations that describes what has been observed.
An experiment carried out as a comparison to the test experiment, as a standard against which the actual experiment can be judged. It is identical to the test experiment, but without the variable that is being tested.
Continuity of Life
The fact that living things arise from other livings.
the sum of all the chemical reactions that occur in the cells of an organism.
living things are made of cells, tissues, organs and organ systems.
The process by which organisms take in and use energy and materials from the environment.
the removal of waste products of metabolism from the body of an organism.
A change in a cell or organism as a result of it receiving a stimulus
the ability of an organism to produce new individuals of its own kind.
the study of living things
the study of the how organisms interact with each other and with their environment.
the place in which an organism lives.
the interacting living and non-living components of a particular area.
the part of the Earth inhabited by living organisms.
all the organisms of the same species in the same habitat.
all the different populations living in the same habitat or area
the influence of non-living parts of the environment on an organism.
The influences on an organism of other living things in its environment.
soil features that influence the growth of plants or animals.
the influences of weather conditions on living organisms in the ecosystem
an organism that makes its own food from inorganic material, using energy from light (photosynthhetic) or from chemical reactions (chemosynthetic). Producers are also called autotrophs.
an organism that cannot make its own food, but instead must obtain it by eating other organisms. Consumers sare also known as heterotrophs.
a series of organisms in which one is eaten by the next.
The position of an organism in the food chain
A series of interconnecting food chains.
Pyramid of Numbers
a chart showing the number of organisms at each trophic level in a food chain.
The functional role of an organism in the community
The struggle between organisms for limited resources. Competition can take place within the same species (intra-specific) or between different species (inter-specific).
The struggle for limited resources between organisms belonging to the same species
The struggle for limited resources between organisms belonging to different species
The struggle for limited resources, whereby each organism gets some of the resource
The struggle for limited resources where there is direct conflict between two individuals and only one is successful in gaining the resource - "the winner takes it all"
any change in the structure or behaviour of an organism that makes it better suited to its environment.
the catching and killing of an animal for food.
an animal that hunts and kills another animal (the prey) for food.
the animal that is eaten by a predator.
Symbiosis (symbiotic relationship)
A close relationship between two organisms of different species living together in which at least one benefits.
A close relationship between two organisms of different species in which one benefits (the parasite), while the other (the host) is harmed
A close relationship between two organisms of different species living together in which one benefits, while the other is unaffected
A close relationship between two organisms of different species that live together, in which both benefit
the movement of essential elements from the abiotic environment into living organisms and back again
the conversion of atmospheric nitrogen into nitrogen compounds such as ammonia (NH3) and nitrate (NO3).
A habitat survey that records the presence or absence of an organism
A habitat survey that records the numbers of individuals of each species present
the chance of finding a particular species in one quadrat throw
an estimate of the amount of ground in a quadrat covered by any species
the addition of anything harmful to the environment.
Any substance that causes harm to the environment
the passive movement of molecules from areas of high concentration to area of low concentration.
the movement of water from an area of high water concentration to an area of low water concentration across a selectively permeable membrane
The activities of organisms to maintain the concentration of a solution at an optimum
the firm state of plant cell due to the outward pressure of the cytoplasm against the cell wall, caused by water entering the cell by osmosis
A process requiring energy (ATP), whereby chemicals are taken into a cell against the concentration gradient
Haploid Cell (n)
cell that has one set of chromosomes present in the nucleus
Diploid Cell (2n)
cell that has two sets of chromosomes present in the nucleus
a form of nuclear division in which one nucleus divides into two, each with the same number of identical chromosomes as another and the original cell
a group of disorders in which cells lose their ability to control the rate and frequency of mitosis.
biological catalyst made of protein
the part of an enzyme that binds to the substrate, and catalyses the reaction to form the product
an enzyme that functions normally
An enzyme that has lost its shape and cannot function
enzymes that are trapped in a soft permeable gel or attached to an inactive support
the use of living cells, their components or enzymes to make products of commercial or scientific value or destroy harmful wastes.
the addition of a phosphate to ADP to form ATP using light energy
the controlled release of energy from food. It is an essential characteristic of all living things.
the controlled release of energy from food using oxygen.
the controlled release of energy from food without the use of oxygen. (It is sometimes known as fermentation)
a sequence of nucleotides which codes for the synthesis of a protein, i.e. It encodes a specific characteristic
The decoding of a gene into a sequence of amino acids (i.e. Protein)
a sequence of bases that codes for one amino acid.
an organism's complete set of DNA, including its genes (like a full 'cookbook' of gene recipes)
the combination of the transcription of a region of DNA followed by translation into protein
the copying of information in the nucleus from a DNA molecule to an RNA molecule
The conversion of the mRNA code into the amino acid sequence in a protein
the artificial manipulation or alteration of the genes of an organism
the production of many copies of a specific gene which occurs when a genetically modified organism (GMO) replicates the DNA during normal cell division.
the use of organisms (or other biological systems) to provide useful products or processes.
DNA that is altered using the techniques of DNA technology.
Genetically modified organism (GMO)
an organism with artificially altered DNA.
A piece of DNA that can have a foreign gene inserted into it and then used to deliver that gene into a cell, tissue or organism.
the process of making a unique pattern of bands (like a barcode) from the DNA of a person, which can be distinguished from the pattern of another person's DNA.
The Law of Segregation (Mendel's 1st Law)
states that each characteristic is controlled by a pair of factors (genes) which separate at gamete formation such that a gamete receives only one of each pair.
an alternative form of a gene
The alleles in a pair are different
The alleles in a pair are the same
An allele that masks its (recessive) partner. A dominant allele is one that is always expressed if it is present
An allele whose expression is masked by the dominant allele
Locus of a gene
The position of a gene on a chromosome
The physical make-up of an organism
A genetic cross which studies the inheritance of one trait
A genetic cross which studies the inheritance of two different traits
The Law of Independent Assortment (Mendel's 2nd Law)
states that during gamete formation, either one of a pair of alleles is equally likely to combine with either one of another pair of alleles.
genes that are located on the same chromosome and are inherited together
The heterozygous genotype produces a phenotype that is intermediate betweeen those produced by the homozygous genotypes.
A characteristic that is controlled by a gene that is carried on a sex chromosome.
the difference between living things in a population caused by genes and environment.
a change in the sequence of a DNA molecule.
an agent that cause mutations.
any factor that results in a DNA mutation that causes cancer
The change in the genetic characteristics in a population over a long period of time, resulting in new species. Evolution is the result of the process of natural selection.
an organism that has no nucleus or other membrane-bound organelles.
An organism that cannot make its own food, but instead must obtain it by eating other organisms. Also called consumers
organisms that feed on dead organic matter.
organisms that make their own food from simple inorganic raw materials such as water and carbon dioxide, using energy and light (photosynthetic autotrophs) or from chemical reactions (chemosynthetic autotrophs). Also called producers
A bacterium that requires oxygen for respiration
A bacterium that does not require oxygen for respiration
An organism that can respire with or without oxygen.
Organisms can only respire in environments without oxygen
chemicals produced by bacteria and fungi which kill or inhibit the growth of other bacteria
a disease-causing organism.
the physical and chemical breakdown of food into smaller soluble particles that can be absorbed into by the circulatory system
a blood pathway that begins and ends in capillaries.
the maintenance of a constant internal environment in an organism.
animals whose body temperature is independent of the environment temperature
animals whose blood temperature varies with the environmental temperature
Neuron (or neurone)
a nerve cell
a cell that can detect a stimulus
a change in the environment of a cell or organism that, if strong enough, results in an impulse.
the minimum intensity of stimulus needed to generate an impulse.
The "All-or-nothing" Law
states that an impulse is only generated if the stimulus is at or above the threshold.
The Refractory Period
the slight delay that occurs after a neuron has carried an impulse, during which the neuron does not respond to a stimulus: it is resetting itself in preparation for the next impulse
a specialised junction at which a neuron comes close enough to a target cell to allow it to pass a signal to that target cell. The target cell could be another a neuron, a muscle cell or a gland
the tiny gap between a neuron and its target cell at a synapse.
strong, slightly elastic fibres that connect bone to bone. Their function is to prevent dislocation
strong, flexible, inelastic fibres that connect muscle to bone
two muscles that that have opposite effects to each other, as one contracts, the other relaxes
Glands that release substances through ducts
ductless, and secrete hormones in to the bloodstream
a chemical messenger produced by an endocrine gland and carried in the blood to another part of the body where it has a specific effect.
the ability of organisms to defend themselves against pathogens and toxins
General Defence System
The part of the immune system consisting of barriers to prevent the entry of all pathogens, and prevent their initial spread.
Specific Defence System
A part of the immune system that protects against particular pathogens. It involves white blood cells either producing specific antibodies or directly destroying infected or abnormal cells
A foreign (non-self) chemical that stimulates the production of antibodies
A specific protein produced by lymphoctyes in response to the presence of an antigen
The body's defences to fight off disease and infection, whereby the body produces its own antibodies
Natural Active Immunity
The ability to protect against and fight infections and toxins that is acquired due to normal infection
Artificial Active Immunity
Immunity acquired when a person is given a dose of inactivated pathogen. This is also known as vaccination
a dose of inactivated pathogen, which doesn't cause disease, but triggers the production of antibodies
The ability to protect against and fight infections and toxins that occurs when someone is given antibiotics made by another organism
Natural Passive Immunity
The ability to protect against and fight infections and toxins that occurs when a baby gets antibodies from its mother
Artificial Passive Immunity
immunity that occurs when a person is injected with antibodies made by another organism.
a small non-cellular infectious particle that replicates only inside the living cells of other organisms.
an animal organ that produces sex cells
the release of an egg from the ovary.
Secondary sexual characteristics
the features that distinguish males from females, other that the presence of the sex organs. They develop at puberty under the control of sex hormones
The Menstrual Cycle
a series of changes that occurs in the female reproductive system every 28 days on average, if fertilisation does not take place
The time during which a woman gradually stops menstruating and therefore cannot reproduce anymore (usually occurs between 45-55)
The time during the menstrual cycle in which fertilisation is most likely to occur.
the shedding of the blood-filled lining of the womb (the endometrium).
the inability to produce offspring
The removal of eggs from the ovary and fertilising them outside the body
the release of semen from the penis
the release of semen into the vagina. It may be natural or artifcially
the fusion of the sperm nucleus with the nucleus of the egg to form a diploid zygote.
the embedding of the fertilised egg into the lining of the womb (endometrium)
a solid ball of cells formed from a zygote by mitosis
A hollow, fluid-filled ball of cells formed from a morula
layers of cells in the blastocyst from which all adult tissues and organs will form.
the length of time spent in the womb from fertilisation to birth. This is usually 38 week in humans
the production of milk by the breasts of the female
the force which can push water up a stem from the root.
the loss of water vapour from the surface of a plant
a growth response of a plant to an external stimulus.
a plant growth response to light
a plant growth response to gravity
a plant growth response to water
a plant growth response to chemicals
a plant growth response to touch
a chemical that controls the growth of a plant.
the asexual reproduction of plants.
reproduction that involves only one plant, and does not involve gametes
the transfer of pollen from the anther to a stigma of a flower of the same species.
the transfer of pollen from the anther to a stigma on a different plant of the same species
the transfer of pollen from an anther to a stigma on the same plant.
the transfer of a seed away from the parent plant.
A resting period when a seed does not germinate even though the environmental conditions are suitable for growth.
The re-growth of an embryo, after a period of dormancy.
Occurs when some bacteria are no longer killed or inhibited by a particular antibiotic
Environmental information relating to aquatic habitat
A healthy eating habit, whereby all the essential nutrients are included in the correct proportions
A vessel in which microorganisms or enzymes are used to make useful products
Chemicals made by an organism
Animal that feeds only on (other) animals
The location on a chromosome where the two sister chromatids are attached
Organisms that use the energy from chemical reactions to make food
One of two identical copies DNA making up a replicated chromosome joined together at a centromere
The fibrous loose mixture of DNA and protein that chromosomes loosen to form. Nuclear material takes this form during interphase
Tightly coiled structures found in the nucleus. They are composed of DNA and protein, and they consist of a particular set of genes. They are only visible as individual structures during nuclear division.
The wise management of our environment to ensure the survival of organisms and their habitat
Methods used to prevent fertilised or implantation
The genetic make-up of an organism
A guide to healthy eating indicating the proportions of different types of food to be eaten in a day
The study of inheritance
Animal that feeds only on plants
Structures that display a similar basic pattern, but have a different function
The harmful colonisation of an organism by another species
The division of a diploid nucleus, resulting in four genetically different haploid daughter nuclei
A chemical released by neutrons at synapses, which transmits signals across the synaptic cleft from the neuron to a target cell
An animal that feeds on plants and animals
Organisms that use the energy from light to make food
Primary sexual characteristics
The sex organs and associated glands
A very fast, automatic and involuntary response to an unexpected stimulus. It is not controlled by the brain.
The absence of any living things
A law that states that an impulse is only generated if the stimulus is at or above the threshold.
A codon is a sequence of three DNA or RNA nucleotides that correspond to a specific amino acid (or astop signal) during protein synthesis.
genetically identical offspring of an organism.
the first stage of respiration that converts glucose into pyruvic acid and occurs in the cytosol.
In Vitro Fertilisation
The removal of eggs from the ovary and their fertilisation outside the body.
the process by which members of a species with traits that allow them to survive in their environment, reproduce and pass on these traits to their offspring.
a zygote with a resistant coating that can survive adverse conditions.
a diploid cell produced by the fusion of two gametes.
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