Catabolic reactions : Complex molecule is broken down to simple molecules. (Releasing energy)
Ecology : The study of the relationships of living organisms with one another and with the environment.
Ecosystem : A community of organisms and their abiotic environment.
Biosphere : Part of the earth in which life can occur.
Habitat : Place in the environment where an organism lives.
Population : All the member of the same species living in an area.
Community : Plants and animals sharing the resources of a particular habitat.
Niche : The functional role of an organism in an ecosystem. Eg – How it feeds, what it eats, who eats it etc.
Abiotic Factors : Non-living factors.
Biotic Factors : Living Factors.
Climatic Factors : Refers to weather over a long period of time.
Edaphic factors : Aspects of the soil that influence an ecosystem such as the soil pH, soil type,moisture, air and mineral content of soil.
Producers : Autotrophs that carry out photosynthesis.
Consumers : Organisms that take in food from another organisms.
Primary Consumers : Organisms which feed directly on producers. Eg – Rabbits
Secondary Consumers : Carnivores that feed on primary consumers. Eg – Fox
Tertiary Consumers : Carnivores that feed on secondary consumers. Eg – Badger
Food chain : The pathway along which energy is transferred in an ecosystem.
Food web : 2 or more interlinked food chains.
Trophic level : Is a feeding stage/energy level in a food chain.
Pyramid of numbers : Based on numbers of organisms at each trophic level in a food chain.
Nutrient recycling : The way in which elements (Carbon and Nitrogen) are exchanged between the living and non-living components of an ecosystem.
Nitrogen Fixation : Conversion of nitrogen gas into ammonia (NH3), ammonium (NH4+) or nitrate ( NO3−)
Nitrification : The ammonia is converted to nitrites and then to nitrates by nitrifying bacteria.
Dentrification : Conversion of nitrates to nitrogen gas. It is carried out by denitrifying bacteria in the soil.
Pollution : Any harmful addition to the environment.
Pollutants : Substances that cause the undesirable change to the environment.
Conservation : The wise management of our natural resources.
Competition : Occurs when organisms actively struggle for a resource that is in short supply.
Intra-specific competition : This takes place between members of the same species. Eg – Buttercups compete with each other for light,water and minerals.
Inter-specific competition : Occurs between members of different species. Eg – Foxes and thrushes compete for earthworms.
Contest competition : Involves an active physical contest between 2 individuals. Eg – Robins actively defend a territory for feeding, nesting and reproduction.
Scramble competition : Involves all the competing organisms getting some of the resources. Eg – Seedlings competing for space around parent plant.
Adaptations : Ways in which organisms are specialised either in structure/behavior to survive competition.
Predation : An organism that lives by killing and consuming other living things. Eg – Ladybirds kill greenfly.
Parasitism : Living organism that feeds on another living organism of a different species knows as host, generally causing harm to the host.
Ectoparasites/Exoparasites : Live on the body of the host. Eg – greenfly on rose bushes.
Endoparasites : Live on the inside of the body of the host. Eg – Disease causing bacteria in the human body (Streptococcus)
Symbiosis : Relationship between 2 organisms of different species that live in close association to the benefit of both organisms.
Saprophytes : Lives on dead organisms.
Quantitative study : A study to find out the number of organisms that exist in an ecosystem.
Qualitative study : A study to find out the type(s) of organism that exist in an ecosystem.
Protoplasm : Is all the living parts of a cell.
Ultrastructure : The fine detail of a cell as seen as with an electron microscope.
Chromatin : Name given to chromosomes when they are not dividing.
Ribosomes : Very small organelles made of protein and RNA. Function is to make proteins.
Organelles : Distinct structures suspended in cytoplasm.
Prokaryotic cells : Cells do not have a nuclear membrane surrounding their DNA. Eg – Monera
Eukaryotic cells : These cells have a membrane bound nucleus and organelles.
Tissue : A group of similar cells specialised to carry out the same function.
Tissue culture : Cells grown on a sterile nutrient medium outside an organism.
Organ : A structure, containing different tissues, which has a specific function.
Organ system : A group of organs and tissues working together to carry out a specific function.
Catalyst : A substance that speeds up the rate of a chemical reaction(metabolism) without itself taking part in the reaction.
Enzymes : Defined as biological catalysts, protein in nature. Enzymes speed up the reactions in the cell without being used up in the reaction.
Substrate : The substance an enzyme reacts with.
Product : Is formed when an enzyme reacts with a substrate.
Active site : The region of the enzyme that binds with the substrate.
Denatured enzyme : An enzyme which has lost its shape and can no longer carry out its function.
Bioprocessing : Use of enzyme-controlled reactions to produce a product.
Bioreactor : A vessel used to carry out enzyme controlled reactions.
Batch processing : Fixed amount of nutrients added at beginning and emptied at the end of production.
Immobilised enzymes : Enzymes that are fixed/attached to each other or to an inert material.
Phosphorylation : Addition of phosphate to a molecule.
Protease : An enzyme which digests protein.
Cell continuity : All cells develop from pre-existing cells.
Chromosome : Coiled threads of DNA and protein that become visible in the nucleus at cell division.
Haploid cell : A cell which contains one of every chromosome type or pair.
Diploid cell : A cell which contains two of each type of chromosome (in homologous pairs).
Homologous pair : Consists of 2 chromosomes that each have genes for the same features at the same positions.
Interphase : The phase in the cell cycle when the cell is not dividing.
Mitosis : A form of cell division that produces two daughter cells, genetically identical to each other and to the parent cell.
Meiosis : A form of cell division that produces four genetically different daughter cells, each of which has half the number of chromosomes of the parent cell.
Cancer : Group of disorders in which certain cells lose their ability to control both the rate of mitosis and the number of times mitosis takes place.
Selectively permeable : Cell membranes allow the passage of some materials but not others.
Diffusion : The movement of a substance from its area of higher concentration to its area of lower concentration. (Passive process)
Active transport : The movement of a substance(usually ions) from its area of lower concentration to its area of higher concentration. (Opposite of diffusion)
Osmosis : The diffusion of water across a selectively permeable membrane, from its area of higher concentration to its area of lower concentration.
Hypotonic sol : Has a low concentration of solutes and thus a higher concentration of water than another solution.
Hypertonic sol : Has a higher concentration of solutes and thus a lower concentration of water than another solution.
Isotonic sol : Has the same concentration of solutes and water as another solution.
Turgor / Turgor pressure : Is the pressure of the cytoplasm and vacuole against the cell wall.
Phagocytosis : Process where large particles are engulfed by the cell and become incorporated into a vacuole within the cell.
Species : A group of similar organisms capable of interbreeding and producing fertile offspring.
Variation within a species : In a group of successfully interbreeding organisms the individual members show different characteristics.
Heredity : The transmission of traits from parents to offspring.
Mutation : Is a spontaneous inheritable change in the structure of the genetic material.
Mutagens : Agents that cause mutations.
Gene(point) mutations : Are changes in a single gene.
Chromosome mutations : Large changes in the number and structure of the chromosomes.
Evolution : Defined as a change of a population of 1 species that gives rise to 1 or more new species.
Natural selection : A mechanism of evolution whereby the best-adapted individuals survive and produce more offspring. Or inheritable change within a population in response to change in the environment by natural selection over time.
Gene : Part of a chromosome, made of DNA and controls a single characteristic/trait.
Gene expression : The process whereby genetic information, encoded in a gene, is transferred to its functional product.
DNA profiling : A process of making unique patterns in the non-coding regions of an individual’s DNA. Or examining DNA for a pattern or band to compare.
Genetic screening : Testing DNA to identify the presence or absence of particular genes.
Transcription : Copying of a sequence of genetic bases from DNA onto mRNA. (Making mRNA using DNA template)
Translation : Conversion of a sequence of genetic bases on mRNA into a sequence of amino acids.
Chromosome : Found in the nucleus, made of DNA and protein and contain genes along their length.
Homologous chromosomes : Pairs of chromosomes that contain genes for the same characteristics at the same positions on the chromosomes.
Gametes : Haploid cells that are capable of fusion.
Allele : Different forms of the same gene. They occupy the same position(locus) on homologous chromosomes.
Locus : The position of the gene on the chromosome.
Genotype : The genotype is the kind of genes present in the cell.
Phenotype : This is the expression of the gene in the environment. This is how genes affect the appearance of the organism.
Progeny : Refers to offspring that are produced.
Homozygous : When 2 alleles for a particular characteristic are the same. Eg – TT = Tall and tt = short
Heterozygous : When 2 alleles for a particular characteristic are different. Eg – Tt = Tall
Dominant : A dominant allele is one that is always expressed in the phenotype. Generally written with a capital letter.
Recessive : A recessive allele is not expressed in the presence of the dominant allele, but only when both recessive alleles are present. Generally written with a small letter.
Incomplete dominance : The condition in which both alleles in the heterozygous condition are expressed in the phenotype, and an intermediate phenotype results.
Fertilisation : Fusion of a haploid sperm and an egg to form a diploid zygote.
The Law of Segregation : An individual has 2 genes for a character. These segregate at gamete formation. Only 1 of a pair of such genes can be carried in a single gamete. At fertilisation, the new organism will have 2 genes for each trait, one from each parent.
The Law of Independent Assortment : When gametes are formed, each member of a pair of alleles can be inherited with any one from another allele pair.
Linkage : That genes are located on the same chromosome.
Sex linkage : A characteristic is controlled by a gene on an X/Y chromosome.
Pedigree : A diagram showing the occurance and appearance of a particular genetic trait from one generation to the next.
Genetic engineering : The artificial manipulation/alteration of genes.
DNA Ligase : An enzyme that is used to stick DNA molecules from sources firmly together.
Restriction enzymes : Enzymes that DNA at specific places.
Genetically Modified organisms ( GMOs) : Living things whose DNA has been altered artificially.
Diversity of Organisms
Autotrophs : Organisms which can make their own food from simple inorganic substances. Eg – Green plants
Photosynthetic : A type of nutrition where organisms make their own food using light energy. Eg – purple sulphur bacteria
Chemosynthetic : A type of nutrition where organisms make their own food using energy from chemical reactions. Eg – nitrifying bacteria.
Heterotrophs : Organisms which cannot make their own food. Eg – Animals, fungi
Saprophytes : Organisms that take in food from dead organic matter. Eg – Bacteria of decay
Parasites : Organisms that take in food from a live host and cause harm. Eg – Disease-causing bacteria
Pathogens : Micro-organisms that cause disease.
Antibiotics : Chemicals produced by some bacteria and fungi that inhibit the growth or reproduction of other bacteria and fungi.
Mycology : Study of fungi.
Hypha : Tube/filament in a fungus.
Mycelium : Made up of network of fine tubular filaments( Hyphae)
Chitin : Fungus’ have rigid cell walls containing chitin.
Sporulation : Process of making spores.
Aseptic/Asepsis : The exclusion of micro-organisms.
Sterile : The absence of micro-organisms/ free from micro-organisms.
Osmoregualtion : The control of water and salt balance in an organism.
Bacteriophage : A virus that infects bacteria.
AIDS ( Acquired Immunodeficiency Syndrome) : A collection of disorders following infection by the HIV (Human Immunodeficiency Virus ). HIV virus contains RNA.
Meristem : Zone of active cell division in plants.
Dermal tissue : A single layer of cells covering the different parts of the plant. Eg – epidermis
Vascular tissue : The tissues involved in transport within the plant, xylem and phloem.
Ground tissue : All the other tissues within the plant.
Cuticle : Living cells often with a waxy layer covering over the outer surface.
Herbaceous : Plants do not contain wood/lignin. Eg – buttercup
Woody : They possess woody tissue Eg – Oak
Transpiration : Loss of water vapour from the leaves and other aerial parts of a plant.
Lenticels : Openings in the stems of plants that allow gas exchange.
Stimulus : Anything that brings about a response in an organism.
Response : The effect the stimulus has on the organism activity. Plants respond to light by growing.
Tropism : The growth response of a plant to an environmental stimulus.
Phototropism : Growth of plants in response to light.
Geotropism : Growth of plants in response to gravity.
Thigmotropism : Growth of plants in response to touch.
Hydrotropism : Growth of plants in response to water.
Chemotropism : Growth of plants in response to chemicals.
Growth regulators : A chemical that controls growth in plants.
Phytoalexins : When a plant is infected by a micro-org, the plant is able to produce stress proteins.
Asexual : Reproduction involves only 1 parent.
Sexual reproduction : Involves the union of 2 sex gametes.
Gametes : Haploid cells capable of fusion.
Stamens : Male parts of the flower.
Carpels : Female parts of the flower.
Pollination : The transfer of pollen from an anther to a stigma of a flower from the same species.
Self-Pollination : The transfer of pollen from an anther to a stigma on the same plant.
Cross-Pollination : The transfer of pollen from an anther to a stigma on a different plant of the same species.
Fertilisation : Union of the male and female gametes to form a diploid zygote.
Non-endospermic seed : Has no endopserm when fully formed.
Endopspermic seed : Contains some endosperm when fully formed.
Dispersal : The tranfer of a seed/fruit away from the parent plant.
Dormancy : Resting period when seeds undergo no growth and have reduced cell activity/metabolism.
Germination : The regrowth of the embryo, after a period of dormancy, if the environmental conditions are suitable.
Vegetative propagation : Asexual reproduction in plants. Eg – Strawberry
Clone : A group of cells/organisms that are genetically identical to each other and are produced by mitosis.
Runners : Horizontal stems that run.grow above ground and from which new plants grow.
Root tuber : A swollen, underground root that remains dormant during winter and from which new plants may grow.
Bulb : Modified bud.
Micropropagation : Involves growing large numbers of plant from small pieces of plant tissue( single cells).
Tissue culture : The growth of tissues outside the organism on an artificial medium. Eg – Micropropagation of plants
Leaf venation : The way in which veins in the leaf are arranged is called leaf venation.
Serum : Is plasma with fibrinogen removed. This prevents plasma from clotting and serum can be stored by hospitals for transfusions.
Granulocytes : Formed in the red bone marrow. They are phagocytic ( Actively seek out and engulf bacteria)
Monocytes : Non granular and are also phagcytic. They often leave the capillaries in search of foreign material.
Lymphocytes : Formed in the bone marrow and matured in the lymph nodes. They recognise proteins(antigens) on the cell membranes of invading organisms and respond by making antibodies which kill the invaders.
Blood pressure : The force the blood exerts against the wall of a blood vessel.
Pulse : Contraction of a wall of an artery/ The rate at which the heart beats.
Valves : Control the direction of blood flow.
Portal system : A blood pathway that begins and ends in capillaries.
Hepatic portal vein : Carries blood rich in food form from the small intestines to the liver.
Diastole : When heart chambers relax.
Systole : When heart chambers contract.
Lymphatic System : A secondary circulatory system consisting of fine tubes ending blindly among the tissues.
Lymph nodes : Along the lengths of these tubes are swellings called lymph nodes.
Lymphatic vessels : The tubes that carry lymph.
Homeostasis : The ability of an organism to maintain a constant internal environment.
Ectotherms : Gain/Lose heat from or to their external environment.
Endotherms : Generate their own heat from metabolic reactions.
Active transport : Energy is used to move molecules against a concentration gradient. Eg – low conc to high concentrations
The Nervous System
Neuron : A nerve cell
Threshold : The minimum stimulus needed to cause an impulse to be carried.
The ‘All or nothing Law’ : States that if the threshold is reached an impulse is carried, but if the threshold is not reached no impulse is carried.
Refractory period : Short timespan after a a neuron has carried an impulse during which a stimulus fails to cause a response.
Synapse : A region where 2 neurons come into close contact.
Synaptic cleft : The tiny gap between the 2 neurons at a synapse.
Reflex action : An automatic,involuntary, unthinking response to a stimulus.
Exocrine glands : Release their product into ducts/tubes.
Endocrine glands : A ductless gland that produces hormones which are released directly into the bloodstream.
Hormone : A chemical messenger produced by an endocrine gland and carried by the bloodstream to another part of the body where it has a specific effect.
Ligaments : Strong, fibrous,slightly elastic tissues that connect bone to bone.
Tendons : Strong,flexible,inelastic fibres that connect muscle to bone.
An antagonistic pair : 2 muscles that have opposite effects to each other.
The Human Defence System
Pathogen : An organism that causes disease.
Immunity : The ability to resist infection.
The general defence system : Acts against all potential pathogens attempting to gain entry to the human body and is divided into 2 lines of defence.
The specific defence system : Attacks particular pathogens.
Antigen : A foreign molecule that stimulates the production of antibodies.
Anitbody : A protein produced by white blood cells (lymphocytes) in response to an antigen.
Induced immunity : The ability to resist disease caused by specific pathogens.
Active immunity : The person produces antibodies in response to invading antigens. This gives long lasting production.
Natural active immunity : When a pathogen enters the body in the normal way.
Artificial active immunity : When a pathogen is medically introduced into the body.
Vaccine : Injected or taken orally into the body, is a small quanitity of a microbe that is dead or is treated in some way to reduce its effect. The vaccine stimulates the production of the corresponding antibody, giving resistance to the microbe, eg – polio, whooping cough.
Passive immunity : Antibodies produced in another individual are given to the person.
Natural passive immunity : Antibodies pass from mother to child across the placenta and in the milk.
Artificial passive immunity : Antibodies produced in another animal/human are given, eg – antitetanus injection.
Gamete : A haploid cell.
Gonad : An organ that produces sex cells in animals.
Ejaculation : The release of semen from the penis.
Secondary sexual characteristics : Are features that distinguish males from female apart from the sex organs.
Infertility : The inability to produce young.
Ovulation : The release of an egg from the ovary.
The menstrual cycle : Series of events that occurs every 28 days on average in the female if fertilisation has not taken place.
Insemination : The release of semen into the vagina, outside the cervix.
Fertilisation : Occurs when the nucleus of the sperm fuses with the nucleus of the egg, forming a diploid zygote.
Birth control : Involves methods to limit the number of children born.
Abortion : Termination of pregnancy.
Contraception : The deliberate prevention of fertilisation/pregnancy.
Implantation : The embedding of the fertilised egg into the lining of the uterus.
In vitro fertilisation (IVF) – Involves removing eggs from an ovary and fertilising them outside the body.
Morula : A solid ball of cells formed from a zygote by mitosis.
Blastocyst : A hollow ball of cells formed from a morula.
Germ layers : Basic layers of cells in the blastocyst from which all adult tissues and organs will form.
Gestation : The length of time spent in the uterus from fertilisation to birth.
Lactation : The secretion of milk from mammary glands(breasts) of the female.