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A
Absorption spectrumA spectrum showing the amounts of the different wavelengths of light absorbed by the different pigments of chlorophyll.
Accommodation
Changing the curvature of the lens so that light from near and distant objects can be focused on the retina to give clear visual images.
Acoelomate
An animal that does not have a fluid filled body cavity that arises from a split in the mesoderm.
Action spectrum
A spectrum showing the rate of photosynthesis for each of the different wavelengths of light.
Active site
The part of the enzyme that the substrate temporarily attaches to. It makes the enzyme specific.
Active transport
This is the movement of molecules against the concentration gradient. It requires energy.
Allele
An alternative form of a gene.
Anaerobic respiration
This is the release of energy from food without using oxygen.
Antibiotic
Chemical secreted by bacteria and fungi, which can be used to kill other bacteria and fungi.
Antibody
A protein produced by white blood cells in response to an antigen.
Antigen
A chemical, which stimulates the production of antibodies.
Autosomes
Non sex chromosomes.
Autotrophic
An organism that can make its own food.
Axon
A nerve fibre that carries messages away from the cell body.
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C
CarnivoreAn animal that feeds on flesh.
Carpal
Bones of the wrist.
Carpal
The female reproductive organ of the flowering plant.
Casparian strip
A band of suberin (fatty substance) which prevents flow of water between the cells of the endodermis in the root.
Catalyst
A chemical substance that can alter the speed of a chemical reaction without getting changed itself.
Cellulose
A structural polysaccharide. It forms the cell walls of plant cells.
Centriole
Found in most cells just outside the nucleus. Their function is to organise the spindle fibres during cell division.
Centromere
Point where two sister chromatids are held together in a chromosome.
Centrosome
The region of cytoplasm surrounding the centrioles.
Cerebellum
Part of the hindbrain. Its functions include balance and muscular co-ordination.
Cerebrum
Part of the forebrain. Its functions include intelligence, memory, emotions and voluntary movements.
Chemotropism
A growth response to a chemical stimulus.
Chitin
A structural polysaccharide. It makes up the exoskeleton of arthropods.
Chromoplast
A plastid found in plants. Contain pigments, which are responsible for the colour in most flowers and fruits.
Chromosome
Structures in the nucleus of the cell made of DNA and protein.
Coelom
A fluid filled body cavity, which arises from the split in the mesoderm.
Co-enzyme
A non-protein part of an enzyme, which is essential for the enzyme to work.
Compensation point
The light intensity when the rate of photosynthesis equals the rate of respiration. The amount of sugars produced during photosynthesis is the same as the amount of sugars being broken down during respiration.
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D
DeaminationThe removal of the amino group (NH2) from the amino acids in the liver. The NH2 is combined with CO2 to form urea, which is excreted.
Denaturation
Change in the shape of the active sight of an enzyme. It then loses its ability to function as a biological catalyst. Heat or a change in pH can cause it.
Diastole
Relaxation of heart wall muscle.
Diffusion
The movement of molecules of a substance from an area of high concentration to an area of low concentration along a concentration gradient.
Diploblastic
An animal that arises from two germ layers - the ectoderm and endoderm e.g. Jellyfish.
Diploid
The nucleus of a cell possesses two of each chromosome i.e. there are two sets of chromosomes.
Dominant gene
A gene that always expresses itself in the phenotype.
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E
EcdysisThe shedding of the exoskeleton of an arthropod to allow for growth.
Endocrine Glands
Glands that have ducts e.g. salivary glands.
Exocrine Glands
Ductless glands that release hormones directly into the bloodstream e.g. Thyroid gland.
Exoskeleton
Skeleton lying outside the body of Arthropods.
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F
FermentationThe breakdown of organic compounds in the absence of oxygen for the purpose of energy production.
Fertilisation
The fusion of two haploid gametes to form a diploid zygote.
Fibrin
One of the elements in blood clotting. An insoluble protein. Strands of fibrin form a mesh at the site of injury, which becomes the base for a scab.
Fibrinogen
One of the elements in blood clotting. A soluble protein which is converted to fibrin by thrombin.
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G
GameteA haploid sex cell capable of fusing with another to form a diploid zygote.
Gametophyte
A plant, which produces haploid sex cells (gametes).
Gene
A specific section of DNA controlling one particular inheritable characteristic.
Genotype
A genetic makeup of an organism.
Genus
A sub-division used in classification. The first part of the binomial name e.g. Homosapiens, "Homo" is the genus and "sapiens" is the species.
Glycogen
Storage carbohydrate in animals. Found in muscle, liver and brain cells.
Goitre
An enlarged thyroid. This occurs when the thyroid is overactive, which is known as Graves's disease.
Guttation:
Forced exudation of liquid water from the leaves of plants.
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H
HaploidThe nucleus of a cell only possesses one of each chromosome i.e. there is only one set of chromosomes.
Herbaceous
Plants that do not develop woody tissue.
Herbivore
An animal that feeds on plant material.
Heterogametes
Sex cells that are totally different in behaviour and size.
Heterotrophic
Organisms that cannot make their own food.
Heterozygous
Having two different alleles.
Hyphae
A single filament of a fungus.
Hyperopia
Long sightedness. Difficulty focussing on objects close to the eye but can see objects at a distance.
Homologous chromosomes
Pairs of chromosomes that come together during meiosis. They carry genes that control the same characteristic.
Homozygous
Containing two identical alleles for a particular characteristic e.g. GG, gg.
Hormone
A chemical produced by the endocrine glands and transported in the blood to a particular site or target organ where it exerts a specific effect.
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I
InsulinA hormone produced by the pancreas. It controls the level of sugar in the blood.
Isogametes
Gametes that are similar and cannot but distinguished as male and female.
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L
LenticelOpenings on the bark of a tree for exchange of gases.
Leucocytes
White blood cells involved in defence against disease.
Leucoplasts
Colourless plastids formed in plant cells. Store food reserve such as starch.
Lichen
An organism formed from a mutual relationship between an alga and a fungus.
Locus
This is the exact position the gene occupies on a chromosome.
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M
Medulla OblongataPart of the hindbrain. It forms a link between the brain and the spinal cord. Its functions include the regulation of heart rate, swallowing and breathing.
Meiosis
A type of cell division, which provides four daughter cells each with only half the original number of chromosomes.
Metamorphosis
The changes under gone by an animal as it develops from larva to adult.
Mitosis
A type of cell division, which produces two daughter cells, each identical to the parent.
Monoecious
Plants that have male and female sex organs on the same plant.
Multiple alleles
When more than two alleles control the same characteristic e.g. blood groups, the three alleles A, B, O.
Mutagen
Any chemical or treatment that can induce a mutation. Examples include UV light, X-rays and various chemicals.
Mutation
A change in genetic make up.
Mycelium
A mass of hyphae (Hypha - a single filament of a fungus).
Myopia
Short sightedness. Can see near objects clearly but have difficulty focusing on distant objects.
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N
NephhridiumAn excretory organ of phylum Annelida e.g. the earthworm.
Nitrification
The conversion of ammonium salts into nitrites and nitrates by bacteria.
Nitrogen fixation
The conversion of atmospheric nitrogen into nitrogenous compounds.
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O
OmnivoreAn animal that feeds on both plants and animals.
Osmoregulation
Control of the water and salt balance in the body.
Osmosis
The movement of water molecules from a dilute hypotonic solution to a more concentrated or hypertonic solution across a semi-permeable membrane until both solutions are the same strength - isotonic.
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P
PathogenA disease causing microorganism.
Pentadactyl limb
A limb with five digits. A study of pentadactyl limbs shows that many animals have the same basic structure but are used for different functions.
Perennation
The ability of a plant to survive from the end of one growing season to the beginning of the next.
Perennial
A plant that survives for more than two years.
Peristalsis
Waves of muscular contraction passing along and causing movement of contents in tubular organs e.g. the oesophagus.
Phenotype
The physical characteristics of an organism as a result of the environment and genotype.
Plasmolysis
The pulling of the cytoplasm away from the cell wall of the plant cells due to loss of water by osmosis.
Pollination
The transfer of pollen from the anther of the stamen to the stigma of the carpal.
Portal system
Two different capillary beds connected to each other by a vein.
Prothrombin
A protein in the blood. It is made in the liver with help of vitamin K. Thromboplastin coverts it into thrombin during the blood clotting mechanism.
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R
Recessive geneA gene that only expresses itself in the phenotype when it is in the homozygous condition.
Ribosome
A cell organelle. The function of the ribosome is to make proteins.
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S
Sphincter muscleA ring of muscle. When it contracts, it closes an opening and when it relaxes it opens an opening e.g. the cardiac sphincter muscle between the oesophagus and the stomach.
Spiracles
Openings on the exoskeleton of insects to allow for the exchange of gases.
Stoma
Openings on the leaf for the exchange of gases.
Stroma
A watery ground substance in the chloroplast in which the lamella and grana are suspended.
Suberin
A waterproof fatty material.
Symbiosis
A relationship between organisms of two different species for the purpose of nutrition e.g. lichens.
Systole
Contraction of the heart wall muscle.
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T
TendonFibrous tissue that connects muscle to bone.
Threshold level
Minimum level of stimulus required for nerve impulse transmission.
Thrombin
An active enzyme produced by the action of thromboplastin on prothrombin. It converts fibrinogen to fibrin.
Tidal Volume
The amount of air exchanged in a normal breath.
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U
UreterThe tube that carries the urine from the kidney to the bladder.
Urethra
The tube that carries the urine from the bladder to the outside of the body.
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V
VaccineA non-disease causing dose of a pathogen or its toxin.
Virus
An obligate parasite, made of protein coat surrounding either DNA or RNA.
Vital capacity
The volume of air, which can be exhaled from the lungs after taking the deepest breath. Vital capacity = tidal volume + inspiratory reserve volume + expiratory reserve volume = 4000cm3.
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X
XerophyteA plant adapted to living in very arid (dry) conditions e.g. Cactus.
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Z
ZygoteThe cell that results from the fusion of a male and female gamete.
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