| The Cell | |
| Cytoplasm | The liquid body of a cell, most of the chemical reactions of life occur here. |
| Cell membrane | the thin sheet surrounding the cell, controls the entry and exit of materials.This is a selectively permeable membrane. |
| Selectively Permeable Membrane | A membrane that controls the passage of particles of solute through it. E.g. a cell membrane. |
| Nucleus | Contains the hereditary material, the chromosomes; it also controls the cells activity. |
| Chloroplast | Found only in plant cells. Contains the chemical chlorophyll and is the site of photosynthesis. |
| Chlorophyll | The green chemical in chloroplasts that is essential for the light reaction. |
| The light reaction | Occurs in photosynthesis and uses light energy to separate water into hydrogen and oxygen. Also ADP + Pi is changed into ATP. |
| Carbon Fixation | Occurs in photosynthesis and uses the hydrogen and ATP from the light reaction and Carbon dioxide from the air to make sugar. |
| Cellulose cell wall | Surrounding plant cells, this is a rigid wall of cellulose fibres that gives shape and rigidity to the cell |
| Large central vacuole | Liquid filled structure in plant cells. This inflates with water by osmosis, presses the cytoplasm against the cell wall and keeps the plant cell turgid. |
| Solute | A chemical dissolved in a liquid. |
| Cheek epithelial cell | The outer layer of cells lining the cheek |
| Parenchyma cell | A packing cell inside plants |
| Epidermal cell | The outer layer of cells round an organism. |
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| Uses of Cells | |
| Gasohol | A fuel made from alcohol. Used for cars in some countries. |
| Antibiotic | A chemical that kills bacteria, usually produced by fungi. |
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| Diffusion and Osmosis | |
| Diffusion | Movement of solute particles, from a region of higher solute concentration to a region of lower solute concentration, until the particles are evenly spread. |
| Osmosis | Movement of water, from a region of higher water concentration to a region of lower water concentration, through a selectively permeable membrane, during osmosis water flows from a higher water concentration to a lower. |
| Organism | A living thing. |
| Water concentration | the more solute that is added to water the lower the water concentration. Pure water has the highest water concentration possible. |
| Hypertonic | where two solutions have different water concentrations, the one with the lowest water concentration is hypertonic |
| Isotonic | where two solutions have the same water concentrations. |
| Hypotonic | where two solutions have different water concentrations, the one with the highest water concentration is hypotonic. |
| Plasmolysis | The state of a plant cells when it is placed in a hypertonic solution. The cytoplasm pulls away from the cell wall and the cell becomes flaccid. |
| Turgid | the state of a plant cell when it is placed in a hypotonic solution. The cytoplasm pushes away from the cell wall and the cell becomes inflated |
| Flaccid | Wilted |
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| Enzymes | |
| Catalyst | A chemical that lowers the activation energy of a reaction causing it to occur or go faster. |
| Activation Energy | The amount of energy needed by a chemical reaction before it will happen |
| Enzyme | A biological catalyst. Enzymes are made of protein. |
| Active site | The place on an enzyme where the reaction between the substrates takes place. |
| Substrate | The chemical(s) that an enzyme acts on. |
| Denature | Change in shape of an enzyme caused by high temperatures (over 65°C). The enzyme is destroyed. |
| Optimum | The best conditions for an enzyme to work, enzymes have and optimum temperature, pH and concentration. |
| pH | A scale of how acid or alkaline a solution is. The scale goes from 1, which is very acid through 7, which is neutral to 14, which is very alkaline. |
| Specific | Refers to the fact that an enzyme catalyses one and only one reaction. |
| Synthesis reaction | An enzyme reaction where smaller substrates are assembled into a larger product. |
| Degradation reaction | An enzyme reaction where a large substrate is broken down into smaller products |
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| Respiration | |
| Aerobic respiration | Release of energy from sugar in the presence of oxygen. This process produces 38 molecules of ATP from every glucose molecule used. The end products are Carbon dioxide and water. |
| Anaerobic respiration | Release of energy from sugar in the absence of oxygen. This process produces 2 molecules of ATP from every glucose molecule used. The end product depends on the organism, being lactic acid in humans and yoghurt bacteria or alcohol in yeast and plants. |
| ATP | Adenosine triphosphate – an energy-carrying chemical in cells |
| ADP | Adenosine Diphosphate – low energy form of ATP |
| Pi | inorganic Phosphate, added to ADP makes ATP |
| Glycolysis | Sugar splitting. The first stage of respiration splits the sugar molecule into two, three-carbon fragments. 2 Molecules of ATP are generated during this process. |
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| Photosynthesis | |
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| Environmental Biology | |
| Ecology | The study of the environment and the interactions between the organisms within it. |
| Ecosystem | A natural grouping of abiotic factors, habitats and populations; e.g. a woodland, a lake, a rock pool. |
| Biotic | to do with living things |
| Abiotic | to do with non-living things |
| Genetics | The study of inheritance. |
| Habitat | the place where an organism lives |
| Population | a group of organisms of the same species within an ecosystem |
| Community | the sum of the populations living within an ecosystem |
| Producer | Organisms that can produce their own food from CO2, H2O and the energy from sunlight. These are the green plants. |
| Primary consumer | The organisms which eat the producers |
| Secondary consumer | The organisms which eat the primary consumers. |
| Herbivore | An animal that eats plants |
| Carnivore | An animal that eats other animals |
| Omnivore | An animal that eats both plants and animals |
| Predator | An animal that hunts other animals for food. |
| Prey | An animal that is hunted by a predator |
| Decomposer | Organisms that are involved in the process of rotting. Usually bacteria and fungi. |
| Bacteria | Simple, single cells organisms that lack an organised nucleus, instead they have a large circular chromosome and smaller Plasmids. |
| Fungi | A group of plant like organisms, which possess cell walls but don’t possess chloroplasts. Fungi include mushrooms, toadstools and yeasts. |
| Species | A group of organisms that can mate successfully together and produce fertile offspring. |
| Pyramid of numbers | A representation of the number of organisms at each feeding level of a food web. The numbers of producers forms the lowest layer, primary consumers the next and so on. |
| Pyramid of biomass | As a pyramid of numbers but the biomass is used to work out the size of the layers |
| Pyramid of energy | As a pyramid of numbers but the energy is used to work out the size of the layers |
| Feeding level | The populations in a food web that are producers, primary, secondary, tertiary consumers and so on. |
| Biomass | The total weight of the organisms in a particular ecosystem, feeding level or population. |
| Biodiversity | The total variety amongst the organisms in an ecosystem or in a species. |
| Pollution | The addition to the environment of material that would not normally be present, or in quantities that is higher than natural. |
| Competition | When organisms require the same limited resource, competition usually results in the removal of one group. Such resources include: space, mates, food, water, shelter etc. |
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| Genetics | |
| Meiosis | The process of cell division resulting in the production of gametes. In meiosis the chromosome number is halved. |
| Gametes | Sex cells (sperm and ova in animals, pollen and ova in plants) |
| Chromosome | The threadlike strands of DNA that are found in the nucleus of cells. The hereditary information is located on the chromosomes. |
| DNA | The chemical that the chromosomes are made of. It is constructed of a long string of bases, which are shaped into a double helix. |
| Fertilisation | The point where gametes fuse together to produce a zygote. |
| Zygote | The fertilised cell formed when a male and female gamete fuse. |
| Sperm | Male gametes in animals. |
| Ovum/ova | The female gamete |
| Testis/testes | The organ that produces male gametes in animals. |
| Pollen | Male gametes in plants. |
| Base | A chemical that is alkaline in solution. There are four bases involved in DNA. |
| Monohybrid cross | A cross between two different strains of homozygous organisms. |
| Mendelian Genetics | The branch of genetics that deals with simple inheritance of characteristics controlled by a single gene. |
| Strain | A population of organisms that share a particular characteristic. E.g. a strain of white eyes fruit flies. |
| Test Cross | A cross between two strains of an organism, both parents are true breeding, one parent for the dominant characteristic, the other for the recessive characteristic. The F1 progeny are allowed to mate together at random with each other |
| P generation | The parental generation in a test cross |
| F1 generation | The first filial (child) generation in a test cross |
| F2 generation | The second filial (child) generation in a test cross |
| Dominant | The allele that is expressed in the heterozygous organism. |
| Recessive | The allele that is not expressed in the heterozygous organism. |
| True breeding | A homozygous strain of organisms. |
| Gene | The region on a chromosome that is responsible for producing one protein. In Mendelian Genetics the gene controls a single characteristic. |
| Allele | Where a gene exists in two or more forms. |
| Heterozygous | Alleles are different |
| Homozygous | Both alleles are the same |
| Genotype | An way of representing the genes present in an organism. Usually written as a single letter of the alphabet, using the capital for the dominant characteristic and lower case for the recessive characteristic. |
| Phenotype | The way the genotype is expressed in the organism |
| Co-dominance | Both alleles in the organism are of equal “strength” so the phenotype is half way between the phenotypes of the true breeding strains. |
| polygenic | a characteristic which is controlled by several genes such as hair colour |
| Natural selection | The process, first described by Darwin, where organisms, which are fittest to survive, breed more successfully. This results in a slow improvement in the species |
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| Biotechnology | |
| Plasmid | A small circular chromosome in a bacterium. |
| Restriction enzyme | An enzyme that cuts a strand of DNA in a particular place. |
| Ligase | An enzyme that reconnects cut strands of DNA |
| Transgenic | An organism that contains genetic material from another species by genetic engineering |
| Genetic Engineering | The science of moving genes between different species of organism. |
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| Digestion | |
| Carbohydrate | Essential food made up of sugar sub-units. Used in the body as a substrate for respiration. |
| Starch | A carbohydrate made up of strings of sugar sub-units in long, branched chains. |
| Fat | Essential food made up of 3 x fatty acids and 1 x glycerol sub units. |
| Protein | Essential food made up of amino acid sub units.Used by cells for growth, repair and replacement. |
| Vitamin | A complex chemical needed in small quantities by the body for good health |
| Mineral | A simple chemical element needed in small quantities by the body for good health |
| Vitamin C | Vitamin needed for connective tissue, deficiency disease is scurvy where gums bleed and skin bruises easily. |
| Vitamin D | Needed for the chemistry of calcium for healthy teeth and bones. Deficiency disease is rickets. |
| Iron | Mineral needed to form haemoglobin in blood. Deficiency disease is anaemia. |
| Calcium | This mineral forms with Pi to form Calcium phosphate, essential for strong bones and teeth |
| Digestion | The process where large, insoluble particles of food are broken down into small, soluble molecules by the action of enzymes. |
| Saliva | Complex liquid found in the mouth, produced by the salivary glands, contains mucus and salivary amylase. |
| Salivary gland | Glands in the mouth that produce saliva |
| Oesophagus | The tube connecting the mouth to the stomach. |
| Mucus | A chemical that has a slimy feel. Used throughout the body as a lubricant. |
| Amylase | The enzyme that changes starch into maltose |
| Maltose | A sugar (disaccharide) made up of two smaller sugars joined together. |
| Alimentary canal | The tube from mouth to anus, more often referred to as the ‘gut’. |
| Peristalsis | A wave of muscular relaxation followed by a wave of muscular contraction that moves food through the alimentary canal. |
| Stomach | The muscular sack at the end of the oesophagus. Here food is churned up with acid and pepsin to begin protein digestion. |
| Polypeptides | Long chains of amino acids, not as complex as proteins. |
| Pepsin | An enzyme, produced by the stomach, which breaks down protein into polypeptides. |
| Villus | The tiny (1mm) finger like projections covering the lining of the small intestine |
| Lacteal | projection of the lymphatic system that runs up the centre of the villus. Products of fat digestion are absorbed into this. |
| Small intestine | The first part of the intestine, digestion is completed here and products of digestion are absorbed. |
| large intestine | The second part of the intestine, water is reabsorbed from the waste food to form faeces, salts are reabsorbed. |
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| Excretion | |
| Kidney | Two structures in the small of the back responsible for the excretion of urea and osmoregulation |
| Nitrogenous waste | product formed from the breakdown of excess protein in the liver |
| Osmoregulation | the process whereby the osmotic pressure of the blood is maintained at the correct level |
| Nephron | The functional part of the kidney made up of the Bowman’s Capsule, convoluted tubules, loop of Henle, and collecting tubule |
| Glomerulus | A small capillary network inside the Bowman’s capsule where the blood is filtered |
| Bowman’s capsule | The cup shaped structure surrounding the glomerulus, which collects the products of filtration. |
| Collecting tubule | The final part of the nephron that collects the urine |
| Urea | Chemical in urine containing the waste nitrogen |
| Convoluted tubule | The part of the nephron that reabsorbs useful molecules from the filtrate |
| Loop of Henle | The part of the nephron that reabsorbs water from the filtrate and thereby controls water balance in the body. |
| Filtration/reabsorption | In the glomerulus the plasma of the blood is filtered into the Bowman’s capsule, at this point all the soluble part of the blood is filtered intro the nephron. The convoluted tubules then reabsorb the useful molecules leaving water and urea. |
| ADH | Anti diuretic hormone, produced by the Pituitary gland, having its action on the loop of Henle, a high water concentration in the blood increases production of ADH that then reduces reabsorption of water in the loop of Henle thereby producing copious dilute urine. The opposite happens when there is a low water concentration in the blood. |
| Hypothalamus | An area in the centre of the brain responsible for many detection and control functions including temperature control and blood pressure |
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| Heart | |
| Atrium | Part of the heart that receives blood from major veins and pumps it into the ventricles |
| Ventricle | Part of the heart that receives blood from the atria and pumps it out into major arteries |
| AV valve | Atrio-ventricular valves, of which there are 2, the left and right. Dividing the atria from the ventricles they allow flow of blood from the atria into the ventricles but close to prevent blood flow back into the atria when the ventricles contract |
| Semi lunar valve | These are found at the exit of the ventricles into their major arteries. The SL valves prevent blood flowing back into the ventricle when the heart muscle relaxes between strokes |
| Artery | The blood vessels which carries blood away from the heart |
| Vein | The blood vessels which carries blood towards the heart |
| Capillary | Tiny, thin walled vessels where exchange of materials with the tissues occurs |
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| Blood Vessels | |
| Coronary artery | The first artery that branches off the aorta that provides the heart muscle with blood |
| Aorta | The major artery that leaves the left ventricle carrying oxygenated blood to all parts of the body |
| Vena cava | The major vein that returns blood from all around the body to the right atrium |
| Renal artery/vein | The blood vessels which supply the kidneys |
| Hepatic artery/vein | The blood vessels which supply the liver |
| Hepatic portal vein | The blood vessels which carries food rich blood from the small intestine to the liver |
| Mesenteric artery | The blood vessel which supplies the small intestine |
| Pulmonary artery/vein | The blood vessels which supply the lungs |
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| Gas Exchange | |
| Alveolus | The air sacs that terminate the bronchioles, gas exchange occurs here |
| Gas exchange surface | a membrane where gasses pass in and out of an organism (such as the alveoli and gills in fish), they have a large surface area, thin membranes, are moist and have a good capillary blood supply |
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| Blood | |
| Red blood cell | Small blood cell, biconcave sphere in shape, contains haemoglobin, carries oxygen and CO2 |
| White cells | A group of several different kinds of cell all of which are involved in the immune response of the body. |
| Plasma | The straw coloured, liquid part of the blood, carries heat and dissolved molecules such as food, hormones and salts |
| Haemoglobin | The molecule in the red blood cell that binds to oxygen at high oxygen levels and releases it in regions of low oxygen levels |
| Macrophage | One of the phagocytotic cells in the blood. |
| Lymphocyte | Cells that produce antibodies in response to antigens on foreign cells. |
| Antibody | A “Y” shaped chemical, produced by lymphocytes that attaches to antigens on the cell wall of foreign cells and is involved in the immune response |
| Antigen | Proteins on the surface of foreign cells that can be recognised by the immune system of the organism and trigger the production of antibodies |
| Phagocytosis | The process by which macrophages engulf and digest foreign cells |
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| Brain | |
| CNS | The central nervous system, consisting of the brain and spinal cord. |
| Cerebrum | The surface layer of the brain responsible for thought, memory, personality and many other higher functions |
| Cerebellum | The structure at the back of the brain where the brain attaches to the spinal cord responsible for balance and coordination |
| Medulla | A swelling at the top of the spinal cord where control of primitive reactions such as control of breathing and heart rate occur |
| Sensory strip | The area on the side of the brain where the sense of touch is controlled. This is just behind the motor strip. |
| Motor strip | The area on the side of the brain where movement is controlled. This is just in front of the motor strip. |
| Hypothalamus | see above |
| Pituitary gland | The “master” control gland under the brain which produces a range of hormones including ADH |
| Spinal cord | The nerve bundle that runs from the brain down and within the vertebrae of the spine |
| Neurone | A nerve cell |
| Sensory neurone | A neurone which connects the brain to a sense organ. These carry sensory information towards the brain |
| Motor neurone | A neurone that connects the brain to a nerve, these carry instruction for movement from the brain towards the muscles. |
| Relay neurone | These connect sensory neurones directly to motor neurones in the spinal cord. These are involved in reflex actions |
| Reflex arc | When body is in danger of damage the processing of the central nervous system is dangerously slow (around a quarter of a second or slower). The reflex arc allows responses which are much faster and don’t involve processing by the CNS. |
| Negative feedback | various processes within the body are kept at a steady level by an interaction between senses and organs. |
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