List of Figures
A baerium. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A pical plant cell. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A pical animal cell. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . The process of osmosis. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A plan lant cell rea reain ingg to diﬀe diﬀere ren nt pes pes of turg turgor or press ressur ure. e. . . . . . . . . . . . . . The aion of an enzyme. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . The alimentary canal (digeﬆⅳe syﬆem). . . . . . . . . . . . . . . . . . . . . . . A cross-seion of a human tooth. . . . . . . . . . . . . . . . . . . . . . . . . . A single human ⅵllus lus om the small inteﬆine. . . . . . . . . . . . . . . . . . . A pical leaf. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A chlo chlorop ropla laﬆ. ﬆ. On each each memb membra rane ne are are many many mole molecu cule less of chlo chloro roph phyl yll. l. . . . . . . A single ﬆoma. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Diagram of a human heart. . . . . . . . . . . . . . . . . . . . . . . . . . . . . Human blood vessels. vessels. The lumen lumen in the the artery artery is much much smaller smaller than the the lumen lumen in the the vein, ein, as the the blood lood is at a much uch hig higher press ressur ure. e. . . . . . . . . . . . . . . . . Red blood cells. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Antigens on a cell. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A lymphoc yte. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A lymphocyt cyte indentiing a baerium. . . . . . . . . . . . . . . . . . . . . . . A root hair cell . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Water vapour build-up around a ﬆoma. . . . . . . . . . . . . . . . . . . . . . . A simp simple le calo calorim rimet eter er – used used to to meas measure ure the energy energy valu valuee of a respi respirat ratory ory subﬆ subﬆrat rate. e. The lungs. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Some alveoli. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . The aion of breathing. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Part of the linin ning of the respiratory passages. . . . . . . . . . . . . . . . . . . . The excretor y syﬆem. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Urea produion. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . The The Su Suu ure re of an amin aminoo aci acid. d. R can ﬆand ﬆand for anythin anything. g. The The NH part of the molecule molecule (ammonia) is toⅺc, toⅺc, and is convert converted ed into urea. Deamination Deamination is the rem removal val of the the nio nioge genn-cconta ontain inin ingg part part of the the amin aminoo acid acid.. . . . . . . . . . . . . How How urine urine is produc produced ed – there there are two process processes: es: ula-ﬁ ula-ﬁla latio tion, n, and seleⅳe seleⅳe reabsorption. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . An indⅳidual glomerulus. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Kidney Kidney fail failure ure – if one one or both both kidneys kidneys fail fail then then dialys dialysis is is used used or a ansplan ansplantt perfor performe medd to to keep keep urea urea and and solut solutee conc concen enati ation on in the blood blood conﬆa conﬆant nt.. . . . . . . Kidney ansplant may be be necessary necessary as Rhenal dialysis is inconvenien inconvenientt for for the the patient patient and coﬆly. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A summ summary ary of how how body body and and bloo bloodd tempe empera ratu ture re are are main mainta tain ined ed.. . . . . . . . . .
The The Varie ariety ty of Li Life fe . . Taxon axonom omy y This is the scientiﬁc name for puing things into groups – classiﬁcation and naming. This largeﬆ group is called a ‘kingdom’. The syﬆem was deⅵsed deⅵsed in the th Century by Carl Linnaeus. — Kingdom i nc r r e ea a s s i in g s — Phylum i i mi l la a r r i i — Class — Order — Family — Genus — Species
. The Binomi Binomial al Naming Naming System System All organisms have two Latin (a unⅳersal language) names – Genus and Species. The Genus is wrien with a capital leer. When handwriting, both words are underlined. When ping, they are put in italics. For example: Homo Sapiens (Handwrien) Sapiens (Handwrien) Felix cattus (Typed)
. . King Kingdo doms ms • Animalia • Plantae • Baeria (monera, (monera, prokaryote) prokaryote) • Fungi • Protoiﬆa Protoiﬆa Animal Kingdom There are Phyla. Among them are: • Chordates (vertebrates) (vertebrates) (in order of evolution:) – Fish
Grasshoppers, buerﬂies, beetles, ants etc. , described world species Three body regions: head, thorax, abdomen Sⅸ legs aached to the thorax (which has segments) Adults with one or two pairs of wings aached to the thorax (some have none) Tow antennae Lateral compound eyes
– Arachnids * * * * * *
Spiders, scorpions, ticks, moites, etc. , described world species Two body regions: cephalothorax, abdomen Eight legs No antennae Mouth parts are chelicerae (modiﬁed appendages) which in spiders are fangs
– Cruﬆaceans * * * * * * *
Technically a subphylum Classes include crabs, shrimps, lobﬆers, barnacles, isopods etc. , described world speies Two body regions Two pairs of antennae or more pairs of legs Primarily aquatic, few terreﬆrial
– Myriapods * Chilopods · Centipedes · , described world species · well-deﬁned head · ﬁrﬆ pair of legs modiﬁed for envenomation · ﬂaened top to boom · one pair of legs persegment
one pair of antennae * Diplopods · Millipedes · , described world species · Two pairs of legs per segments, ﬁrﬆ four segments have pair of legs · one pair of antennae · well-deﬁned head · usually cylindrical ·
• Nematodes – Roundworms – Can be microscopic, or up to m in length – Can be ee lⅳing or parasitic – No circulatory or respiratory syﬆem – Suure is a “tube within a tube” – No chaetae – Use sexual reporoduion • Molluscs – So bodied – No segmentation – Single muscular foot – Hard external shell (calcium carbonate) or internal shell – Moﬆ have rasping tongue (radula) – Filter feeders – mussels – Carnⅳorous – oopi – Marine organisms with shells (except barnacles and cruﬆaceans) – Terreﬆrial – snails & slugs • Annelids – Segmented worms (e.g. earthworm) – Leeches – Sexual and asexual reporoduion (depending on species) – Vascular and nervous syﬆem – No legs but may have chaetae (ﬆiﬀ hairs) to aid movement – may have obⅵous head
. Characteristics of Living Things M ovement R espiration S ensitⅳi G rowth R eproduion E xcretion N uition
. Branching Keys A key is a means of identiing an unfamiliar organism om a seleion. Indⅳidual organisms are found by following a series of paired, numbered options, or a chart which oﬀers no more than two choices at each ﬆage. A key either wrien in couplets, or as a chart: ¹They have a proper nucleus as opposed to Baeria. Eukaryots are aquatic/plant-like organisms that don’t ﬁt in the Animal/Plant/Baeria kingdoms.
Couplets . Hairy skin — . Non-hairy skin — go to . . External pips — . No external pips — go to . . Near spherical shape — go to . Other shape — . . Smooth surface — . Indented surface — go to . . Suure made up of sub-units — . Suure made up of single unit — . Key
Moop: Does it have three antennae?
Does it have three eyes?
It’s a Woop.
Is it round?
It does not eⅺﬆ.
It’s a Moop.
It’s a Foop.
Cells, Diﬀusion & Osmosis . Specialised Cells All cells are designed to do a particular job in an organism. This is called . Examples of specialised cells are shown below.
Capsule Cell wall Plasma membrane Cytoplasm Ribosomes Plasmid Pili
Plant cells Animal Cells Always have cell wall made of cellulose and hence a deﬁnite shape No cell wall, hence no diﬁnite shape Usually have large, permanent vacuole Any vacuoles are small and temporary Some have chloroplaﬆs Never have chloroplaﬆs Up to mm long Usually less than .mm long. Examples: palisade cells cheek lining cells phloem sieve tube elements muscle ﬁbres root hair cell red blood cells
Table : Diﬀerences between plant and animal cells.
Organelle Function Nucleus Conols the cell’s aⅳities, contains DNA Cytoplasm Where metabolic reaions take place Cell membrane Partially permeable, conols the eny/eⅺt of subﬆances Mitochondria Where aerobic respiration takes place Cell wall (plants only) Fully permeable, prevents cell om burﬆing Permanent vacuole Storage area, contains cell sap Chloroplaﬆ (plants only) Where photosynthesis takes place Figure : A pical plant cell.
Sperm cell designed to fertilise eggs A sperm cell is very small and has a lile tail which proⅵdes movement so it can swim and ﬁnd an egg to fertilise. Its head contains enzymes (in the vacuole) which allow it do digeﬆ its way through an egg membrane so the two nuclei can join. It contain half the number of chromosomes in the nucleus – these caryy genetic information om the father, which will be passed on to the oﬀspring.
Organelle Function Nucleus Conols cell aⅳities, contains DNA Cytoplasm Where metabolic reaions take place Cell membrane Partially permeable, conols eny/eⅺt of subﬆances Mitochondia Site of aerobic respiration Figure : A pical animal cell.
Ovum (egg) cell designed to be fertilised An ovum is large and bulky because no aⅳe ovement is needed – it juﬆ sits and waits for the sperm to ﬁnd it. It contains yolk (in the cytoplasm) which proⅵdes a large food ﬆore needed for the developing young organism once it’s fertilised. It contains half the number of chromosomes, which carry genetic information om the mother – this will be passed on to the oﬀspring. Palisade cell for photosynthesis
A palisade cell is tall with a large surface area. It’s found on the top side of a leaf – ideal for good absorpion of carbon dioⅺde and light – both are needed for photosyntheses. They’re packed with chloroplaﬆs, which contain the green pigment chlorophyll, which is needed for photosynthesis. Ciliated cell to ﬆop lung damage Ciliated cells line all the air passages in the lungs. Mucus is ﬆicky and so aps duﬆ and baeria. The cilia wa and sweep up the mucus to the back of the throat where it is swallowed. The baeria are then killed by the acid in the ﬆomach. Root hair cell for absorbtion The long hair cell increases the surface area of the root, which helps absorption of water and minerals. It has a very thin cell wall, which makes it easier for minerals to pass across into the root itself. Red blood cells (erythrocytes) for ansport They do not contain a nucleus, so there is more room for the protein molecule to carry oxygen. Their biconcave shape gⅳes them a large surface area for gas exchange. Muscle cells for movement Muscle cells have protein ﬆrands that can slide across each other for conaion. Each cell has several nuclei. There are pes – smooth, skeletal and cardiac. Tissues A tissue is a group of similar cells, working to perform the same funion, e.g. muscle tissue is made om muscle cells. Organs Diﬀerent tissues are arranged to form an organ. They work together to perform a particular funion, e.g. the heart. Organ Systems A group of organs working together form an organ syﬆem, e.g. the circulatory syﬆem.
. Cell Activities All cells exchange gases, nuients and other materials between themselves and their surroundings. Diﬀusion is the ee movement of particles of a subﬆance (atoms, ions or molecules) om regions of high concenation to regions of lower concenaion. The process continues until the particles are evenly diﬆributed. This is movement down a concenation gradient. Diﬀusion is the usual way in which molecules move into or out of cells. Concentration gradient refers to the diﬀerence in concenation between one region and another. The greater the diﬀerence in concenaion, the ﬆeeper the concenation gradient, and the faﬆer the rate of diﬀusion. Surfaces qhere gas exchange occurs oen maintain a ﬆeep diﬀusion gradient so that idﬀusion occuras rapidly. For example:
• across the linging of the air sacs (alveoli) in the lungs of humans • across the surface of cells bordering air spaces in the leaves of plants Osmosis is a speciﬁc pe of diﬀusion. It is the diﬀusion of water om a dilute solution to a more concenated soution throuh a partially permeable membrane. Cell membranes are partially permeable membranes, and it is by osmosis that water moves into and out of cells. In osmosis, water diﬀuses om a high water concenation to a low water concenation (see Figure ). • Cells placed in diﬆilled water will gain water by osmosis. This is because there is a lower concenation of water inside than outside. The cells are said to be turgid. • Cells placed in a concenated solution will lose water by osmosis. This is because there is a greater concenation of water inside the cell. The cells are said to be ﬂaccid. In severe cases the cell membrane is pulled away om the cell wall. The cells are then said to be plasmolysed. Eventually the process may ﬆop because the concenations on both sides of the cell membrane have equalised (see Figure ). Active transport is a chemical process that results in a movement of particles in an opposite direion to that expeed by diﬀusion. Subﬆances are taken scross a membrane om a region of low concenation to a region of higher concenation, i.e. againﬆ a concenation gradient. As its name implies, it is an aⅳe process and requires energy supplied by respiration. Par t ially per meable membrane
Water S olute, e.g. sugar
Dilute s olut ion (High wate r concentr ation)
Concent r ated solut ion ( Low wat er concentr ation)
Dir ect ion of wate r movement
Figure : The process of osmosis.
Enzymes Enzymes are biological catalysts. They speed up the chemical reaions which go on inside lⅳing things, and are exemely eﬃcient.
Figure : A plant cell reaing to diﬀerent pes of turgor pressure.
Enzymes are made inside cells. Once formed, the enzymes may leave the cell and do its job outside. Such enzymes are called extracellular enzymes. They include the digeﬆⅳe enzymes which break down food subﬆances in the gut. Other enzymes work inside the cell. They are called intracellular enzymes. Their job is to speed up he chemical reaions occurring in cells, and also conol them. An example of a reaion conolled by an enzyme: maltase(enzyme)
maltose(substrate) −−−−−−−−−−→ glucose(product)
The subﬆance which the enzyme as on it called the substrate – in this case maltose. The new subﬆance or subﬆances formed as a result of the reaion are the products. In this case there is juﬆ one produ, glucose. The enzyme catalysing this particular reaion is maltase. This reaion can go in either direion – it is reversible. If there is a lot of maltose present compared with glucose, the reaion will go om le to right. If there is a lot of glucose compared to maltose, it will go om right to le. Moﬆ metabolic reaions are reversible.
. Properties of Enzymes . They are always proteins We need to take proteins in, ⅵa our food to produce enzymes. . They are speciﬁc in their action Each enzyme conols one particular reaion, or pe of reaion – maltase will only a on maltose, and sucrase on sucrose. . They can be used multiple times They are not altered by the reaion that they catalyse. However, they “run down” eventually and have to be replaced.
. They are destroyed by heating In common with all proteins, they are denatured by proteins. Normally this happens at C. ◦
. They are sensitive to pH Their eﬀeⅳeness depends on the degree of acidi or alkalini of the solution which they are in. Moﬆ inacellular enzymes work beﬆ in neual conditions.
Figure : The aion of an enzyme. Figure shows in a simpliﬁed way how enzymes are believed to work. When a subﬆrate molecule happenes to impa on the aⅳe site of an enzyme, the reaion takes place and the produs leave, eeing up the enzyme for another reaion. Each enzyme’s aⅳe site has a speciﬁc shape, into which only one pe of subﬆrate will ﬁt. This is why the enzyme is speciﬁc in its aion. When an enzyme is denatured by heat, the shape of its aⅳe site changes, so subﬆrates no longer ﬁt in it, and it is not eﬀeⅳe. Anything which helps subﬆrates to come into conta with the enzyme at a faﬆer rate will increase the rate at which the enzyme can catalyse reaions. Higher temperatures mean that molecules move around mroe quickly – a rise in temperature of Ccan double the rate of reaion. Some minerals and ⅵtamins also increase the rate of reaion. Some poisons, such as cyanide and arsenic, inhibit enzymes by blocking the aⅳe site. Some poisons block aⅳe sites permanently, others temporarily. This is also how some peﬆicides work. ◦
. Uses for Enzymes Enzymes can be exaed om organisms in a puriﬁed form, and then used in many scientiﬁc, domeﬆic and induﬆrial processes. A common useage is in biological washign powders. Various protein-digeﬆing (proteases) are added to the washing powder, and they dissolve protein ﬆains.
Biological washing powders are advantageous because they work at relatⅳely low temperatures. This means they are usefulfor washing delicate fabrics, and can save elerici. However, some people are allergic to them. Enzymes are normally exaed om microbes, which are grown on a large scale in fermenters. Some examples of enzyme use: Proteases are used for tenderising meat, skinning ﬁsh, remoⅵng hair om hides, and breaking down proteins in baby foods. Amylases convert ﬆarch to sugar in making syrups, uit juices, chocolates and other food produs. Cellulase breaks down cellulose and is used for soening vegetables, remoⅵng the seed coat om cereal grain, and exaing agar jelly om seaweed. Isomerase converts glucose into uose. Fruose is muchsweeter than glucose; this makes it useful in sweets, syrups and slimming foods, as only small amounts are needed to sweeten the produ. Catalase releases oxygen om hydrogen peroⅺde, and is used in making foam rubber om latex.
. Immobilisng Enzymes Biotechnologiﬆs have developed a beer method of using enzymes than simply mⅸing the enzyme with the subﬆrate. The enzymes are aachedf to an inert surface, usually glass or plaﬆic beads. The beads are then brought into conta with the subﬆrate so that the reaions can take place. One way of bringing the beads into conta with the subﬆrate is to immerse them in a solution of the subﬆrate, and then wait for the reaion to be completed before colleing the produ and ﬆarting again. This is called batch processing . The other way is to slowly pour a solution of the subate through a column of the beads, and the colle the produ om the boom. The subﬆrate is aed upon progressⅳely as the solution ickles down the column. This is calledcontinous ﬂow processing , because the produ is colleed all the time. it is more eﬃcient than batch processing.
Nutrition & Balanced Diets Nuition is the ﬆudy of food and feeding processes. Food is the material om which organisms obtain the energy and the raw materials to conﬆru, maintain and repair the body. Plants are autotrophic – they produce their own food, and come at the boom of the food chain. Humans and other animals are heterotrophic (also known as holozoic) – they eat other plants and animals, and cannot produce their own food. Humans require a balanced diet . This is one which supplies the diﬀerent pes of food in adequate amounts and the corre proportions, and proⅵdes the body with suﬃcient energy for its needs. A balanced diet maintains a healthy and aⅳe life and, where necessary, growth. Humans use food for:
• Energy for body processes (usually obtained om carbohydrates and fats – sometimes om protein when in a ﬆate of ﬆarvation). • Building materials, to build the cells of the body (proteins, fats, ⅵtamins, minerals). • Chemical reaions in the body (proteins, ⅵtamins, minerals, water). There are seven chemical components of a balanced diet: Carbohydrates To proⅵde energy. Sugar Diﬀerent kinds of food contain diﬀerent pes of sugar: glucose or uose in uit, laose in milk, or sucrose in ordinary table sugar. The formula for glucose, the simpleﬆ possible sugar, is C H O . It is a monosaccharide – it is made into chains of polysaccharides. Two glucose molecules bonded together form one maltose molecule. Starch is found in bread, potatoes and cereals. Starch is a polysaccharide made of a spiral chain of glucose molecules, and is used as the food reserves of plants. Cellulose is a polysaccharide made of a ﬆraight chain of glucose molecules, and is used to build plant cell walls. Glycogen is a polysaccharide, and is used as the food reserves of animals, ﬆored in the lⅳer and muscles. Fats To proⅵde energy, insulation, and to conﬆru parts of cells. Animal fats are obtained om lⅳeﬆock, such as cale or pigs. They are eaten in the form of buer, dripping or lard. They contain saturated fa acids, which are unhealthy in large amounts. Fat contains twice as much energy per gram as carbohydrates and proteins do, and they are solid at room temperature. Plant fats, or oils, for example olⅳe oil or corn oil, are liquid at room temperature. They contain polyunsaturated fa acids, which are more healthy than satureated fa acids. Proteins To build muscle, make enzymes and hormones, and conﬆru parts of cells. It is normally obtained om the muscles of animals. The disease caused by protein deﬁciency is called kwashiorkor. Some plants, such as soya beans and maize, contain relatⅳely large amounts of protein compared to other plants, so it is possible to obtain moﬆ of the necessary amino acids om plant-based foods. Proteins are made om amino acids. of which there are diﬀerent pes. An organism’s DNA proⅵdes the template for linking amino acids in diﬀerent orders to produce proteins (there are a large number of possible combinations). Protein contains Niogen and Sulphur. Minerals are ions of certain elements (i.e. inorganic), which are needed for particular purposes within the body. For example: Calcium is needed for bone formation. Without calcium, bones are so. Calcium deﬁciency is called rickets.
Iron is required for haemoglobin, in blood. Oxygen is ansported around the body by binding to haemoglobin. Iron is plentiful in lⅳer and kidneys. Iron deﬁciency results in anaemia . Vitamins Various biological compounds required by the body. Some examples: Vitamin A is neede by the eyes. Vitamin A deﬁciency is called xerophthalmia and leads to blindness. Vitamin C keeps the lining of the mouth and gums healthy. It is found in green vegetables, but is deﬆroyed by heating. Lack of it causes scurvy . Vitamin D is needed to enable calcium to harden bones. Lack of it causes rickets. Water Makes of -% of the body. The body’s chemical reaions take place in it. Humans need about lie of water every day. Fibre Stimulates the smooth passage of food through the gut. Mainly made of cellulose, it aids faeces formation. Too much energy-rich food will cause the indⅳidual to become overweight, while too lile will cause them to become underweight. Malnuition is the result of not haⅵng a properly balanced diet. If the body does not receⅳe the corre chemical components in the right proportions, it cannot funion eﬃciently. In humans, as in other animals, complex organic food can enter body cells only if it is ﬁrﬆ broken down into smalll soluble molecules. In humans, the ﬆages int his process are: Ingestion Food is taken into the mouth. Digestion The breakdown of complex organic foods into small, soluble molecules. Absorption The uptake of soluble food subﬆances into the body across cell membranes. Assimilation The use of soluble food subﬆances by cells in the body. Egestion The removal of undigeﬆed food om the body (not to be confused with excretion or secretion). In humans, the alimentary canal (gut) is responsible for the ingeﬆion, digeﬆion, absorption and egeﬆion of food.
. Food Tests Sugar . Mash the food and add water. . Add cm3 of the food to a teﬆ tube.
. Add cm3 of Benedi’s solution to the teﬆ tube. . Shake the teﬆ tube. . Place the teﬆ tube in a waterbath for approⅺmately minutes. If a precipitate develops, sugar is present. The colour of the mⅸture gⅳes a rough indication of how much sugar is present: green is the loweﬆ concenation, yellow higher, brown ﬆill higher, and red the higheﬆ concenation. Starch . Add drops of dilute iodine solution to the food sample. . If the colout changes to blue-black, ﬆarch is present. Fat . Pour approⅺmately cm3 of absolute ethanol into a teﬆ tube. . Add a small amount of the food sample to the ethanol. . Shake the teﬆ tube. . Add approⅺmately cm3 of water to the teﬆ tube. . If the mⅸture turns cloudy white, fat is present. Protein (Biuret test) . Mash the food and add water. . Add cm3 of the food to a teﬆ tube. . Add a small amount of dilute sodium hydroⅺde solution until the mⅸure clears. . Add a few drops of dilute copper sulphate solution. . Shake the teﬆ tube. . If the solution turns purple, protein is present.
. Drugs A drug is something which changes the way the body works. Useful drugs include painkillers and antibiotics. Harmful drugs can be addiⅳe, and harm the body in some way. Addiion can be chemical – when the body becomes adjuﬆed in such a way that it needs the drug, or psychological – when the addied person feels a conﬆant need for the drug. Withdrawal symptoms om a drug include fever, and nausea.
Alcohol • Reduces aⅳi of nervous syﬆem. • Removes inhibitions, causes relaxation. • Impairs judgement • Is poisonous to the lⅳer. Alcohol poisoning causes a coma and death.
Digestion & Absorption Food muﬆ get into the blood in order to be carried to the bodiy’s cells. Only soluble food can do this. Moﬆ food is insoluble, and is broken down into soluble particles through the process of digeﬆion, which occurs in the digeﬆⅳe syﬆem (see Figure ). Digeﬆⅳe juices break down the food, ﬆarting in the mouth with salⅳa (om the salⅳary glands). The food is then swallowed, and other juices om the lⅳer and pancreas are added. Bile is producewd in the lⅳer, and then ﬆored in the gall bladder, before being added to food in the ﬆomach. Muscles keep the walls of the ﬆomach and small inteﬆine moⅵng, mⅸing up the food and digeﬆⅳe juices, and keeping blood mⅵng through the digeﬆⅳe syﬆem. When the food has been completely broken down, it is absorbed into the blood in the small inteﬆine, which has a good blood supply and thin walls, which allows food to pass easily into the blood through the process of diﬀusion. Some food cannot be digeﬆed, and is egeﬆed through the anus. . Food in chewed and mⅸed with salⅳa in the . ( minute) salivary
Starch −−−−−→ Sugars amylase
. The carries the chewed-up food to the ﬆomach, using muscular walls which push food with a wave of conaion (peristalsis). (– seconds) . Acid digeﬆⅳe juices, ideal for pepsin (an enzyme that breaks down proteins), are added in the . The food and the digeﬆⅳe juices are mⅸed. (– hours) pepsin
Proteins −−−−→ Amino acids
. More alkaline juices om the pancreas (to neualise the ﬆomach acid) are added in the . There is more mⅸing, then the fully digeﬆed food is absorbed into the blood. (– hours) pancreatic Starch −−−−−−→ Sugars amylase
Cecum Appendix Rectum Anus Source: http://commons.wikimedia.org/wiki/File:Digestive_system_diagram_en.svg(Public Domain)
Figure : The alimentary canal (digeﬆⅳe syﬆem).
. Only undigeﬆed waﬆe material reaches the . The water is taken back into the body, leaⅵng solid waﬆe. (– hours) . Undigeﬆed food is ﬆored in the reum, and then the solid waﬆe is egeﬆed through the anus as faeces.
Figure : A cross-seion of a human tooth. An adult teeth has, at moﬆ, teeth. Thre are four main pes: , , - and . Incisors are for cuing pieces oﬀ food, while canines are for griping it. Pre-molars and molars are for grinding the food down until it can be swallowed easily. The outside of a tooth is formed by hard enamel. Beneath this is a layer of hard dentine. In the cene is a so area called the pulp caⅵ, which contains small blood vessels and a nerve (see Figure ). Tiny channels containing extensions of lⅳing cells tun outom the pulp caⅵ into the dentine. These make the dentine sensitⅳe. The enamel and dentine are made hard by the presence of calcium phosphate, the same subﬆance that makes bones hard. The outside of the root is covered by a material called cement. Aached to the cement are tough ﬁbres which run into the jaw bone. These ﬁbres hold the tooth in its socket; they allow the tooth to move slightly, and cushion it om being jarred when it hits something hard. Tooth Decay Tooth decay is caused by baeria in the mouth. These baeria form an inⅵsible layer called plaque on the surface of the teeth. Aer a meal, the baeria feed on any sugar present and turn it into acid. The acid eats into the
teeth. Within approⅺmately one hour the acid is neualised by the salⅳa. However, the decay has oen already ﬆarted by this time. Decay usually ﬆarts between the teeth and in the creⅵces on the crowns. The acid eats through the enamel into the dentine, allowing baeria to get into the pulp caⅵ. In severe cases the baeria may spread to the base of the tooth, causing an abscess. Baeria may also get between the tooth and the gum, causing the gum to bleed. Sometimes the ﬁbres aaching the tooth to the jaw are aacked, in which case the tooth gets loose and eventually falls out. There is ﬆrong eⅵdence that ﬂuoride helps to prevent tooth decay. It ﬆrengthens teeth when they are forming, and makes the enamel more resiﬆant to acid. Where there is not enough ﬂuoride naturally occuring in public drinking water supplies, it is added artiﬁcially. This has led to a large improvement in the general dental health of the population.
. Duodenum Food leaⅵng the ﬆomach enters the . Secretions om the lⅳer and pancreas are added (pancreatic juice contains all three pes of digeﬆⅳe enzymes). Bile is ﬆored in the gall bladder, and emulsiﬁes fats. Sodium hydrogen carbonate neualises the ﬆomach acid.
. Small Intestine (Ileum) Digeﬆion is completed in the (or ), which secretes digeﬆove enzymes, and absorbs food. The small inteﬆine is covered in millions of tiny protusions called (see Figure ). They increase the surface area, and so increasing the rate at which the small inteﬆine can absorb food. Each ⅵllus has a thin surface layer, so there is only a short diﬆance for absorption. Inside is a network of capillaries to caryy away the absorbed sugars and amino acids. There is also a laeal, to carry away the absorbed fa acids to the lymhpatic syﬆem. Conneed to the capillaries is a blood vessel, which carries the absorbed foods to the hepatic portal vein, and then on to the lⅳer.
. Liver Many cells perform a wide range of funions in the lⅳer, in processing the absorbed foods. a g o n ⇒ g l u c = = = = ⇐ s u l i n i n
Glucose −→ Energy ⅵa Respiration − →
to other tissue ⅵa the circulation
Thin surfac e la yer
Figure : A single human ⅵllus om the small inteﬆine.
Synthesis of plasma proteins e.g. ﬁbrinogen
Amino acids −→ Excess are deaminated −→ Urea for excretion − →
to other tissue ⅵa the circulation
Fa acids −→ Fats for cell membranes − →
Energy ⅵa respiration
. Large Intestine Water and salt are absorbed in the C. Undigeﬆed food is ﬆored in the , along with baeria and some dead cells. This forms faeces and is passed through sphiners out of the anus.
Nutrition in Plants . Photosynthesis P is the process by which green plants make glucose and other organic molecles om inorganice molecules, using light energy. The light energy is apped by chlorophyll. The overall process for photosynthesis can be summarised as: chlorophyll
Carbon Dioxode + Water −−−−−−−→ Glucose + Oxygen light energy
Glucose is not the only organic subﬆance made by photosynthesis. Other carbohydrates are also formed, which can then be converted to fats, or, by combining with minerals, form amino acids and ⅵtamins. Photosynthesis is the source of all organic subﬆances in the plant. chlorophyll
Carbon dioxide + Water −−−−−−−→ Glucose and other sugars + Oxygen light energy
respired or used to make: • ﬆarch • sucrose • cellulose
excreted or respired
• proteins • fats • ⅵtamins • chlorophyll
Products of Photosynthesis Glucose and other sugars: • Much of the glucose is converted to for temporary ﬆorage in the leaf. At night, the ﬆarch may be broken down to the sugar and ansported through th phloem to other parts of the plant. • In the leaf, and throughout the plant, glucose is broken down in to release energy. • In growing regions, glucose is converted to to make cell walls.
• In the leaf, some glucose is combined with niate to form . These are later incorporated in to to make enzymes and to make ﬆruural parts of cells, such as membranes. If there is a shortage of niate, the plant is unable to grown properly, and is weak and unhealthy. • In the leaf and elsewhere, glucose and other sugars are used to make for ﬆruures such as cell membranes and to make which have essential uses for the plant. • Some glucose is combined with minerals, especially magnesium, to form , the green pigment used to ap light in photosynthesis. Oxygen: • Used in throughout the plant. • Excreted through ﬆomata as a .
. The Leaf Cuticle Upper epidermis Palisade mesophyll
Each leaf is aached to the ﬆem or branch by a , This leads to the in the leaf. Leaves are covered by a layer of waxy meial called the , which is normally thick and waterproof. It prevents the leaf om losing too much water in hot weather. Immediately under the cuticle is a layer of cells called the . which forms the ‘skin’ of the leaf. The epidermis may be pierced by lots of tiny holes called (singular ). The ﬆomata are mainly on the lower side of the leaf. They allow gases to diﬀuse in and out of the leaf, and water vapour to escape. Each ﬆoma is ﬂanekd bvy a pair of which can open and close. They close in hot, dry weather to prevent too much water evaporating om the leaves.
Leaves are generally ﬂat, sometimes large, and oen numerous. The result is that they have a large surface area for aborbing Carbon dioⅺde and ligt. The veins help to support the leaf, and hold it out ﬂat, so that it can catch the maⅺmum amount of light. In many plants the leaves are positioned in such a way that they don’t shade each other. Between the upper and lower epidermis are ltos of cells which together makes up the . These cells contain , and this is where photosynthesis takes place. The mesophyll towads the upper side of the leaf consiﬆs of cells shaped like bricks, and arranged neatly side by side. They are called . The other mesophyll cells are rounded and more irregular in their arrangement. They are called . Between the mesophyll cells are into which he ﬆomata open. When photosynthesis is taking place, carbon dioⅺde diﬀuses through the open ﬆomata into the air spaces. It then diﬀuses into the cells. Phototsynthessis takes place mainly in the palisade cells. They contain moﬆ of the chloroplaﬆs, and they are near the surface of he leaf that gets moﬆ light. the chloroplaﬆs are oen cluﬆered towards the tops of the cells, in the beﬆ position for catching light. The vein is made up of two parts: the towards the top, and the below. The xylem brings water and mineral salts to the elaf. The phloem takes soluble sugar and other produs of photosynthesis away om the leaf. Together thexylem and phloem are calld . Chloroplasts Chloroplaﬆs are ﬁlled with rows of thin interconneed . Millions of molecules are laid out on these membranes. Chlorophyll is a complex organic green which contains , and it plays a ⅵtal role in photosynthesis, by absorbing blue and red light, but reﬂeing green light. Stomata Stomata allow carbon dioⅺde and oxygen to diﬀuse in and out of leaves. They are also the main route by which water vapour excapes om the plant. In hot, dry weather there is a risk that the plant may run short of water. For this reason it is important that the ﬆomata should be able to open or close according to the weather conditions. When th eﬆoma opens, the guard cells take up water om the neighbouring epidermal cells; as a result the guard cells swell up and become more turgid. As they swell up they bend, so the gap between them widens (see Figure ). They swell up because the inner wall of the guard cells is thicker, and less elaﬆic, than the outer wall. The ﬆoma closes by the reverse rocess. Water passes out of the guard cells, so they become less turgid. As a result the guard cells ﬆraighten, and the gap between them narrows. Around the ﬆoma are sausage-shaped .
granum (stack of thylakoids)
outer membrane intermembrane space
stroma (aqueous fluid)
thylakoid lumen (inside of thylakoid)
plastoglobule (drop of lipids)
Source: http://commons.wikimedia.org/wiki/File:Chloroplast.svg (CC-BY-SA-(any version) or GNU FDL)
Figure : A chloroplaﬆ. On each membrane are many molecules of chlorophyll.
Transport in Animals All organisms which are large require a ansport syﬆem, to move subﬆances around the body. Single-celled organisms with low levels of aⅳi do not require ansport syﬆems. Humans have two main ansport syﬆems: • Circulatory syﬆem • Lymphatic syﬆem
. The Circulatory System Single Circulatory Systems
e.g. ﬁsh: Heart
Blood passes once through the heart on its way around the body. Double Circulatory Systems
s t oma almost close d guar d ce ll vacuole chloroplast
epider mal ce ll
s t oma wide open
The guard ce lls have t aken in wat er by osmosis, as indicate d by t he ar r ows .
Figure : A single ﬆoma.
Tissues deoxygenated blood
deoxygenated blood Lungs
Arteries Aorta takes oxygenated blood om the heart to the body
Pulmonary artery takes deoxygenated blood om the heart to the lungs. The only artery which carries deoxygenated blood. Veins Superior Vena Cava brings deoxygenated blood om the head and arms back to the heart Inferior Vena Cava brings deoxygenated blood om the body back to the heart Pulmonary Vein brings oxygenated blood om the lungs back to the heart. The only vein which carries oxygenated blood.
• When the heart is relaxed (), both sides ﬁll up with blood om the veins. • The aia then cona ( ). So blood is forced into the venicles through the valves. • A aion of a second later, the venicles cona ( ). The valves between the aia and venicles close, so blood is squeezed in to the arteries.
• The heart relaxes again and ﬁlls up with blood. Cardiac arrest/Myocardial infarction Heart aack Atheroschlerosis/atheroma/angina Lack of oxygen to ehart due to fat build-up in coronary arteries, leading to cheﬆ pain. Sinoatrial node Group of cells taht regulate heart beat (pacemaker). Hypertensive High blood pressure Stroke Atheroschlerosis deprⅳes an arteryin the brain of oxygen. Artery
Collagen ¯bre s
Thin layer of musc le and elast ic ¯bre
S mooth endothelium
Capillary Nucleus of endothelial c ell
S ingle layer of endothelial cells
Figure : Human blood vessels. The lumen in the artery is much smaller than the lumen in the vein, as the blood is at a much higher pressure.
Composition of the Blood Plasma is % water. Plasma ansports carbon dioⅺde om the organs to the lungs, soluble produs om the small inteﬆine to the organs, and urea om the lⅳer to the kidneys. The following cells are suspended in it:
Red Blood Cells – Erythrocytes Red blood celsl are disc-shaped and biconcave. These cells have no nucleus, so they can carry more oxygen. Red blood cells contain a chemical called . This combines with oxygen to form oxyhaemoglobin. A red blood cell’s lifespan is about four months. Aer this time it goes to the spleen, which removes worn out red blood cells om circulation.
White Blood Cells – Phagocytes & Lymphocytes There are several diﬀerent pes of white blood cells. They are all larger than red blood cells, and have a nucleus. Lymphocytes have a nucleus which occupies moﬆ of the cell. White blood cells prote the body om baeria. Phagocytes can squeeze through capillary walls, move towards baeria, and ingeﬆ them. Lymphocytes produce chemicals which deﬆroy baeria, by makign them ﬆick together. Platelets These are agments of blood cells budded oﬀ in the red blood marrow. These cells have a ﬆicky surface, and help to clot the blood at wounds, to ﬆop bleeding. Blood Clotting . Blood vessel wall is damaged or broken. . The protein within the blood vessel wall is exposed. This causes platelets to release an enzyme (thrombin). . Blood plasma carries a soluble protein called . . Enzymes secreted by platelets cause soluble ﬁbrinogen to turn into insoluble .
. Fibrin forms long threads which precipitate out of the blood. . The ﬁbrin threads tangle together and ap red and white blood vessels in the clot. . The clot dries and hardens, forming a scab. Tissue Fluid Formation . Arteriole brings blood into the capillary bed . The arteriole dⅳides into a network of small capillaries . Fluid leaks out of the capillaries, especially at the beginning of the capillary bed, and bathes the body cells. . The ﬂuid is called . It carries glucose and oxygen om the blood to the cells. . Tissue ﬂuid containing CO and urea leaks back into the cappillaries at the venous end of the capillary bed. . Venule carries blood back to a vein.
. The Lymphatic System Lymph nodes contain white blood cells, and a as aps for baeria and foreign particles. Tissue ﬂuid containing foreign and waﬆe materials drain into the lymphatic syﬆem, pass through a lymph node, and re-enter the blood circulation. The Immune System All cells have protein molecules on their surface membranes called (See Figure ). Lymphocytes (see Figure ) produce . These are chemicals which rea to foreign antigens and deﬆroy the foreign cells. Lymphocytes ‘recognise’ antigens on the surface of body cells and do not produce antibodies againﬆ them. Figure : Antigens on a cell. If foreign cells, e.g. baeria, enter the body, lymphocytes recognise these as foreign due to their diﬀerent antigens. The lymphocytes will then release antibodies to deﬆroy the baeria. There are thousands of lymphocytes which each produce a difFigure : A lymphocyte. ferent antibody. Thus, thousands of diﬀerent pathogens can be deﬆroyed. Lymphocytes also produce ‘memory cells’, which remain in the lymph nodes. These memory cells can produce antobodie very quickly if the same foreign antigen enters the body again. These antibodies deﬆroy the baeria before they cause a large infeion – the body is immune to that species of baerium.
Transplants If a patient needs to have an organ ansplanted into their body, dors muﬆ ensure that the antigens on the donor organ are very similar to the patient’s antigens. Otherwise, there is a chance that the patients lymph nodes will produce antibodies againﬆ the organ, rejeing it. Brothers and siﬆers have similar DNA and are oen used as donors. Patients are kept in ﬆerile conditions aer the operation, and are on drugs to suppress their immune syﬆem for the reﬆ of their life immunosuppressⅳe drugs).
Transport in Plants Plants need ansport syﬆems to: • Move water om the soil to the leaves for use in photosynthesis. • Move photosynthetic produs om the leaves to other parts of the plant e.g. uit amd growing parts of the plant. Xylem vessels ansport water om the roots to the leaves. Xylem vessels are long, continuous tubes – it is dead tissue containing . Lignin makes the xylem vessels ﬆrong, and is deposited unevenly, which leads to pits in the walls through which water can enter and leave the tubes. Phloem tubes (sieve tubes) are lⅳing tissue. At the end of each cell making up the tube, the cell wall is perforated to allow easy movement of sucrose. The movement of sucrose om the leaves to where it is needed is called anslocation. Phloem cells contain few organelles. The majori of aⅳities are performed by a companion cell which proⅵdes energy to the phloem cell. Root hair cells are found on young roots. They increase the surface area of the root for absorption of water an mineral ions. They laﬆ for approⅺmately one day.
. Osmosis Water moves by osmosis across the root. Osmosis is the net diﬀusion of water molecules om a region of high water potential to a region of low water potential through a partially permeable membrane (down a water potential gradient). Water potential of a subﬆance is a measure of how much water there is int it, and how easily the water molecules can move around. Subﬆances with a lot of water have a high water potential. Subﬆances with a lile water have a low water potential. Water moves om areas of high water potential to areas of low water potential.
. Transpiration Water does not move by osmosis in the xylem. The xylem is dead tissue, and there are no cell membranes. Water moves up the xylem because of anspiration. Transpiration is the loss of water vapour om a leaf through the ﬆomata. • % of water that is absorbed is loﬆ in anspiration. • The remaining % is used in photosynthesis. As water leaves the xylem vessels it reduces the water pressure at the top of the x ylemm, so water moves upwards towards a lower pressure. Transpiration produces a tension (pull). Water molecules are ﬆicky; they ﬆick to each other (), and this helps water to be pulled up the xylem. Transpiration is aided by this cohesion. Factors Aﬀecting Transpiration Wind speed Wind removes water vapour om around the ﬆoma, so it increases the water potential gradient (the water potential of the atmosphere around the toma becomes more negatⅳe) (see Figure ). higher wind speed, higher transpiration
Humidity The higher the humidi, the lower the water potential gradient, so less water evaporates om the leaves. higher humidity, lower transpiration
Light intensity During sunlight, ﬆomata open to allow CO in for use in photosynthesis. higher light intensity, higher transpiration
Temperature One a hot day, water evaporates more quickly om the leaf higher temperature, higher transpiration
If the plant loses too much water, it loses turgor pressure in the cells and may wilt – the ﬆomata will close at this point. Water supply If there is not enough water, the plant will clsoe its ﬆomata to conserve water. lower water supply, lower transiration
Leaf surface area A greater leaf surface area means more ﬆomata for water to siﬀuse out of. higher surface area, higher transpiration
Stomata Water is mainly loﬆ through ﬆomata – the more ﬆomata there are, the more anspiration there is. Moﬆ ﬆomata are located on the underside of the leaf. more stomata, higher transpiration
Air spaces More air spaces in the spongy mesophyll of a leaf mean there is mroe space for water to colle. mroe air spaces, higher transpiration
. Xerophytes Xerophytes are plants taht are specially adapted to lⅳe in exeme conditions. Some examples of adaptations: Thick cuticle ﬆops unconolled evaporation through leaf cells. Small leaf surface area less surface area for evaporation, e.g. conifer needles, caus spines Low stomata density smaller surface area for diﬀusion Sunken stomata maintains humid air around ﬆomata, e.g. marram grass, cai Stomatal hairs (trichores) maintains humid air around ﬆomata, e.g. marram grass, couch grass Rolled leaves maintains humid air around ﬆomata, e.g. marram grass Extensive roots maⅺmise water uptake, e.g. cai
. Movement of Photosynthetic Products Photosynthesis occurs in the leaves. It produces glucose – leaves are a . Glucose is converted into sucrose for ansport around the plant. Sucrose is a disaccharide. it is less reaⅳe than glucose, and does not get used up as easily as glucose. Sucrose enters the phloem tubes, and is taken to wherever it is needed, e.g. growign shoots, developing uits, roots (anywhere where respiration is happening). The places where sucrose is taken to are called . movement of organic subﬆances is called (also applies to amino acids, lipids etc.). Once at the sink sucrose may be converted to ﬆarch for ﬆorage (e.g. potatoes), or it may be converted to other sugars (e.g. uose in uits). In this way very high concenterations of sugars can be built up without aﬀeing the water potential of cells. Sucrose can also be converted back to glucose for respiration.
. Systemic Pesticides Syﬆemic peﬆicides are absorbed into the plant and ansported throughout the plant in the phloem. The targeted organism (e.g. an inse) feeds on the plant and eats the peﬆicide and dies. Syﬆemic peﬆicides are much more eﬀeⅳe than conta peﬆicides, but long term eﬀes on humans are unknown, and consumers may not want to eat produs eated with them.
Respiration & Gaseous Exchange Every cell in every lⅳing organism needs energy. Energy is obtained om food by the process of respiration. There are two pes of respiration:
. Aerobic Respiration The break-down of glucose using oxygen to release energy used by cells ( mol Adenosine Triphosphate (ATP)). Energy (in the form of ATP) is used in muscle conaion, aⅳe ansport, reaions (building up subﬆances), reaions (deﬆroying subﬆances). Anabolic and catabolic reaions are together known as reaions. Some energy is released as heat. Glucose + Oxygen
C6 H12 O6 + 6 O2
Carbon dioxide + Water + energy
6 CO2 + 6 H2 O + 38 mol ATP
CO and H O are byprodus of respiration.
. Anaerobic Respiration The break-down of glucose without oxygen to release energy used by cells. Less energy is produced ( mol ATP). Yeast Yeaﬆ is a single-celled fungus which can respire anaerobically. Glucose −→ Ethanol + Carbon dioxode + energy C6 H12 O6
2 C2 H5 OH + 2 CO2 + 2 mol ATP
. Calorimeters Diﬀerent foods contain diﬀerent amoutns of energy. Fats contain about twice as much energy as carbohydrates and proteins. The amount of energy in food can be measured using a calorimeter.
. The Lungs The alveoli are adapted for eﬃcient gas exchange: Large surface area Increased by the alveoli. ,, alveoli ≈ m2 . Thin epithelium A Two cell layer separates the air in the alveoli om the blood in the capillaries – only a short diﬆance forgases to diﬀuse. Moist Gases dissolve in solution before diﬀusion – more eﬃcent eﬀusion. Prevents dehydration of cells.
Blood supply A good blood supply to and om the lungs by a capillary network keeps concenation gradients diﬀerent by remoⅵng oxygenated blood om the lungs and bringing deoxygenated blood to the lungs. Increase in Breathing Rate ncreased respiration causes an increase in the produion of CO . CO dissolves in water to form carbonic acid. CO2 + H2 O H2 CO3
H+ + HCO3
H+ ions lower the pH of the blood, and are taken up by oxyhaemoglobin, which then releases oxygen. Increased CO is deteed by chemoreceptors located in the carotid arteries, aorta, and medulla in the brain. Chemoreceptors send impulses to the medulla. The medulla then sends impulses to the intercoﬆal muscles and the diaphragm, causing them to cona more equently (increased ventilation). Cigarette Smoke There are three major chemicals in cigaree smoke: Nicotine
• An addiⅳe drug
• Higher heart rate • Higher blood rate Tar
• Paralyses the cilia on ciliated cells • Makes goblet cells over-produce mucus • Too much mucus – Smoker’s cough to remove the mucus – This can damage the alveoli walls, which can lead to emphysema (surface area of alveoli reduced, so less oxygen can be absorbed) • Is a carcinogen (benzene)
Carbon monoxide binds irreversably with haemoglobin, therefore the oxygen carrying capaci of the blood is greatly reduced. Smokers have ≈ 10% of their haemoglobin bound to CO – this forms Carbaminohaemoglobin. Other smoking-related diseases: Chronic bronchitis Smoke irritates the bronchi and bronchioles, damages the mucus membranes, and narrows the tubes. It reduces the cilia aion, so mucus cannot be removed, which leads to baerial infeions. It is more diﬃcult for O to diﬀuse into the blood.
Excretion & Homeostasis . Excretion Excretion is the removal om the body of waﬆe produs of metabolism (which may be toⅺc) and subﬆances which are in excess of requirements, e.g. CO and urea. CO is removed ⅵa the lungs. Urea is removed ⅵa the kidneys. Rhenal artery Brings oxygenated blood full of urea to the kidneys. Rhenal vein Takes deoxygenated blood which is ee om urea back towards the heart ⅵa the Vena Cava. Kidney Removes unwanted (and excess) subﬆances om the blood, turns them into urine, and passes the urine on to the bladder. It does this by ﬁltering the blood. cm3 of blood is ﬁltered by the kidneys every minute. Ureter Tubes which conne the kidneys to the bladder. Bladder A muscular bag which can ﬆore urine. Can ﬆore up to about cm3 before the need to urinate (miuration) becomes compelling. Sphincter Muscle which, when it conas, urine is prevented om leaⅵng the body, and when it relaxes, urine can leave the body. Urethra Tube which carries urien om body.
. Homeostasis Homeoﬆasis is the maintenance of a conﬆant internal enⅵronment. Examples: • Body temperature • Blood pH • Blood pressure • Blood glucose concenation • Blood water concenation The mechanism by which homeoﬆasis is maintained is by using negatⅳe feedback syﬆems, which maintain ﬆabili in the body.
Rise above Norm
NORM Decrease below Norm
Return to Norm
Body detes change and a correⅳe mechanism is put in place.
NORM Body detes change and a correⅳe mechanism is put in place.
Return to Norm
(i.e. a change)
deteed by a
co-ordinated by a -
a change occurs in an
which causes a
• water evaporates, takes heat om the surface of the skin
• causes more blood to avel to capillaries near skin surface
• heat is radiated away om the body • skin appears ﬂushed, because there is more blood ﬂowing through the surface capillaries Raised hairs Vasoconstriction
• aps air (which insulates) next to skin surface • reduces blood ﬂow to surface capillaries
• skin is pale, because there is hardly any blood ﬂowing through surface capillaries
. The Pancreas The pancreas is both an gland and an gland. Exocrine gland a gland that secretes externally through a du — the pancreas secretes pancreatic juice, produced in Acinar cells, into the pancreatic du. Endocrine gland a gland that secretes hormones direly into the bloodﬆream — the pancreas secretes the hormones insulin and glucagon, om the Islets of Langerhans, into the bloodﬆream.
Reproduction . Asexual Reproduction • One parent • Oﬀspring is genetically indentical • Does not involve gametes • New diploid cells are produced direly by mitosis (by other diploid cells) Bacteria Baeria reproduce by binary ﬁssion.
antibodies can bind to t he bacterial antige ns, and des tr oy the bacterium
lymphocyt e DNA
body cell bacterium
Figure : A lymphocyte indentiing a baerium.
cell wall Figure : A root hair cell
boundary layer (water vapour)
Figure : Water vapour build-up around a ﬆoma.
antibodies do not bind to body cell ant igens, and body cell is not dest royed
water crucible oxygen
Figure : A simple calorimeter – used to measure the energy value of a respiratory subﬆrate.
Figure : Part of the lining of the respiratory passages.
rhenal vein adrenal glands (s ecr et e adre nalin)
kidney u r eter
Figure : The excretory syﬆem.
1. Protein is taken to alimentary c anal.
5 . Amino acids which are not needed are deaminate d to ammonia or a c arbohydrate .
6. Ammonia is convert ed to urea.
2. Protein is digest ed to amino acids. 3. Amino acids ar e absorbed into blood, and taken to liver in hepatic port al vein.
7. Urea is car ried to kidney, where it is filte re d from the blood. 4. Amino acids t hat ar e needed are r eleased into circulation.
Figure : Urea produion.
H Figure : The Suure of an amino acid. R can ﬆand for anything. The NH part of the molecule (ammonia) is toⅺc, and is converted into urea. Deamination is the removal of the niogencontaining part of the amino acid.
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l e a l n u e b h u R t
e h t a ⅵ y e n d i k e h t . n f i o e t v u l o a s n e e h s s a R p d o o l b n a e l C .
f o l e p n o e o L H
. e d b n u a t s t l a l n a e s h , r R e t e a h w t g g n n i o n l i a a t s n e u o c i n d i t u n o l F c . a e r u . r e t e r u e h t a ⅵ y e n d i k e h t s t ⅺ e e n i r U .
e f h o t p f o o . o t u e u L o s s e s i h t e s t e u h g ﬀ t n i i d d o n r t n i u e t o a e r r w l u t n e s a H s e h t f u s s n o s p i t a e o o m L l a e S l n . e H
. n o i t p r o s b a e r e ⅳ e l e s d n a , n o i t a l ﬁ a l u : s e s s e c o r p o w t e r a e r e h t – d e c u d o r p s i e n i r u w o H : e r u g i F
. e n o m r o h a s i H D A a
Source: Gray’s Anatomy (Public Domain)
Figure : An indⅳidual glomerulus.
Venous pressure monitor Air ap and air deteor Clean blood