| cholera | a disease caused by a bacterium which is transmitted in contaminated water |
| what does cholera bacterium do | produces a toxin that causes secretion of chloride ions into the small intestine, causing osmotic movement of water into the gut, causing diarrhoea, dehydration and loss of ions from the blood |
| uses of energy in living organisms including | muscle contraction, protein synthesis, cell division, active transport, growth, the passage of nerve impulses and the maintenance of a constant body temperature |
| aerobic respiration | the chemical reactions in cells that use oxygen to break down nutrient molecules to release energy |
| word equation for aerobic respiration | glucose + oxygen → carbon dioxide + water |
| balanced chemical equation for aerobic respiration | C6H12O6 + 6O2 → 6CO2 + 6H2O |
| anaerobic respiration | the chemical reactions in cells that break down nutrient molecules to
release energy without using oxygen |
| energy releases | anaerobic respiration releases much less energy per glucose molecule than aerobic respiration |
| word equation for anaerobic respiration in yeast | glucose → alcohol + carbon dioxide |
| balanced chemical equation for anaerobic respiration in yeast | C6H12O6 → 2C2H5OH + 2CO2 |
| word equation for anaerobic respiration in muscles during vigorous exercise | glucose → lactic acid |
| lactic acid | builds up in muscles and blood during vigorous exercise, causing an oxygen debt |
| how the oxygen debt is removed after exercise | - continuation of fast heart rate to transport lactic acid in the blood from the muscles to the liver
- continuation of deeper and faster breathing to supply oxygen for aerobic respiration of lactic acid
- aerobic respiration of lactic acid in the liver |
| nitrogen cycle | nitrogen cycle |
| the role of anaerobic respiration in yeast during the production of ethanol | under anaerobic conditions, yeast converts the glucose into ethanol, which is then purified for use as biofuel |
| the role of anaerobic respiration in yeast during bread-making | the carbon dioxide produced during fermentation is trapped in the dough, causing it to rise and creating the soft, porous texture of bread |
| factors affecting anaerobic respiration in yeast | the optimal temperature range is around 30°C to 37°C, a slightly acidic pH is preferred, higher concentrations of glucose can increase ethanol production, extremely high levels can be inhibitory |
| the use of pectinase in fruit juice production | adding pectinase to the chopped up fruit, more juice is released, pectinase breaks down pectin that is found inside plant cell walls, once broken more juice can be squeezed out of the fruit |
| use of biological washing powders that contain enzymes | biological washing powders contain enzymes similar to the digestive enzymes produced in the alimentary canal that help to break down large food molecules |
| advantages of using biological washing powders | - quickly breaking down large, insoluble molecules such smaller, soluble ones that will dissolve
- they are effective at lower temperatures, meaning less energy (and money) has to be used in order to wash
- they can be used to clean delicate fabrics that would not be suitable for washing at high temperatures |
| use of lactase to produce lactose-free milk | milk can be made lactose free by adding the enzyme lactase to it and leaving it to stand for a while to allow the enzyme to break down the lactose |
| how fermenter's can be used for the large-scale production of useful products | fermenters are containers used to grow micro-organisms like bacteria and fungi in large amounts, these can then be used for many biotechnological processes like producing bacteria and the penicillium mould that produces penicillin |
| conditions that need to be controlled in a fermenter | temperature - monitored using probes and maintained using a water jacket
pH - monitored using a probe
oxygen - required for aerobic respiration to take place
nutrient supply - needed for use in respiration to release energy for growth and reproduction of the micro-organisms
waste products - contents are filtered to remove waste created |
| binomial system of naming species | internationally agreed system in which the scientific name of an organism is made up of two parts showing the genus and species |
| ferns | Have leaves called fronds
Do not produce flowers but instead reproduce by spores produced on the underside of fronds |
| flowering plants | reproduce sexually by means of flowers and seeds, can be divided into two groups – monocotyledons and dicotyledons |
| difference between monocotyledons and dicotyledons in flowers | flowers from monocotyledons contain petals in multiples of 3 while flowers from dicotyledons contain petals in multiples of 4 or 5 |
| difference between monocotyledons and dicotyledons in leaves | Leaves from monocotyledons have parallel leaf veins while leaves from dicotyledons have reticulated leaf veins, leaves from monocotyledons are narrow and grass-like while leaves from dicotyledons tend to have broader leaves that come in a wide range of shapes |
| main features of all fungi | usually multicellular, cells have nuclei and cell walls not made from cellulose, do not photosynthesize but feed by saprophytic (on dead or decaying material) or parasitic (on live material) nutrition |
| main features of all protoctists | most are unicellular but some are multicellular, all have a nucleus, some may have cell walls and chloroplasts meaning some protoctists photosynthesise others don't |
| main features of all Prokaryotes | (bacteria, blue-green algae), often unicellular
cells have cell walls (not made of cellulose) and cytoplasm but no nucleus or mitochondria |
| features of a virus | features of a virus |
| micrometer to mm | 1 micrometer = 0.001 |
| where in the cells does diffusion and osmosis take place | cell membrane |
| words to use when talking about enzymes | active site, enzyme-substrate complex, substrate, product |
| chlorophyll | a green pigment that is found in chloroplasts |
| importance of nitrate ions for photosynthesis | making amino acids |
| importance of magnesium ions for photosynthesis | making chlorophyll |
| role and adaptation of the cuticle | role - primarily functions to reduce water loss through evaporation
adaptation - the cuticle's thickness is an adaptation to environmental conditions, varying to balance water retention with the need for light absorption |
| role and adaptation of the guard cell and stomata | role - gas exchange
adaptation - guard cells swell or shrink in response to environmental stimuli, thereby regulating the opening of stomata, which is crucial for maintaining a balance between gas exchange and water conservation |
| role and adaptation of the epidermis | role - serves as a protective barrier against environmental damage, pathogen entry and excessive water loss
adaptation - being transparent, it allows sunlight to pass through to the underlying photosynthetic cells |
| role and adaptation of the palisade mesophyll | role - where most light absorption occurs
adaptation - the arrangement of palisade cells maximises light absorption |
| role and adaptation of the spongy mesophyll | role - facilitates gas exchange
adaptation - the structure enhances the diffusion of CO2 to the photosynthesising cells |
| role and adaptation of the air spaces | role - efficient diffusion of gases (CO2, O2, and water vapour)
adaptation - connect the stomata with the photosynthetic cells, ensuring that gases reach their target sites rapidly |
| role and adaptation of the vascular bundles | role - xylem transports water and dissolved minerals from the roots to the leaves, essential for photosynthesis, phloem distributes the sugars produced during photosynthesis to other parts of the plant
adaptation - vascular bundles help in maintaining leaf structure, ensuring optimal positioning for light absorption |
| what organs are in the alimentary canal | mouth, oesophagus, stomach, small intestine (duodenum and ileum) and large intestine (colon, rectum and anus) |
| digestion of starch | amylase - breaks down starch to maltose
maltase - breaks down maltose to glucose on the membranes of the membranes of the epithelium lining on the small intestine |
| digestion of protein by proteases | pepsin - breaks down protein in the acidic conditions of the stomach
trypsin - breaks down protein in the alkaline conditions of the small intestine |
| effect of number of stomata, size of stomata and air spaces on evaporation | all lead to higher evaporation of water |
| why some parts of a plant may act as a source and a sink | can become a sink during its growth phase or when it undergoes repair after damage |
| body circuits | body circuits |
| structure of blood vessels relates to the blood pressure | muscular walls of veins are thinner as the blood they carry is at a lower pressure, muscular walls of arteries are thicker as the blood they carry is at a higher pressure |
| how structure of capillaries is related to their functions | contain one layer of cells - substances can easily diffuse in and out of them |
| white and red blood cells | white and red blood cells |
| lymphocytes in diagrams | lymphocytes in diagrams |
| active immunity | gained after an infection by a pathogen or by vaccination |
| importance of vaccination | vaccinations give protection against specific diseases and boost the body’s defence against infection from pathogens without the need to be exposed to dangerous diseases that can lead to death |
| importance of breastfeeding for infants | fast-acting, short-term defence, it helps the infant to fight off infections until they are older and stronger and their immune system is more responsive |
| examples of chemical control of a plant growth | phototropism, gravitropism |
| why is only using antibiotics when essential important | can limit the development of resistant bacteria such as MRSA |
| advantages of asexual reproduction to a population of species in the wild | populations can be increased rapidly when conditions are right, can exploit suitable environments quickly |
| disadvantages of asexual reproduction to a population of species in the wild | limited genetic variation in the population as offspring are genetically identical to their parents, the population is vulnerable to changes in conditions and may only be suited for one habitat |
| advantages of asexual reproduction to a crop production | more time and energy efficient, reproduction is completed much faster than sexual reproduction |
| disadvantages of asexual reproduction to a crop production | disease is likely to affect the whole population as there is no genetic variation |
| advantages of sexual reproduction to a population of species in the wild | increases genetic variation, the species can adapt to new environments due to variation, giving them a survival advantage |
| disadvantages of sexual reproduction to a population of species in the wild | takes time and energy to find mats, difficult for isolated members of the species to reproduce |
| advantages of sexual reproduction to a crop production | disease is less likely to affect the population (due to variation) |
| disadvantages of sexual reproduction to a crop production | slower colonization |
| cross-pollination | occurs when the pollen from one plant is transferred to the stigma of another plant of the same species |
| cross-pollination effects | the way most plants carry out pollination, as it improves genetic variation, able to respond to changes in the environment as they are more likely to have adaptations that suit new conditions, relies on pollinators |
| self-pollination effects | reduces genetic variety, if environmental conditions change as it is less likely that any offspring will have adaptations that suit the new conditions well, doesn't rely on pollinators |
| what happens in early development, of the zygote | forms an embryo, which is a ball of cells that implants into the lining of the uterus |
| placenta label | placenta label |
| function of placenta | exchange of substances between the mother's blood and that of the fetus
Substances that travel from the mother's blood to the fetus include:
oxygen
nutrients, e.g. glucose, amino acids and mineral ions |
| function of amniotic sac | contains amniotic fluid |
| function of amniotic fluid | protects the embryo during development by cushioning it from bumps when the mother moves around |
| function of umbilical cord | connects the embryo’s blood supply to the placenta |
| oestrogen levels and timing | levels rise from day 1 to peak just before day 14, this causes the uterine wall to start thickening and the egg to mature |
| progesterone levels and timing | line stays low from day 1 – 14 and starts to rise once ovulation has occurred, the increasing levels cause the uterine lining to thicken further; a fall in progesterone levels causes the uterine lining to break down (menstruation / ‘period’) |
| FSH | causes an egg to mature in an ovary, stimulates the ovaries to release oestrogen, line stays relativley the same |
| LH | triggers ovulation, line stays relatively the same and peaks in the middle |
| adaptive features of hydrophytes | large air spaces in their leaves for flotation, to keep the leaves close to the surface of the water where there is more light for photosynthesis, small roots as they can also extract nutrients from the surrounding water through their tissues, stomata usually open all the time and mainly found on the upper epidermis of the leaf where they can exchange gases much more easily with the air |
| pyramid of numbers | pyramid of numbers |
| pyramids of biomass | pyramids of biomass |
| pyramids of energy | pyramids of energy |
| trophic levels | producers, primary consumers, secondary consumers, tertiary consumers, quaternary consumers |
| plastics effects in marine | animals often try to eat plastic or become caught in it, leading to injuries and death, as the plastic breaks down it can release toxins that affect marine organisms, once it has broken down into very small particles it is commonly ingested by animals and enters the food chain |
| plastics effects on land | plastic is generally disposed of by burying in landfills, as it breaks down it releases toxins into the surrounding soil and as such the land is no good for growing crops or grazing animals and can only be used for building on several decades after burial |
| sources and effects of methane pollution | livestock farming, enhanced greenhouse effect |
| sources and effects of carbon dioxide pollution | fossil fuels, climate change |
| why are bacteria useful in biotechnology and genetic modification | rapid reproduction rate and ability to make complex molecules, few ethical concerns over their manipulation and growth, presence of plasmids |
| features of gas exchange surfaces in humans | large surface area - to allow faster diffusion of gases across the surface
thin walls - to ensure diffusion distances remain short
good ventilation with air - so that diffusion gradients can be maintained
good blood supply - to maintain a high concentration gradient so diffusion occurs faster |
| body diagram | body diagram |
| inhaled air composition | contains around 21% oxygen, around 0.04 % carbon dioxide, less water vapour, 78% nitrogen (gas composition matches atmospheric levels) |
| exhaled air composition | around 16 % oxygen, around 4 % carbon dioxide, more water vapour (respiration), 78% nitrogen |
| reason for difference in oxygen | oxygen is removed from blood by respiring cells so blood returning to lungs has a lower oxygen concentration than the air in the alveoli which means oxygen diffuses into the blood in the lungs |
| reason for difference in carbon dioxide | carbon dioxide is produced by respiration and diffuses into blood from respiring cells; the blood transports the carbon dioxide to the lungs where it diffuses into the alveoli as it in a higher concentration in the blood than in the air in the alveoli |
| reason for difference in water vapour | water evaporates from the moist lining of the alveoli into the expired air as a result of the warmth of the body |
| reason for difference in nitrogen | nitrogen gas is very stable and so cannot be used by the body, for this reason its concentration does not change in inspired or expired air |
| effects of physical activity on the rate and depth of breathing | exercise increases the frequency and depth of breathing, the number of breaths per minute will have increased and the chest expansion will also have increased |
| reason for this increase of rate and depth of breathing | During exercise, increased carbon dioxide in the blood lowers pH, triggering chemoreceptors in the brain. This signals the diaphragm and intercostal muscles to increase breathing rate and depth to remove CO2 and supply more oxygen |
| lungs diagram | lungs diagram |
| function of cartilage in the trachea | surround the trachea (and bronchi), the function of the cartilage is to support the airways and keep them open during breathing, if they were not present then the sides could collapse inwards when the air pressure inside the tubes drops |
| role of ribs | During strenuous activity, the internal intercostal muscles pull the ribs down and in, reducing thorax volume and forcing air out quickly—this is called forced exhalation. It helps remove excess carbon dioxide and increases gas exchange |
| role of external intercostal muscles | During inhalation, the external intercostal muscles contract, pulling the ribs up and out, increasing chest volume and drawing air in. During exhalation, the internal intercostal muscles contract, pulling the ribs down and in, decreasing chest volume and forcing air out |
| role of diaphragm | when the diaphragm contracts, it flattens, increasing chest volume and lowering lung air pressure, drawing air in. When it relaxes, it moves up, decreasing chest volume and raising lung air pressure, forcing air out |
| role of ciliated cells in protecting the breathing system | The passages down to the lungs are lined with ciliated epithelial cells, have tiny hairs on the end of them that beat and push mucus up the passages towards the nose and throat where it can be removed |
| role of goblet cells in protecting the breathing system | The mucus is made by special mucus-producing cells called goblet cells because they are shaped like a goblet, or cup |
| role of mucus in protecting the breathing system | mucus traps particles, pathogens like bacteria or viruses, and dust and prevents them getting into the lungs and damaging the cells there |
| carbon dioxide excretion | excreted through the lungs |
| what do kidneys excrete | urea and excess water and ions |
| excretory system diagram | excretory system diagram |
| structure of the kidney | structure of the kidney |
| structure of the kidney | structure of the kidney |
| structure of a nephron | each kidney contains around a million tiny structures called nephrons, also known as kidney tubules or renal tubules, nephrons start in the cortex of the kidney, loop down into the medulla and back up to the cortex |
| contents of the nephrons | drain into the innermost part of the kidney and the urine collects there before it flows into the ureter to be carried to the bladder for storage |
| nephron | nephron |
| function of a nephron | is removing all waste products including the solid wastes, and other excess water from the blood, converting blood into the urine, reabsorption, secretion, and excretion of numerous substances |
| ultrafiltration | blood is delivered to the kidneys by the renal arteries and taken away by the renal veins, blood enters the kidney at high pressure, the pressure helps to filter all the small molecules from the blood into the kidney |
| role of the glomerulus in filtration | role of the glomerulus in filtration |
| filtrate in the kidney is made up of | water, salts, sugars, urea, amino acids, proteins and blood cells are too big to filter into the kidney |
| filtration | filtration |
| reabsorption | as the filtrate travels around the nephron in the kidney the useful substances are reabsorbed - glucose, amino acids, water, salts |
| loop of Henle | the longer the loop of Henle the more water will be reabsorbed. Therefore, animals that live in dry habitats such as the desert have a long loop of Henle. This means the medulla of the kidney is also thicker |
| nephron in reabsorption | nephron in reabsorption |
| kidney position | kidney position |
| formation of urine containing urea | the molecules which are not selectively reabsorbed (the urea, excess water and ions) continue along the nephron tubule to the collecting ducts as urine. This eventually passes down to the bladder. |
| role of the liver in the assimilation of amino acids | excess amino acids absorbed in the blood that are not needed to make proteins cannot be stored, so they are broken down in a process called deamination |
| deamination | removal of the nitrogen containing part of amino acids to form urea |
| urea formation | formed in the liver from excess amino acids |
| importance of excretion | urea is toxic to the body in higher concentrations and so must be excreted |
| homoeostasis | the maintenance of a constant internal environment |
| negative feedback | occurs when conditions change from the ideal or set point and returns conditions to this set point, usually a continuous cycle of bringing levels down and then bringing them back up so that overall, they stay within a narrow range of what is considered ‘normal’ |
| how negative feedback works | if the level of something rises control systems are switched on to reduce it again, if the level of something falls control systems are switched on to raise it again |
| blood glucose levels rise | insulin is produced when blood glucose rises and stimulates liver and muscle cells to convert excess glucose into glycogen to be stored |
| blood glucose levels fall | Glucagon is produced when blood glucose falls and stimulates liver and muscle cells to convert stored glycogen into glucose to be released into the blood |
| type 1 diabetes treatments | It can be treated with insulin injections, a controlled diet to avoid blood sugar spikes, and exercise to lower glucose through increased muscle respiration. |
| temperature regulation by the skin | The brain regulates body temperature using receptors that detect blood temperature. Skin receptors send signals to the brain, which then triggers effectors in the skin to maintain a stable 37°C. Fatty tissue under the skin insulates the body and helps prevent heat loss. |
| when we are hot - sweating | sweat is secreted by sweat glands, this cools skin by evaporation, heat energy from the body is lost as liquid water in sweat becomes water vapour |
| when we are hot - hair | hairs lie flat against the skin allowing air to freely circulate this increases heat transfer to environment by radiation |
| when we are cold - shivering | skeletal muscles contract rapidly, and we shiver, these involuntary muscle contractions need energy from respiration and some of this is released as heat |
| when we are cold - hair | erect hairs trap a layer of air around the skin which acts as an insulator, preventing heat loss by radiation |
| vasconstroction | when we are cold, blood flow in capillaries slows down because arterioles leading to the skin get narrower, this reduces the amount of heat lost from blood by radiation as less blood flows through the surface of the skin |
| vasodilation | when we are hot blood flow in capillaries increases because blood vessels to the skin capillaries get wider, this cools the body as blood (which carries heat around the body) is flowing at a faster rate through the skin's surface and so more heat is lost by radiation |
| skin when it's hot | skin when it's hot |
| skin when it's cold | skin when it's cold |
| advantages of genetic modification | more nutrition, increased yields, reduced use of chemicals |
| disadvantages of genetic modification | reduced biodiversity, antibiotic resistance, increased cost of seeds |
| nitrogen fixation | converting nitrogen gas into nitrogen-containing ions |
| process of nitrogen cycle | 1. Nitrifying bacteria are present in soil that convert ammonium ions into nitrates
2. Nitrogen fixing bacteria take in/convert nitrogen gas into ammonium ions via lightning.
- Plants absorb the nitrates and form amino acids, and then protein
- Animals then feed on the proteins and digest them
- Then, deamination takes place where the nitrogen containing part of amino acids are broken down and converted to urea, then to be excreted as urine.
- Denitrifying bacteria are present in soil, they will break down nitrogen gas and return nitrogen to the atmosphere.
- The cycle repeats |
| nitrogen cycle | nitrogen cycle |
| denitrification | Denitrifying bacteria convert nitrates in the soil back into nitrogen gas, primarily in anaerobic conditions like waterlogged or compacted soil. Farmers can reduce this bacteria's activity by ploughing the soil to improve aeration. |
| nitrification | Decomposers like bacteria and fungi return nitrogen to the soil as ammonia. Nitrifying bacteria convert ammonia into nitrates, which plants can absorb |
| nitrogen fixation | Nitrogen fixation, done by bacteria or through lightning and fertilizers, converts atmospheric nitrogen (N₂) into usable ammonium compounds and nitrates. Plants then absorb these nitrates from the soil to build proteins |
