| MRS GREN | Movement as an action by an organism
Respiration as the chemical reactions realise energy
Sensitivity to detect and respond to changes in environment
Growth as a permanent increase in size
Reproduction that makes more of the same kind of organism
Excretion as the removal of waste products
Nutrition, taking in materials for energy, growth and development |
| plant cell | plant cell |
| animal cell | animal cell |
| bacteria cell | bacteria cell |
| function of the cell wall | gives shape to cells, stops cells from bursting when they fill with water, allows water and dissolved substances to pass through freely |
| function of the cell membrane | controls movement of other substances into and out of the cell, keeps contents of the cell inside, forms a barrier between the cell and its surroundings |
| function of the nucleus | controls all activities in the cell, controls how cells develop |
| function of the cytoplasm | place where chemical reactions take place (like respiration and making proteins for the cell) |
| function of the vacuole | stores salts and sugars, full of water to maintain shape and firmness of cell |
| function of the chloroplasts | stores starch, produce energy through photosynthesis and oxygen-release processes, site of photosynthesis |
| ciliated cells function | movement of mucus in the trachea and bronchi |
| palisade mesophyll cells function | contains lots of chloroplasts, close to where the light is so max amount of light hits the leaf, for photosynthesis |
| red blood cells function | carry oxygen from the lungs and deliver it throughout our body |
| sperm and egg cells (gametes) function | carry out fertilization in sexually reproducible organisms, reproduction |
| cell | Building blocks, muscle cells contract and relax |
| tissue | similar cells working together in the same way, cardiac muscle tissue is made of muscle cells that contract and relax together |
| organ | group of tissues working together, your heart is made of muscle and other tissues and pumps blood around your body |
| organ system | a group of organs working together, your heart and blood vessels make up your circulatory system which carries blood around your body |
| organism | a single or individual living species, which exhibits all the properties of life |
| diffusion | net movement of particles from a region of their higher concentration to a region of their lower concentration, as a result of their random movement |
| where does energy for diffusion come from | kinetic energy of random movement of molecules and ions |
| importance of diffusion of gases and solutes in living organisms | allows them to gain the useful substances they require to obtain energy and grow, and lets them get rid of waste products, allows for gas exchange |
| how does surface area influence diffusion | as the surface area of the membrane increases, the rate of diffusion also increases, as there is more space for molecules to diffuse across the membrane |
| how does temperature influence diffusion | molecules move faster and collide more often as the temperature increases, diffusion is faster at warmer temps |
| how does concentration gradient influence diffusion | higher the concentration the higher diffusion rates |
| how does distance influence diffusion | The greater the distance that a substance must travel, the slower the rate of diffusion |
| role of water | solvent in organisms with reference to digestion, excretion and transport |
| how does water move in and out of cells | osmosis, through the cell membrane |
| how are plants supported | by the pressure of water inside the cells pressing outwards on the cell wall |
| osmosis | the net movement of water molecules from a region of higher water potential (dilute solution) to a region of lower water potential (concentrated solution) through a partially permeable membrane |
| the importance of water potential and osmosis in the uptake and loss of water by organisms | If the water would only diffuse out or into the cell, it would shrink or burst, nutrients and minerals are diffused along with the water. |
| active transport | the movement of particles through a cell membrane from a region of lower concentration to a region of higher concentration (against the concentration gradient) using energy from respiration |
| importance of active transport | as a process for movement of molecules or ions across membranes, including ion uptake by root hairs |
| what happens during active transport | protein carriers move molecules or ions across a membrane |
| chemical elements that make up carbohydrates, fats and proteins | carbon, hydrogen, and oxygen |
| what is starch made of | glycogen and cellulose from glucose |
| what are fats and oils made of | fatty acids and glycerol |
| iodine test for starch | changes from brown to a blue/black colour |
| Benedict solution for reducing sugars | from blue to green/yellow if the amount is low and red if it is high |
| biurets test for proteins | lilac |
| Ethanol test for fats and oils | milky white |
| DCPIP test for vitamin C | It changes from blue to red with acids but loses its colour in the presence of certain chemicals, one of which is ascorbic acid (vitamin C) |
| structure of a DNA molecule | 2 strands coiled together, each strand contains bases, bonds between pairs of bases hold the strands together, bases always pair with each other (A&T, C&G) |
| catalyst | a substance that increases the rate of a chemical reaction and is not changed by the reaction |
| enzymes | proteins that are involved in all metabolic reactions where they function as biological catalysts |
| describe why enzymes are important to all living organisms in terms of a reaction rate necessary to sustain life | Without enzymes reactions simply would not occur or would run too slowly to sustain life, for example without enzymes digestion would be impossible |
| lock and key model | only a substrate molecule with a shape that fits into the active site will take part in the reaction catalysed by this enzyme |
| photosynthesis | the process by which plants synthesise carbs from raw materials using energy from light |
| what does chlorophyll do | chlorophyll transfers energy from light into energy in chemicals for the synthesis of carbs |
| why do plants store starch | plants store starch as an energy store |
| why do plants store cellulose | to build cell walls |
| why do plants store glucose | used in respiration to provide energy |
| why do plants store sucrose | for transport in the phloem |
| why do plants store nectar | to attract insects for pollination |
| why does chlorophyll need magnesium ions | regulate the activity of key photosynthetic enzymes. |
| why does photosynthesis need chlorophyll | to absorb the energy from light |
| why does photosynthesis need light | provides energy for the process |
| why does photosynthesis need carbon dioxide | diffuses into the leaves from the air |
| balanced chemical equation for photosynthesis | 6CO2+6H2O→C6H12O6+6O2 |
| how leaves have adapted for photosynthesis | a large surface area to absorb light rays, a thin shape so gasses can diffuse in and out easily |
| leaf diagram | leaf diagram |
| balanced diet | a diet consisting of a variety of different types of food and providing adequate amounts of the nutrients necessary for good health |
| Principal dietary source and importance of carbs | sugars, provide you with energy |
| Principal dietary source and importance of fats and oils | long term energy store, good thermal insulators, butter |
| principal dietary source and importance of proteins | growth and repair, needed to make your own proteins, nuts |
| principal dietary source and importance of vitamin C | repair resistance to disease, citrus fruits |
| principal dietary source and importance of vitamin D and calcium | strengthens bones and teeth, milk |
| principal dietary source and importance of iron | formation of haemoglobin in red blood cells for transport of oxygen, eggs |
| principal dietary source and importance of fibre | helps the movement of food in the alimentary canal, cabbage |
| principal dietary source and importance of water | needed for chemical reactions to take place |
| cause of scurvy and rickets | vitamin C deficency, vitamin D deficency |
| digestive system | digestive system |
| ingestion | the processes of taking food, drink, or another substance into the body by swallowing or absorbing it |
| digestion | the process of mechanically and enzymatically breaking down food into substances for absorption into the bloodstream |
| absorption | the movement of nutrients from the intestines into the blood |
| assimilation | uptake and use of nutrients by cells |
| egestion | the removal of undigested food from the body as faeces |
| physical digestion | the breakdown of food into smaller pieces without chemical change to the food molecules |
| what does physical digestion do | increases the surface area of food for the action of enzymes in chemical digestion |
| tooth structure | tooth structure |
| function of the stomach in physical digestion | Your stomach releases gastric juices that begin to break down all of the food you've eaten |
| chemical digestion | break down of large insoluble molecules into small soluable molecules |
| what does amylase break down | breaks down starch to simple reducing sugars (maltose) |
| where is amylase secreted | produced by the salivary glands and the pancreas |
| where does amylase act | salivary glands |
| what does proteases break down | protein into amino acids |
| where is protease secreted | pancrease |
| where does protease act | breaks down protein in the acidic conditions of the stomach |
| what does lipase break down | fats and oils into fatty acids and glycerol |
| where is lipase secreted | pancreas |
| where does lipase act | small intestine |
| functions of hydrochloric acid in gastric juice with killing harmful micro-organisms in food | gastric juice contains pepsin, which starts the digestion of proteins to smaller molecules called polypeptides, it also contains hydrochloric acid which kills any bacteria in food |
| functions of hydrochloric acid in gastric juice and providing an acidic pH for optimum enzyme activity | gastric juice contains hydrochloric acid, as a result the enzyme pepsin works in acid pH of about 1.5-2 |
| what does trypsin do | breaks down protein in the alkaline conditions of the small intensive |
| bile and function | alkaline mixture that neutralises the acidic mixture of food and gastric juices entering the duodenum from the stomach to provide suitable pH for enzyme activity |
| small intestine | the region where nutrients are absorbed, most water is also absorbed here, but some is also absorbed from the colon |
| villus | villus |
| function of xylem | transports water and mineral ions, upward direction only, made of dead cells, found in the centre of the root called a stele, walls separating them made of lignin, outer shells are not living, no end walls between cells |
| function of phloem | transports dissolved sugars like sucrose and amino acids, goes in both directions, made of living cells, found in bundles around the stele, where translocation happens, has end walls (sieve plates) |
| xylem and phloem position | xylem and phloem position |
| root hair cells function | absorb water and mineral ions |
| how have root hair cells adapted | large surface area to increase the uptake of water and mineral ions |
| pathway taken by water through the root stem and leaf | root hair cells, root cortex cells, xylem, mesophyll cells, much of the water enters the cell walls, evaporates to form water vapour and then diffuses through stomata to atmosphere |
| how does water move upwards through the xylem | a transpiration pull that draws up a column of water molecules held together by forces of attraction between water molecules |
| transpiration | loss of water vapour from the plant leaves by evaporation of water at the surfaces of the mesophyll cells and then diffuses out of the leaves through the stomata as water vapour |
| how wind speed affects transpiration | windy conditions increase the rate of transpiration, water molecules are blown away from the leaf surface so more water molecules diffuse out of the stomata |
| how temperature affects transpiration | warm conditions increase the rate of transpiration as warm air can hold more water vapour |
| how humidity affects transpiration | humid conditions decrease the rate of transpiration as humid air has a lot of water molecules, so the concentration gradient for water vapour is less steep |
| how and why does wilting occur | if the plant doesn't get enough water the cells are no longer turgid so they can't hold it up any more |
| translocation | movement of sucrose and amino acids from their source to a sink |
| source | parts of the plant that release sucrose or amino acids |
| sink | part of the plant that use or store sucrose or amino acids |
| what do electrical impulses travel along | electrical impulses travel along neurons |
| what is the CNS | Central nervous system, consisting of the brain and the spinal cord |
| what is the PNS | Peripheral nervous system, consisting of the nerves outside the brain and spinal cord |
| role of nervous system | coordination and regulation of body functions |
| neurons | neurons |
| neurons | neurons |
| simple reflex arc | receptor - sensory neurone - relay neurone - motor neurone - effector |
| reflex action | automatically and rapidly integrating and coordinating stimuli with the responses of effectors |
| synapse | junction between two neurons, ensures that impulses travel in one direction only |
| structure of a synapse | have vesicles containing neurotransmitter molecules, the synaptic gap and receptor proteins |
| events at a synapse | an impulse stimulates release of neurotransmitters from vesicles into the synaptic gap, the neurotransmitters diffuse across the gap, neurotransmitter molecules bind with receptor proteins on the next neurone, an impulse is stimulated in the next neurone |
| sense organs | groups of receptor cells responding to specific stimuli - light, sound, touch, temperature, chemicals |
| eye diagram | eye diagram |
| cornea | refracts light rays into the pupilcornea |
| iris | controls how much light enters the pupil |
| lens | focuses light rays onto the retina |
| retina | contains light receptors, some sensitive to light of different colours |
| optic nerve | carries impulse to the brain |
| pupil reflex in bright light | pupil becomes smaller so less light enters the eye, radial muscles relax, circular muscles in iris contract |
| pupil reflex in dim light | radial muscles contract, circular muscles relax, pupil enlarges so more light enters the eye |
| eye looking at a distant object | ciliary muscles relax, suspensory ligaments are tight, so the lens becomes more thin and light rays are refracted as they pass through the lens and focus on the retina, so the distant object is in focus |
| eye looking at a near object | ciliary muscles contract, suspensory ligaments are not pulled, so the lens becomes fatter and light rays are refracted more so the near object is in focus |
| where are rods and cones in the eye | located mainly around the periphery of the retina |
| function of rods | greater sensitivity of rods as they are responsible for night vision |
| function of cones | 3 different types absorbing light of different colours, for colour vision |
| function of fovea | a region of the retina with the highest density of cones where the eye sees particularly good detail |
| hormone | chemical substance produced by a gland and carried by the blood which alters the activity of one or more specific target organs |
| what hormone does the pancreas secrete | insulin and glucagon |
| what does insulin do | decrease blood glucose concentration |
| adrenaline | hormone secreted in fight or flight situations |
| effects of adrenaline | increased breathing rate, heart rate and pupil diameter |
| homoeostasis | the maintenance of a constant internal environment |
| how to control blood glucose levels | when your blood glucose levels increase, insulin in secreted into the blood which liver cells to convert glucose into glycogen. this stimulates the liver cells to absorb lots of glucose from the blood, so the concentration decreases and returns to normal. |
| skin | skin |
| gravitropism | a response in which parts of a plant grow towards or away from gravity |
| phototropism | a response in which parts of a plant grow towards or away from the direction of the light source |
| gravitropism in the roots | Positively gravitropic, the growth in the same direction as gravity |
| gravitropism in the shoots | negatively gravitropic, always grow in the opposite direction of gravity, |
| phototropism in the shoots | Positively phototrophic because shoots grow towards the light |
| auxin | made in the shoot tip, diffuses through the plant from the shoot to the tip, unequally distributed in response to light and gravity, stimulates cell elongation |
| drug | any substance taken into the body that modifies or affects chemical reactions in the body |
| use of antibiotics in bacterial infections | used to kill pathogens or stop their growth, acts on bacteria by inhabiting cell wall formation leading to a breakdown of the cell wall and the leakage of cell contents |
| antibiotics resistance | some bacteria are resistant to antibiotics which reduces the effectiveness of antibiotics, also doesn't affect viruses |
| how antibiotics become resistant | antibiotics kill all the non-resistant bacteria and the more you use the antibiotic the more the resistant bacteria grow and the more the non-resistant bacteria are killed until all that is left is non-resistant bacteria |
| role of testosterone in puberty | growth of the male sex organs, testes to make sperm cells, growth of facial codes, deeping of the voice, development of muscles in the body |
| role of oestrogen in puberty | growth of female sex organs, menstrual cycle, growth of hair, growth and development of breasts, widening of hips |
| sun use | principal sources of energy input to biological systems |
| food chain | showing the transfer of energy from one organism to the next, beginning with a producer |
| food web | a network of interconnected food chains |
| producer | an organism that makes its own organic nutrients, usually using energy from sunlight through photosynthesis |
| consumer | an organism that gets its energy by feeding on other organisms |
| how food chains are classes | consumers might be classed as primary, secondary, tertiary and quaternary according to their position in a food chain |
| herbivore | an animal that gets its energy by eating plants |
| carnivore | an animal that gets its energy by eating other animals |
| pyramid of numbers | a way to show numbers of organisms at each trophic level in an ecosystem, the area of each horizontal bar is proportional to the number of individuals at each trophic level |
| pyramid of biomass | way to show biomass at each trophic level in an ecosystem, the area of each horizontal bar is proportional to the mass of living material at each trophic level |
| decomposer | an organism that gets its energy from dead or waste organic material |
| trophic level | the position of an organism in a food chin, web or ecological pyramid |
| advantages of using a pyramid of biomass rather than a pyramid of numbers to represent a food chain | gives indication of the size, measures biomass instead of numbers |
| carbon cycle | - photosynthesis, where plants and algae absorb carbon dioxide from the air
- respiration, which releases carbon back into the atmosphere when living organisms breathe
- feeding transfers carbon from one organism to another
- decomposition returns carbon to the environment when organisms die
- some carbon is buried over millions of years, forming fossil fuels, which, when burned, release carbon back into the atmosphere as carbon dioxide |
| population | a group of organisms of one species living in the same area at the same time |
| community | all the populations of different species in an ecosystem |
| ecosystem | a unit containing the community of organisms and their environment interacting together |
| lag phase in growth of a bacteria colony | doubling of the numbers has little effect as numbers are so small, bacteria takes up water and nutrients to make new cytoplasm, DNA and enzymes |
| log (exponential) phase in growth of a bacteria colony | when the population is increasing rapidly, population increases by doubling and there is no limiting factors like food or water |
| death in growth of a bacteria colony | more cells are dying than are being produced, so population declines, causes of death may be lack of food, shortage of oxygen or build up of toxic waste products |
| stationary in growth of a bacteria colony | bacterial cells are dying at the same rate they are being produced, this may be because of shortage of food or waste product build up |
| factors affecting the rate of population growth | food supply, competition, predation, disease |
| how competition affects population | plants compete for light, space, water and soil nutrients, animals compete for food, space, mates |
| how predation affects population | predators may limit the growth of a population of prey animals, but the lack of prey may reduce the amount of predators |
| how disease affects population | pathogens are transmitted between individuals more easily when organisms live close together, disease can cause population crashes if the species has no resistance or immunity |
| how have humans increased food productions | machinery, chemical fertilisers, insecticides, herbicides, selective breeding |
| advantages of large-scale monocultures of crop plants | monocultures of crop plants, improves efficiency, easier to manage |
| disadvantages of large-scale monocultures of crop plants | uses more water for irrigation, harms the environment, exterminated bee colonies |
| advantages of intensive livestock production | high yield, protection of livestock, sustaining food supply with the demand |
| disadvantages of intensive livestock production | heavy deformation, excessive use of fertilizers and pesticides, poor living condition for livestock |
| biodiversity | the number of different species that live in an area |
| reasons for habitat destruction | extraction of natural resources, freshwater and marine pollution, increased area for housing crop plant production and livestock production |
| humans impact on habitats | through altering food webs and food chains, humans can have a negative impact on habitats |
| effects of deforestation | reducing biodiversity, extinction, loss of soil, flooding, increase carbon dioxide |
| Effects of untreated sewage on waterways | reduces oxygen concentration in rivers, destruction of freshwater communities |
| effects of excess fertiliser on waterways | eutrophication in fresh water |
| effects of non-biodegradable plastics | buried in ground, does not decay so it takes up space, pollutes waterways |
| sources of carbon dioxide pollution | burning fossil fuels |
| effects of carbon dioxide pollution | greenhouse gasses |
| process of eutrophication | - increased availability of nitrate and other ions
- algae bloom
- increased decomposition after death
- decreased oxygen levels
- death of other organisms in the waterways due to lack of oxygen |
| effects of methane pollution | greenhouse gasses |
| sources of methane pollution | cattle and paddy fields for growing rice, coal and oil extraction |
