3Features of all living things MovementRespirationSensitivityGrowthReproductionExcretionFoodAll living things are madeup of cells.
4EnzymesEnzymes are proteins that speed up chemical reactions in cells.They need a specific constant temperature to work at their optimum.Enzymes become denatured (stop working) above about 55oC.Most enzymes work best at about 40oC.The higher the temperature the faster molecules move around and therefore (a) collide more frequently and (b) collide with more energy.This results in an increased rate of reaction.lock and keyactive siteThe active site can be changed by heating above a certain temperature and altering the pH, so that the molecules can no longer fit and the reaction cannot happen.click to reactenzymemolecule
5Enzymes at work in plants Photosynthesis equation (takes place in chloroplasts)light energy6CO H2O C6H12O O2chlorophyllCarbon dioxide water glucose oxygenChlorophyll absorbs light and uses the energy to kick-startphotosynthesisGlucose is used by plant cells in 3 waysMaking other chemicals needed for cell growthStoring energy in starch moleculesReleasing energy in respiration
6Diffusion (passive transport) This is the movement of molecules from a region of their high concentration to a region of their lower concentrationRegion of high concentrationRegion of low concentrationDiffusion causes the molecules to become evenly distributed due to their random movement.It is like as if the molecules have moved from the region of high concentration to the region of low concentration.= eg oxygenDiffusion in the leaf happens through the stomata- carbon dioxide in and oxygen out
7movement of water molecules Osmosis is the same as diffusion but applies to water molecules passing through a partially permeable membrane.partially permeable membrane= starch= watermovement of water moleculesStarch molecules cannot pass through the partially permeable membrane but water molecules can.Low concentration of starchHigh concentration of starchHigh concentration of waterLow concentration of water
8If too much water passes into a cell by osmosis then it may rupture. Osmosis in plant cellscellIf too much water passes into a cell by osmosis then it may rupture.potato chiplow salt concentrationhigh salt concentrationthe potato chip absorbs water and expandsthe potato chip loses water and shrinksMolecules like glucose are moved by active transport.
9Minerals from the soilPlants take in nitrogen from the soil as nitrate ions, theyare absorbed by root hair cells.The cells use a process called active transport to pumpnitrates from the soil and into the roots against theirdiffusion gradient.
10The rate of photosynthesis Increasing the amount of light a plant receives increasesthe rate of photosynthesis up to a point.Increasing the light intensity stops having an effect on therate of photosynthesis because one of the other factors e.g.carbon dioxide, water, chlorophyll or temperature is inshort supply. This factor is called the LIMITING FACTOR
11Environments and adaptations A habitat is a place where an organism lives.A quadrat is used to survey the plants in asquare metre.The positioning of a quadrat in the area beinginvestigated is random.Samples can be taken at regular intervals alonga straight line called a transect.
12Energy for lifeAerobic respirationGlucose + oxygen carbon dioxide + water (+ energy released)C6H12O O2 6CO H2OWhat happens to the energy from respiration?used in active transportmovementbuilding molecules used for growth and repairAnaerobic respirationGlucose lactic acid (+energy released) – in animalsGlucose ethanol + carbon dioxide (+ energy released)– in plants and microorganisms
13Useful products from respiration Bioethanol (used to fuel car engines) is made fromsugars in plant material.Yeast cells take sugars and convert them into ethanolduring the process of anaerobic respiration, this is calledfermentation.Biogas is a fuel obtained from animal manure or humanwaste using bacteria, it produces methane gas.The fuel can be used to heat buildings and runelectricity generators
17Cytoplasm – where proteins are made Nucleus – where the genes are locatedDNA has a double helix structureThe base pairs always pair up the same way A to T and G to Cadenine
18Each gene codes for a specific protein nucleuscytoplasmG-A-T-C-CTAGCTAGgeneThe DNA zips up againA copy of the code is made using RNAThe DNA unzips to expose the codeThe mRNA travels to the cytoplasmThe mRNA is used to produce a protein(using ribosomes)
19This is the simplest amino acid - valine Protein is made up of amino acids joined together in chainsThe order of bases in a gene determines the order of amino acids that make a particular protein.The order of amino acids determines the 3D structure of a particular protein.The 3D structure of a protein determines its function (job)
20Cell divisionMitosis involves copying the chromosomes exactlyCell division by mitosis produces two new cells identical to each other and to the parent cellMeiosis is a type of cell division that produces gametes, ie sperm and egg cells.Cells produced by meiosis only contain half the chromosome number of the parent cell
22In a human embryo, up to the eight cell stage, all the cells are identical and could produce any sort of cell required by the organism (embryonic stem cells);After this point the cells become specialised and form different types of tissue.Adult and embryonic stem cells have the potential to produce cells needed to replace damaged tissues.In carefully controlled conditions of mammalian cloning, it is possible to reactivate inactive genes in the nucleus of a body cell to form cells of all tissue types.
23Making stem cells using the DNA from a patient means the cells wont be rejected when they are transplanted into the patientThis means that the patient’s immune system wont attack the transplanted stem cellsXThe antibodies help to kill the foreign cellforeign cell with antigenWhite blood cells recognise it as a foreign cell and make antibodiesWith this technique the white blood cells do not recognise the transplanted stem cells as foreign and therefore don’t attack them
24New cells in plants specialise into cells of roots, leaves or flowers. Some plant cells remain unspecialized and can develop into any type of plant cell, unlike animal cells.Most plants continue to grow in height and width throughout their lives, unlike animals.Plant meristems divide to produce cells that result in increased height, length of roots, and girth of the plant.If the hormonal conditions in their environment are changed, unspecialised plant cells can develop into a range of other tissuesTransport vessels:xylem and phloemOrgans: leaves, roots and flowers
25Cut stems from a plant can develop roots in the presence of plant hormones (auxins) and grow into a complete plant which is a clone of the parent.
26shoot tipThe action of light causes auxin to move across the shoot tip from the side getting the light to the shaded side.This causes the cells on the shaded side to elongate which causes the stem to bend towards the light.This helps the plant to grow towards the light which helps its survival.plant stem
47neurotransmitter receptor site axon dendrite synapse acetylcholine The neurotransmitter diffuses across the gapReceptor molecules only bind to specific chemicals, initiating a nerve impulse in the motor neuron.
48At the end of a sensory neuron an impulse triggers the release of chemicals into the synapse, which diffuse across and bind to receptor molecules on the membrane of a motor neuron.
49stimulus is detected by a receptor Sequencestimulus is detected by a receptornerve impulse travels along a sensory neuroneneurotransmitter diffuses across a synapsenerve impulse travels along a relay neuroneat the same timenerve impulse travels along a neurone to the brainneurotransmitter diffuses across a synapsenerve impulse travels along a motor neuronemuscle contracts / hormone is released from a glandConscious awareness of the stimulus
50stimulusreceptorsensory neurone (nerve)central nervous system (brain and spinal cord)motor neurone (nerve)effector (muscle or gland)nervous systems use electrical impulsesFast and short lived responses
51Glands in the body melanin ADH ACTH, FSH, LH, growth H thyroxine PTH Involved in producing T cellsadrenalineInsulin, glucagonoestrogen, progesteronetestosterone
52Hormones are chemicals which travel in the blood Hormonal controlControl of blood sugarHigh blood sugar levelLow blood sugar levelHormones are chemicals which travel in the bloodinsulin released from the pancreasglucagon released from the pancreasslow and long lastingdecrease in blood sugar levelincrease in blood sugar levelhomeostasis
53How can reflex actions be an advantage for survival ?
54A new born baby has a set of reflex actions, eg: Grasping reflex: Touching a baby’s palm will cause the baby’s fingers to curl.Sucking reflex: Putting an object in a baby’s mouth will cause the baby to suck the object .Diving reflex: Putting a baby in water will cause the baby to hold it’s breath and move it’s arms around
55Pupil reflexWhen the surroundings get darker the iris relaxes causing the pupil to dilateWhen the surroundings get lighter the iris contracts causing the pupil to get smallerThis reflex helps to protect the light sensitive receptors in the eye when it is too light and to get more visual information when dark.
56Some caterpillars have a poisonous toxin in their skin. Some birds develop a learned conditioned reflex or have an evolved reflex to avoid eating particular caterpillars on the basis of their colours.
57Simple animals rely on reflex actions for the majority of their behaviour
58This is a reflex response to move towards lighter areas This is a unicellular organism which needs light to survive, eg plankton
67adrenaline / epinephrine Neurotransmitters[you don’t have to know the structures]dopamineseratoninmelatoninCentral nervous systemPeripheral nervous systemacetylcholineadrenaline / epinephrine
68reasoningspatial sensevisualcerebral cortexmovementauditory, speechessential functionsThe cerebral cortex is the part of our brain most concerned with intelligence, memory, language and consciousness.
69A variety of methods can be used to map the brain CT scannerMRI scannerCT and MRI scanners can be used to get images of structures.PET scanners can be used to monitor activity in the brainPET scanner
70Electrical stimulation of the brain can be used in studies
71MDMA - ecstasyEcstasy blocks the re-uptake of serotonin in the synapses of the brain.This causes an increase in the serotonin concentration which leads to mood-enhancing effects.
72Eventually we build up a vast array of efficient pathways. During development, the interaction between mammals and their environment results in neuron pathways forming in the brain.Here, neuron pathways in the visual cortex interplay with neuron pathways in the motor cortex in order to grab an object.Story about how a baby learns to grab thingsAfter many attempts the neuron pathways get fine tuned to produce the responses that we intend.Eventually we build up a vast array of efficient pathways.
73Click 1 then 2 then 3 then 4 1 2 3 4 Brain stem The second set of nerve cells are not stimulated enough to fire2One of the nerve cells in the second set receives enough input to fireOne of the nerve cells in the second set receives enough input to fire and this neuronal pathway is strengthened by a nerve impulse from the brain stem34The neuronal pathway doesn’t need the extra input to workBrain stemThis gives you a very basic idea about how neuron pathways are formed
74This is why some skills may be learnt through repetition. Learning is the result of experience where certain pathways in the brain will become more likely to transmit impulses than others.This is why some skills may be learnt through repetition.The variety of potential pathways in the brain makes it possible for animals to adapt to new situations.There is evidence to suggest that children may only acquire some skills at a particular age, eg language development in feral children.A feral child is one who has been brought up by wild animals from early childhood.
75Memory is basically the storage and retrieval of information. Verbal memory can be divided into short-term memory and long-term memory.Humans are more likely to remember information if:they can see a pattern in itthere is repetition of the information, especially over an extended period of timethere is a strong stimulus associated with it, eg colour, light, smell, sound etc
76By the time you have become consciously aware of the snake your brain has already set into play a series of responses.