13/06/2016 Biology 2 AQA Additional Science

13/06/2016 A typical plant cell: Cell wall – made of cellulose which strengthens the cell Cell membrane – controls what comes in and out Nucleus – controls what the cell does and stores information Large vacuole – contains sap and helps support the cell Cytoplasm – Chemical reactions happen here Chloroplasts (containing chlorophyll) – this is needed for photosynthesis

13/06/2016 4) 1) 5) 3) A Typical Animal Cell Ribosomes – protein synthesis happens here Mitochondria - energy is released here Cell Membrane – controls what comes in and out Cytoplasm - this is where the reactions happen and these are controlled by enzymes 2) Nucleus – controls the cell’s activities

13/06/2016 More specialised animal cells Red Blood Cell Carries oxygen around the body No nucleus and large surface area I.D: Function: Features: White blood cell Egg cell (ovum) Ciliated epithelial cell Nerve cell (neurone)

13/06/2016Diffusion Diffusion is when something travels from an area of high concentration to an area of low concentration. For example, consider the scent from a hamburger… The “scent particles” from this hamburger are in high concentration here: Eventually they will “diffuse” out into this area of low concentration: Oxygen passes into cells by diffusion

13/06/2016 Diffusion Summary Diffusion is when particles spread from an area of high concentration to an area of ___ concentration. The particles move along a “concentration _____” and this process takes no _____ (it’s a “passive” process”). Diffusion can be accelerated by increasing the _______ of the particles, which makes them move _______. Words – faster, low, gradient, temperature, energy

13/06/2016Osmosis Osmosis is a “special kind of ___________”. It’s when water diffuses from a __________ area to a less concentrated area through a partially permeable _________ (i.e. one that allows water to move through but not anything else): WaterSugar solution In this example the water molecules will move from left to right (along the concentration ______) and gradually _____ the sugar solution. Words – membrane, concentrated, dilute, diffusion, gradient

13/06/2016 Strong sugar solution Medium sugar solution Weak sugar solution Potato cells

13/06/2016 Travels up from the roots WATER CARBON DIOXIDE Enters the leaf through small holes on the underneath SUNLIGHT Gives the plant energy CHLOROPHYLL The green stuff where the chemical reactions happen Photosynthesis – the 4 things you need

13/06/2016 Leaf Structure Palisade cells

13/06/2016 Carbon dioxide + _____ glucose + _____ 6CO 2 + 6H 2 0C 6 H 12 O 6 + 6O 2 Sunlight Chlorophyll Sunlight Chlorophyll The GLUCOSE produced by photosynthesis is used by the plant for _______ (through ____________). It is stored in the plant as ___________. Words – respiration, starch, water, oxygen, energy Photosynthesis equations

13/06/2016 Three factors can affect photosynthesis: 1.Temperature – the best temperature is about 30 0 C – anything above 40 0 C will slow photosynthesis right down 2.CO 2 – if there is more carbon dioxide photosynthesis will happen quicker 3.Light – if there is more light photosynthesis happens faster

13/06/2016 Drawing graphs of these factors 1. Temperature Photosynthesis is controlled by enzymes – these are destroyed at temperatures above 40 0 C 2. Carbon dioxide 3. Light Photosynthesis increases at first but is then limited by a lack of increase in temp or CO 2 Photosynthesis increases at first but is then limited by a lack of increase in temp or light

13/06/2016 What is the glucose used for? Glucose (sugar) can be used to make long chains of starch… Glucose molecules Starch molecule This glucose is then used by the plant as a store of _____ and some of it may be used for _________. The energy released from respiration can be used to make ______ acids or to build up fats and _____ as a food store in a _____. Words – seed, amino, glucose, respiration, oils

13/06/ common nutrients… Nitrates:  Used to make proteins  Lack of it leads to stunted growth Magnesium:  Used to make chlorophyll  Lack of it leads to yellow leaves

13/06/2016 Food chains A food chain shows where the energy goes in a food chain (in other words, “what gets eaten by what”): Cabbage Rabbit Stoat Fox The arrows indicate where the energy is going Plants convert the sun’s energy into food

13/06/2016 Pyramids of biomass In this food chain we can see that the mass of organisms in each stage is less than in the previous stage: CabbageRabbitStoatFox We can draw a “Pyramid of Biomass” to show this pattern: Mass of cabbages Mass of rabbits Mass of stoats Mass of foxes

13/06/2016 Energy flow in a food chain Consider the energy flow in this food chain: CabbageRabbitStoatFox 100%10%1%0.1% Clearly, not all of the ___’s energy that becomes stored in the _______ will end up in the fox. Only around ______ is passed on to the next stage in each food chain. Energy is lost at each stage because of a number of reasons: 1)Each organism has to ____, keep warm etc 2)Energy is lost through faeces (______) Words – 10%, move, sun, waste, cabbage

13/06/2016 Sankey Diagrams for animals Cold blooded animalWarm blooded animal Faeces Movement Heat Faeces Movement Heat

13/06/2016 Improving the efficiency of a food chain Clearly, food chains aren’t very efficient. How could the efficiency of a food chain be improved? 1) Reduce the number of stages in the chain: Cabbage Rabbit Stoat 2) Limit an animal’s movement or keep it warm: Fox 3) Use plant hormones to regulate the ripening of fruit

13/06/2016 Farming Methods There are basically two types of farming method; “intensive” and “organic”: IntensiveOrganic Cost Produce Fertilisers/ food Space

13/06/2016 Recycling ourselves Microbes are the key to this – they break down waste and dead bodies so that the products can be used by plants for growth. Microbes work best in warm, moist conditions where there is plenty of oxygen. Eating Waste Death Broken down Absorption

13/06/2016 The Carbon Cycle CO 2 in air 1. CO 2 is taken in by plants for photosynthesis and turned into carbohydrates 2. Plants release CO 2 through respiration 3. The carbon taken in by plants is then eaten by animals 5. Animals (and plants) die and their remains are fed on by microbes and detritus feeders 6. These microbes also release CO 2 through respiration 4. Animals release CO 2 through respiration

13/06/2016 Introduction to Enzymes Enzymes are biological catalysts. They help the reactions that occur in our bodies by controlling the rate of reaction. An enzyme is basically a protein molecule made up of long chains of amino acids. These molecules are then “folded” to create a certain shape: The enzyme’s shape helps another molecule “fit” into it: This shape can be destroyed by high temperatures or the wrong pH: Enzyme Substrate

13/06/2016 Enzyme use in nature Cells use glucose to generate energy – this process is called “respiration”. Respiration happens in mitochodria and is catalysed by enzymes. Photosynthesis is catalysed by enzymes in the cells.

13/06/2016 (Aerobic) Respiration Words – breathing, energy, grow, respiration, food All living organisms have to move, _____, reproduce etc. Each of these life processes needs ENERGY. ___________ is the process our bodies use to produce this energy: Glucose + oxygen water + carbon dioxide + ENERGY The glucose we need comes from ______ and the oxygen from _________. Water and carbon dioxide are breathed out. The MAIN product of this equation is _________.

13/06/2016 Uses for this energy Animals and plants have many uses for the energy they generate from respiration: 1)To perform the life processes, such as moving, _____ etc 2)To build up body _______ 3)To maintain a constant body ___________ (warm-blooded mammals only) 4)To build up sugars, ________ and other nutrients in plants 5)To build up amino acids and ________ Words – nitrates, tissue, proteins, respiration, growing, temperature

13/06/2016 Enzymes in digestion Enzymes can be produced by the body to help _______. When they come into contact and react with food they break it down into ______ pieces which can then pass into the ______: Carbohydrase (produced in the mouth, pancreas and small intestine) breaks _______ (a carbohydrate) down into glucose: Protease (produced in the stomach, pancreas and small intestine) breaks _______ down into amino acids: Lipase (produced in the pancreas and small intestine) breaks fats (_____) down into fatty acids and glycerol: Words – blood, lipids, proteins, digestion, starch, smaller Bloodstream

13/06/2016 Bile and The Liver Bile is a chemical produced in the liver and stored in the gall bladder. It has 2 functions: 1)It neutralises stomach acid and produces alkaline conditions for enzymes to work in 2)It emulsifies (“breaks down” fats: Fat globules Fat droplets

13/06/2016 Enzymes are denatured beyond 40 O CEnzymes Enzymes work best in certain conditions: Enzyme activity TemppH 40 0 C Could be protease (found in the stomach) Could be amylase (found in the intestine)

13/06/2016 Industrial uses of enzymes 1) Enzymes are used in washing powders to help digest fats and proteins in food stains. Biological washing powders will only work on 40 0 C or lower. 2) Enzymes are used in baby foods to “pre-digest” the proteins. 3) Enzymes are used to convert starch into sugar which can then be used in food. 4) Conversion of glucose into fructose – glucose and fructose are “isomers” (they have the same chemical formula), but fructose is sweeter.

13/06/2016Homeostasis Homeostasis means “controlling internal conditions”: Waste products that need to be removed + how CO 2 Urea Internal conditions that need controlling + how Temperature Ion content Water content Blood glucose Produced by respiration, removed via lungs Produced by liver breaking down amino acids, removed by kidneys and transferred to bladder Increased by shivering, lost by sweating Increased by eating, lost by sweating + urine Increased by drinking, lost by sweating + urine Increased and decreased by hormones

13/06/2016 Controlling Body Temperature Wow it’s hot! Also, temperature sensors in the skin detect the heat and send information to the brain. The thermoregulatory centre in the brain detects “warm blood”. When the brain detects the high temperature it takes two main steps....

13/06/2016 Maintaining Body Temperature ColdHot Vasodilation Vasoconstriction

13/06/2016 Controlling Blood Sugar levels We need glucose in our bodies to help our cells to respire and produce energy. What happens if we have too much glucose? If blood sugar is too high the pancreas releases insulin The liver then converts glucose into insoluble glycogen and is removed from the blood

13/06/2016Diabetes Diabetes is a ________ in which a person’s blood sugar (i.e. glucose) level may rise to a _______ level. This is because the ______ doesn’t produce enough _________. Diabetes can be treated by __________ carefully or by injecting extra insulin when needed. Diabetics have to test their blood sugar level before they decide how much insulin to _______ themselves with. Words – insulin, disease, inject, dangerous, eating, pancreas

13/06/2016 Modern Genetics Guten tag! My name is Gregor Mendel. I am the father of modern genetics because of the work I did on pea plants in 1865… Take two plants; one which is pure-bred for tallness and one pure-bred for shortness, and cross them: X Mendel’s experiment:

13/06/2016 Modern Genetics All the plants produced were tall. Now cross two of these plants… 3 out of every 4 plants were tall, leading Mendel to hypothesise that “for every characteristic there must be two determiners”

13/06/2016 Modern Genetics Achtung! Unfortunately, nobody knew about chromosomes or genes when I published my findings so no one believed me until after my death, when more powerful microscopes were available.

13/06/2016Mitosis Each daughter cell has the same number of chromosomes and genetic information as the parent.

13/06/2016Meiosis Each daughter cell has half the number of chromosomes of the parent.

13/06/2016 Mitosis vs. Meiosis Mitosis: 1.Used for growth and repair of cells 2.Used in asexual reproduction 3.Cells with identical number of chromosomes and genetic information are produced Meiosis: 1.Used to produce gametes for sexual reproduction 2.Each daughter cell has half the number of chromosomes of the parent

13/06/2016 Sexual Reproduction The human egg and sperm cell (“GAMETES”) contain 23 chromosomes each and are created by meiosis. When fertilisation happens the gametes fuse together to make a single cell called a ZYGOTE. The zygote has 46 chromosomes (23 pairs) and continues to grow through mitosis.

13/06/2016 Boy or Girl? XY X XXXY GirlBoy “Allele”

13/06/2016 Father Mother Son Daughter Boy or Girl?

13/06/2016 Key words Gamete Zygote Allele Dominant Recessive Homozygous Heterozygous This allele determines the development of a characteristic This is formed when an egg is fertilised by a sperm This allele will determine a characteristic only if there are no dominant ones This word refers to a pair of chromosomes being made of two different alleles of a gene An egg or a sperm are called this This word refers to a pair of chromosomes being made of two of the same alleles of a gene An alternative form of a gene

13/06/2016 Genes, Chromosomes and DNA

13/06/2016 Some facts: - Made up of paired bases - Contain instructions on what a cell does, how the organism should work etc - The instructions are in the form of a code - The code is made up from the four bases that hold the strands together - The bases represent the order in which amino acids are assembled to make proteins - Everyone (apart from identical twins) has different DNA and people can be identified by “DNA finger printing” How genes work

13/06/2016 Eye colour In eye colour the brown eye allele is dominant, so we call it B, and the blue eye is recessive, so we call it b: bbBBBb Homozygous brown-eyed parent Heterozygous brown-eyed parent Blue-eyed parent What would the offspring have?

13/06/2016 Eye colour Example 1: A homozygous brown-eyed parent and a blue-eyed parent: Example 2: 2 heterozygous brown-eyed parents BBbb X Bb X Parents: Gametes: Offspring: Bb BBBbbbbB BBbbBbBb (FOIL)(FOIL) All offspring have brown eyes25% chance of blue eyes

13/06/2016 Eye colour Example 3: A heterozygous brown-eyed father and a blue-eyed mother: Bb bb bbBb Equal (50%) chance of being either brown eyed or blue eyed.

13/06/2016 Bb b b Another method Example 3: A heterozygous brown-eyed father and a blue-eyed mother: Bb bBbbb bBbbb Father Mother

13/06/2016 Example questions 1) In mice, white fur is dominant. What type of offspring would you expect from a cross between a heterozygous individual and one with grey fur? Explain your answer with a genetic diagram. 2) A homozygous long-tailed cat is crossed with a homozygous short-tailed cat and produces a litter of 9 long-tailed kittens. Show the probable offspring which would be produced if two of these kittens were mated and describe the characteristics of the offspring (hint: work out the kitten’s genotype first).

13/06/2016 Inherited diseases 1) Cystic fibrosis – a disease that causes thick and sticky mucus to coat the lungs, gut and pancreas. It’s caused by recessive alleles: 2) Huntingdon's disease – a disease of the nervous system that causes shaking and eventually dementia. It’s caused by a dominant allele: Embryos can be screened for alleles that cause these diseases before birth. FfFfFfFf X CcCccc X

13/06/2016 Stem Cells A while ago we considered examples of specialised cells: White blood cell Egg cell (ovum) Ciliated epithelial cell Nerve cell (neurone) A “stem cell” is a cell that hasn’t yet become specialised and can be found in embryos or bone marrow. These cells can be used to treat certain conditions but the use of these cells is very controversial.

13/06/2016 Research tasks Task Present an argument concerning one of these two topics: 1) Use of stem cells from embryos in medical research 2) The use of embryo screening to identify deformities