Biology 2

1. Biology 2 AQA Additional Science

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

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

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

5. Diffusion The “scent particles” from this hamburger are in high concentration here: Eventually they will “diffuse” out into this area of low concentration: 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… Oxygen passes into cells by diffusion

6. 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

7. Osmosis 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): Water Sugar 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

8. Strong sugar solution Medium sugar solution Potato cells Weak sugar solution

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

10. Leaf Structure Palisade cells

11. Photosynthesis equations Sunlight Carbon dioxide + _____ glucose + _____ 6CO2 + 6H20 C6H12O6 + 6O2 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

12. Three factors can affect photosynthesis: • Temperature – the best temperature is about 300C – anything above 400C will slow photosynthesis right down • CO2– if there is more carbon dioxide photosynthesis will happen quicker • Light – if there is more light photosynthesis happens faster

13. Drawing graphs of these factors Photosynthesis is controlled by enzymes – these are destroyed at temperatures above 400C Photosynthesis increases at first but is then limited by a lack of increase in temp or light Photosynthesis increases at first but is then limited by a lack of increase in temp or CO2 1. Temperature 2. Carbon dioxide 3. Light

14. What is the glucose used for? Glucose molecules Starch molecule Glucose (sugar) can be used to make long chains of starch… 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

15. 2 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

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

17. Pyramids of biomass Cabbage Rabbit Stoat Fox Mass of foxes Mass of stoats Mass of rabbits Mass of cabbages In this food chain we can see that the mass of organisms in each stage is less than in the previous stage: We can draw a “Pyramid of Biomass” to show this pattern:

18. Energy flow in a food chain Cabbage Rabbit Stoat Fox 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: • Each organism has to ____, keep warm etc • Energy is lost through faeces (______) Consider the energy flow in this food chain: 100% 10% 1% 0.1% Words – 10%, move, sun, waste, cabbage

19. Sankey Diagrams for animals Faeces Movement Heat Cold blooded animal Warm blooded animal Faeces Movement Heat

20. Improving the efficiency of a food chain Cabbage Rabbit Stoat Fox 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: 2) Limit an animal’s movement or keep it warm: 3) Use plant hormones to regulate the ripening of fruit

21. Farming Methods There are basically two types of farming method; “intensive” and “organic”: Intensive Organic Cost Produce Fertilisers/ food Space

22. Recycling ourselves Eating Waste Death Absorption Broken down 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.

23. The Carbon Cycle CO2 in air 2. Plants release CO2 through respiration 6. These microbes also release CO2 through respiration 1. CO2 is taken in by plants for photosynthesis and turned into carbohydrates 4. Animals release CO2 through respiration 5. Animals (and plants) die and their remains are fed on by microbes and detritus feeders 3. The carbon taken in by plants is then eaten by animals

24. Introduction to Enzymes Enzyme 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: Substrate This shape can be destroyed by high temperatures or the wrong pH:

25. 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.

26. (Aerobic) Respiration 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 _________. Words – breathing, energy, grow, respiration, food

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

28. 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: Bloodstream Lipase (produced in the pancreas and small intestine) breaks fats (_____) down into fatty acids and glycerol: Words – blood, lipids, proteins, digestion, starch, smaller

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

30. Enzymes Enzymes are denatured beyond 40OC Could be protease (found in the stomach) Could be amylase (found in the intestine) Enzyme activity 400C Temp pH pH Enzymes work best in certain conditions:

31. Industrial uses of enzymes Daz 1) Enzymes are used in washing powders to help digest fats and proteins in food stains. Biological washing powders will only work on 400C 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.

32. Homeostasis Homeostasis means “controlling internal conditions”: 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

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

34. Maintaining Body Temperature Vasodilation Cold Hot Vasoconstriction

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

36. Diabetes 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

37. Modern Genetics X 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… Mendel’s experiment: Take two plants; one which is pure-bred for tallness and one pure-bred for shortness, and cross them:

38. 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”

39. 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.

40. Mitosis Each daughter cell has the same number of chromosomes and genetic information as the parent.

41. Meiosis Each daughter cell has half the number of chromosomes of the parent.

42. Mitosis vs. Meiosis • Mitosis: • Used for growth and repair of cells • Used in asexual reproduction • Cells with identical number of chromosomes and genetic information are produced • Meiosis: • Used to produce gametes for sexual reproduction • Each daughter cell has half the number of chromosomes of the parent

43. 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.

44. Boy or Girl? X Y X “Allele” XX XY Girl Boy

45. Boy or Girl? Daughter Mother Son Father

46. 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

47. Genes, Chromosomes and DNA

48. How genes work 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”

49. 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: BB Bb bb Homozygous brown-eyed parent Heterozygous brown-eyed parent Blue-eyed parent What would the offspring have?

50. Eye colour BB Bb bb Bb B B b b B b B b Bb Bb Bb Bb BB Bb bB bb Example 1: A homozygous brown-eyed parent and a blue-eyed parent: Example 2: 2 heterozygous brown-eyed parents X X Parents: Gametes: (FOIL) Offspring: All offspring have brown eyes 25% chance of blue eyes