Biology Unit B3

1. Biology Unit B3 EdExcel Triple Science N Smith St Aidan’s

2. Topic 1 – Control Systems

3. The Urinary System Renal artery Renal vein Ureter (tube that takes urine down to bladder) Bladder and urethra Metabolism in cells causes us to produce waste products such as carbon dioxide and urea. Urea is formed by the breaking down of amino acids in the liver and kidneys are responsible for removing it.

4. Dialysis Partially permeable membranes Dialysis fluid Blood Dialysis fluid Sometimes kidneys can fail due to infections, toxic substances or genetic reasons. One possible answer is to use a dialysis machine: Urea Sugar Sugar Urea Urea and salt diffuse out of the blood into the dialysis fluid. Also, the dialysis fluid contains the same concentration of sugar and minerals as the blood so these don’t diffuse.

5. Kidney transplants Instead of dialysis a kidney could be transplanted into the patient. This option is cheaper than _____ but it requires a _______ (a normal person can still function with one kidney). This donor must have a similar ______ type to the patient. Also, the new kidney might be rejected by the body’s ______ system which will try to destroy the new organ by using _______ to attack the antigens on the surface of the kidney. To work around this problem the patient can take “immunosuppresant ___” which suppress the immune system. Words – dialysis, donor, immune, tissue, drugs, antibodies

6. Kidneys 1. ULTRAFILTRATION - Lots of water and products of digestion are squeezed out of the blood and into tubules under pressure. 2. SELECTIVE REABSORPTION – the blood takes back the things it wants (e.g. glucose and ions) even though this means going against a concentration gradient. 3. WASTE – excess water, excess ions and any urea are now removed through the ureter Kidneys work in 3 stages: Blood vessel Tubule

7. Kidney structure 1) Ultrafiltration happens in the glomerulus and Bowman’s capsule 2) Selective reabsorption happens in the convoluted tubules 3) Excretion

8. Controlling Water Content – “Negative Feedback” Low blood water level causes a high salt concentration Receptors in the hypothalamus detect the high salt content More ADH is secreted into the blood The kidney becomes more permeable to water so more is absorbed. The bladder fills with a small quantity of urine Normal blood water level is achieved.

9. Controlling Water Content 2 High blood water level causes a low salt concentration Receptors in the hypothalamus detect the low salt content Less ADH is secreted into the blood The kidney becomes less permeable to water so more is absorbed. The bladder fills with a large quantity of urine Normal blood water level is achieved.

10. Fertility The amount of glucose in our blood is an example of a process controlled by hormones. Hormones are “chemical messengers”, produced by glands and transported by blood. Another example of a process controlled by hormones is the menstrual cycle, where hormones can... • …stimulate the release of eggs • …inhibit the release of eggs In normal circumstances natural hormones are responsible for releasing the egg and for thickening the lining of the womb. These hormones are produced by the pituitary gland in the brain and in the ovaries.

11. The 4 stages of the menstrual cycle: Thickness of uterus lining Day 0 Day 4 Day 14 Day 21 Day 28 Day 1: Bleeding starts when the lining of the uterus breaks down and passes out the vagina – “Having a period” Day 4: The lining starts to build up again and thickens into a spongy layer of blood cells Day 14 (approx): An egg is released and lasts for around 3 days Day 28: The lining stays thick awaiting the arrival of a fertilised egg. If one doesn’t come then the lining breaks down again.

12. Fertility Step 3: LH stimulates the release of the mature egg at day 14. The remains of the follicle develop into a structure called a “corpus luteum” which then secretes progesterone Step 1: FSH produced by the pituitary gland causes both a follicle (an egg and its surrounding cells) to mature and the ovaries to start producing oestrogen Step 2: The rising levels of oestrogen cause the uterus lining to thicken and the pituitary gland to stop producing FSH and produce LH instead 4 hormones are involved in the menstrual cycle: oestrogen, progesterone, LH and FSH. Here’s how: Step 4: The progesterone then maintains the lining of the uterus and inhibits production of FSH and LH. When the level of progesterone falls (and there’s a low oestrogen level) the lining breaks down. This allows FSH to be produced and the process starts again. If the woman is pregnant then progesterone levels stay high.

13. The Menstrual Cycle Thickness of uterus lining Day 0 Day 7 Day 14 Day 21 Day 28 Progesterone – produced by the empty ________ and maintains the ______. If egg is _______ progesterone continues to be produced to maintain the lining for the fertilised egg Hormone concentration Oestrogen – produced in the _______ and causes the lining of the uterus to ______ Words – follicle, lining, ovaries, thicken, fertilised

14. Eggs Nucleus The nucleus in the egg cell is a “_______”, meaning it only contains one set of _______ material and isn’t complete until it is ______. When this happens the egg’s membrane changes its structure to stop any more _______ getting in. Words – nutrients, sperm, fertilised, haploid, genetic The female egg cell is an example of a gamete: The egg cell is basically an enlarged cell with massive _______ reserves in the cytoplasm

15. Sperm Haploid nucleus A middle section with lots of ________ to produce a lot of _______ The head has an acrosome packed with “enzymes” to ______ its way through the egg’s ________ Strong tail for ________ The sperm cell is also specialised: Words – swimming, energy, mitochondria, digest, membrane

16. IVF Some couples cannot have children naturally. In-vitro fertilisation (IVF) can help. Here’s how it works: 1. Eggs are removed from the womb and placed in a solution of oxygen and water to keep them alive 2. Sperm is added 3. The fertlised egg is allowed to grow into an embryo (a group of 4-8 cells) 4. Usually 3 of these embryos are transferred back into the uterus

17. Other fertility treatments Artificial insemination – this is used when the sperm count is low or if a woman’s oviducts are blocked. Sperm is put directly into the uterus and oviducts to increase the chance of fertilisation. Egg donation – if the woman cannot produce eggs herself eggs can be donated by another woman which are then fertilised using IVF treatment (see next slide) Ovary transplants – these are used if a woman’s ovaries do not function Surrogacy – this is when an embryo produced through IVF is implanted into a surrogate mother who then carries the baby. When the baby is born he/she is given to the biological parents.

18. Boy or Girl? X Y X XX XY Girl Boy

19. Boy or Girl? Daughter Mother Son Father

20. Genetic Diagrams xx xy x y x x xx xx xy xy Here’s what happens (genetically) when an egg is fertilised: Mother Father Equal (50%) chance of being a boy or a girl

21. Genetic Diagrams Here’s another way of drawing it: Father Mother

22. Inheriting colour blindness and haemophilia X XNXn XnY Parents: Gametes: Y XN Xn Xn XNXn XNY XnXn XnY Colour blindness and haemophilia are two “sex-linked” genetic disorders - they are caused by faulty alleles located on sex chromosomes. For example, here’s a female who carries the recessive allele for colour blindness crossed with a “normal” male: XN = Normal colour vision allele Xn = faulty colour vision allele (FOIL) Offspring: Carrier female Normal male Normal female Colour blind male

23. Bacteria revision No. of bacteria Bacteria – containing cytoplasm and a membrane surrounded by a cell wall. The genes are NOT in a distinct nucleus. Time In unit B2 we met bacteria: Bacteria grow VERY fast. For example, if a certain bacteria doubles itself every 5 minutes calculate how many bacteria you would have after one hour.

24. How our bodies fight bacteria You’re going down Step 1: The lymphocyte “sees” the pathogen (bacteria) Step 2: The cell produces antibodies to “fit” the pathogen Step 3: The antibodies fit onto the pathogens and cause them to “clump” Step 4: The pathogens are “eaten” by the white blood cells

25. Vaccinations Vaccinations work by doing the following: • A harmless ________ or antigenic material is introduced • The antigens trigger an ________ response which causes the production of _________ • The antigens also trigger the production of “_______ lymphocytes” that “_______” the illness in case your body is exposed to the real pathogen in the future. Vaccinations can also cause concerns, such as the recent controversy over the _____ vaccine. Words – remember, pathogen, immune, MMR, memory, antibodies

26. The Development of Vaccinations In 1796 Jenner took bits of scab from a girl who had ______ (a less deadly disease than smallpox). He then put them into a cut in the arm of a boy and then exposed the boy to ________ and discovered that the boy was ______ to it. Edward Jenner, 1749-1823 The vaccination worked because the cowpox _____ triggered the boy’s B-lymphocytes to produce _______. Smallpox has the same antigens as cowpox so when the boy was exposed to smallpox his body quickly made antibodies for it. Words – smallpox, cowpox, antibodies, antigens, immune Hi. I was a doctor in England and in the late 18th Century I discovered that you can vaccinate people against smallpox:

27. Specific antibodies Microbe Antigen Antibodies are specific – they will neutralise the microbe they have been made for. They do this by recognising the antigen on the surface of the microbe. Once the body has made the antibody “memory cells” can make it again very quickly if needed, which protects you from catching the disease again.

28. Immunity to later infections When the person catches the disease again at a later time the body responds much quicker Concentration of antibody in the blood Time When this person first catches a disease the response takes time Memory lymphocytes then stay in the body for a long time

29. Vaccinations For Against MMR vaccine Some people argue that the MMR vaccine is a good idea, others think it is a bad idea. Briefly summarise each side of the argument:

30. Vaccination Policies Is the infection a big risk? Is the vaccine safe? Factors to consider about vaccinations Who is at risk? How much does it cost?

31. Monoclonal Antibodies Monoclonal antibodies are basically “identical antibodies” that can be made to bind to anything you want. They are the same because they are made from the same parent cell. Here’s how: Eek! Step 1: Take an animal (e.g. mouse) and inject it with an antigen Step 2: Extract the B-lymphocytes that the mouse makes in reaction to the antigen Step 3: Fuse this lymphocyte with fast-growing tumour cells to make a “hybridoma” (a cell that produces lots of antibodies) Step 4: The hybridoma then divides really quickly (due to it being made from a tumour cell) which gives you lots of identical antibodies called monoclonal antibodies

32. Uses of Monoclonal Antibodies Diagnosis of cancer and the location of cancerous cells Pregnancy testing What are monoclonal antibodies used for? Treating cancer by targeting specific cancerous cells Task: Find out how monoclonal antibodies are used in each of the above uses.

33. Louis Pasteur Pasteur, 1822 - 1895 I did a lot of work on germs in the 1850s. The process of “pasteurising milk” is named after me. Pasteur took two flasks and put some boiled broth in each one. One of the flasks had a curve in it, the other one didn’t. He observed the fact that the broth in the non-curved flask went bad but the one with the curved neck didn’t – what was his conclusion?

34. Drugs from Plants Plants produce chemicals to defend themselves against pests: Back off Some of these chemicals can be used as drugs to treat human diseases or to relieve pain symptoms. Some examples: • Aspirin – made from a chemical found in the leaves and bark of a willow tree • Taxol – an anti-cancer drug from the bark of the Pacific yew tree • Quinine – used for treating malaria, it comes from the South American cinchona tree

35. Plant Diseases and Pests Plant disease Damage by pests How might these factors affect the availability and price of food? Bad weather Weeds

36. Periodicity in Plants and Animals Many plants and animals show various forms of periodicity. For example: • Plants show “photoperiodicity” – this means that they respond to changes in the length of a day. For example, many plants only flower at the start of the summer season whereas other plants only flower in autumn. Doing this means that they flower when the right insects for pollination are around. • Animals, plants and microorganisms show “Circadian Rhythms” – rhythms that follow a 24-hour cycle. For example, sleep patterns are affected by hormonal reaction to light and the body’s production of urine also slows down overnight. Plants control their stomata using similar rhythms.

37. Topic 2 - Behaviour

38. Mating Patterns Here’s a random selection of animals: This is my harem! Animals have many different mating strategies – some will have one mate for life, others will have one mate for each mating season while others have many mates.

39. Behavioural Strategies Most animals engage in some sort of display that advertises their qualities… Some animals, particularly birds and mammals, have developed special behaviours for looking after their young (which can sometimes endanger the parents): These behavioural adaptations can increase the chances of survival and increase the chance of the parental genes being passed on.

40. Types of Animal Behaviour 1) Innate behaviour – this is when an animal does something almost by instinct, e.g. feeding from a bottle. 2) Learned behaviour – this is when an animal learns from a previous experience and changes its behaviour accordingly. Having a lot of learned behaviour can lead to “habituation” – the animal learns not to respond to something. Whatever 3) Imprinting – this is when an animal recognises its parents and instinctively follows them around, a combination of learned behaviour and innate behaviour.

41. Classical Conditioning - Pavlov’s Dog Ivan Pavlov, 1849-1936 I won the Nobel Prize in 1904 and am most famous for investigating “conditioned responses”: • Steak + dog = saliva • Steak + bell + dog = saliva • Bell + dog = saliva

42. Operant Conditioning – Skinner’s Box Burrhus Skinner, 1904-1990 Conditioning is a form of learned behaviour and there are two main types: Operant conditioning is when an animal learns a behaviour by trial and error, i.e. by learning that some behaviours give a reward whereas others don’t. For example, consider my Skinner Box: Combinations of classical and operant conditioning are used to train animals such as police horses, sniffer dogs and dolphins. How?

43. Signals in Animals Animals use a variety of ways to communicate with each other, such as: Squawk Sound signals: Chemical signals (pheromones): Visual signals (e.g. gestures and body language):

44. Studying Behaviour in Animals Task: summarise the work of the following ethologists: • Tinbergen, who studied innate behaviour in gulls • Fossey, who studied social behaviour in gorillas • Goodall, who studied social behaviour in chimpanzees • Lorenz, who studied imprinting in geese For each of these people find out how they studied this behaviour and some of their main observations and conclusions.

45. Signals in Plants Back off As we’ve said before, plants can use chemicals to warn off unwanted insects: They can also use chemicals to attract insects, such as bees to help them pollinate. Plants can also release chemicals to warn other plants of predators: My friend is in danger – I’m going to harden my leaves Yum

46. Co-Evolution in Plants and Animals Co-evolution is when two organisms evolve in ________ to each other. For example, consider an orchid: Orchids have a very deep store of _____ so only certain types of ____ can reach it. This may mean that this type of moth will probably only pollinate other ______. Some plants are also poisonous to most insects. This means that the ones who can eat it have an evolutionary ________ over other insects while the plant in question has evolved a defence mechanism to help it protect itself. Words – advantage, response, orchids, moth, nectar

47. Human Evolution Task: Find out how the following famous fossil hominids have provided evidence for human evolution: • Ardi (4.4 million years old) • Lucy (3.2 million years old) • Various fossil hominids found by Leakey (1.6 million years old) For each fossil find suitable images and explain how these images show human development over the last few million years. Then find images to show the development of tools over the last 2 million years and how these tools show human evolution.

48. Mitochondrial DNA Recall our basic animal cell: These are mitochondria and they have a small piece of DNA inside them Mitochondrial DNA is only inherited from your mother. Everyone on Earth has similar mitochondrial DNA but it also has a high mutation rate. Scientists have used the mutation rate and the fact that it is only passed down by the mother to come to this conclusion: Everyone on Earth has descended from ONE WOMAN – scientists call her “Mitochondrial Eve” or “African Eve” and she lived in Africa around 200,000 years ago. Scientists can also use Nuclear DNA to study human evolution and migration. However, mitochondrial DNA is more useful as there are lots of mitochondria in one cell and mitochondrial DNA degrades less over time.

49. Climate Change and Human Behaviour As humans migrated out of Africa they would have moved to a different climate. How would they have had to adapt their behaviour to this new climate? Changes in diet Hunting methods Changes in human behaviour due to a different climate Getting food from trees/fish Use of tools/clothes

50. The Effect of the Ice Age Ice ages are very long periods of time where the climate goes very cold and ice sheets and glaciers spread across most of the Earth. To survive the last ice age what would early humans have had to do? Think about the following: • Where they would live • What they would do for heating • How their clothing would change • How their hunting patterns changed • Use of tools • How their cooperation and communication might have had to change