AQA BIOLOGY paper 2 notes (combined science-trilogy)

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homologous chromosomes as the pair that isn't, determines the sex Punnett square- diagram which shows all possible Genetic outcomes dominant- only need one gene to express characteristics, always expressed recessive- need two identical recessive genes to express the characteristic homozygous- genes are the same, two same alleles. heterozygous- genes are different, two different alleles. genotype- what genes you have, what alleles are present. phenotype-collection of characteristics that you have (how you look) amino acids- molecules that combine to form proteins. gamete-sex cell carrier- someone carries the recessive allele for a disease but does not have the disease www.Primrosekit.com @primrose kitten Rr mothers genotype mothers phenotype: Camer Rr fathers genotype fathers phenotype Carrier mothers gametes fathers gametes: polydactyly- Pother L mother R RR homozygous non-suffer Rr heberggygous Camer 8. Primorse Kitten fe R-dominant r-recessive heterog, gour Camer гг homozygous Suff ● ● ● ● ● www.Primrosekit.com #primrose kitten mothers genotype: dd mothers phenotype five fingers. Dd Six fingers fathers genotype fathers phenotype mothers gametes fathers gametes. cystic fibrosis- an inherited conditions that causes you to have extra digits to have polydactyly, one parent must have the disease a dominant allele causes polydactyly. dd= no polydactyly heterozygous child for polydactyly has the disease. if both parents are Dd, the chance of the child having it is 3/4 if one parent has DD and other is dd, the child will have polydactyly one parent is Dd and other is dd, the chance is 1/2 ● ● ● ● www.muggligt Pother O mother d dD dd Polydactyl D/d heterozygous Six Primuose kitten hamas gaus five -dominant inherited condition affects the lungs and pancreas by producing think and sticky mucus which can lead to respiratory problems caused by recessive allele. ● an offspring can have cystic fibrosis without the parents having it as both parents could be carriers heloz your dD Sx dd hangygos five 2 parents need to have the allele for the child to have the disease neither parent must have the disease for the child to have it the child must be homozygous recessive to show cystic fibrosis ● ● ● if both parents are carriers, the chance of the child having cystic fibrosis is 1/4 if one parent is a carries and the other has CF the chance is 1/2 if one has CF and the other has no allele for CF, the chance is 0 www.Primrosekitten.com @primrose kitten mothers genotype Ff mothers phenotype Courrier fathers genotype f f fathers phenotype: normal mothers gametes fathers gametes. 08 Cystic Fibrosis ||| Pather f mother Primrose kitten Cysishc fibrosis recessive Fle hehergygous Ff como heterozygous Ff camer ff. ff homosygous name hanes your ho evolution= change in the inherited characteristics of a population -Mutations in DNA occur continuously - some mutations are small and ignored whilst others are big and get copied (evolution) mutation rarely causes variation -eye colour is controlled by more than one gene -mutations occur when cells divide evolution-life began on earth as simple organisms more than 3 billion years ago. all life has evolved from these simple organisms. natural selection- organisms that are better adapted to an environment will survive and reproduce. This means that the advantageous alleles of this variant organism are passed on to offspring. random mutations in genes lead to variations in a population, individuals with characteristics better suited to the environment are more likely to survive and reproduce genetic engineering- modification and manipulation of an organism's genes using technology can give plant crops more fruit, disease resistance, bigger fruit GM crops- genetically engineered crops GM crops can: resist herbicides, resist insects, resist disease genetically engineered bacterial cells can produce human insulin to help treat diabetes GM bacteria can: produce vaccination antigens, produce bovine growth hormone, produce enzymes for washing powders in the future, GM bacteria could treat inherited disorders and be used to make medicines enzymes are used in genetic engineering to isolate the required gene once the gene is isolated, it is inserted into a vector like a bacterial plasmid or virus the vector inserts the gene into the new organism without rejection ● ● ● Herbicides- chemicals that kill plants variation-presence of differences in sequences of genes between individual organisms of a species. speciation-one species become different species due to separation selective breeding- breeding an animal for a particular characteristic. Classification: ● ● taxonomy-grouping living things together. naming system= genus. Species made by Carl Linnaeus Three domains system: kingdom-Phylum-class-order-family-genus-species ● made by Carl Woese the three domains are Archaea, bacteria and Eukaryota. embryo screening- if your family has a history of a genetic disease or if your child has had one, you can get IVF and do an embryo screening before it is implanted back into you. ● ● ● ● ● ● sexual reproduction- ● ● a single cell from each embryo is tested. occurs at 12 and 20 weeks of pregnancy. first stage is scans and blood tests. advantages- you can test the embryo and only put back healthy embryos, genetic match for child already born ● disadvantages- embryos destroyed, religious objections, expensive, not always accurate DNA from embryo cells can also be tested meiosis- ● the fusion of female and male gametes 2 parents mixing of genetic information leads to genetic variation in the offspring. gametes form by meiosis. cells divide to form gametes. 2 stages 4 daughter cells Meiosis is the process in eukaryotic, sexually-reproducing animals that reduces the number of chromosomes in a cell before reproduction. It reduces the number of chromosomes in the parent cell by half and produces four gamete cells. gametes have 23 chromosomes (haploid cells) asexual reproduction- ● ● common in plants, bacteria/fungi makes a genetically identical population as they are dividing by mitosis so all daughter cells will be the same a new offspring is produced by a single parent. The new individuals produced are genetically and physically identical to each other, i.e., they are the clones of their parents. does not involve fusion of gametes or change in number of chromosomes mitosis- ● ● ● ● genetic variation ● no fusion of gametes no variance due to no mixing of genetic material genetically identical offspring are clones does not involve gametes Each daughter cell receives a complete set of chromosomes from the parent cell. This process allows the body to grow and replace cells - as an embryo develops, the cells differentiate -as an embryo gets bigger, the number of cells increases causes for extinction: ● disease ● ● ● the embryo divides by mitosis cells divide in two 1 parent 1 stage 2 identical daughter cells mitosis produces body cells cells have 46 chromosomes ● environment runs out ● ● catastrophic events Antibiotic resistance: environment changes too quickly if a new species inhabits the environment- competition bacteria divide by binary fusion at a very fast rate moisture and warmth help them reproduce quicker ● ● ● ● you have to finish your course antibiotics so that all bacteria is killed. if you do not finish it, some bacteria could remain and mutate surviving bacteria can cause resistant strains made from mutation of bacterial pathogens. MRSA-bacteria that is resistant to most antibiotics. development of new antibiotics is very slow. overusing antibiotics leads to more resistant strain production washing hands helps to reduce resistant bacteria strains in patients. - two microorganisms that can cause decay are: bacteria and fungi HOMOESTATIS & RESPONSE Homeostasis- Maintenance of the internal conditions of a cell/body for optimum cell/enzyme activity. An organism can maintain internal stability while adjusting to changing external condition. - blood glucose levels - water levels -temperature organs in homeostasis: brain-control centre the CNS-sending signals. the pancreas- produces insulin. effectors/muscles- moving glands-production of other hormones -the brain and spinal cord are the central nervous system CNS The Central nervous system: oestrogen (ovaries)- maturation of eggs and menstrual cycle www.PrimroseKitten.com @primrose kitten brain -Spinal cora reflex receptors teffectas. CNS thyroxine (thyroid)- metabolism regulation pituitary gland-FSH, LH -teshes testosterone male endocme System Slow Chemical Signal Synapse long insulin(pancreas)- regulating blood glucose levels adrenaline (adrenal gland) - important for fight or flight response, helps you prepare for stressful or dangerous situations nene al female endocrine system 8. Primuose kitten -the stored form of glucose is glycogen and glucagon can convert that back into glucose -Pituitary FSH gland LH ・thyroid thyroxine fast electrical Signa · adrenal glands adrenaline •pancreas Insulin Ccvaris oestrogen diabetes- type 1-pancreas does not work properly and don't make insulin. type 2- cells insensitive to insulin. still produces insulin but the body cells cannot respond to it. symptoms of both loss of weight, need to urinate, thirsty, blurry vision, fatigue, hunger treatment for type 1- insulin injections treatment for type 2- controlling diet and exercise Homeostasis blood glucose. @primrose kitten After eating, blood glucose levels rise the this is picked up by pancreas -pancreas produces insulin -Insulin Causes cells to remove glucose from blood -liver and muscle cells can Convert glucose into glycogen and share it. -removing glucose from blood Causes blood glucose lends to fall IVF- • Primuose kitten -If blood glucase gets loo low pancreas. advantages: baby disadvantages: is picked up by the -pancreas starts to produce glucagon -glucose that is stored in muscle. and liver alls starts to retum to the blood glycogen menstrual cycle: FSH- follicle stimulating hormone- rises, makes the egg grow to be released LH- luteinizing hormone- has to release the egg oestrogen-builds up until it stimulates LH glucose glucagon -This causes blood glucose levels to rise progesterone-builds up slowly as it builds the lining of uterus. if no embryo implanted in it the lining will break down drugs for long amount of time which have side effects. long term consequences as it increases chance of cancer. very expensive doesn't always work. around 40% success rate Ruler drop test for reaction time: (REQUIRED PRACTICAL) 1. hold the ruler above the students open hand so that their finger is just above the Ocm 2. drop the ruler and the other student will catch it as soon as possible 3. record where the ruler is caught (distance on the ruler where the top of the finger is) control variables that could have been used= -starting point of the ruler above the hand -use the same hand -students need to be of the same age, height, gender, have the same amount of sleep etc Ruler drop test is not a reflex because you are catching the ruler voluntarily and not automatically. involves conscious part of the brain. ECOLOGY ecosystem- animals and plants that live within an area. community- animals and plants which live in that ecosystem, two or more populations of organisms. biodiversity- range of plants and animals that live within a habitat. population- all the organisms of the same or closely-related species in an area. interdependence- all organisms that live in an ecosystem depend on each other for food, protection, shelter etc. Competition- All photosynthesising plants and algae in an ecosystem compete for light, space, water and minerals from the soil. Animals in an ecosystem compete for food, mates and their territory. Organisms which have more of these resources tend to grow more healthily and are more likely to have offspring. Quadrats: (REQUIRED PRACTICAL) A square wire frame grid 25 x 25cm count the abundance of each species in it. needs to be very randomised. repeating the counting of species in several areas reduces the chance of bias. exemplar answer to ESQ: ● ● Road Trees 130 m Sports pitches School buildings Field 164 m Road 62 m Gate Explain how different biotic factors and abiotic factors could have caused an uneven distribution of daisy plants. 6marks The trees will reduce the light available for photosynthesis The trees will absorb water and mineral ions from the soil. there will be a lot of trampling on the sports pitches which would kill daisies other plants will compete for water and mineral ions so daises might get less of the essential growing factors ● ● effects of climate change: rise in sea levels. change in species distribution. extreme weather ice caps melting coral bleaching crop failure change in migration patterns. Desertification ● ● ● the school building will create shade over certain areas so less photosynthesis will occur the daises might also be sensitive to the Pollution from the road ● carbon cycle: Stage 1-Carbon enters the atmosphere as carbon dioxide from respiration and combustion. stage 2-Carbon dioxide is absorbed by producers to make carbohydrates in photosynthesis. stage 3-Animals feed on plants, passing the carbon compounds along the food chain. Most carbon they consume is exhaled as carbon dioxide during respiration. The animals and plants eventually die. stage 4-Dead organisms are eaten by decomposers and carbon in their bodies is returned to the atmosphere as carbon dioxide. In some conditions decomposition is blocked. The plant and animal material may then be available as fossil fuel in the future for combustion. Process Photosynthesis Respiration Combustion (burning) Carbon starts as Carbon dioxide Glucose Fuel Carbon ends as Glucose Carbon dioxide Carbon dioxide Describe how carbon from the atmosphere is cycled through living organisms. 6marks. Photosynthesis- carbon dioxide diffuses through the stomata into a leaf. Carbon dioxide and water are both needed for photosynthesis to take place and glucose to be produced. Some of this glucose will be used by the plant for respiration, meaning that the carbon from this glucose will be released from the plant as carbon dioxide. The glucose made in photosynthesis can be converted into other carbon compounds such as amino acids, lipids and can also be stored as starch. These organic compounds can be consumed by animals, the animals will use these carbon compounds to release energy through respiration, Aerobic respiration will mean that carbon will be released into the atmosphere in carbon dioxide Carbon compounds will also make up the animal's biomass. Microorganisms can feed off or digest decaying plant or animal waste. These microorganisms will, help to return the minerals from the waste into the soil but they will also be carrying out respiration which means some of the carbon they have absorbed will be released into the atmosphere through respiration The Water cycle: www.PrimroseKitten.com @primrose kitten Evaporation Condense Transpiration rain ground off precipitation in Sail through flow. Primrose Kitten YouTube tutorials for Science and Maths Percolate to survive and reproduce- food ● ● ● ● abiotic-non-living factors light intensity Ph ● ● ● ● water air mate(sometimes) biotic-living factors. ● temperature water levels iron levels wind CO2 levels ● oxygen levels food -increase/decrease of any of these factors can severely affect a community predators pathogens adaptations: Structural- Structural adaptations of organisms are the physical features, which allow them to compete. cacti and roses can stop a plant being eaten by grazing animals. some plants have wide ranging, shallow roots to absorb lots of water, large leaves to ● ● Behavioural- Behavioural adaptations of organisms are behaviours which give them an advantage. All plant shoots grow quickly towards the light to maximise photosynthesis mating rituals like male peacock showing his tail feathers to attract a female mate. working together like a pack of wolves to hunt prey. crocodiles use twigs to lure birds. ● maximise photosynthesis flowers which attract insects to pollinate them. sharp claws to catch prey, dig burrows predators and prey have good vision and hearing. prey have eyes on the side to spot predators and predators have eyes in the front to judge distance to prey. physiological- Physiological adaptations of organisms are processes which allow them to compete. the formation of poisons for defence. The nettle plant stings us when we brush the tiny needles on its leaves, which contain poison venom production- snakes & spiders ● ● animals need to adapt to their environment in order to survive. e.g.1 cacti are well adapted the desert environment because they have shallow roots, spines to prevent them being eaten, can store water in their leaves e.g.2 foxes are white to blend in, small ears to reduce heat loss, thick coat. Extremophiles: an organism that lives in an extreme environment which most organisms would find it difficult or impossible to survive. The organisms that live in these places have highly specialised adaptations. Examples of extreme environments include the Polar Regions, deserts, the deep ocean bed, hot geothermal springs and the tops of our highest mountains. how do orchid adaptations help them survive and compete: growing attached to other plants help them to be supported and obtain water/minerals having bright colours attracts pollinators. large quantities of pollen increase chances of fertilisation/reproduction tiny light seeds are more likely to be spread over wider areas more chance that they will survive -