Biology Past Paper Questions - OCR

Best of Luck For all the future applicants Determine establish an answer using the information available Biodiversity Use captive breeding, pollution, research, sustainable, climate change often in questions relating to conservation Read about Invitro fertilizatio...

Best of Luck For all the future applicants Determine establish an answer using the information available Biodiversity Use captive breeding, pollution, research, sustainable, climate change often in questions relating to conservation Read about Invitro fertilization in detail as it is just added in the syllabus and is more likely to come. How humans degrade biodiversity Habitat loss For agriculture/ shelter Hunting/ predation Pollution Spread diseases Why to maintain biodiversity Medicine For plants: Timber Aesthetic uses Maintain gene pool Food Resource material Ecotourism Soil stabilitiy Fishing Maintaining stability of ecosystem May have future use Research Ecotourism Climate stability Medicinal uses Food chain/ web How to protect endangered species Captive breeding Species to its own native environment/ ecosystem/ habitat research Reasons for extinction If it is about water animals then, Pollution Ph Temperature of water Hardy-Weinberg principles: - No mutation Climate change so pond are drying up - No migration - No selection via selection pressure Mark release recapture conditions - Large population - Random mating 1. Mobile - Sexual reporduction 2. Sufficient time for the species to mix - Diploid organism 3. The marks must be harmless and permanent 4. No migration Why alien species should be controlled 1. May become invasive species 2. May lack predator 3. May spread diseases 4. It may affect the food web 5. May compete with the native species 6. Decrease species diversity. 7. May feed on/eat native species Photosynthesis Temperature: ma enzymes ko kura, light intensity ma photoactivation ani light independent and dependent NADPH2, ATP less released, less RUBP generation Difference between Non cyclic and cyclic photophosphorylation Similarlities: 1. ETC occurs in both 2. Both ATP 3. Photoactivation Differences: 1. Cyclic PSI only and Non Cyclic PSI and PSII 2. Cyclic ATP only, Non cyclic ATP and reduced NADP DCPIP and methylene blue Any photosynthesis’s Graph question (describe) At lower (x-axis), x axis is limiting therefore as x increases rate increases until (at specific x axis). Then it forms plateau, now x-axis is no longer limiting now other factors are limiting.. Example: At lower CO2 concentrations, CO2 is the limiting factor but at higher CO2 concentration CO2 no longer limiting factor now temperature and Light intensity limiting factor. Value Quote If ‘explain’ is used then only explain How grana is adapted to its function? Why insertion of sox 4 / any genes results in more photosynthesis Role of abscissic acid in closing stomata How structure of chloroplast is related to its structure and function? Genetic Engineering Keywords to use: restriction enzymes to cut, electrophoresis, genetic fingerprinting, microarray Microarray? Explain the social benefit of gene editing Outline principles of genetic engineering? DNA is manipulated to modify organism's characteristics Why promotor is needed? Role of primers in the PCR used for detection of _____: - bind to base pairs by complementary base pairing - primers anneal with single-stranded DNA - specific to ___ DNA (so if there is a PCR product that means the DNA for ___ is present) - Allows Taq polymerase to bind Why gene editing is better? No risk of cancer/ immune response Patient's own gene can be edited (no insertion of new gene) It is accurate and exact No need to introduce promoter Why gene editing in plasmid? List enzymes used in genetic engineering? Marker genes fluorescense Why are gene probes used to detect specific alleles of genes: -they have complementary base sequences that bind to specific parts of the gene Probes are short, single-stranded DNA or RNA Gmo positive and negative What is gene therapy Ethical considerations of using retrovirus in gene therapy: - retrovirus must not insert in whrong place - must not cause cancer - must not cause immune response Gene therapy with virus: 1. Functional gene coding for _____ is extracted 2. Inserted into virus 3. Remove stem cells Negative feedback 4. Insert virus into stem cells 5. Return stem cells to body Challenges of using a virus for gene therapy: - may cause side effects - ineffective immune response against virus - retrovirus can insert DNA of virus into host DNA at random times - DNA may be inactivated or may inactivate another gene - virus (retrovirus especially) may not enter target cell Selection and Variation Keywords must use: allopatric/ sympatric, natural selection, genetic drift, selection pressure, AI, vigour Why genetic diversity is needed? Natural selection: Explain how artificial selection is different from natural selection? Humans apply the selection pressure To produce the offspring that are beneficial for human beings Inbreeding depression Loss of hybrid vigour Harmful recessive alleles may be expressed Faster increased homozygousity and reduced heterozygousity Gene pool small Evolution: Why f1 generation does not match with the ratio Maize hybridisation Respiration Note In respiration and photosynthesis use Electron Transport Chain, phosphorylation often Describe the role of NAD? Hydrogen Carrrier (H2 or H+ and e- ) Acts as coenzyme Why Lipid has more energy than carbohydrates? More C-H bond More Reduced NAD form, More ETC, Outline how ATP is synthesised by oxidative phosphorylation? Describe anaerobic respiration? Outline the process of glycolysis? Describe the series of reactions that make up the Krebs Cycle? How ATP is produced from: Link reaction/ Glycolysis: Substrate Level Phosphorylation When oxygen is used in chemiosmosis: oxidative phosphorylation ATP as a energy source: Inherited change Keywords: chiasma, autosomal linkage, episatasis, chance, gametes How meiosis causes variation? Crossing over and independent assortment Homeostasis Frequently use: set point, corrective action, receptor Then bind with receptor, g protein camp secondary messenger, kinase enzyme. Negative feedback Dipstick test Glucose biosensor mechanism: 1. blood on strip inserted into biosensor 2. glucose oxidase 3. glucose ---> hydrogen peroxide (H2O2) + gluconic acid 4. Electric current 5. Current is proportional to glucose concntration 6. Digital/ numerical reading How insulin works? How stomata opens? Negative feedback How bowman’s capsule is adapted? How PCT is adapted? ADH? Gibberellin? Role of ATP in muscle contraction Paper 5: How to ensure a fair test when people are involved in experiement (usually reaction time) Discuss does it support hypothesis? Yes: because there is increase or decrease in mean In vitro fertilisation Gel electrophoresis Mechanism by which guard cells open Function of bowman’s capsule: Reabsorption of glucose: How adrenaline affects liver cells: Coenzymes in aerobic respiration How the structure of chloroplast is adapted (again) Similarities between cyclic and non-cyclic photophosphorylation Why light energy may be a limiting factor: How roots of rice plants are adapted to paddy fields: Role of reduced NADP: Role of accessory pigments: Separating and identifying pigments: Difference between biochemistry of C3 and C4 plants: How an action potential is transmitted along a sensory neuron in a mammal: Role of synapse: How myelin sheath increases speed: Role of troponin, tropomyosin, actin and myosin heads in sliding filament model: Role of sensory receptor cells: Role played by gibberellin in germination: Amylase, maltase and protease are produced in the aleurone layer and then act on subtrate in the endosperm Role of Acetylcholinesterase: Response of the Venus fly trap to touch: Difference in structure and function of motor and sensory neurone: Endocrine vs nervous system: Ultrastructure of striated muscle: Describe how a neurone maintains resting potential: Explain how lele gene results in dwarf plants: Why two genes assort independently: Role of auxin in cell elongation: Importance of homeostasis: Role of oxygen in aerobic respiration: Eukarya vs. bacteria: Why ATP synthesis stops in oxidative phosphorylation when oxygen is absent: 1.​ Oxygen is final electron acceptor 2.​ ETC stops 3.​ Less/ no H+/ protons move into intermembrane space 4.​ No H+ gradient 5.​ No H+ move through ATP synthase 6.​ No recycling of NAD How does bacteria evolve resistance to antibiotics/disease: Outline the process of cyclic photophosphorylation: Describe the principles of PCR (denature, anneal, extension) : Or (if asked to outline the process of PCR) Advantages of recombinant DNA techniques to produce human proteins: Outline the role of the IUCN: Procedure of embryo transfer: Compare the characteristics between Archaea and Bacteria: Advantages of genetic screening for mutations in a gene: 1.​ Decrease worry if test is negative 2.​ LIfestyle changes 3.​ Early treatment 4.​ Informed decision about having children 5.​ Counselling 6.​ Could lead to lower death rates from condition Role of carriers in the inner mitochondrial membrane: 1.​ Splits H into H+ and electrons 2.​ Electrons passing through ETC provide energy 3.​ Energy used to pump H+ into intermembrane space Difference in chemiosmosis of mitochondria versus chloroplast: Why is it important to maintain biodiversity: Outline the practical techniques that can be used to test the hypothesis that _____ has a genetic basis: Roles of NAD and FAD in aerobic respiration: Why is the actual net no. of ATP synthesised less than the theoretical no.: How an ecological survey can measure the biodiversity of a terrestrial habitat: How microarrays be used in detection of different alleles: Advantage and disadvantage of genetic screening for diseases: Role of calcium ions in the contraction of striated muscle: Describe the main structural features of thick filaments and thin filaments in the sarcomere: Methods to conserve endangered plant species: Control of gibberellin synthesis and outline how gibberellin stimulates stem elongation: How the Calvin cycle produces triose phosphate and outline the conversion of triose phosphate into amino acids: Link reaction: 1.Pyruvate is dehydrogenated and decarboxylated to form acetate 2.Reduced NAD produced 3.Acetate + CoA —---> Acetyl CoA formed Relationship between blood glucose concentration and blood glucagon concentration: 1.​ Decrease in blood glucose concentration causes an increase in glucagon concentration 2.​ Glucagon acts on liver cells 3.​ Glycogenolysis 4.​ Gluconeogenesis 5.​ So glucose is released into blood 6.​ Negative feedback Link reaction only occurs when oxygen is present because: 1.​ Oxygen is final electron acceptor so ETC only works if oxygen is present 2.​ Pyruvate —--> acetyl 3.​ NAD required—---> reduced NAD formed 4.​ So reduced NAD is oxidised/ NAD is regenerated LDS of photosynthesis leads to production of carbs such as starch in plant leaves: 1.​ RUBP joins with carbon dioxide —--> 6C intermediate forms (unstable)/ GP forms (6C compound immediately splits to 2 GP molecules) 2.​ GP (is reduced to) ----> TP 3.​ This conversion requires ATP and reduced NADP 4.​ TP —-> glucose —--> starch 5.​ Condensation/ polymerisation/ glycosidic bonds Three molecules, other than coenzymes, that are found in the mitochondrial matrix and their role in aerobic respiration: To obtain vigorous, uniform varieties of maize by selective breeding: 1.​ Breed plants with desirable features 2.​ Breed better offspring repeatedly/ for many generations 3.​ Inbreeding 4.​ Hybridisation/ outbreeding 5.​ Gives hybrid vigour 6.​ F1 have the same genotype (uniformity) Genetic basis for continuous variation: Principles of selective breeding in livestock: Describe how the structure of a mitochondrion is related to its function: Outline practical techniques that could be used to conduct genetic analysis of ___ species: How a small size of ___ population resulted in a high frequency of normally rare variant forms: 1.​ Features are controlled by genes 2.​ Genetic drift 3.​ Bottle-neck 4.​ Low genetic diversity 5.​ Inbreeding 6.​ Low heterozygosity 7.​ Rare recessive alleles come together and show their effects How mutation in a small population accounts for a very high % of cases when compared with general global population: 1.​ Mutation occurred a long time ago 2.​ Founder effect 3.​ Smaller gene pool/ population is closely related 4.​ Population is small 5.​ Isolated population 6.​ High frequency of mutation Functions of the internal membranes of the chloroplast in photosynthesis: How a tumour develops: Role of zoos in conservation of endangered species: 1. mutation in ONCOGENE - safe location/ protected from predators - education/ raise awareness 2. uncontrolled mitosis/ cell division - captive breeding programmes - medical care 3. Abnormal mass of cells formed - research diet, diseases, etc 4. No programmed cell death - raise funds - work with local communities Why immunofluorscent tagging is not a suitable Different ways in which genetic technology can be applied in medicine choice for a investigation: with named references to disease: - Antibodies are too big to enter cells - genetic engineering - Making monoclonal antibodies is expensive - drug from GM bacteria / yeast - Immunofluorescent is only used on dead cells - make insulin - Making MABs harms mice - make factor VIII for haemophilia - genetic screening - detect BRCA1, Huntington's, cystic fibrosis - gene therapy - insert normal allele into cells of host - to treat eye diesases - to treat SCID Process that produces oxygen during non-cyclic photophosphorylation: Explain the relationship between a gene, protein and phenotype, using haemophilia as an example: Identify the protein D and the group of proteins A, B, and C and describe their roles in oxidative phosphorylation: Gene mutation that causes sickle cell anaemia and the reduced oxygen-carrying capacity of red blood cells: Outline how a gene mutation may occur: How different types of gene mutation can affect the phenotype: How the presence of a mutant allele can result in albinism: Outline the effects of the mutant alleles that cause Huntington’s disease on the phenotype of a person: