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A Level Biology OCR A Questions

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Overview of A Level in Biology A:

Content is split into six teaching modules:
Module 1 – Development of practical skills in biology
Module 2 – Foundations in biology
Module 3 – Exchange and transport
Module 4 – Biodiversity,evolution and disease
Module 5 – Communication,homeostasis and energy
Module 6 – Genetics,evolution and ecosystems

A Level Biology OCR A Questions

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25 Questions

1. Define natural active immunity.

Repolarisation - change in potential difference from positive back to negative across the membrane of a neuroneNatural active immunity - results from response of body to invasion of a pathogenLarge-scale timber production sustainability: Selective cutting - removing only largest treesReplanting treesPlant trees at optimal distance to reduce competitionManage pests and pathogensEnsure areas of forest remain for indigenous peopleTransplantation: Healthy kidney from a donor is placed within the bodyBlood vessels are joined up, ureter is inserted into bladder and if successful, the kidney will function normally for many years

2. Describe how transplantation can treat kidney failure.

Natural active immunity - results from response of body to invasion of a pathogenRepolarisation - change in potential difference from positive back to negative across the membrane of a neuroneTransplantation: Healthy kidney from a donor is placed within the bodyBlood vessels are joined up, ureter is inserted into bladder and if successful, the kidney will function normally for many yearsLarge-scale timber production sustainability: Selective cutting - removing only largest treesReplanting treesPlant trees at optimal distance to reduce competitionManage pests and pathogensEnsure areas of forest remain for indigenous people

3. Define repolarisation.

Large-scale timber production sustainability: Selective cutting - removing only largest treesReplanting treesPlant trees at optimal distance to reduce competitionManage pests and pathogensEnsure areas of forest remain for indigenous peopleRepolarisation - change in potential difference from positive back to negative across the membrane of a neuroneNatural active immunity - results from response of body to invasion of a pathogenTransplantation: Healthy kidney from a donor is placed within the bodyBlood vessels are joined up, ureter is inserted into bladder and if successful, the kidney will function normally for many years

4. Describe 5 practices that can help large scale timber production to be sustainable.

Repolarisation - change in potential difference from positive back to negative across the membrane of a neuroneNatural active immunity - results from response of body to invasion of a pathogenTransplantation: Healthy kidney from a donor is placed within the bodyBlood vessels are joined up, ureter is inserted into bladder and if successful, the kidney will function normally for many yearsLarge-scale timber production sustainability: Selective cutting - removing only largest treesReplanting treesPlant trees at optimal distance to reduce competitionManage pests and pathogensEnsure areas of forest remain for indigenous people

5. Define sticky ends.

Sticky ends - regions of DNA with unpaired, exposed basesRepolarisation - change in potential difference from positive back to negative across the membrane of a neuroneTransplantation: Healthy kidney from a donor is placed within the bodyBlood vessels are joined up, ureter is inserted into bladder and if successful, the kidney will function normally for many yearsNatural active immunity - results from response of body to invasion of a pathogen

6. Describe 3 sources of evidence for cohesion-tension theory.

Repolarisation - change in potential difference from positive back to negative across the membrane of a neuroneTransplantation: Healthy kidney from a donor is placed within the bodyBlood vessels are joined up, ureter is inserted into bladder and if successful, the kidney will function normally for many yearsNatural active immunity - results from response of body to invasion of a pathogenEvidence for cohesion-tension theory: Poisons - if cut shoot is placed in cyanide water, uptake and transpiration continues as usual showing that transpiration does not rely on live cells and therefore isnt an active processDyes - if leafy shoot is cut and dipped into dye the dye will visibly be taken into the xylem vessels supporting that major water pathway is thru xylemDiameter of tree trunk over 24 hour period is narrowest at midday and widest at midnight - cohesive forces in xylem cause negative pressure that draws tissues in and reduces diameter bc highest rate of photosynthesis is at midday & lowest around midnight

7. List 4 types of sensory receptor and the stimulus they detect.

Repolarisation - change in potential difference from positive back to negative across the membrane of a neuroneReceptors: Mechanoreceptors - pressure/movementChemoreceptors - chemicalsThermoreceptors - heatPhotoreceptors - lightNatural active immunity - results from response of body to invasion of a pathogenTransplantation: Healthy kidney from a donor is placed within the bodyBlood vessels are joined up, ureter is inserted into bladder and if successful, the kidney will function normally for many years

8. Define cardiac output. + state units

Natural active immunity - results from response of body to invasion of a pathogenTransplantation: Healthy kidney from a donor is placed within the bodyBlood vessels are joined up, ureter is inserted into bladder and if successful, the kidney will function normally for many yearsRepolarisation - change in potential difference from positive back to negative across the membrane of a neuroneCardiac output - product of heart rate and stroke volume (liters per minute) Represents amount of blood pumped out of each ventricle of the heart per minute

9. Define the term nucleic acid. + state the chemical elements in them

Nucleic acid - large polymers formed from nucleotides Contain: C, H, N, P, ONatural active immunity - results from response of body to invasion of a pathogenRepolarisation - change in potential difference from positive back to negative across the membrane of a neuroneTransplantation: Healthy kidney from a donor is placed within the bodyBlood vessels are joined up, ureter is inserted into bladder and if successful, the kidney will function normally for many years

10. Define oxidative phosphorylation.

Natural active immunity - results from response of body to invasion of a pathogenOxidative phosphorylation - phosphorylation of ADP to form ATP in the presence of oxygenRepolarisation - change in potential difference from positive back to negative across the membrane of a neuroneTransplantation: Healthy kidney from a donor is placed within the bodyBlood vessels are joined up, ureter is inserted into bladder and if successful, the kidney will function normally for many years

11. Define leaf abscission.

Leaf abscission - fall of leavesRepolarisation - change in potential difference from positive back to negative across the membrane of a neuroneTransplantation: Healthy kidney from a donor is placed within the bodyBlood vessels are joined up, ureter is inserted into bladder and if successful, the kidney will function normally for many yearsNatural active immunity - results from response of body to invasion of a pathogen

12. State the full name of CITES and explain how it helps protect biodiversity.

Transplantation: Healthy kidney from a donor is placed within the bodyBlood vessels are joined up, ureter is inserted into bladder and if successful, the kidney will function normally for many yearsNatural active immunity - results from response of body to invasion of a pathogenRepolarisation - change in potential difference from positive back to negative across the membrane of a neuroneCITES - Convention on International Trade in Endangered Species Regulates international trade of wild plant and animal specimens and their productsProtects species from over-exploitation that could endanger them

13. Outline the structure and function of lysosomes.

Transplantation: Healthy kidney from a donor is placed within the bodyBlood vessels are joined up, ureter is inserted into bladder and if successful, the kidney will function normally for many yearsLysosomes - types of vesicles that contain digestive (hydrolytic) enzymes Responsible for breaking down food/waste material in cells (incl old organelles) by fusing with a food vacuole or a vesicle containing old organellesResponsible for breaking down pathogens ingested by phagocytic cellsImportant role in programmed cell deathRepolarisation - change in potential difference from positive back to negative across the membrane of a neuroneNatural active immunity - results from response of body to invasion of a pathogen

14. Draw a table to compare mitosis and meiosis.

Natural active immunity - results from response of body to invasion of a pathogenSimilaritiesDifferences Both begin with one diploid parent cellBoth stages end with cytokinesisBoth consist of multiple stages including: interphase, prophase, metaphase, anaphase, telophase and cytokinesisBoth stages duplicate the DNABoth stages condense the DNA into chromosomesBoth require the chromosomes to be pulled apart by a centrosome (1 or 2 centrioles)Both are pulled apart by spindle fibres formed from the centrosomeBoth require the nuclear membrane to go awayMitosis is used in asexual reproduction, meiosis is used in sexual reproductionCrossing over occurs in meiosis and not in mitosisThe cells produced in mitosis are genetically identical, but the cells in meiosis are genetically differentMitosis is used for growth and repairing the body, meiosis is used for genetic diversity through sexual reproductionCells divide once in mitosis, twice in meiosis2 diploid cells are produced in mitosis, 4 haploid cells are produced in meiosisThe number of chromosomes stay the same in mitosis, but in meiosis the number is halvedCentromeres split during anaphase in mitosis and in meiosis they split during anaphase IIMitosis is used to create any cell but sex cells, meiosis is only used to create sex cellsRepolarisation - change in potential difference from positive back to negative across the membrane of a neuroneTransplantation: Healthy kidney from a donor is placed within the bodyBlood vessels are joined up, ureter is inserted into bladder and if successful, the kidney will function normally for many years

15. Outline the structure of the two types of nitrogenous base.

Transplantation: Healthy kidney from a donor is placed within the bodyBlood vessels are joined up, ureter is inserted into bladder and if successful, the kidney will function normally for many yearsRepolarisation - change in potential difference from positive back to negative across the membrane of a neuroneStructure of types of bases: Pyrimidines - smaller, contain single carbon ring structuresPurines - larger, contain double carbon ring structuresNatural active immunity - results from response of body to invasion of a pathogen

16. Define initial rate of reaction and describe its significance in investigations into factors affecting rate of enzyme-controlled reactions.

Transplantation: Healthy kidney from a donor is placed within the bodyBlood vessels are joined up, ureter is inserted into bladder and if successful, the kidney will function normally for many yearsNatural active immunity - results from response of body to invasion of a pathogenInitial rate of reaction - instantaneous rate at the start of the reaction Gradient of tangent to curve at t=0Important because concentration of substrate always changes as the experiment proceeds - rate constantly changesTherefore the only true rate of reaction is the initial rate of reaction (only moment where the two variables investigated are the only ones influencing rate)Repolarisation - change in potential difference from positive back to negative across the membrane of a neurone

17. Draw, label and annotate diagram to show how squamous epithelium is specialised for its function.

Repolarisation - change in potential difference from positive back to negative across the membrane of a neuroneNatural active immunity - results from response of body to invasion of a pathogenTransplantation: Healthy kidney from a donor is placed within the bodyBlood vessels are joined up, ureter is inserted into bladder and if successful, the kidney will function normally for many yearsSquamous epithelium: Made up of specialised squamous epithelial cellsVery thin bc it is one cell thick & the cells are flat - small diffusion distanceIts present when rapid diff. across a surface is essential (lining of lungs)

18. Explain how histone modification can affect gene expression.

Transplantation: Healthy kidney from a donor is placed within the bodyBlood vessels are joined up, ureter is inserted into bladder and if successful, the kidney will function normally for many yearsNatural active immunity - results from response of body to invasion of a pathogenHistone modification: DNA wraps around histones bc DNA is negatively charged, histones are positively chargedAcetylation/phosphorylation reduces positive charge on histones and causes DNA to coil less tightly - certain genes can be transcribedMethylation makes histones hydrophobic so they bind more tightly to each other, causing DNA to coil more tightly - certain genes transcription preventedRepolarisation - change in potential difference from positive back to negative across the membrane of a neurone

19. State functions of the blood.

Transplantation: Healthy kidney from a donor is placed within the bodyBlood vessels are joined up, ureter is inserted into bladder and if successful, the kidney will function normally for many yearsNatural active immunity - results from response of body to invasion of a pathogenRepolarisation - change in potential difference from positive back to negative across the membrane of a neuroneFunctions of the blood - transport of: O2 to and CO2 from respiring cellsDigested food from small intestineNitrogenous waste products from cells to excretory organsHormonesFood molecules from storage mols to cells that need themPlatelets to damaged areasCells and antiboides involved in immune response Other functions: Maintaining steady body tempBuffer to minimise pH changes

20. Explain why analysis of urine can act as a good diagnostic test for different diseases.

Analysis of urine: Contains breakdown products of a range of chemicalsIf affected by one of many diff diseases, new substances will show up in urineTransplantation: Healthy kidney from a donor is placed within the bodyBlood vessels are joined up, ureter is inserted into bladder and if successful, the kidney will function normally for many yearsNatural active immunity - results from response of body to invasion of a pathogenRepolarisation - change in potential difference from positive back to negative across the membrane of a neurone

21. Define chromatin.

Repolarisation - change in potential difference from positive back to negative across the membrane of a neuroneChromatin - complex of DNA and protein (histones)Transplantation: Healthy kidney from a donor is placed within the bodyBlood vessels are joined up, ureter is inserted into bladder and if successful, the kidney will function normally for many yearsNatural active immunity - results from response of body to invasion of a pathogen

22. What type of pathogen causes ring worm?

23. Describe the adaptations of phloem.

Adaptations of phloem: Sieve tube elements - no nucleus & no/small amount cytoplasm to allow transport of assimilates more easilySieve plates allow assimilates to pass thru phloem tubesLots of plasmodesmata between companion cells, lots of mitochondria & dense cytoplasm in companion cells, to allow them to fulfill sieve tube elements with metabolic needsTransplantation: Healthy kidney from a donor is placed within the bodyBlood vessels are joined up, ureter is inserted into bladder and if successful, the kidney will function normally for many yearsRepolarisation - change in potential difference from positive back to negative across the membrane of a neuroneNatural active immunity - results from response of body to invasion of a pathogen

24. Define etiolated plant.

Transplantation: Healthy kidney from a donor is placed within the bodyBlood vessels are joined up, ureter is inserted into bladder and if successful, the kidney will function normally for many yearsEtiolated plant - pale leaves and stem becuase it did not receive enough light from the sunRepolarisation - change in potential difference from positive back to negative across the membrane of a neuroneNatural active immunity - results from response of body to invasion of a pathogen

25. Describe the structure of adrenal glands.

Natural active immunity - results from response of body to invasion of a pathogenAdrenal gland structure - made up of two distinct parts, surrounded by a capsule: Adrenal cortex - outer region which produces essential hormones (cortisol, aldosterone)Adrenal medulla - inner region which produces non-essential hormones (adrenaline)Repolarisation - change in potential difference from positive back to negative across the membrane of a neuroneTransplantation: Healthy kidney from a donor is placed within the bodyBlood vessels are joined up, ureter is inserted into bladder and if successful, the kidney will function normally for many years

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25 Questions

❤ If you liked Fatskills, consider supporting us by checking out The Life Manuals You Never Got.

About | Explore | User Guide | Topics | Subjects | Doubt Solver | Career Aptitude Test | Answers | Free Tools | What Should We Know? Privacy | Terms |

Without work one finishes nothing. - Ralph Waldo Emerson© 2026 Fatskills.com

All trademarks, logos and brand names are the property of their respective owners. All company, product and service names used in this website are for identification purposes only. Use of these names, trademarks and brands does not imply endorsement.

About | Explore | User Guide | Topics | Subjects | Doubt Solver | Career Aptitude Test | Answers | Free Tools | What Should We Know?
Privacy | Terms |

Without work one finishes nothing. - Ralph Waldo Emerson
© 2026 Fatskills.com