Leaving Cert Biology – Numeracy & Literacy Cheat Sheet

  

    Quick-reference formulas, key numbers and definitions across the four Biology strands.
  


  
  

    

      
Unifying Strand – Nature of Science

      
Core scientific method – used in all Biology experiments.

    


    

      
        

          Item
          Formula / Key Idea
        

      
      
        

          Scientific method steps
          
            Observation → Hypothesis → Experiment (with controls) → Collect & analyse data →
            Conclusion → Report & publish.
          
        

      
    

  


  
  

    

      
Strand 1 – Organisation & Continuity of Life

      
Cells, biomolecules, genetics & basic physiology.

    


    

      
        

          Item
          Formula / Key Numbers
        

      
      
        

          Eleven characteristics of life
          
            Organisation, Response, Respiration, Nutrition, Excretion, Reproduction, Growth,
            Metabolism, Homeostasis, Heredity, Cellular.
          
        


        

          Microscope magnification (lens powers)
          
            Total magnification = eyepiece × objective.

            Examples: 10× eyepiece with 4× / 10× / 40× objectives → total
            magnifications of 40×, 100×, 400×.
          		
        


        

          Magnification triangle
          
            I = image size, A = actual size, M = magnification.

            M = I ÷ A  |  I = A × M  |  A = I ÷ M.
          		
        


        

          Glucose & ribose formulas
          
            Glucose: C6H12O6 (hexose).

            Ribose: C5H10O5 (pentose).
          		
        


        

          General carbohydrate formula
          
            Cx(H2O)y, where x = y in simple carbohydrates.
          
        


        

          Mono-, di- & polysaccharides
          
            Monosaccharide (e.g. glucose) → join two → disaccharide (e.g. maltose) → many units →
            polysaccharide (e.g. starch, glycogen, cellulose).
          
        


        

          Triglyceride vs phospholipid
          
            Triglyceride = glycerol + 3 fatty acids.

            Phospholipid = glycerol + 2 fatty acids + phosphate group.
          		
        


        

          General amino acid structure
          
            Central C with: NH2 (amine group), COOH (carboxyl group), H, and R (variable side chain).
          
        


        

          From peptide to protein
          
            Amino acid + amino acid → dipeptide → polypeptide (long chain) → protein (folded,
            functional shape).
          
        


        

          Number of amino acids
          20 common amino acids in human proteins.
        


        

          Body water content
          
            Plants: roughly 80–90% water by mass.

            Humans: roughly 60–70% water by mass.
          		
        


        

          Reducing sugar test colours
          
            Benedict’s / Fehling’s test: blue solution → green → yellow → orange → brick-red
            precipitate as reducing sugar concentration increases.
          
        


        

          Trace elements (examples)
          
            Plants: Fe, Zn, Cu, Mn, B, Mo.

            Humans: Fe, Cu, Zn, I, Mn, etc. (needed in tiny amounts).
          		
        


        

          DNA & RNA terms
          
            DNA = Deoxyribonucleic acid; RNA = Ribonucleic acid.

            Codon = 3-base sequence on mRNA that codes for one amino acid.
          		
        


        

          Nucleotide (basic structure)
          
            Phosphate group + 5-carbon sugar (deoxyribose or ribose) + nitrogenous base (A, T, C, G, or U).
          
        


        

          Base-pair rule
          
            In DNA: A pairs with T, C pairs with G.

            In RNA: A pairs with U, C pairs with G.
          		
        


        

          Chromosome numbers (human)
          
            Normal human cell: 46 chromosomes (23 pairs).

            Down syndrome: 47 chromosomes (extra chromosome 21).
          		
        


        

          ADP & ATP
          
            ADP = Adenosine diphosphate; ATP = Adenosine triphosphate.

            ADP + P + energy → ATP (energy stored).

            ATP → ADP + P + energy (energy released).
          		
        


        

          NADH & NADPH
          
            NAD+ + 2e- + H+ → NADH (reduced form, carries electrons).

            NADP+ + 2e- + H+ → NADPH (used mainly in photosynthesis).
          		
        


        

          F1, F2 & dihybrid ratios
          
            F1 = first filial generation; F2 = second filial generation.

            Typical monohybrid ratio: 3 : 1; dihybrid: 9 : 3 : 3 : 1 (in simple Mendelian crosses).
          		
        


        

          pH scale
          
            pH 0–14. pH < 7 = acidic, pH 7 = neutral, pH > 7 = basic/alkaline.
          
        


        

          Enzyme temperatures (general idea)
          
            Many animal enzymes: optimum around 37 °C; plant enzymes: often lower
            optima (~20–30 °C). High heat or extreme pH can denature enzymes.
          
        

      
    

  


  
  

    

      
Strand 2 – Structures & Processes of Life

      
Photosynthesis, respiration, reproduction, digestion & circulation.

    


    

      
        

          Item
          Formula / Key Numbers
        

      
      
        

          Decomposition of hydrogen peroxide
          
            2H2O2 → 2H2O + O2 (catalase speeds up reaction).
          
        


        

          Photosynthesis (word & formula)
          
            Word: Carbon dioxide + water —light / chlorophyll—→ glucose + oxygen.

            Balanced: 6CO2 + 6H2O → C6H12O6 +
            6O2.
          		
        


        

          Photolysis of water
          
            2H2O → 4H+ + 4e- + O2 (in the light stage of photosynthesis).
          
        


        

          Aerobic respiration
          
            Word: Glucose + oxygen → carbon dioxide + water + energy (ATP).

            Balanced: C6H12O6 + 6O2 →
            6CO2 + 6H2O + energy.
          		
        


        

          Anaerobic respiration / fermentation
          
            In muscles: glucose → lactic acid + small amount of energy.

            In yeast: glucose → ethanol + CO2 + energy.
          		
        


        

          Glycolysis summary
          
            Glucose (6C) → 2 pyruvate (3C) + small ATP gain + NADH (in cytosol, no oxygen needed).
          
        


        

          Haploid & diploid
          
            N = haploid number (single set of chromosomes).

            2N = diploid number (two sets, in homologous pairs).
          		
        


        

          Mitosis stages (order)
          Prophase → Metaphase → Anaphase → Telophase (→ cytokinesis).
        


        

          CNS & PNS
          
            CNS = Central Nervous System (brain + spinal cord).

            PNS = Peripheral Nervous System (all nerves outside CNS).
          		
        


        

          Key endocrine glands & hormones
          
            Pituitary: FSH, LH, growth hormone, etc.

            Thyroid: thyroxine. Parathyroids: parathormone.

            Adrenals: adrenaline. Ovaries: oestrogen, progesterone. Testes: testosterone.
          		
        


        

          28-day menstrual cycle (outline)
          
            Days 1–5: menstruation. Days 6–13: repair & thickening of endometrium; FSH stimulates
            follicle.

            Day 14: ovulation (LH surge). Days 15–28: corpus luteum, progesterone maintains
            endometrium; if no fertilisation, hormone levels drop & cycle restarts.
          		
        


        

          Dental formula (adult human)
          
            One half of jaw: 2/2 incisors, 1/1 canines, 2/2 premolars, 3/3 molars → written as
            2.1.2.3 / 2.1.2.3.
          
        


        

          Digestive breakdown of carbs
          
            Starch —amylase—→ maltose; maltose —maltase—→ glucose.
          
        


        

          Digestive breakdown of proteins & lipids
          
            Protein —protease/pepsin/trypsin—→ amino acids.

            Lipid —lipase + bile—→ fatty acids + glycerol.
          		
        


        

          Inhaled vs exhaled air (approx.)
          
            Inhaled: ~21% O2, 0.04% CO2, ~79% N2.

            Exhaled: ~16% O2, ~4% CO2, ~80% N2, saturated with water vapour.
          		
        


        

          Typical blood pressure & heart rate
          
            Adult at rest: ~120/80 mmHg (systolic/diastolic).

            Resting heart rate: roughly 60–100 beats per minute.
          		
        


        

          Blood composition & haemoglobin
          
            ~55% plasma, ~45% cells (mostly red blood cells).

            Hb + O2 ⇌ HbO2 (haemoglobin ↔ oxyhaemoglobin).
          		
        

      
    

  


  
  

    

      
Strand 3 – Interactions of Life

      
Ecology, energy flow, carbon & nitrogen cycles.

    


    

      
        

          Item
          Formula / Key Numbers
        

      
      
        

          Energy flow in ecosystems
          
            Sun → producers (plants) → primary consumers → secondary consumers → top consumers;
            energy lost at each trophic level (heat, movement, waste).
          
        


        

          Simpson’s index of biodiversity (one version)
          
            D = 1 − [ Σ(n(n−1)) ÷ N(N−1) ], where n = number of individuals of each species,
            N = total individuals of all species.
          
        


        

          Capture–recapture population estimate
          
            Population size ≈ (number captured first time × number captured second time)
            ÷ number marked in second sample.
          
        


        

          Percentage frequency
          
            % frequency of a species = (number of quadrats in which the species occurs ÷ total
            quadrats) × 100.
          
        


        

          Percentage cover (quadrat pins)
          
            % cover = (hits on target species ÷ total pins or hits) × 100.
          
        


        

          Key processes in the carbon cycle
          
            Photosynthesis (CO2 → biomass), respiration (biomass → CO2), 
            decomposition, combustion of fossil fuels / biomass, formation of fossil fuels & 
            carbon in rocks/oceans.
          
        


        

          Key processes in the nitrogen cycle
          
            Nitrogen fixation (N2 → ammonia / nitrates), nitrification (ammonia → nitrite
            → nitrate), assimilation into plant & animal protein, ammonification (waste &
            dead matter → ammonia), denitrification (nitrates → N2 gas).