biology

• Chromosomes are long strands of DNA that carry genes.
• Genes determine an organism's physical appearance, including eye color, hair texture, skin tone, height, etc.
• Genes determine inherited characteristics such as eye color or height.
• Chromosomes are long strands made up of DNA molecules, which carry genes responsible for specific traits or characteristics.
• The nucleus contains the genetic material (DNA) that controls all cellular activitie
• The nucleus is the control center of the cell, containing genetic material.
• DNA is made up of nucleotides, which consist of a sugar molecule, phosphate group, and nitrogenous base (Adenine, Thymine, Cytosine, Guanine).
• Cell membrane separates the inside from outside of the cell and controls what enters/exits the cell.
• Cytoplasm contains enzymes to catalyze chemical reactions within the cell.
• eukaryotic cell = cell with a nucleus and membrane bound organelles
• prokaryotic cell = single celled microorganisms
• Animal cells – nucleus, cell membrane, mitochondria and ribosomes Plant cells – nucleus, cell membrane, cell wall, chloroplasts, mitochondria, vacuole and ribosomes Bacteria – chromosomal DNA, plasmid DNA, cell membrane, ribosomes and flagella
• Plant cells

  • Cell wall- rigid made of cellulose which supports and strengthens cell
  • Chloroplasts- where photosynthesis occurs for food and contains chlorophyll
  • Large vacuole- contains cell sap for internal pressure for support
• Animal cells

  • Nucleus- contain genetic material that controls activites of cell(chromosomes)
  • Ribosomes- translation of genetic material in synthesis of proteins.
  • Mitochondria- reactions of respiration take place here which transfers energy for cell to work
  • Cell membrane- holds cell together controls what goes in and out.
  • Cytoplasm- gel-like substance where chemical reactions occur (contains enzymes)
• Bacterial cells

  • Chromosomal DNA- (long circular chromosome) controls activities and replication floats free
  • Cell membrane Plasmid DNA- small loops of extra DNA which contain genes like drug resistance
  • Flagellum- long hair like structure rotates to move away from toxins towards nutrients & oxygen
  • Ribosomes - protein synthesis
• Egg cell

  • changes in the cell membrane after fertilisation (to stop anymore sperm getting in)
  • nutrients in the cytoplasm (feed embryo)
  • haploid nucleus
• Ciliated Epithelial Cell

  • line surface of organs
  • beat to move substances along the surface of tissue
  • lining airways to move mucus up throat to be swallowed and not get to lungs.
• • Light microscopes : low resolution and low magnifications
  • Electron microscopes : high resolution and high magnification
• • UNITS: (going up /1000) (going down x1000)
  • millimetre (10^3)
  • micrometre(10^6)
  • nanometre (10^9)
  • picometre (10^12)
• ENZYME + SUBSTRATE -> ENZYME-SUBSTRATE COMPLEX -> ENZYME + PRODUCTS
• • Enzymes = biological catalyst that can break down molecules (digestion) or join substrate molecules (synthesis) if the substrate does not fit the active site the reaction will not be catalysed
• • Denature = when a enzyme becomes denatured there is a change to the enzymes active site therefore it cannot catalyse the reaction of its specific substrate.
• TEMPERATURE - EFFECT ON ENZYMES

  • higher the temp=quicker the rate
  • if it gets to hot the enzyme will denature as bonds break= decrease in rate
• pH - EFFECT ON ENZYMES

  • optimum pH (7) pepsin is pH (2) breaks down proteins in stomach.
  • if its too high or too low it will interfere with the enzymes bonds causing it to denature
• SUBSTRATE CONCENTRATION - EFFECT ON ENZYMES

  • after a certain point there are too much molecules as all active sites are full the rate remains constant.
  • high the conc=faster the rate (more likely to meet substrate)
• 1. Protein -> Amylase
  2. Starch -> Glucose
  3. Lipid -> Fatty Acids + Glycerol
• • ENERGY IN FOOD (J)= mass of water(g) X temp change of water(dc) X 4.2ENERGY PER GRAM OF FOOD (J/g) = energy in food (J) / mass of food (g)
• • DIFFUSION = the net movement of particles from a area of higher concentration to an area of lower concentration
• • OSMOSIS = the net movement of water molecules across a partially permeable membrane from a region of higher concentration to a region of lower water concentration.
• • ACTIVE TRANSPORT = the movement of particles across a membrane against a concentration gradient using energy transferred during respiration.
• Biuret test - test for protein



  An equal volume of 1% strong base (sodium or potassium hydroxide) followed by a few drops of aqueous copper(II) sulfate. If the solution turns purple, it contains protein.
• Iodine Solution - Test for starch


  Blue-black (positive) Yellow-Brown (negative)
• Benedict's solution - Test for reducing sugars 


  Benedict's reagent starts out aqua-blue. As it is heated in the presence of reducing sugars, it turns yellow to orange. The "hotter" the final color of the reagent, the higher the concentration of reducing sugar.

  Little - green More - yellow/orangeLots - brick red Blue (negative)
• Ethanol emulsion test - test for fats and oils 


  Take the sample and mix it with equal volumes of ethanol and water followed by shaking. A cloudy white emulsion will form if lipids are present. If lipids are absent, no emulsion will form.
• • Mitosis is the process of cell division, important for growth and repair.
• Before mitosis even starts, cells spend about 90 percent of their time in interphase, replicating their DNA and making more of their organelles like mitochondria and ribosomes.
• • Mitosis begins with prophase, where the nucleus breaks down and spindle fibers appear.
• • During metaphase, the spindle fibers pull the chromosomes to the middle of the cell.
• • Anaphase is when the spindle fibers pull the chromatids away to each end of the cell, the chromatids are just one half of a chromosome.
• • Telophase is the last stage of mitosis, where the nucleus reforms.