TOPIC 4 - BIOLOGY

• Photosynthesis


  The process by which plants make glucose from sunlight
• Endothermic reaction


  Energy is transferred from the environment to the chloroplasts by light
• Photosynthesis


  Carbon dioxide + water → glucose + oxygen
• Factors affecting rate of photosynthesis

  • Temperature
  • Light intensity
  • Carbon dioxide concentration
  • Amount of chlorophyll
• Measuring oxygen production to calculate rate of photosynthesis


  1. Pondweed in test tube

  2. Capillary tube and syringe

  3. Lamp at measured distance

  4. Measure distance bubble moves to calculate oxygen volume

  5. Control variables except independent variable
• Limiting factor


  An environmental condition (such as light intensity) which, in low levels, restricts any increase in the rate of photosynthesis
• Light intensity


  Inversely proportional to the square of the distance (inverse square law)
• Uses of glucose from photosynthesis

  • For respiration
  • Converted into insoluble starch for storage
  • To produce fat or oil for storage
  • To produce cellulose to strengthen cell walls
  • Combined with nitrates to form amino acids which produce proteins
• Respiration


  The process of transferring energy from glucose so living processes can occur
• Exothermic


  Energy is transferred to the environment
• Types of respiration


  • Aerobic (with oxygen)
  • Anaerobic (without oxygen)
• Anaerobic respiration in animals

  Glucose → Lactic acid
• Anaerobic respiration in plants and yeast

  Glucose → Ethanol + Carbon dioxide
• Oxygen debt


  The amount of extra oxygen the body needs after exercise to react with the accumulated lactic acid and remove it from the cells
• Metabolism


  The sum of all the reactions in a cell or the body, controlled by enzymes
• Metabolic reactions


  • Glucose to starch, glycogen and cellulose
  • Glycerol and fatty acids to lipids
  • Glucose and nitrates to amino acids and proteins
  • Respiration reactions
  • Urea forming from protein breakdown
• Ribosomes are responsible for protein synthesis
• The nucleus is the control centre of the cell, containing DNA which controls all activities within the cell.
• Mitochondria produce energy through respiration
• Mitochondria produce energy through respiration
• Protein synthesis is made up of two stages; transcription and translation.
• Lysosomes contain digestive enzymes that break down waste material inside the cell
• Vacuoles store water, nutrients and wastes
• Chloroplasts contain chlorophyll and carry out photosynthesis
• Chloroplasts carry out photosynthesis
• Vacuoles store water and waste products
• Vacuoles store water and waste products
• Lysosomes contain digestive enzymes that break down waste material inside cells
• Lysosomes contain digestive enzymes that break down waste material inside cells
• Transcription occurs in the nucleus where DNA is transcribed into mRNA (messenger RNA). The sequence of bases on the mRNA determines which amino acids will be joined together to form a specific polypeptide chain.
• Lysosomes break down food particles and worn-out organelles
• Translation occurs at ribosomes where tRNA molecules bring the correct amino acids to join them together according to the code on the mRNA.
• Transcription occurs when RNA polymerase reads the base sequence on one strand of DNA and creates an mRNA molecule that has complementary bases.
• The nucleus contains genetic information (DNA) which controls all activities within the cell
• Transcription involves RNA polymerase copying sections of DNA to make mRNA molecules.
• Translation involves ribosomes using mRNA as a template to build proteins from amino acids.
• The nucleus contains genetic information (DNA)
• Translation occurs when ribosomes read the code on the mRNA and create a polypeptide chain using tRNA as a carrier.
• Vacuoles store water and other substances such as pigments or starch
• Cell membrane regulates what enters or leaves the cell