BIO PAPER 1

• formula for photosynthesis?

  6CO2 + 6H2O + light energy -> C6H12O6 + 6O2
• Where are stem cells found?

  brain, bone marrow, blood vessels, skin, teeth and heart.
• where are stem cells found in plants?

  Meristems (tips of roots and shoots)
• How are base pairs bonded together in a DNA molecule?

  Weak Hydrogen bonds
• What is the shape of a DNA molecule?

  Double helix
• Why is ice cold ethanol poured into filtrate (food test)

  to precipitate the DNA as its insoluble in ethanol
• Why can chlamydia be treated with antibiotics?

  As chlamydia is caused bacteria, it can be killed by antibiotics
• How can HIV lead to AIDS

  HIV destroys WBC , then weakens immune system, making person more susceptible to other diseases
• How can bacteria develop resistance to antibiotics?

  • by natural selection
  • mutation in bacteria population
  • resistant bacteria survive antibiotics/survive when people don't finish course
  • bacteria reproduces and offspring receive resistant allele
• Features of a prokaryotic cell?

  No nucleus, cytoplasm , ribosomes, cell wall, DNA
• Stages of antibiotic development?

  • development phase
  • pre clinical trials
  • testing on animals/on cells
  • testing on healthy volunteers
• Why would milk rise to the surface when placed into water?

  It contains high fat content
• Why does the pH of fatty milk not change when boiled lipase is added?

  • temp above optimum
  • so enzyme denatures, active site changes shape
  • substrate cannot bind
• How can a student prepare a microscope slide to show mitosis in the growing roots of a garlic plant?

  • use root tip (meristem)
  • take thin section of root
  • stain root
  • add drop of water to slide
  • add with cover slip
• What is produced when a single cell divides by mitosis?

  Two genetically identical diploid cells
• How has bacteria been genetically engineered to produce human insulin?

  1. gene for human insulin found
  2. removed using restriction enzyme
  3. plasmid of bacteria cell removed using lysozyme
  4. plasmid cut open with R.enzyme and leaves sticky ends
  5. human gene inserted into plasmid using enzyme ligase
  6. plasmid returned to bacterial cell and multiplies.
• How does an impulse pass from relay neurone to motor neurone?

  1. Impulse in relay triggers release of neurotransmitter
  2. neurotransmitter diffuses across synapse
  3. new impulse triggered in motor neurone
• What is the function of a reflex arc?

  • process that occurs in response to danger which defends body from harm
• Differences between non communicable and communicable diseases?

  • communicable passed from person to person
  • communicable caused by pathogens
  • non communicable not passed from person to person
  • non communicable cannot be inherited
• How can the spread of tuberculosis be prevented ?

  Vaccination, proper ventilation, early detection.
• Why are people with AIDS more susceptible to Tuberculosis?

  Weakened immune system. Means body unable to destroy TB pathogen
• Name 2 processes that occur during prophase

  1. Chromatids condense
  2. nuclear membrane breaks down
• Benefits from using stem cell therapy for arthritis?

  1. can replace damaged cells
  2. reduce symptoms of arthritis
  3. stem cells can become specialised
• Disadvantages from using stem cell therapy for arthritis?

  1. new cells do not function correctly
  2. stem cells continue to divide
  3. risks of side effects/ rejecting cells
• How does cancer develop in the liver?

  • Mutations in DNA
  • cell division uncontrolled
  • leads to formation of cancerous cells (tumour)
• Safety precautions when removing blood from a person?

  1. gloves
  2. sterile needle
• What is a genotype and phenotype?

  Genotype: Genetic makeup of an organism. Phenotype: Observable characteristics of an organism.
• How does specific immune system defend body from disease?

  1. antigens trigger antibodies to be produced by lymphocytes
  2. pathogen destroyed by antibodies
  3. memory lymphocytes produced
• Describe the function of meristem in growth of plants


  Meristem cells are undifferentiated and can divide to produce more cells by mitosis
• Explain how natural selection could have caused increase in beak length because of bird feeders

  1. bird feeders provide selection pressure
  2. birds with big beaks get more food from feeder
  3. these birds more likely to survive and reproduce
  4. allele passed onto offspring
• Why was the classification system produced?

  Genetic analysis
• Why is amylase not produced in the stomach?

  Stomach has low pH, which will denature the enzyme , changes shape of active site so substrate will not fit
• Explain how a signal is transmitted at a synapse and how the painkillers reduce the pain felt by the person

  1. neurones transmit electrical impulses
  2. triggers release of neurotransmitters as chemical signal
  3. neurotransmitters bind to receptors on next neurone, triggers electrical impulse in next neurone.
  4. painkillers prevent neurotransmitters binding onto next neurone
  5. electrical impulse not sent, signal not received by CNS
  6. person doesn't feel pain
• Compare the outcomes of mitosis and meiosis

  1. Mitosis produces 2 cells, Meiosis produces 4
  2. Mitosis produces genetically identical cells, Meiosis produces genetically different cells
  3. Mitosis produces diploid cells , Meiosis produces haploid cells
  4. Mitosis produces body cells, Meiosis produces gametes
• What is the name of the domain plants belong to?

  Eukarya
• What happens in a chloroplast?

  Oxygen produced, sunlight absorbed by chlorophyll
• Features of a bacterial cell?

  No nucleus, Cell wall, cell membrane, flagellum, ribosomes, DNA.
• What is a control variable?

  anything that is held constant or limited in a research study
• What is an independent variable?


  The variable that isn't manipulated or changed in an experiment.
• What is a dependant variable?


  The variable that is being measured or observed in an experiment.