Biology Past Paper Knowledge

• 5 Key Features of Sperm Cells and how they're adapted?

  • Tails to help them swim
  • Nucleus that contains genetic information (23 Chromosomes)
  • Acrosome which contains digestive enzyme that digests through the egg cell's wall
  • A streamlined shape, allowing them to manoeuvre faster
  • Mitochondria in the midpiece that respire, creating energy to generate the energy to swim
• Evaluate the use of embryonic stem cells, compared to adult stem cells:

  • Embryonic stem cells can differentiate to any cell, but adult stem cells are limited
  • Embryonic stem cells could be used to treat currently untreatable diseases
  • Embryonic stem cells have ethical issues as using an embryo for stem cells instead of letting it develop offends some people
  • Embryonic stem cells can be used to create new organs for transplants
• Describe how a Microscope should be set up:

  1. Place specimen on the slide ( stain it if needed )
  2. Cover specimen with a cover slip
  3. Place slide onto microscope and hold in place with clips
  4. Turn microscope on
  5. Set it to the lowest objective lens
  6. Use the coarse focusing knob to adjust the focus, and then the fine focusing knob
  7. View the specimen in the eyepiece
• Compare the functions of Phloem and Xylem:

  • Xylem carry water and minerals up the plant
  • This is called transpiration
  • Phloem carry sugars up and down the plant
  • This is called translocation
• Food Tests:

  • Sugar - Benedict's Solution: Colour change blue to red
  • Starch - Iodine Solution: Colour change brown to blue/black
  • Protein - Biuret Solution: Colour change blue to purple
  • Lipids - Ethanol Solution: Colour change colourless to cloudy
• What's the name given to a cancerous growth which can form secondary tumours?

  Malignant
• How does smoking and obesity lead to non-communicable diseases?

  Smoking - Chemicals, like tar, damage the alveoli in the lungs and can lead to cancer of the lungs

  Obesity - Excess consumption of sugar reduces the effect of insulin on the body, causing type 2 diabetes
• How can we reduce the spread of pathogens via direct contact or droplet infections and vectors?

  • Destroying vectors
  • Having good hygiene
• What is the word equation for anaerobic respiration in yeast?

  Glucose -> Ethanol + Carbon Dioxide + Energy
• What are the 2 ways the body deals with lactic acid?

  • Oxidising it to make carbon dioxide and water
  • Transporting it to the liver via the blood and converting it back to glucose
• What are 3 reasons the body requires energy?

  • Chemical reactions to build bigger molecules from smaller ones
  • Muscle contractions to allow movement
  • Maintaining the a constant core temperature in the body suitable for enzymes
• How do vaccines work?

  • Introduce a small dead part of a pathogen to the body via an injection
  • This stimulates the WBCs to make antibodies specific to the pathogen, and remember the pathogen
  • The next time the pathogen enters the body, the WBCs fight it faster
• What 4 ways do plants use glucose, other than photosynthesis?

  • Converted to starch, as a storage of glucose
  • Used to produce oils
  • Used to produce cellulose, for cell walls
  • Combined with nitrate ions, taken in from the soil, to produce amino acids for protein synthesis
• How are monoclonal antibodies made?

  • Inject someone with antigens to stimulate mouse lymphocytes to produce specific antibodies
  • The lymphocyte is extracted and combined with a type of tumour cell to produce a hybridoma cell
  • This means it can divide repeatedly, and produces the antibody
  • They are then cloned repeatedly resulting in many identical cells that produce the antibody
  • Large amounts of the antibody are produced, collected, and purified, ready for use
• Advantages and disadvantages of monoclonal antibodies?

  • Cheaper to develop than conventional drugs
  • Can bind to specific diseases, or specific cells needing treatment
  • Can treat a wide range of conditions
  • Can have many side effects
  • Expensive
• What are nitrate ions used for in plants?

  The production of amino acids, which are used to make protein
• What are potassium minerals used for in plants?

  For the production of their flowers or fruit
• How do aphids damage plants?

  • They feed on the sugar filled cell sap by piercing the stem
  • This removes large amounts of sap, resulting in weakened plants
  • Aphids can also act as vectors for disease
• What do a lot of plants produce, as a chemical defense?

  Chemicals with antimicrobial properties