Biology paper 1

• Animal cells contain a cell membrane, nucleus, mitochondria, ribosomes and cytoplasm. 


  A plant cell has three additional structures, large vacuole, cell chloroplasts and cell wall.
• Anaerobic respiration occurs in cytoplasm. Aerobic respiration occurs in mitochondria, protein synthesis in ribosomes, and photosynthesis occurs in chloroplasts.


  Aerobic respiration uses oxygen while anaerobic respiration doesn’t
• Chromosomes make up a human body human skin cells contain 23 pairs of diploid chromosomes are human gamete has 23 single haploid


  differentiation is when cells are specialised to carry out a specific function in the body.
• Sperm cells:

  have acrosomes, which contain enzymes to help digest through the egg cell membrane.They contain a middle section also known as plasma membrane that contains lots of mitochondria, help the sperm travel to the egg cell.
• Bacterial cell:

  cell membrane

  Pili

  circular DNA chromosome

  cell wall

  flagella

  plasmid
• Mitosis - produces new cells for growth and repair

  1. Chromosomes lineup at the centre of the cell and copies are pulled apart by spindle fibres to opposite ends of the cell
  2. nuclear membranes form around the chromosomes to make two nuclei
  3. finally cell splits into two identical daughter cells
• Interphase


  cell growth increases the amount of organelles and replicate its DNA
• Diffusion - spreading out of particles of any gas or liquid from area of high concentration to an area of low concentration


  Oxygen

  carbon dioxide

  amino acids
• Osmosis - movement of water molecules from area of high water concentration to an area of low water concentration across a partially permeable membrane
• embryonic stem cells -undifferentiated cells, found in the early embryo 


  can treat:

  diabetes,

  spinal injuries/paralysis
• Describe how to prepare uncontaminated culture of bacteria, using aseptic technique:

  1. sterilise, petri dish, inoculating loop, culture, medium and working area to kill unwanted microorganisms
  2. lift lI’d, slightly to inoculate plate and replace quickly to prevent microorganisms from getting in
  3. secure Petri dish with small piece of tape and store upside down to prevent bacteria entering.
• Adult stem cells - found in bone marrow, can only turn into certain cell types, such as blood cells
• Advantages of cloning plants


  Can produce clones of desired plant quickly

  Relatively cheap

  Saves rare species from extinction
• Resolution - to distinguish between two points, higher resolution produces a clearer image
• Two factors affecting rate of diffusion-

  temperature

  Concentration gradient
• Root hair cells


  Specialised cells

  Have a large surface area for rapid absorption of water and mineral ions from the soil
• Active transport


  In animals-

  Absorb nutrients (example, glucose)when they are at low concentrations from small intestine

  Plants-

  Obtain mineral ions from the soil
• Magnification = image size/ real size


  some people object against embryonic stem cell research as they believe embryos have the potential to become a human being, so should not be used for experimentation
• Prokaryotic cells are much smaller than eukaryotic cells as they don’t have mitochondria or chloroplasts
• Amylase is found in the salivary gland/pancreas and produces glucose.

  pepsin found in stomach and produces amino acids.

  Lipase is found in pancreas and produces fatty acids and glycerol.


  Lock and key method:

  1. substrate bind to active site of an enzyme
  2. Create enzyme substrate complex
  3. This makes products
• Enzymes are biological catalysts


  They speed up useful chemical reactions in the body
• Test for reducing sugars

  1. P Please test sample into a test tube
  2. add an equal amount of Benedict reagant
  3. heat in a water bath for five minutes
  4. noticed colour change from blue to green,yellow or red, (depending on how much sugar is present)
• The active site of an enzyme has a complementary shape to the substrate molecule. The active site of an enzyme has a unique shape, and only the substrate with a complementary shape can fit and bind to form an enzyme substrate complex.
• Bile helps digestion

  • Bile neutralises stomach acid to raise pH, so protease enzymes work
  • Emulsifies fats to give them larger surface area for lipase to work, which speeds up digestion
• Transpiration- evaporation and diffusion of water from the leaves of a plant

  Temperature

  Light intensity

  Airflow and humidity
• Phloem tissue

  Transports food substances (dissolved sugars)around the plant process called translocation


  xylem tissue

  transport water and dissolved minerals from the roots to the stem and leaves process called transpiration stream
• Test for protein

  1. place test sample into a test tube
  2. add equal amount of buried reagant and mix
  3. noticed colour change from blue to purple
• Test for starch

  1. Place test sample into test tube
  2. add a few drops of iodine, solution and mix
  3. Colour change from orange to blue black
• The heart


  Vena cava

  right atrium

  Right ventricle,

  pulmonary artery

  pulmonary vein,

  aorta

  left atrium,

  left ventricle
• Tobacco effects


  adults - can cause, lung, disease, cancer and cardiovascular disease

  unborn babies - can cause low birth weight and premature birth
• Archery

  • Thick, layers of muscle for strength
  • Elastic fibres, so can spring back to help withstand high blood pressure
• factors that impact health

  Diet

  Stress

  Exercise

  Drinking alcohol

  Smoking cigarettes
• Coronary heart disease


  Layers of fatty material block coronary arteries and restrict blood flow to heart muscle cells. This results in lack of oxygen and a half muscle cells stop respiring which can lead to heart attack.
• stents

  advantages -

  Patients recover quickly, and they are effective for a long time

  disadvantage -

  Risk of the patient developing a blood clot near the stent can lead to heart disease
• The left ventricle is thicker than the right ventricle, because it pumps blood at high-pressure to all parts of the body, whereas the right ventricle only pumps blood to the lungs.
• Three Adaptions of lungs for gas exchange.

  large surface area

  Moist lining

  Thin walls
• Carcinogen


  Substance,/chemical that causes cancer
• Four main components of blood


  Red blood cells - transport oxygen

  White blood cells - defend against pathogens

  platelets - help clot blood

  plasma - liquid part of blood carries many substances
• Process of heart


  deoxygenated blood enters the heart through the vena cava

  down to the right atrium

  into the right ventricle

  then leaves the heart through the pulmonary artery into the lungs,

  where it turns into oxygenated blood

  then enters the heart through the pulmonary vein

  into the left atrium,

  then down to left ventricle

  and out through the aorta to the rest of the body
• Rejection


  When bodies immune system attacks and destroys, the donor, heart muscle cells