Paper 1

• What are prokaryotic cells?

  . Bacteria cells

  . Single celled

  No nucleus

  Single loop of DNA

  Small rings of DNA called plasmids
• What are eukaryotic cells?

  . Plant and animal cells

  . Have a nucleus

  . DNA that forms chromosomes
• How are root hair cells specialised?

  Hair increases surface area of the root to allow more mineral ions to be absorbed
• How have xylem tissue been specialised?

  . Very thick walls ~~>> contain lignin which provides support to plant an withstand water pressure

  . End walls been broken down to form long tube ~~>> water an dissolved minerals can flow easily
• How have phloem tissues been specialised?

  . Phloem vessel cells have sieve plates ~~>> allow sugars to move through cell interior

  . Each phloem vessel cell has a companion cell ~~>> provides energy
• Which resolution is higher, electron or light microscopes?

  Electron ~~>> very short wavelength so resolution is 2000x better than light
• What is a disadvantage of using electron microscopes?

  Cannot view living specimens

  Can get artefacts ( false images )
• How are stem cells formed?

  . Fertilisation

  . Fertilised ovum undergoes mitosis ~~>> embryo

  . Cells continue to mitosis and begin to form specialised cells
• What medical conditions can therapeutic cloning he used for?

  . Diabetes

  . Paralysis
• What are meristems?

  . Can differentiate into any plant tissue

  . Clone a rare plant to prevent it going extinct

  . Produce cloned crop plants for farmers
• What happens during exercise?

  . Glucose is used up in respiration

  . Water and salts lost in sweats
• what happens to the SA : VOL ratio as organisms get larger?

  SA : VOL ratio falls sharply
• Gills in fish:

  • Oxygen water passes into mouth
  • Flows over gills
  • Oxygen transported to bloodstream
• Where do gases pass in and out of the blood in gills?

  Fine filaments
• What are 3 adaptations of filaments in gills?

  . Give gills massive surface area for gas exchange

  . Thin membrane

  . Efficient bloody supply ~~>> ensures concentration gradient is always high
• Describe active transport in humans?

  . LUMEN OF SMALL INTESTINE

  . Low concen of sugars are carried into cell by active transport

  . Once in cell, sugars can be transported into blood
• Where are protease found?

  . Stomach

  . Pancreas

  . Small intestine
• Where are amylase found?

  . Saliva

  . Pancreas
• Where are lipase found?

  . Pancreas

  . Small intestine
• What is the resting heart rate controlled by?

  Pacemaker in the right atrium
• What chamber of the heart pumps blood all around the body?

  Left ventricle
• Oxygen used in respiration to provide energy for contraction