combined higher aqa biology (paper 1)

• Describe how the xylem is adapted for carrying water and mineral ions around a plant.

  Made of dead cells made to form hollow tubes

  Walls are made of lignin
• Name the different parts of a light microscope.

  • Eyepiece lens
  • Objective lens
  • Stage
  • Mirror / light
• How is an onion cell prepared on a microscope?

  • With tweezers, extract the onion’s epidermal tissue.
  • Use a drop of water onto a cover slip.
  • Place the tissue onto the slide.
  • Stain the tissue with a drop of iodine to make the structure is clear and visible.
  • Ensure that the tissue is one cell thick.
  • Place another cover slip atop.
  • Tap to remove any air bubbles.
  • Dab to remove excess iodine.
• What are the instructions when creating a biological drawing?

  • Make clean lines
  • Do not shade
  • Label features with clear and uncrossing lines.
• What is the difference between the nucleus of a sperm and a muscle cell?

  Muscle cells have 46 chromosones, whereas sperm cells have 23.
• Why is differentiation in animals different to differentiation in plants?

  Differentiation in animal cells occur at an earlier stage

  Differentiation in plant cells occur when the plant is matured
• What is the function of mitochondria?

  Releases energy

  Site of aerobic respiration
• State the equation for magnification.

  Magnification = image size / actual size
• Specialised cells develop from unspecialised cells by differentiation when an organism develops.

  What happens when a cell differentiates?

  • Becomes specialised
  • In order to carry out a specific function
• Why does a bacterial cell NOT contain mitochondria?

  Mitochondria would be larger in shape compared to a bacterial cell.
• The failure of a root hair cell in a plant root can be catastrophic for the plant.

  Suggest an explanation as to why.

  • Root hairs expand surface area
  • To absorb water through osmosis
  • Less root hair cells would result in reduced rates of photosynthesis
  • Lack of photosynthesis leads to mineral deficiencies which then can lead to stunted growth.
• Salivary gland cells are adapted to produce salivary amylase, an important enzyme in digestion.

  Suggest how salivary gland cells are adapted to their function.

  • Contain ribosomes
  • For proteinsysnthesis
  • Contain mitochondria
  • To provide energy to make enzymes
• How does a zygote develop into a baby?

  • Fertilised egg divides via mitosis
  • Cells differentiate into different cells/organelles
• Identify the three stages of the cell cycle.

  • Duplication - DNA is replicated and duplicated
  • Mitosis - A set of chromosones align across different poles of the cell.
  • Cytokenisis - Cytoplasm divides to produce two genetically identical daughter cells.
• Define a stem cell.

  • An undifferentiated cell
  • Capable of dividing into a specialised cell
• Desribe one use of stem cells.

  Cloning disease-resistant plants
• Describe how a nerve cell is adapted.

  • Long cytoplasm to communicate with other nerve cells, muscles and glands
  • Axons speed up nerve impulses
• How is a muscle cell adapted?

  Has high amounts of mitochondria to provide energy for muscle movement.
• Name two advantages and disadvantages of a light microscope.

  • Cheaper and affordable for schools
  • Can view living specimen
  • Lower magnification
  • Lower resolution
• Name two advantages and disadvantages of an electron microscope.

  • High magnification
  • High resolution
  • Can only view dead specimen
  • Can only be viewed in black of white
• Describe the process of mitosis.

  • Duplication - The cell will duplicate its DNA.
  • Mitosis - Chromosones line up on the equator of the cell and chromatids are pulled to the poles which are on opposite sides of the cell
  • Cytokenesis - The cytoplasm and cell membrane divides, producing two genetically identical daughter cells.
• What is osmosis?

  Osmosis is the movement of water molecules from an area of lower solute concentration to an area of higher solute concentration across a semi-permeable membrane.
• What is diffusion?

  Diffusion is the movement of particles from an area of high concentration to an area of low concentration.
• What is active transport?

  Active transport is the movement of molecules or ions across a cell membrane against their concentration gradient.
• Describe how to view a specimen under a light microscope.

  • Clip slide onto stage
  • Turn on and ensure lens is on lowest power
  • Adjust knob to bring stage below lens
  • Look into the eyepiece and adjust focus through the knob until a clear image is produced and focused
  • Continue to observe image with higher magnification and adjust knob to a higher power.
• What are the main factors that affect diffusion?

  Concentration gradient, temperature, surface area.
• What is an embryonic stem cell?

  An embryonic stem cell is a type of cell that can differentiate into any type of cell in the body and has the potential to regenerate damaged tissues and organs.
• Where can adult stem cells be found?

  Bone marrow.
• What are the ethical issues of using embryonic stem cells?

  • Destruction of potential life
  • Embryo cannot consent
• Where can stem cells in a plant be found?


  Meristems, within roots and shoots of the plant
• What are advantages of using the meristem of a plant?

  Ability to reproduce disease-resistance plants, or endangered species
• What is an enzyme?

  A biological catalyst.
• What are factors that can affect an enzyme?

  Temperature, pH.
• Name the digestive enzymes and what they break down.


  Amylase - Breaks starch into glucose

  Protease - Breaks down proteins into animo acids

  Lipase - Breaks fats down to fatty acids and glycerol
• What organs are each digestive enzymes found in?

  Amylase - Salivary glands, pancreas, small intestine

  Protease - Stomach, small intestine, pancreas

  Lipase - Pancreas, small intestine
• Write the biological structures in the correct order of each size (smallest to largest) - Cell, chromosone, gene, nucleus


  Gene

  Chromosone

  Nucleus

  Cell
• To use qualitative reagents to test for a range of carbohydrates, lipids and proteins. To include: Benedict's test for sugars, Iodine test for starch, the emulsion test for lipids and the Biuret reagent for protein
• Required Practical: Food Tests


  1. Prepare a sample by breaking up the food using a pestle and mortar, transfer to a test tube and add distilled water, mix and filter

  2. Carry out the food tests methodically, recording observations carefully

  3. Identify and reduce hazards such as Biuret solution containing copper (II) sulfate, iodine being an irritant, and ethanol being flammable
• Food tests


  • Qualitative tests that indicate if a substance is present or absent in a sample (although it doesn't tell you how much is present)
  • Look for colour changes which can indicate the presence or absence of substances
• What is the product of starch digestion?

  Glucose