Cram

• What is the focus of AQA GCSE biology paper 1?

  Cells, organization, infection, and bioenergetics
• What can we see with a normal light microscope?

  Cells and possibly the nucleus
• What does an electron microscope allow us to see?

  Finer details of organelles
• What is the formula for magnification?

  Magnification = image size / object size
• How do you calculate the actual size of a cell?

  Divide image size by magnification
• What are the two main groups of cells?

  Eukaryotic and prokaryotic cells
• What characterizes eukaryotic cells?

  They have a nucleus containing DNA
• What characterizes prokaryotic cells?

  They do not have a nucleus
• What does semi-permeable mean in relation to the cell membrane?

  It allows certain substances to pass through
• What do plant cells and most bacteria have that provides structure?

  An extra cell wall made of cellulose
• What is cytoplasm?

  The liquid where most chemical reactions occur
• Where does respiration take place in a cell?

  In the mitochondria
• What is the function of ribosomes?

  Where proteins are assembled
• What is the function of the cell membrane?

  It keeps everything inside the cell
• What do chloroplasts contain and what is their function?

  Chlorophyll for photosynthesis
• What do plant cells contain that stores sap?

  A permanent vacuole
• How do bacteria multiply?

  By binary fission
• What technique is used to produce a culture on agar?

  Aseptic technique
• Why do we lift the lid of the dish towards a flame?

  To move microbes away and destroy them
• What do we use to hold the lid on the petri dish?

  A few bits of tape
• Why is it important to not seal the petri dish completely?

  To allow air for bacterial respiration
• At what temperature do we incubate the culture?

  25 degrees Celsius
• How do we calculate the area of the culture?

  Using $\pi r^2$ or $\frac{p_d^2}{4}$
• What do eukaryotic cell nuclei contain?

  DNA stored in chromosomes
• How many pairs of chromosomes do humans have?

  23 pairs
• What type of cells are gametes?

  Haploid cells
• What is the process by which new cells are made for growth and repair?

  Mitosis
• What happens during mitosis?

  Genetic material is duplicated and divided
• What are stem cells?

  Cells that haven't specialized yet
• Where are stem cells found in humans?

  In embryos and bone marrow
• How can stem cells be used in medicine?

  To combat conditions like diabetes and paralysis
• What is diffusion?

  The movement of molecules from high to low concentration
• What is osmosis specifically?

  The diffusion of water across a membrane
• How does a higher concentration of glucose outside a cell affect water movement?

  Water moves out of the cell
• What factors can increase the rate of diffusion and osmosis?

  Concentration difference, temperature, surface area
• What is the practical method for osmosis using potatoes?

  Cut cylinders, weigh, and place in sugar solutions
• How do you calculate percentage change in mass?

  Final mass - initial mass / initial mass × 100
• What does it mean if a potato cylinder is lighter after osmosis?

  There was a negative change in mass
• What does the x-axis crossing point represent in the osmosis graph?

  The concentration with no change in mass
• What is active transport?

  Movement against a concentration gradient using energy