Biology Paper 1

• What is osmosis?

  diffusion of water across a partially permeable membrane
• What is active transport?


  The movement of particles from an area of low concentration to an area of high concentration (against the concentration gradient).
• What is diffusion?

  The movement of particles from an area of high concentration to an area of low concentration.
• What does an animal cell have?


  - cytoplasm

  - nucleus

  - ribosomes

  - cell membrane

  - mitochondria
• What is the function of the nucleus?

  Contains the cell's genetic material that controls the cells activties
• What is the function of the cell membrane?

  holds the cell together and controls what goes in and out
• What is cytoplasm?

  gel-like substance where most of the chemical reactions happen. It contains enzymes which control these chemical reactions
• What is the function of ribosomes?


  involved in the translation of genetic material in the synthesis of proteins
• Function of the cell wall?

  Supports and strengthens the cell
• Function of chloroplasts?

  where photosynthesis occurs. they contain a green substance called chlorophyll
• Function of mitochondria?

  where most of the reactions for respiration take place
• What is a prokaryotic cell?


  cell that does not have a nucleus or organelles
• What is a eukaryotic cell?

  cell that has a nucleus and organelles
• Formula for magnification?

  Magnification = image size / real size
• What does a plant cell have that an animal cell doesn't?

  cell wall, chloroplast, vacuole
• What is the function of a vacuole?

  Contains cell sap and helps maintain internal pressure of cell
• What features do bacterial cells have?

  -chromosomal DNA

  -ribosomes

  -cell membrane

  -plasmid DNA

  -flagellum
• What is the function of the flagellum?

  rotates to make the bacterial cell move. it can be used to move the bacteria away from harmful substances and towards beneficial things
• What is the function of chromosomal DNA in a bacterial cell?

  It controls the cell's activities and replication. It floats free in the cytoplasm.
• What is the function of plasmid DNA in a bacterial cell?


  they are small loops of extra DNA that aren't part of the chromosome- they contain genes for things like drug resistance and can be passed between bacteria
• What is a specialised cell?

  cells that are adapted to their function
• What is the function of an egg cell?

  To carry the female DNA and to nourish the developing embryo in the early stages
• How is an egg cell adapted to its function?

  > Haploid nucleus with one set of genetic material

  > Cytoplasm contains nutrients that the embryo will use to grow and develop

  > Cell membrane changes immediately after fertilisation to not let more sperm in
• What is the function of a sperm cell?


  To transport the male's DNA to the female's egg
• How are sperm cells adapted to their function?

  - Acrosome contains enzymes so the sperm can penetrate the egg

  - Haploid nucleus

  - Tail so that it can swim to the egg

  - Lots of mitochondria for energy (from respiration)
• What is the function of ciliated epithelial cells?

  To move substances - the cilia beat to move substances in one direction, along the surface of the tissue
• What are enzymes?

  biological catalysts that speed up reactions
• How does changing temperature affect enzyme activity?

  If temperature passes its optimum, bonds holding the enzymes together will break, the active site will change shape and ESCs will no longer be able to form (enzyme is denatured)
• How does changing pH affect enzyme activity?

  if pH is too high or low, it interferes with the bonds holding the enzyme together and so the active site changes shape and the enzyme denatures
• How does substrate concentration affect enzyme activity?

  The more substrate molecules there are, the more likely there are to be collisions between enzyme and substrate molecules, forming more enzyme-substrate complexes. However, after a certain point all the active sites will be full and adding more substrates won't make a difference
• How do you investigate the effect of pH on enzyme activity? (core practical)

  1- put a drop of iodine solution into every well of a spotting tile

  2- place a bunsen burner on a heat proof mat. place a tripod and a gauze over the bunsen burner.

  3- put a beaker of water on the tripod and heat until it is 35 degrees

  4- use a syringe to add 3cm^3 of amylase solution and 1cm^3 of buffer solution with a pH of 5 to a boiling tube

  5- put the boiling tube into the beaker of water and wait for five minutes

  6- use a different syringe and place 3cm^3 of starch solution to the boiling tube

  7- mix the contents of the boiling tube and start a timer

  8- record how long it takes amylase to break down all of the starch by using a pipette to take a sample from the boiling tube every 10 seconds and putting a drop into a well. when the iodine solution remains browny-orange, starch has been broken down.

  9- repeat the experiment with different pH values
• How to calculate the rate of reaction?

  1000/time
• What enzyme breaks down starch into...?

  Amylase (carbohydrase) breaks down starch into maltose
• What enzyme breaks down proteins into....?

  Protease breaks down proteins into amino acids
• What enzyme breaks down lipid into...?

  Lipase breaks down lipids into glycerol and fatty acids
• How do you investigate osmosis?


  - Prepare sucrose solutions with concentrations ranging from pure water to very concentrated

  - Cork borer to cut potato into same sized cylinders

  - Divide cylinders into groups of three and use mass balance to measure the mass of each group

  - Place one group in each solution and leave for at least 40 minutes, leaving the same one for the same amount of time

  - Remove cylinders and gently pat dry with paper towel

  - Measure mass of each group again and record

  - Compare percentage change in mass for each.
• How do you calculate percentage change?

  final- intial/ initial x100
• What are the stages of mitosis?


  interphase, prophase, metaphase, anaphase, telophase, cytokinesis
• What happens in interphase?

  DNA duplicates so theres one copy for each cell
• What happens in prophase?

  chromosomes condense and the membrane around the nucleus breaks down