biology paper 1

• What is the function of a nucleus?

  • contains the genetic materials (DNA) which controls the activities of the cell.
• What is the function of a cytoplasm?

  • A gel- like structure substance which supports internal cells structures.
  • site of many chemical reactions
• What is the function of a cell membrane?

  • Holds the cell together, separating the inside of the cell from the outside.
  • controls which substances can enter and leave the cell.
• What is the function of ribosomes?

  • found in the cytoplasm
  • site of protein synthesis by amino acids
• What is the function of a mitochondria?

  • site of most of the reactions involved in aerobic respiration, where energy is released to fuel cellular processes
• What is the function of a cell wall?

  • made of cellulose (a polymer of glucose)
  • gives the cell extra support defining its shape.
• What is the function of a chloroplast?

  • contains green chlorophyll pigments to absorb light energy and the enzymes needed for photosynthesis.
• What is the function of a permanent vacuole?

  • contains cells sap (a solution of sugars and salts) dissolved in water
  • used for storage of certain materials also helps support the shape of the cell.
• What is the function of a nerve cell?

  • conduction of impulses
• What is the adaptations of a nerve cell?

  • has cell body where most of cellular structures are located and most protein synthesis occurs
  • extension of the cytoplasm from the cell body from dendrites (which receive signals) and axons (which transmits signals) allowing neurones to communicate
• What’s is the function of a muscle cell?

  • Contraction for movement
• What is the adaptations of a muscle cell?

  • all muscles have layers of proteins filaments in them. These layers can slide over each other causing muscle contraction.
  • muscles have high density of mitochondria to provide sufficient energy (respiration) for muscle contraction
• What is the function of a sperm cell?

  • reproduction (pass on fathers genes)
• What’s is the adaptations of a sperm cell?

  • the head contains a nucleus which contains 23 pairs chromosomes
  • the acrosome in the head contains digestive enzymes that can break down the outer layer of an egg cell.
  • The mid piece is paced with mitochondria to release energy (respiration) for the tail
  • the tail rotates, propelling the sperm cell forwards (allowing it to swim)
• What is the function of a root hair cell?

  • absorption of water and minerals ions from soil
• What is the adaptation of root hair cells?

  • root hair increase surface area so the rate of water uptake by osmosis is greater.
  • thinner walls than other plant cells so that water can move through easily due to shorter diffusion distance.
  • permanent vacuole contains cell sap which is more concentrated than soil water, maintaining a water potential gradient
• What is the function of the xylem cell?

  • transport tissues for water and dissolved ions
• What is the adaptation of a xylem cells?

  • No top and bottom walls between cells to form continuous hollow tubes through which water is drawn upwards towards the leaves by transpiration
  • cells are essentially dead with organelles or cytoplasm to allow free passage of water
• What is the function of a phloem cells?

  • cells are joined end to end and contain holes in the end cell walls forming tubes which allow sugars and amino acids to flow easily through
  • cells also have very few sub cellular structures to aid the flow of materials
• What’s is the formula for magnification?

  • magnification = image size / actual size
• What is an electron microscope?

  • an electron microscope has much higher magnification and resolving power than light microscope
• What is a light microscope?

  • A light microscope is used to visualise fine detail of a sub cellular structure
• What is mitosis?

  • a type of cell division that results in 2 daughter cells each having the same number of chromosomes as the parent.
• What happens during stage 1 of mitosis?

  • during the interphase stage, the cell and its organelles grow and multiply in number.
  • protein synthesis takes place and DNA replicates, forming the recognisable X shape
• What happens during stage 2 of mitosis?

  • in the mitosis stage, chromosomes align at the cells’s equator.
  • the cell fibres actively pull each arm of the X shaped chromosome to opposite sides of cell
• What happens during stage 3 of cytokinesis?

  • during cytokinesis, the cytoplasm and cell membrane divide, resulting in two identical daughter cells