b1

• the world of microscope?

  electron microscope have a higher magnification than light microscope

  magnification=size of image/size of real object
• animal and plant cells

  animal cell features-nucleus,cytoplasm,cell membrane,mitochondria and ribosomes

  plant and algal cells contain all the structures seen in animal cells as well as a cellulose cell wall

  plant cells features-chloroplasts,permanent vacuole filled with sap
• eukaryotic and prokaryotic cells

  eukaryotic cells have a cell membrane,cytoplasm,and genetic material enclosed in a nucleus

  prokaryotic cells consist of cytoplasm and a cell, membrane surrounded by a cell wall.

  the genetic material is not in a distinct nucleus

  forms a single DNA loop

  prokaryotes may contain one or more extra small rings of DNA
• specialisation in animals

  as an organism develops,cells differentiate to form different types of cells

  as an animal cell differentiates to form a specialised cell it aquires different sub cellular structures

  to enable it to carry out a certain function
• what are examples of specialisation in animals?

  nerve cells

  muscle cells

  sperm cells
• specialisation in plant cells

  plants cells are specialised to carry out a particular function
• what are examples of specialised plant cells?

  root hair cells

  photosynthetic cells

  xylem cells

  phloem cells
• what is diffusion?


  The movement of particles from an area of high concentration to an area of low concentration.
• what affects the rate if diffusion?

  concentrations

  temperature

  surface area
• what dissolved substance move in and out of cells by diffusion?

  glucose and urea
• what is osmosis?


  The movement of water molecules from an area of high concentration to an area of low concentration across a semi-permeable membrane.
• why is osmosis in plants important?

  to maintain turgor in plant cells
• what is active transport?

  Movement of molecules across a cell membrane that requires energy.
• what does active transport in plants allow?

  allow plant root hairs to absorb mineral ions required for healthy growth from very dilute solutions in the soil against a concentration gradient
• what does active transport enable?

  sugar molecules used for cell respiration to be absorbed from lower concentrations in the gut into the blood where the concentration of sugar is higher
• what do exchange surfaces usually have?

  large surface area

  efficient blood supply

  gaseous exchange
• what is the role of the nucleus?

  control centre of the cell.contains genetic information
• what is the role of the cytoplasm?

  where chemical reactions take place
• what is meant by the cell membrane?

  controls what goes in and out of the cell
• what is the role of the cell wall?

  provides support to the cell,keeping it turgid
• what is the role of chloroplasts?

  absorb the sunlight energy for use in photosynthesis
• what is the role of the vacuole?

  stores cell sap
• what is the role of the ribosome?

  to make proteins