Biology key concepts

• What are the two main types of cells?

  Eukaryotic and Prokaryotic
• What is a characteristic of eukaryotic cells?


  They have a nucleus
• What is a characteristic of prokaryotic cells?


  They do not have a nucleus
• What are the similarities and differences between plant and animal cells?


  Similarities:

  • Both have a nucleus
  • Both have mitochondria
  • Both have ribosomes

  
  

  Differences:

  • Plant cells have chloroplasts
  • Plant cells have a cell wall
  • Plant cells have a large central vacuole
• Where is DNA stored in animal cells?


  In structures called chromosomes
• What is the function of the cell membrane?


  It holds the cell together and controls what goes in and out
• What is the role of mitochondria in cells?


  They are where respiration occurs
• What is the function of ribosomes?


  They link amino acids together to make proteins
• What is the function of chloroplasts in plant cells?


  They are where photosynthesis happens
• What does photosynthesis produce for the plant?


  Food for the plant
• What is stored in the large central vacuole of plant cells?


  A solution of sugar and salts
• What type of DNA do bacterial cells have?


  Chromosomal DNA
• What is the structure of chromosomal DNA in bacterial cells?


  One long circular strand of DNA
• What are plasmids in bacterial cells?


  Small loops of DNA
• What is the function of the flagellum in bacterial cells?


  It helps the cell move
• What are the key structures found in bacterial cells?

  • Chromosomal DNA
  • Ribosomes
  • Cell membrane
  • Plasmid DNA
  • Flagellum
• What are specialised cells?


  Cells that have a structure adapted to their function.
• Why do multicellular organisms have different types of cells?


  Because they perform various functions that require different structures.
• What is the function of an egg cell?


  • Carry female DNA
  • Feed the developing embryo
• What is the function of a sperm cell?


  • Carry male DNA to the egg
  • Help in fertilisation
• What happens after fertilisation of an egg cell?


  The cell membrane changes structure to prevent more sperm from entering.
• What does "haploid" mean?


  It means the cell has half the number of chromosomes found in a normal body cell.
• How do ciliated epithelial cells function?


  They move substances by beating cilia along the surface of the tissue.
• What is the role of cilia on epithelial cells?


  Cilia are tiny hair-like structures that help move substances.
• Why are microscopes important in studying cells?


  They allow us to magnify and view cells and their structures.
• What do light microscopes allow us to see?


  Some sub-cellular structures like chloroplasts and the nucleus.
• How do electron microscopes differ from light microscopes?


  Electron microscopes show more detail and can magnify specimens more than light microscopes.
• What are the steps to prepare a specimen for viewing under a light microscope?


  1. Take a thin slice of the specimen.
  2. Place a drop of water on a clean slide.
  3. Add the specimen to the slide.
  4. Optionally add a drop of stain.
  5. Lower a cover slip carefully.
• What is the procedure for viewing a specimen using a light microscope?


  1. Clip the slide onto the stage.
  2. Select the lowest magnification lens.
  3. Adjust the stage to focus on the specimen.
  4. Use fine adjustment for clarity.
  5. Change to a higher magnification if needed.
• What are the guidelines for making a scientific drawing of a specimen?


  1. Use a sharp pencil for smooth outlines.
  2. Label features with straight lines.
  3. No coloring or shading.
  4. Drawing should occupy at least half the space.
  5. Include magnification and scale.
• What is the formula for total magnification in microscopy?

  Total magnification = eyepiece lens magnification × objective lens magnification.
• If the eyepiece lens magnification is ×10 and the objective lens magnification is ×40, what is the total magnification?


  Total magnification = $10 \times 40 =$$400$
• How can you calculate the magnification of an image if you know the image size and real size?


  Magnification = image size / real size.
• If the width of a specimen is 0.02 mm and its image is 8 mm, what is the magnification used?


  Magnification = $8 \text{ mm} \div 0.02 \text{ mm} =$$400$
• If the width of a specimen's image is 3 mm and the magnification is ×100, what is the real width of the specimen?


  Real width = $3 \text{ mm} \div 100 =$$0.03 \text{ mm}$
• What units are commonly used to measure very small objects like cells?


  • Millimetres (mm)
  • Micrometres (µm)
  • Nanometres (nm)
• How do you convert 0.007 mm to micrometres?


  Multiply by 1000 to get 7 µm.
• What is diffusion?


  Diffusion is the movement of particles from an area of higher concentration to an area of lower concentration.
• What are specialised cells?


  Cells that have a structure adapted to their specific function
• What is the significance of multicellular organisms having different types of cells?


  • They perform various functions
  • They have different structures suited to their roles