Aqa biology triple cell biology

• What are the two main types of cells discussed in cell structure?


  Eukaryotes and prokaryotes.
• What is the function of the nucleus in a cell?

  The nucleus controls cell activities and contains DNA for protein synthesis.
• What is the role of the cytoplasm in a cell?

  The cytoplasm is where chemical reactions take place.
• What does the cell membrane do?

  The cell membrane controls what goes in and out of the cell and is partially permeable.
• What are ribosomes responsible for?

  Ribosomes make proteins from amino acids through protein synthesis.
• What is the function of mitochondria in a cell?

  Mitochondria release energy by respiration.
• What is the size of an animal cell approximately?

  About 10 micrometers.
• What is the approximate size of a plant cell?

  About 50 micrometers.
• What is the approximate size of a prokaryotic cell?

  About 5 micrometers.
• What is cell differentiation and specialization?

  • Cell differentiation is the process by which undifferentiated cells become specialized.
  • Specialized cells in animals include nerve cells, muscle cells, and sperm cells.
  • Specialized cells in plants include xylem, phloem, and root hair cells.
• What happens to specialized cells in animals when they divide?

  They usually divide for repair and replacement of those cells.
• What is unique about many plant cells regarding differentiation?

  Many plant cells retain the ability to differentiate into any other type of plant cell.
• Describe the structure and function of a nerve cell.

  • The nerve cell has a cell body containing cytoplasm.
  • Dendrites connect to other nerve cells.
  • The axon carries impulses around the body.
  • An insulating sheath speeds up electrical impulses.
• Describe the structure and function of a sperm cell.

  • The midpiece contains mitochondria for energy.
  • The tail enables swimming towards the egg.
  • The acrosome contains enzymes for penetrating the egg cell membrane.
  • The nucleus contains 23 chromosomes.
• Describe the structure and function of muscle cells.

  • Muscle cells have fibers that shorten for contraction.
  • They contain many mitochondria for energy.
  • They store glycogen for energy.
• Describe the structure and function of xylem cells.

  • Xylem cells are long tube-shaped and have no end plates.
  • They are dead cells that allow water to flow through.
  • They contain lignin for support.
• Describe the structure and function of phloem cells.

  • Phloem cells are elongated and have end plates with pores.
  • They contain little cytoplasm to allow solution flow.
  • Companion cells provide energy for sugar transport.
• Describe the structure and function of root hair cells.

  • Root hair cells have a large surface area for absorption.
  • They contain many mitochondria for active transport.
• What are the differences between simple microscopes and electron microscopes?

  • Simple microscopes have low magnification and resolving power.
  • Electron microscopes have high magnification and resolving power.
  • Electron microscopes provide higher resolution images.
• What are the units used to measure sizes in microscopy?

  Millimeters, micrometers, and nanometers.
• How do you convert millimeters to micrometers?

  Multiply by a thousand.
• How do you convert micrometers to nanometers?

  Multiply by a thousand.
• How do you convert nanometers to micrometers?

  Divide by a thousand.
• How do you convert micrometers to millimeters?

  Divide by a thousand.
• What is the formula for magnification?

  Magnification = size of image / size of real object.
• If the size of an image is 5 millimeters and the real size is 20 micrometers, what is the magnification?

  250 times.
• If the magnification of a sperm cell is 2000 and the image size is 10 millimeters, what is the real length of the sperm cell in micrometers?

  5 micrometers.
• What is binary fission in bacteria?


  • Binary fission is the process by which bacteria divide.
  • One bacterium can divide into two, then four, and continue doubling.
  • This can happen as fast as every 20 minutes under suitable conditions.
• If a colony of bacteria starts with 200 cells and doubles every 20 minutes, how many cells will there be after 4 hours?

  There will be 819200 cells.
• How do you grow uncontaminated cultures of microorganisms?

  • Sterilize the workspace and materials with disinfectant and heat.
  • Use an inoculating loop to transfer bacteria to agar gel.
  • Incubate at 25 degrees Celsius to allow growth.
  • Seal the petri dish to prevent contamination.
• How do you test the effectiveness of antibiotics or antiseptics?

  • Place sterile paper discs with antibiotics on agar gel with bacteria.
  • Observe areas of dead bacteria around the discs.
  • Calculate the area of inhibition using the formula $\pi r^2$.
• What are control variables in an antibiotic effectiveness experiment?

  Control variables include the area of the disks, concentration, and volume of the antibiotic.
• What are the stages of the cell cycle?

  1. Stage one: Cell growth and increase in subcellular structures.
  2. Stage two: Mitosis, where chromosomes line up and are pulled apart.
  3. Stage three: Cytoplasm and cell membranes divide to form two identical cells.
• What is the purpose of mitosis?

  Mitosis is for cell division, repair, and growth.
• What are stem cells?

  • Stem cells are undifferentiated cells that can develop into specialized cells.
  • They are found in embryos and can differentiate into various cell types.
• What is the result of fertilization in terms of cell development?

  Fertilization results in a small ball of undifferentiated cells.
• What is the key event that occurs during mitosis?

  The chromosomes line up along the center and are pulled to each end of the cell.
• What occurs after mitosis in the cell cycle?

  The cytoplasm and cell membranes divide to form two genetically identical cells.
• What happens to the DNA during the cell growth phase?

  The DNA replicates to form two copies of each chromosome.
• How are the two new cells formed after mitosis related to the parent cell?

  They are genetically identical to each other and to the parent cell.