Topic 2 Cells and Control

• What does the nucleus contain?

  Genetic information
• In what form is genetic information found in the nucleus?

  In the form of chromosomes
• What do chromosomes contain?

  Coils of DNA
• What is a gene?

  A short section of DNA coding for a protein
• How many pairs of chromosomes are in each body cell?

  23 pairs
• How many total chromosomes are in each body cell?

  46 chromosomes
• How many chromosomes are in gamete cells?

  23 chromosomes
• What is the diploid number of chromosomes in humans?

  46 chromosomes
• What is the haploid number of chromosomes in humans?

  23 chromosomes
• What are the stages of the cell cycle?

  1. Interphase
  2. Mitosis
  3. Cytokinesis
• What happens during Interphase?

  The cell grows and DNA is replicated
• What shape does DNA form during replication?

  'X' shape
• What occurs during Mitosis?

  Chromosomes line up at the equator
• What happens during Cytokinesis?

  Cytoplasm and cell membranes divide
• Why is mitosis important in multicellular organisms?

  For growth and replacing damaged cells
• How many daughter cells are produced by mitosis?

  2 daughter cells
• What type of cells do mitosis produce?

  Genetically identical diploid daughter cells
• How does growth occur in animals?

  Through cell division and differentiation
• What happens to most specialized cells in animals?

  They lose the ability to differentiate
• What replaces red blood cells that cannot divide?

  Adult stem cells
• When does cell division mostly occur in mature animals?

  To repair or replace damaged cells
• How do plant cells grow longer?

  By absorbing water into their vacuoles
• What controls the elongation of plant cells?

  Substances called auxins
• When do plant cells differentiate?

  When they reach their final position
• What causes cancer?

  Uncontrolled cell division
• What is a tumour?

  A group of cells from uncontrolled division
• Why is it important to measure growth?

  To check progress in crops or children
• What do percentiles charts measure?

  The growth rate of an organism
• What can be measured to assess a baby's growth?

  Mass, length, or head circumference
• What does being in the 50th percentile for mass indicate?

  Heavier than 50% of babies
• What does being in the 25th percentile for mass indicate?

  Heavier than 75% of babies
• What does being in the 75th percentile for mass indicate?

  Heavier than 25% of babies
• What can indicate a health problem in babies?

  Being in a high percentile
• What is a stem cell?

  An undifferentiated cell that can divide
• What are the types of stem cells?

  1. Embryonic stem cells
  2. Adult stem cells
  3. Meristems in plants
• What do embryonic stem cells form from?

  When an egg and sperm cell fuse
• What can embryonic stem cells differentiate into?

  Any type of cell in the body
• What can adult stem cells form?

  Many types of cells including blood cells
• Where are meristems found in plants?

  In root and shoot tips
• What can meristems differentiate into?

  Any type of plant cell