Topic 2 Cells and Control

• What does the nucleus contain?

  Genetic information
• What are chromosomes made of?

  Coils of DNA
• What is a gene?

  A section of DNA coding for a protein
• How many pairs of chromosomes are in human cells?

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

  46 chromosomes
• What is the chromosome count in gametes?

  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 is the cell cycle?

  A series of steps for cell division
• What is mitosis?

  A step in the cell cycle for division
• What happens during interphase?

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

  'X' shape
• What occurs during mitosis?

  Chromosomes line up at the equator
• What is cytokinesis?

  Division of cytoplasm and cell membranes
• Why is mitosis important in multicellular organisms?

  For growth and replacing damaged cells
• How many daughter cells does mitosis produce?

  2 daughter cells
• What type of cells does 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 monitoring growth important?

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

  The growth rate of an organism
• How can a baby's growth be measured?

  Using mass, length, or head circumference
• What does 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 does a high percentile indicate?

  Possible health problems
• What is a stem cell?

  An undifferentiated cell that can divide
• What are embryonic stem cells?

  Cells that can differentiate into any type
• What can embryonic stem cells potentially replace?

  Insulin-producing cells in diabetes
• Where are adult stem cells found?

  In bone marrow
• Where are meristems found in plants?

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

  Any type of plant cell
• What is therapeutic cloning?

  Producing an embryo with the patient's genes