Biology paper 1 topic 2 cells and control

• Why do cells need to divide?

  To survive and grow
• What do chromosomes contain?

  • Genetic information
  • Coiled lengths of DNA molecules
• Where is genetic material found in most cells?

  In the nucleus
• What is the structure of chromosomes?

  They are coiled lengths of DNA molecules
• What type of cells are body cells classified as?

  Diploid cells
• How many copies of each chromosome do body cells have?

  Two copies
• From whom do body cells receive their chromosomes?

  One from the mother and one from the father
• What process do cells undergo to divide and create identical cells?

  Mitosis
• What is the result of a cell dividing by mitosis?

  Two identical cells
• How does the number of chromosomes in new cells compare to the original cell after mitosis?

  They contain the same number of chromosomes
• What is the process called when body cells in multicellular organisms divide to produce new cells?

  The cell cycle
• What is the stage of the cell cycle when the cell divides?

  Mitosis
• Why do multicellular organisms use mitosis?

  To grow or to replace damaged cells
• What is asexual reproduction in the context of mitosis?

  It is when some organisms use mitosis to reproduce
• Give an example of an organism that reproduces asexually through mitosis.

  Strawberry plants
• What are the main stages of the cell cycle?

  1. Interphase (cell growth and DNA duplication)
  2. Mitosis (cell division)

  • Prophase
  • Metaphase
  • Anaphase
  • Telophase

  1. Cytokinesis (division of cytoplasm)
• What happens to DNA in a cell that is not dividing?

  The DNA is spread out in long strings
• What must a cell do before it divides?

  It must grow and increase the amount of subcellular structures
• What happens to the DNA during the preparation for mitosis?

  The DNA duplicates and forms X-shaped chromosomes
• What are the arms of the X-shaped chromosomes called?

  Chromatids
• How are the chromatids related to each other?

  Each arm is an exact duplicate of the other
• What are the four stages of mitosis?

  1. Prophase: Chromosomes condense and the nuclear membrane breaks down
  2. Metaphase: Chromosomes line up at the center of the cell
  3. Anaphase: Spindle fibers pull chromatids apart
  4. Telophase: Membranes form around each set of chromosomes
• What occurs during telophase?

  Membranes form around each set of chromosomes, creating nuclei for the new cells
• What is cytokinesis?

  The process where the cytoplasm and cell membrane divide to form two separate cells
• What is produced at the end of mitosis?


  Two new daughter cells
• How do the daughter cells compare to each other and the parent cell?

  They are genetically identical diploid cells
• What is the formula to calculate the number of cells after multiple divisions by mitosis?

  Number of cells = \(2^n\)
• In the formula \(2^n\), what does 'n' represent?

  'n' represents the number of divisions by mitosis
• What is growth in biological terms?

  Growth is an increase in size or mass.
• What processes contribute to growth in plants and animals?

  • Cell differentiation
  • Cell division
  • Cell elongation
• What is cell differentiation?

  Cell differentiation is the process by which a cell changes to become specialized for its job.
• Why is having specialized cells important for multicellular organisms?

  Specialized cells allow multicellular organisms to work more efficiently.
• How do plants grow in terms of cell division?

  Plants grow by cell division through mitosis.
• What is cell elongation in plants?

  Cell elongation is where a plant cell expands, making the cell bigger and thus making the plant grow.
• How does growth in animals primarily occur?

  All growth in animals happens by cell division.
• When do animals typically stop growing?

  Animals tend to grow while they're young and then reach full growth and stop growing.
• What happens to the rate of cell division as animals reach adulthood?

  Cells divide at a fast rate when young, but most cell division in adults is for repair.
• What is the primary function of cell division in adults?

  In adults, cell division primarily replaces old or damaged cells.
• What does the loss of cell differentiation in animals imply?

  In most animals, cell differentiation is lost at an early stage.
• Where does cell division mainly occur in plants?

  Cell division usually happens in the tips of the roots and shoots, in areas called meristems.