Memory Anchor:

• Super Challenge:

  Stretch:

  Challenge:

Key Questions:

1. How did Oregor Mendal develop our understanding of genetics?
   • Oregor Mendel (1822-1884) studied the inheritance of different characteristics in pea plants. He found that when he bred red-flowered plants with white-flowered plants, all the offspring produced red flowers. If he bred these plants with each other, most of the offspring had red flowers, but some had white. This was because the allele for red flowers is dominant, and the allele for white flowers is recessive.
2. Why was the importance of Mendel's discovery not accepted until after his death?
   • It took long time for Mendel's ideas to be accepted. That was because scientists did not know about chromosomes and genes until after Mendel died. Also, Mendel was a monk, not a scientist, and his work was not widely published or published at all in any science journal.
3. What observation did Mendel make of the inheritance of plants?
   • In the mid-19th century Oregor Mendel carried out breeding experiments on plants. One of his observations was that the inheritance of each characteristic is determined by ?units? that are passed on to descendants unchanged.
4. What wasn't observed about cell division until the late 19th century?
   • The behaviour of chromosomes.
5. What happened in the early 20th century to link Mendel's 'units' and chromosomes and what idea did this lead to?
   • In the early 20th century it was observed that chromosomes and Mendel?s ?units? behaved in similar ways. This led to the idea that the 'units', now called genes, were located on chromosomes.
6. What happened in the mid-20th century to further develop gene theory?
   • In the mid-20th century the structure of DNA was determined and the mechanism of gene function worked out.