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Basic genetics:  In the 19th century, a Czech monk, Gregor Mendel, experimented with pea plants.  He noticed that plants were either tall or short, but when he crossbred a tall plant with a short one he didn't get a medium sized plant - he got a tall one.  However, when he crossbred these new tall plants, sometimes it would result in a short one.  He concluded that 'tall' was dominant and 'short' recessive.

Experiments with true-bred green and yellow pea plants led him to conclude that each parent contributed either a G or a Y characteristic (gene), and that G is dominant over Y, so that GG, GY, and YG plants all appear green, and only YY plants appear yellow.  He concluded that crossing a GG plant with a YY plant would result in offspring which all appeared to be green.  However in the following generation, a GY or YG plant could give its offspring a Y gene rather than a G one.  If the GY or YG plant was cross-bred with a YY plant, not all of the offspring would be green.

Coola breeds pea plants. She plants a pea and thinks about its family tree.

Coola knows that there is a small chance the plant will be the same height and colour as grandparent 1, but it is more likely it will be the same height and colour as parent 1. She knows it won't be the same height and the same colour as grandparent 3.

1. Can you determine the colour of parent 2?

2. Can you describe the height of grandparents 1 and 2?

3. How likely is it that the pea will grow into a short yellow plant?

4. How likely is it that the plant will be green?