Download Japanese knotweed, Fallopia japonica, was introduced to Britain

Japanese knotweed, Fallopia japonica, was introduced to Britain from Japan
during the nineteenth century as an exotic garden plant. It has spread and is very
invasive. Its roots grow downwards to a depth of 3 m and outwards to 7 m. It can
destroy walls and damage buildings and pavements.
Its natural enemies that keep it in check in Japan do not thrive in the British
climate. It does not form viable seeds that can germinate in Britain. All Japanese
knotweed plants are derived from one plant that was introduced here.
A What type of reproduction has been involved in the spread of Japanese
knotweed plants in Britain?
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B Why is this plant a problem in Britain but not in its native Japan?
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C Why is it extremely difficult to remove this plant by digging it out of the soil?
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D Why are all these plants in Britain described as clones?
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E In March 2010, an insect that feeds on Japanese knotweed was released in
Britain to try to control the plant. Many tests had been carried out before this
insect was released to make sure it would not cause any problems. What
possible problems might releasing such an insect cause?
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Couch grass is a problem weed. It has underground stems that spread outwards
and send up new shoots and leaves. Two gardeners had couch grass growing in
their vegetable plots. They each tackled their couch grass weeds in different
ways in the autumn. Neither used weedkiller because they had tried it and found
that the grass was resistant to it.
Gardener A carefully dug and pulled the couch grass out by hand, making sure
every bit was removed form the soil.
Gardener B used a mechanical rotavator and chopped up the couch grass and
dug it into the soil, expecting it to decompose.
The following spring, gardener A had very little couch grass in his garden.
However, gardener B had a worse problem than before, with a lot of couch grass
all over his vegetable plot.
F What type of reproduction does couch grass use when it spreads by
underground stems that send up new shoots?
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G What type of cell division is involved in this type of reproduction?
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H Why do you think gardener B had a lot of couch grass growing in his
vegetable plot the following spring?
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I Why do you think he did not treat this new couch grass with his weedkiller?
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J Gardener B expected his chopped up couch grass to decompose in the soil.
What type of organisms in the soil are mainly responsible for decomposing
dead matter?
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