For unrooted trees, the number of unrooted tree topologies (NU) is ________

For unrooted trees, the number of unrooted tree topologies (NU) is ________ Correct Answer NU = (2n− 5)!/2n−3(n− 3)!

The number of possible topologies increases extremely rapidly with the number of taxa. For six taxa, there are 105 unrooted trees and 945 rooted trees. If there are ten taxa, there can be 2,027,025 unrooted trees and 34,459,425 rooted ones.
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A gardener has to plant trees in rows containing equal number of trees. If he plants in rows of 6, 8, 10 or 12 then five trees are left unplanted. But if he plants in rows of 13 trees each, then no tree is left. What is the number of trees that the gardener plants ?
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Manja, or the glass-coated string used for flying kites, not only poses threat to humans, animals and birds but also to trees. A study by the country's oldest botanical garden has revealed that it poses a great threat to trees. But how can a snapped string struck in a tree kill the tree? Apparently, it does so by allying with the creepers in the garden.
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Read the passage carefully and choose the best answer to each question out of the four alternatives.
Manja, or the glass-coated string used for flying kites, not only poses threat to humans, animals and birds but also to trees. A study by the country's oldest botanical garden has revealed that it poses a great threat to trees. But how can a snapped string struck in a tree kill the tree? Apparently, it does so by allying with the creepers in the garden.
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Manja, or the glass-coated string used for flying kites, not only poses threat to humans, animals and birds but also to trees. A study by the country's oldest botanical garden has revealed that it poses a great threat to trees. But how can a snapped string struck in a tree kill the tree? Apparently, it does so by allying with the creepers in the garden.
A research paper by three scientists of the Acharya Jagdish Chandra Bose Indian Botanic Garden, located in West Bengal's Howrah district, illustrates in detail how the manja, in collusion with climbers, does the damage. "The abandoned, torn kite strings act as an excellent primary supporting platform for the tender climbers, giving easy passage to reach the top of the trees. Lateral branches from the top of the climber and other accessory branches from the ground reaches the top taking support of the first climber, completely covers the treetop, thus inhibiting the penetration of sunlight," says the research paper.
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Read the passage carefully and choose the best answer to each question out of the four alternatives.
Manja, or the glass-coated string used for flying kites, not only poses threat to humans, animals and birds but also to trees. A study by the country's oldest botanical garden has revealed that it poses a great threat to trees. But how can a snapped string struck in a tree kill the tree? Apparently, it does so by allying with the creepers in the garden.
A research paper by three scientists of the Acharya Jagdish Chandra Bose Indian Botanic Garden, located in West Bengal's Howrah district, illustrates in detail how the manja, in collusion with climbers, does the damage. "The abandoned, torn kite strings act as an excellent primary supporting platform for the tender climbers, giving easy passage to reach the top of the trees. Lateral branches from the top of the climber and other accessory branches from the ground reaches the top taking support of the first climber, completely covers the treetop, thus inhibiting the penetration of sunlight," says the research paper.
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