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Cycads /ˈsaɪkædz/ are seed plants that typically have a stout and woody (ligneous) trunk with a crown of large, hard, stiff, evergreen and (usually) pinnate leaves. The species are dioecious, therefore the individual plants of a species are either male or female. Cycads vary in size from having trunks only a few centimeters to several meters tall. They typically grow very slowly[3] and live very long, with some specimens known to be as much as 1,000 years old.[citation needed] Because of their superficial resemblance, they are sometimes mistaken for palms or ferns, but they are not closely related to either group.
Cycads are gymnosperms (naked seeded), meaning their unfertilized seeds are open to the air to be directly fertilized by pollination, as contrasted with angiosperms, which have enclosed seeds with more complex fertilization arrangements. Cycads have very specialized pollinators, usually a specific species of beetle. Both male and female cycads bear cones (strobili), somewhat similar to conifer cones.
Cycads have been reported to fix nitrogen in association with various cyanobacteria living in the roots (the "coralloid" roots).[4] These photosynthetic bacteria produce a neurotoxin called BMAA that is found in the seeds of cycads. This neurotoxin may enter a human food chain as the cycad seeds may be eaten directly as a source of flour by humans or by wild or feral animals such as bats, and humans may eat these animals. It is hypothesized that this is a source of some neurological diseases in humans.[5][6]
Cycads all over the world are in decline, with four species on the brink of extinction and seven species having fewer than 100 plants left in the wild.[7] The plant has a very long fossil history, with evidence that they existed in greater abundance and in greater diversity before the Jurassic and late Triassic mass extinction events.
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Producers
Explanation:
Autotrophs make their own food from chemical or light energy sources.
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when we crossed Pp with pp out result will have a phenotype ratio of 2Pp:2Pp or Pp:Pp and genotype will be 50%Pp and 50%Pp.
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Explanation:
Phototropism is the growth of organism characterize by their response to light stimulus. It occurs mainly in plant and some Algae.
The response of plant to light enable them use energy from light needed for photosynthesis.
Plant Phototropism characterise some plant growth and development such as flowering,fruiting and seedling formation.
Inability of plant to respond to light reduces it ability to photosynthesize and make sugar needed for their activities ,flower and fruits. It reduces it growth and development.
We have positive and negative response. Positive response is the response of plant towards the direction of light while negative response is the response of plant away from light.
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The modern organisms would have more muscular bodies
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