Answer:
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.
Explanation:
~Dr.Smiley~
(Jane)
Dextromethorphan. This is a drug that is used for this purpose and is considered an anti-tussive.
d is correct answer of a question
Answer:
A animal 2b has no cell wall
Answer:
The correct answer is - The neuron's intracellular charge must get more positive to meet a certain thresh hold in order to depolarize. If the neuron does not hit that threshold, then the neuron will not fire
Explanation:
In neuroscience, the depolarization of neurons shows the all or none law which is also called as all or nothing response. It states that all action potentials have the same size and the potential or strength of a nerve cell does not depend on the stimulus strength as all are the same size.
If a stimulus reaches a particular threshold cell or fiber will fire so either it will fire or not cross the threshold this is all or nothing response or law and depolarization is an example of it.
