All of the choices are correct.
Explanation:
Viruses are non cellular entities which are made up of either a DNA or RNA enclosed within a protein coat.
Viruses cannot reproduce by themselves. They can reproduce only within living cells and hence they are obligate intracellular parasites.
Viruses have a wide range of hosts including animals, plants, bacteria etc.
However, each viral species has a very limited host range.
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)
spindle-fiber structure because this is used to divide cells; cancer is just cells dividing way too much. so if the <em>spindle-fiber structure </em>were to fail it could cause cancer.
Answer: The function of muscle cells is to move your body and helps you Push or Move things, throughout any ways that it is flexible.
Explanation: It is because muscle cells are usually what makes your body operate and to work and move, to you hair to the tip of your toes. These muscles are very strong and make you move whatever weight you are. For example, you are running, the muscles in your feet and legs push you upward and downward and it keeps repeating lick a cycle. When your pushing or pulling things, you can use your strength, or Muscles to use a force on any object.
Hope this helps :).
