Thursday, April 30, 2009

I need homework help on plants?

the question is :in many flowers the pistils and stamens reach maturity at different times why would this be an advantage to the plant?


if the petals are absent or reduced how is the plant pollinated?

I need homework help on plants?
It prevents the plant from self-pollinating.

If the plants lacks colourful petals to attract bugs, it usually has an attractive scent.
Reply:To the first: it would be advantageous b/c if the plant did fertilized itself nothing bad would happen but there would not be any genetic variation in the offspring of the plant. And of course, genetic variation and thus natural selection is the basis of evolution and the improving of a species as a whole.

Also as was already stated, petals are meant to attract pollinators. The other way a plant could be pollinated is by the wind. Ex: Gymnosperms (non flower producing plants like pine trees) are pollinated by the wind.

Hope this helps!
Reply:The advantage to the plant is that this prevents self - fertilisation. If a plant pollinates itself this can lead to defects in the 'baby' plants so to avoid this many species have the male and female flowering parts mature at different times.

In general, if a flower has reduced petals it is likely to be wind pollinated (eg grasses) - large petals are used to attract pollinators, wind pollinated plants do not need these and need to have their style and stamens exposed to the wind so the petals cannot cover them.
Reply:Different maturation of stamens and pistils avoids self-fertilization of the ovules in the pistils. Usually pollination by a different plant of the same species increases genetic variations, some of which may be better adapted to the environment such as disease resistance, more vigorous growth, or more viable seeds. Some flowers are self-sterile. They have to have pollen from a different plant.

Most flowers that have reduced or absent petals (corolla) are pollinated by the wind rather than animals, grasses for example.
Reply:The first one would give the plant opportunities to pollinate other plants and be pollinated by other plants before it self-pollinates.

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