'Good Life' elusive for nuclear families

post from Science Blog - on 13 August 2006 11:41:44 PM. © Science Blog -

In research to be presented at the American Sociological Association's annual meeting, Phyllis Moen, McKnight Presidential Chair in Sociology at the University of Minnesota, says that middle class couples who both work struggle to compete in job environments designed for single earners with no family responsibilities. According to Moen, couples still are operating under outdated work policies and practices and institutional and organizational rules designed for a one earner, one homemaker model.

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http://www.scienceblog.com/cms/good-life-elusive-for-nuclear-families-11270.html

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Ancient war paint in fight against breast cancer

post from Science Blog - on 13 August 2006 11:39:48 PM. © Science Blog -

A plant that gave ancient Britons and Celts their blue war paint, has been found to be a rich source of the anti-cancer compound, glucobrassicin, traditionally associated with broccoli. Glucobrassicin has been found to be effective against breast cancer. The war paint, a blue dye, is obtained from Woad, a member of the Brassicaceae family.

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http://www.scienceblog.com/cms/ancient-war-paint-in-fight-against-breast-cancer-1
1269.html

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The St. Andrews Prize for the Environment

post from Ponderfodder - Because Great Minds Discuss Ideas | Community Blog on 13 August 2006 10:09:07 PM. © Ponderfodder - Because Great Minds Discuss Ideas | Community Blog

Description:

The Prize recognises significant contributions to environmental conservation. Submissions for the an

...

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http://www.ponderfodder.com/st-andrews-prize-environment

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Behind the Rings

post from Wolverine's Den on 13 August 2006 09:38:00 PM. © Wolverine's Den

The rings cannot hide the ragged, icy crescent of Rhea, here imaged in color by the Cassini spacecraft. The second-largest moon of Saturn shines brightly through gaps in the rings.Rhea (1,528 kilometers, or 949 miles across) lies beyond the dim, unlit side of the rings. A diffuse clump of material lies in [...]

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http://www.wolverinesden.org/2006/08/13/behind-the-rings/

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What Are Flowers For

post from Science In Action on 13 August 2006 09:31:00 PM. © Science In Action

Flowers, sex and seeds

Flowers are the specialized plant structures which produce pollen and where seeds develop within an enclosing fruit. Each seed (like the faba bean seeds at the right) contains a baby plant.

A baby plant (plant embryo), and its surrounding seed, cannot develop unless pollen is transferred from the pollen-producing parts of the flower to the parts which contain ovules, which can become seeds.

So flowers serve two basic purposes:

they package genetic material (into pollen and ovules) and help move it around so it can combine to produce the seeds for the next generation, and

they enclose those seeds in a fruit to help them successfully grow into a new plant.

Picture of peanuts from Purdue University site http://www.hort.purdue.edu/ext/senior/fruits/peanut2.htm

If you look closely at this picture of some peanuts, you can see a baby plant where one of the peanut seeds has split in two. Each seed was enclosed in a "seed coat" (the red, papery covering) and several seeds were in each fruit (the peanut shell with the seeds inside -- not shown). (Better yet -- get some peanuts and look at them carefully. This is called "observation" -- a big part of science.)

Not all plants have flowers

Some plants don't make seeds at all (like ferns or mosses). And others (gymnosperms like pines, ginkgos and cycads) make seeds without flowers. (The seeds of gymnosperms aren't enclosed in a fruit that develops from part of a flower. They are just borne externally, although a cone or fleshy outgrowth may surround them as they mature.)

Flowers facilitate plant sex

They typically include structures which produce pollen and other structures where seeds can develop if pollen reaches them. Sexual reproduction means the parent organisms produce ?gametes?, which carry a sample of the parent's genetic information (just half of it, but one of every chromosome). These gametes must unite to reconstitute the complete genetic complement that the next generation will need?two of each chromosome. In people the gametes are sperm and the egg. In seed plants they are pollen and ovules.

Usually a seed can develop from union of pollen and an ovule on the same plant. But many flowering plants promote broader mixing of genetic material. They have have forms which encourage the transfer of pollen from one flower to another, and thus often from one plant to another. This transfer of pollen can be done by wind, or by birds, insects or other animals which visit the flowers. Many flowers have evolved specific forms, colors, or other features to attract such ?pollinators?.

After pollination (the transfer of pollen to the parts of the flower where the ovule is waiting) and fertilization (the joining of the genetic material from the two gametes), a seed can develop. In flowering plants, seeds are enclosed in a structure called a fruit. A fruit can contain just one seed (like an olive) or many (like a tomato). A fruit can be dry and hard, like a grain of rice, or fleshy like an apple.

Picture of dandelion seeds from http://photos.jibble.org/Dandelions/dandelion_seeds_being_blown

Many fruits have specialized structures to help carry the seeds away from their parent plants, like a dandelion (which floats on the wind), burdock (which has prickles to catch on fur of passing animals), Impatiens (?touch-me-not?, where the fruit explodes and scatters the seeds), coconuts (which can float), or the cherry (which has an edible portion surrounding a tough digestion-resistant seed).

So flowers make fruits, and a fruit has three parts:

the embryo (baby plant)

the seed that contains the embryo

the fruit that contains the seed (or seeds). The fruit develops from the structure that contained the ovules before fertilization.

More about plant sex

Flowers are all about sex. Sexual reproduction produces offspring which are not genetically identical to their parents. In fact, each offspring can contain a novel combination of genes never seen before. This helps plants deal with changing environments and other challenges (new competitors, new predators). The plant gets the most novel new combinations if pollen is transferred from one parent to another. Plant sexuality is very diverse, with many complicated sexual mechanisms even just within the flowering plants. These various mechanisms include differences in which flowers produce pollen and which produce ovules, whether the pollen-producing flowers and the ovule-producing flowers are even on the same plant, where within the flowers pollen is released and where it can be received, when the pollen is released and when the ovules are receptive, how the pollen is transferred, and chemical signals which determine which pollen will be allowed to fertilize an ovule. The incredible diversity of the flowering plants (90% of all plants living today, comprising hundreds of thousands of species) is all about trying new ways to have sex.

Although many plants don't use pollinators such as insects (wind pollination is common), the fossil record suggests that flowers and insects evolved together, and that the diversity of each stimulated diversity in the other.

Flowers work

Flowering plants provide the basis of nearly all human nutrition, except for the wild-caught fish we eat. (A few calories also come from algae, pine nuts, fern fiddleheads and the like.) Without flowering plants civilization would certainly be impossible with today's technology. (Could a civilization develop that depended entirely on fish for nutrition?) Flowers, seeds and fruits have, ultimately, made the internet, and every other aspect of civilization, possible.

To review:

Flowers have pollen. If pollen is transferred, flowers grow seeds, and turn into fruits.

Homework

So next time you are looking at a flower, try to see where the pollen is and where it might go to make a seed. How does pollination happen?

Next time you are looking at a fruit, consider how it formed and how it helps its seeds get around. Where are the seeds and how are they dispersed?

Next time you consider a seed, think about the baby plant inside, and how it might grow into a mature plant with flowers of its own.

Here are some links for further information:

Wikipedia: flowers, flowering plants, seeds

Parts of a flower (floral structure)

Good pdf document about floral structure

Good summary page with images of various flowers

Diversity of flowering plants

The Seed Biology Place

David Wheat's Science In Action site has articles about science and math in the real world, weird science, science news, unexpected connections, and other cool science stuff. There is an index of the articles by topic here.

tags: science, botany, science education, math, education, Science In Action

Read The Full Article:
http://sxxz.blogspot.com/2006/08/what-are-flowers-for.html

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Smacking down more lies about Plan B

post from Pharyngula on 13 August 2006 08:42:50 PM. © Pharyngula

It's really not that hard to understand, but what's blocking acceptance are the amazing lies people say about Plan B emergency contraception. Ema found a ghastly op-ed that got everything wrong; try reading my summary of Plan B, then the op-ed by Abby Wisse Schachter, and see if you can spot all the errors. You won't be as thorough as Ema, though, who has posted a wonderfully detailed, complete annihilation of Schachter's article.

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http://feeds.feedburner.com/~r/scienceblogs/pharyngula/~3/12266638/smacking_down_
more_lies_about.php

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Promoting Science and Engineering

post from Curious Cat Science and Engineering Blog on 13 August 2006 08:23:00 PM. © Curious Cat Science and Engineering Blog

Sexing Up Science by Mac Margolis and Karla BruningAnother article discussing the need to focus on science and engineering education in the USA and the United Kingdom. It is nice to see the Duke study has worked its way into most recent articles.Being in the field “teaches you to be flexible and ruthlessly creative,” [...]

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http://engineering.curiouscatblog.net/2006/08/13/promoting-science-and-engineerin
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Agent Orange Depleted Uranium

I was on the Presidential advisory committee that examined Gulf War Syndrome at the end of the Gulf War. I did not believe that the kind of monitoring and surveillance of our soldiers and civilian contractors in that war was adequate to detecting much less explaining the syndrome that some exhibited. Not much has been done to rectify the inadequate epidemiology and health monitoring present in that conflict in the current Iraqi conflict. That is what makes this inevitable report from Iraq so very disturbing.
- Art Caplan

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http://blog.bioethics.net/2006/08/agent-orange-depleted-uranium.html

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Bones of Contention

Well no problem with here. missing links. The latest move of the Intellegent Design crowd is not to haggle about the evidence for evolution. it is simply to hide it!
- Art Caplan

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http://blog.bioethics.net/2006/08/bones-of-contention.html

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HIV and responsible journalism

If I could have been at this week's conference for one session, it would have been this morning's symposium on AIDS denial and responsible journalism. Hannah has already mentioned it and given her impressions and thoughts. The session itself was moderated by HIV researcher Daniel Kuritzkes and journalist Laurie Garrett, currently a Senior Fellow on Global Health at the Council on Foreign Relations. Talks were also given by HIV researcher John Moore, South Africa-based science journalist Tamar Khan, Toronto Star science reporter Kim Honey, and Nathan Geffen of the

(Continued at The AIDS conference blog...

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http://feeds.feedburner.com/~r/scienceblogs/aetiology/~3/12240157/hiv_and_respons
ible_journalism.php

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