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How Does Cell Theory Describe The Levels Of Organization Of Living Organisms 

by on December 19, 2007

Q: How does cell theory describe the levels of organization of living organisms?

A: Thank you for posting such an intriguing question! It is nice to get a break from computer questions every now-and-then.

Basically, cell theory attempts to prove that all living organisms are made of cells. It also suggests that all cells originate from other cells. Of course, that is like the chicken or the egg question. Where did the first cell come from? Science has not yet been able to provide an answer to that question. But a man named Robert Hooke first discovered cells in the 1600s. And the cell theory itself was formulated sometime in the 1800s. Modern science has discovered some possible exceptions to the theory, such as viruses. But otherwise the theory is still proving to be true.

The idea of levels of organization assumes that cell theory is correct, and then takes it to the next logical steps. The list below describes how the levels of organization as we are using the term here works.

  1. All living things are made of cells.
  2. All tissues are made of cells.
  3. All organs are made of tissues.
  4. All organ systems are made of organs (examples of organs include hearts, lungs, etc).
  5. All organisms are made of organ systems.

I find this all to be very interesting. I hope that you do as well!


Are There Healthy Halloween Treats 

by on October 31, 2007

Q: I have been wondering if there is actually a somewhat healthy treat that I could give out for Halloween without getting my house egged?

A: I completely understand where you are coming from because my wife is really into watching fat grams and calories in what we eat but during Halloween it is not reasonable to give out fruits and probably not a good idea to give out cash so what are the alternatives? You can find one great alternative down a different isle of the grocery store, as my wife found out and wrote about here at Halloween Treats.

She wrote, “I went down the snack isle to find myself staring at fruit snacks. I was reading the label and much to my surprise they actually have nutrition value, and with 100% vitamin C to boost the immune system, that is what every kid needs. In a whole pouch they have 100 calories and 1 gram of fat (a heck of a lot less that a couple of those mini candy bars) and the kids can bring them to school the next day instead of the candy.”

So all you have to do is go down the snack isle and look for the Halloween packaged fruit snakes and you will have some happy trick or treaters at your house tonight and no eggs!


Earth Is Tilted at 23.5 Degrees 

by on October 16, 2007

Q: How do we really know that the earth is tilted at 23.5 degrees?

A: First, let’s clarify that the tilt mentioned in your question is in relation to our sun. Now let’s think about observations that anyone in our modern world can make of the sun. For one thing, the sun does not rise at exactly the same time or in exactly the same place from one day to the next. Likewise, the sun is not in the same place in the sky at any time today as it will be during the same time tomorrow. We could use photographs of the sun in the sky at a certain time of day for several days to prove this.

Also, consider that the amount of time the sun is in the sky is different at each degree of latitude. For instance, the amount of time that the sun is up on a given day in Alaska is different than during the same day in Texas. An exception to this rule occurs during periods of equinox. Ancient and modern scientists alike agree that the best explanation for all of this is that the earth is tilted in relation to the sun. But, how can we calculate the amount of the tilt?

According to a Middle School Astronomy Activity written by Judy Young and Bill Randolph, only basic math skills are required to make the calculation. Observe where the sun is in relation to the horizon from a specific spot on the ground at a certain time of day during an equinox, and then again during a solstice from that spot at the same time of day. Subtract the lesser result from the greater and you should arrive at about 23.5 degrees. To increase the accuracy of this exercise, you could take measurements of many equinoxes and solstices. Interestingly, the earth’s tilt changes slightly over a period of about 41,000 years. The predicted minimum is 22.1 degrees and the supposed maximum is 24.5 degrees. A page on the NOAA website has an interesting explanation of this cycle of change.