|
|
|||
Activity 1: “The Small (Big) Picture” Objective Background | Materials | Procedure | Discussion Background What comes to your mind when you think of life in the ocean? Many people immediately think of whales, dolphins, sharks, sea turtles, seals, sea otters or other animals. Sure, they’re cute and/or cool, but they have something else in common - they’re all macroorganisms, which means they’re big and visible. But what about the microorganisms – all the living things so small you can’t see them with your normal vision? What about life in the sea you can’t see? Microbes are a diverse collection of single-celled organisms that have been on Earth for billions of years. They include bacteria, archaea (bacteria look-alikes), protists, fungi and viruses. Many people associate all microbes with germs and disease (and some do cause illness), but many microbes are very beneficial and even essential to other organisms. In fact, without microbes there wouldn’t be any other life on the planet, including us! For example, microbes in the ocean help produce the air we breathe, microbes in the soil help produce the food we eat, and microbes in our digestive system help process the food that we eat and make vitamins for us. Microbes have evolved to live just about everywhere on the planet, and the ocean is no exception. From shallow bays and coral reefs to frozen polar waters and hydrothermal vents miles below the surface – microbes play a big role in how matter and energy move between organisms and their environment in the ocean. Materials
The Mission is Fission How can organisms as small as microbes play a big role in anything, you ask? Numbers …big numbers! Microbes may not be big individually, but they make up for their small size with their large numbers. Click here to learn how microbes can be so abundant. An Educated Guess If you look around your classroom it probably isn’t too difficult to get an exact count or a close estimate of the number of people present. But what if that same room was filled with grains of rice – could you do the same? Assuming you didn’t have the time to count every grain, can you think of how you could get a good estimate of how many grains are in the room? Record any ideas on your worksheet. Let’s make it a little easier and use a bag of rice instead … Follow these steps in your group:
Scientists face the same dilemma when trying to imagine and measure the numbers of microbes in the ocean. They can’t count all the microbes directly, so instead they use extrapolation (x-trap-oh-lay-shun), which means they make estimates based on information they have already obtained. Scientists can take smaller samples at certain places and times in the ocean, count the microbes, and then use that information to make better estimates for larger areas. You just used extrapolation to determine how many grains of rice were in the bag assigned to your group. How much of a difference was there between your first estimate of the number of grains of rice in the bag compared to the number the group found using extrapolation? Crunching the Numbers Whether they are studying the speed of light or the number of bacteria in seawater, it can quickly become a burden for scientists to have to express very large or small numbers in the normal way known as standard notation. In response to this, scientists have developed a method known as scientific notation to make it easier to write and manipulate (multiplying, dividing) these long numbers. All numbers can be expressed in scientific notation using a combination of three types of numbers:
The general format for scientific notation can be expressed as N
x 10x, where: To write a number in scientific notation:
For example, let’s say you wanted to convert the large number 4,560,000,000 from standard notation into scientific notation. You would first place a decimal after the first number (4.560000000), then count the number of places from the decimal to the end of the number (in this example 9 places) to find your exponent for the base number 10. If you drop the zeros from the end of the number to create your coefficient you would get 4.56 x 109. You can use the same method to express very small numbers. The only difference is that the exponent will be negative for numbers less than 1. For example, the number 0.000015, which is less than 1, would be expressed as 1.5 x 10-5. Click here to practice converting numbers to and from scientific notation. Continue to do problems until you get at least five correct, and record your answers on your worksheet.
|
|||
|
|
|||