When you hear the word “bacteria” what do you think of? If you’re like most people, you probably think of things that can make you sick. Although some bacteria do make us sick, this is not true for all of them. In fact, as we’ll see a little later, some bacteria are very helpful.

Did you know that bacteria can have a virus? It’s true! But first, you might be wondering: what’s the difference between viruses and bacteria?

Bacteria grows and reproduces on its own, while viruses cannot exist or reproduce without being in a living cell of a plant, animal, or even bacteria. Size-wise, bacteria are enormous.

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The T4 bacteriophage is a virus that looks like a spaceship from an alien planet. It attaches to the surface of the Escherichia coli (E. coli) bacteria using its six legs and injects DNA into the bacteria. The DNA then tells the bacteria to multiply and essentially fill the bacterial cell to bursting. This is how the T4 kills E. coli.

In this video below, you’ll first see large E. coli bacteria floating around, one of which is attacked by a T4 bacteriophage. Notice how the T4 injects the DNA strand into the bacterium. (What’s not shown is how it bursts, but we’ll leave that to your imagination!)

Some bacteria are responsible for diseases in humans and other organisms. Strep throat, tuberculosis, and pneumonia are all the result of bacteria.

Bacteria can also be responsible for food poisoning. Raw eggs and undercooked meats can contain bacteria that can cause digestive problems. One simple step everyone can take to reduce these kinds problems is washing your hands before cooking or eating. Cleaning cooking surfaces and fully cooking food can also help.

In 2007 the United States Food and Drug Administration (FDA) approved using bacteriophages on all food products. Other places you’ll find bacteriophages are in hospitals, uniforms, sutures and surgery surfaces where it’s important to keep surfaces very clean.

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Bacteria have a bad reputation. Walk down the cleaning aisle of any store and you’ll see rows and rows of products promising to kill them. There are definitely some bacteria that cause problems for people, and we’ll talk about them soon, but we are going to start off positive, and talk about the many ways bacteria can be helpful.

First, decomposers help control waste. Without these bacteria, the amount of waste in soil would quickly make the soil a place where nothing could grow. Bacteria are even used in sewage treatment plants to treat our waste. Decomposers also help provide organisms with nitrogen, as was discussed earlier.

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Bacteria also have an important role in the foods we eat. Yogurt and some cheeses are made from using bacteria to ferment milk, and sauerkraut is made from using bacteria to ferment cabbage.

Once we’ve eaten, bacteria continue to help us. Bacteria line the digestive tract and help us digest food. In your gut, the number of bacteria cells is greater than the number of your own cells.

In science labs, researchers have found ways to use bacteria to produce medicines. For example, some people with the disease diabetes need insulin. Mass-produced insulin, made possible by bacteria, has lowered the cost of insulin for people suffering from this disease.

Researchers from Japan’s National Institute of Advanced Industrial Science and Technology (AIST) have figured out a way to get motion from bacteria. This team of scientists have developed a motor that is powered by bacteria movement.

Because this motor is so small (it’s only 20-microns across, where 1 micron = 1 millionth of a meter), we’ve posted a picture (above) so you can see the six revolving motor blades. Each blade has a tab that sits in a circular groove area, which is treated with a substance that makes the bacteria move only in one direction. As the bacteria moves, they push the tabs (which spins the motor). This is a great way to get power for tiny devices, such as tiny pumps inside medical devices.

What is true about bacteria is that they are made of only a single cell, are prokaryotes, and are very common. They are the most common living things on Earth. In fact, there are more bacteria living in the mouth of a single person than there are people on the planet!

Since bacteria are made of only one cell, they are very small. The only way to see bacteria is to look at them in a microscope. When you look at bacteria in a microscope, they usually have one of three shapes.

Bacilli are shaped like rods, cocci are shaped like spheres, and spirilli are shaped like spirals. Using shapes to describe bacteria helps scientists but bacteria into groups, which is often called classification.

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Ah-chooo! Influenza (the “flu”) is when you get chills, fever, sore throat, muscle pains, headaches, coughing, and feel like all you want to do is lie in bed. The flu is often confused with the common cold, but it’s a totally different (and more severe) virus.

The flu is passed from person to person (or animals or birds) by coughing or sneezing. With plants, it’s transmitted through the sap via insects. In the case of birds and animals, the flu is usually transmitted by touching their droppings, which is why hand-washing is so important! In addition to soap, the flu virus can be inactivated by sunlight, disinfectants and detergents.

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A virus can only replicate inside the living cells of organisms, and most are way too small to be viewed through a microscope. Viruses can infect organisms, animals, plants, bacteria and archaea. Virus particles (virions) are made up of two or three parts, including the genetic material (from either DNA or RNA), long molecules which bring genetic information, and a special coat that protects the genes.

Viruses can be helical or complex structures, but they are a lot smaller than bacteria usually by about a hundredth.

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One place where bacteria can be found is on your teeth. This is why it’s so important to brush well. Don’t believe me? Then this experiment is for you. You’ll need to gather your materials and make sure you have a toothbrush and microscope nearby.

This is important because prokaryotes are incredibly common and have a huge impact on our lives.  You may already know some of the ways bacteria can be harmful to you, and this is certainly important information.  Scientists have used knowledge of prokaryotes to create medications, vaccines, and healthy living habits that have led to a healthier life for billions of people.

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Materials:

• water
• toothbrush
• microscope with coverslips and slides

Experiment:

1. Place a drop of water on a microscope slide.
2. Gently brush your toothbrush against your teeth and then apply the saliva from the brush to the slide.
3. Add a cover slip, and observe under the microscope. Draw what you see.

Here’s a short video on a real bacterial colonization of the mouth after only 8 hours of having a cleaning done at the dentist:

If you’ve ever gone to the store to buy toothpaste, you know there many brands. Do any actually do a better job of getting rid of bacteria on your teeth? This is a great question for the scientific method. Here’s what you do:

1. Brush your teeth really well.
2. Swab your teeth with a cotton ball and apply to a petrie dish of agar.The next day, brush with a different brand of toothpaste, and again, swab and apply to a different dish.
3. Repeat for five days with five different brands. Record the growth of bacteria on each dish for each day.
4. Remember that “day 1” for the first dish will be different than “day 1” for the second dish, and so on.
5. Which brand left the fewest bacteria? Could there be factors that caused the difference besides toothpaste brand? (Hint: Do you eat the same thing every day?)

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Some organisms, like bacteria, consist of only one cell. Other organisms, like humans, consist of trillions of specialized cells working together. Even if organisms look very different from each other, if you look close enough you’ll see that their cells have much in common.

Most cells are so tiny that you can’t see them without the help of a microscope. The microscopes that students typically use at school are light microscopes.

Robert Hooke created a primitive light microscope in 1665 and observed cells for the very first time. Although the light microscope opened our eyes to the existence of cells, they are not useful for looking at the tiniest components of cells. Many structures in the cell are too small to see with a light microscope.
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In this experiment, you will get to observe single-celled organisms (bacteria, actually) that live in the mouths of both humans and dogs using your compound microscope.

1. You’ll need to get your materials together. Be sure to label the Petri dishes and have your other equipment out: the cotton swabs, the canine volunteers and the human volunteers.

2. First, scrape the inside of a volunteer’s cheek use the cotton tip to swab. Swirl the cotton swab onto a Petri dish.

3. Repeat this for the rest of your human and dog volunteers.

4. Find a dark, warm spot for your Petri dishes to live in that won’t be disturbed for at least 24 hours.

5. After a day, remove the Petri dishes and place it next to your compound microscope.

6. Use a fresh swab to move the bacteria from the Petri dish to the slide and use a staining technique (covered in the Microscope Lab).

7. View each of your specimens, recording everything as you go along.

8. So what do you think? Whose mouth is cleaner – dogs or people?

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If you have ever seen mold growing on an old loaf of bread or eaten a mushroom, you have encountered a fungus. Fungi (that’s the plural of fungus) are a group of organisms, or living things, that are all around us. Mold on bread and mushrooms on pizza are both examples of fungi.

Fungi have an important job. They help break down other material, so that living things are able to grow in soil. This helps make nutritious foods for other organisms. Fungi are needed for life!

Do you think mushrooms are plants? Scientists used to think that all fungi were plants. Now they know that there are some very important different between these two groups of organisms. One of the most important differences is that plants are autotrophic. This means that they can make their own food, just by using the sunlight. Fungi can’t do this. They have to “eat” other living things in order to get the energy they need. This is called being heterotrophic.

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Another difference between plants and fungi is that fungi have cell walls like plants do, but their cell walls are made of chitin. Chitin is a material containing nitrogen that is also found in the shells of animals including beetles and lobsters.

Fungi do not have a vascular system, the system used to transport water and nutrients in plants, but do have hyphae, a structure you will learn about in the next section. Although mold and mushrooms are easy to see, most fungi are a lot harder to see. Some are so small they can only be seen with a microscope.

Others are big enough to see, but live in places that make them hard to find. For example, some fungi live deep in the soil, in decaying logs, inside plants and animals, or even inside or on top of other fungi!

Scientists have estimated that there are 1.5 million species of fungi, and these organisms live all over.  Most are found on land, although some do live in water.  Some fungi can even live in deserts.  No matter their environment, fungi act as decomposers.  This means that the fungi break down materials to make their environment better for other organisms to grow.

Humans use fungi for many purposes.  One of the most common uses is in food.  Mushrooms are eaten by many people on pizza or in salads. But yeast is used in the fermentation process to make beer, wine, and bread.

We’re going to learn how to grow our own mushrooms in this video below. Remember, never eat a mushroom unless you check with an expert first. Poisonous mushrooms look similar to edible ones, so be absolutely certain which kind it is before popping one in your mouth.

NEVER pick wild mushrooms! In addition to the uncertainty in the type of mushroom, there’s also possible harmful bacteria growing on the mushroom.

Fungi are also important in the production of some antibiotics, including penicillin and the chitin in cell walls has been said to have wound healing properties.

Learn more about Kenny and mushrooms from Veggie Gardening Tips!

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Art and science meet in a plant press. Whether you want to include the interesting flora you find in your scientific journal, or make a beautiful handmade greeting card, a plant press is invaluable. They are very cheap and easy to make, too!

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Here’s what you need:

• Newspaper
• Cardboard
• Belt buckle or large, strong rubber bands
• Sheets of paper

Download Student Worksheet & Exercises

Here’s how you make it:

1. Cut the cardboard into square pieces.
2. Cut or fold the sheets of newspaper into squares the same size as the cardboard.
3. Place 4 sheets of newspaper between each piece of cardboard. You can also use white copy paper.
4. Place the plants you want to press in between the newspaper.
5. If you want, you can sandwich the plant press with the wood planks for added pressure.
6. Bind it tightly with the rubber bands or a belt buckle.
7. Leave it in a dry place for two to four days.

How does it work? The pressure from the rubber band/string pushes the water from the plants. The water is then absorbed by the newspaper. Since the pressure is the key to the press, it’s important not to open the press for at least two days (more is better).

Troubleshooting: The press works by pushing the moisture out of the plants, so any way moisture can stay in (or get back in) to the plants will make the press less effective. First, storing the press in a dry place is essential. If the press is left in a moist area not only will in not work, but it will grow mold and ruin the press and the plants. Conversely, if the pressure is not great enough, the moisture will not be pressed out. Thus make sure that the plants fit in the press, are bound tightly, and that the press is stored in a dry area for at very least two days.

Exercises

1. Draw and describe the functions of the following plant parts: root, stem.
2. What two major processes happen at the leaf?
3. Why are flowers necessary?
4. Do all plants have roots, stems, leaves and flowers?

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Here we’re going to discuss the differences between three types of worms; flatworms, roundworms, and segmented worms. The word “worm” is not, in fact, a scientific name. It’s an informal way of classifying animals with long bodies and no appendages (no including snakes). They are bilaterally symmetrical (the right and left sides mirror each other). Worms live in salt and fresh water, on land, and inside other organisms as parasites.

The differences between the three types of worms we will discuss depend on the possession of a body cavity and segments. Flatworms have neither a body cavity nor segments. Roundworms only have a body cavity, and segmented worms have both a body cavity and segments.

Flatworms (Phylum Platyhelminthes) have incomplete digestive systems. That means that their digestive system has only one opening. The gas exchange occurs on the surface of their bodies. There are no blood vessels or nervous systems in flatworms. Some are non-parasitic, like the Sea flat worm, and some are parasitic, like the tapeworm.

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Roundworms (Phylum Nematoda) have body cavities—as contrasted with flatworms which do not. The body cavity allows roundworms to have complete digestive tracts (both a mouth and an anus). The mouth and anus are connected by a gut—where the food is digested. They also have a simple nervous system and brain.
Roundworms can be parasites of plants and animals. In dogs they are often know to cause heart problems. In humans roundworm parasites can sometimes cause a swelling disease called elephantitis.

Annelids or Segmented Worms (Phylum Annalida) the most developed of the three, have both a body cavity and segments. Their body cavity helps give them structure—it serves as a hydroskeleton. By “segmented” it’s meant that they are divided into repeating units. They can be non-parasitic (i.e. earthworms) or parasitic (i.e. leeches). Interestingly, the giant red leech only eats giant earthworms.

Worm Column

If you’re fascinated by worms but frustrated that you can’t see them do their work underground, then this worm column is just the ticket for you. By using scrap materials from the recycling bin, you’ll be able to create a transparent worm farm. here’s what you need:

• two 2-liter soda bottles, empty and clean
• one brown paper grocery bag
• 20 red worms
• newspaper, old leaves, peat moss, and/or straw for worm bedding
• last night’s dinner, organic scraps, plant material for worm food

Here’s what you do:

Download Student Worksheet & Exercises

Things to Compare with your Worms:

1. Look at the worms under the magnifying glass.
2. Measure the lengths of the worms.
3. Make note of:
   1. The outer layer of the worms: Is it hard? Is it segmented? What are other observations that can be made?
   2. Do they have legs?
   3. Do they have antenna?
   4. What are the main differences?
   5. What are the main similarities?

Garden Worm Tower

Here’s how you can make your own worm tower right in your garden:

Build your own worm farm and watch them turn food scraps into soil!

Materials:

• 2 polystyrene boxes with lids the same size. (Let’s call them Bin A and Bin B.)
• A sheet of insect screen to fit the bottom of the boxes
• Newspaper clippings
• Garden soil
• Food scraps (half-eaten fruits and veggies, stale biscuits and cakes, crushed egg shells, coffee grounds)
• Water
• Worms (Either “Tiger”, “reds”, or “blues”; ask for them at your local garden store)

Build the farm:

1. Punch evenly spaced holes in the bottom of Bin A.
2. Place the insect screen on the bottom of Bin A (this is so that the worms don’t fall out).
3. Fill Bin A ¾ full with wet newspaper clippings.
4. Add a layer of garden soil to Bin A.
5. Add the worms.
6. Place Bin A in Bin B. Make sure there’s enough room in Bin B when Bin A’s placed in it to collect the worm pee and waste. Be sure to empty and clean Bin B every couple days.
7. Add food to bin A! Start off small. You don’t want to over-feed the worms. Start out with a couple scraps in the corner and see how long it takes for them to disappear—that should give you a good idea of how much to feed your worms.

Earthworm Dissection

You can dissect a earthworm right at home using this inexpensive earthworm specimen and simple dissection tools!

Exercises

1. What are three types of worms?
2.  What are the characteristics of each?
3.  What are the elements of a complete digestive system?
4.  What are some benefits of worms in gardening?

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How does salt affect plant growth, like when we use salt to de-ice snowy winter roads? How does adding fertilizer to the soil help or hurt the plants? What type of soil best purifies the water? All these questions and more can be answered by building a terrarium-aquarium system to discover how these systems are connected together.

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Here’s what you need:

• two 2-liter soda bottles, empty and clean
• two bottle caps
• scissors and razor with adult help
• tape
• water, soil, and plants

Here’s what you do:

Download Student Worksheet & Exercises

Water drips off the roof of your house, down your driveway, over your toothbrush and down the sink, through farm fields, and into rivers, lakes and oceans. While traveling, this water picks up litter, nutrients, salts, oil, and also gets purified by running through soil. All of this has an affect on fish and animals that live in the oceans. The question is, how does it affect the marine ecosystem? That’s what this experiment will help you discover.

Land and aquatic plants are excellent indicators of changes in your terraqua system. By using fast-germinating plats, you’ll see the changes in a relatively short about of time. You can also try grass seeds (lawn mixes are good, too), as well as radishes and beans. Pick seeds that have a life cycle of less than 45 days.

How to Care for your TAC (Terra-Aqua Column) EcoSystem:

1. Keep the TAC out of direct sunlight.
2. Keep your cotton ball very wet using only distilled water. Your plants and triops are very sensitive to the kind of water you use.
3. Feed your triops once they hatch (see below for instructions)
4. Keep an eye on plant and algae growth  (see below for tips)

About the plants and animals in your TAC:

1. Carnivorous plans are easy to grow in your TAC, as they prefer warm, boggy conditions, so here are a few tips: keep the TAC out of direct sunlight but in a well-lit room. Water should condense on the sides of the column, but if lots of black algae start growing on the soil and leaves, poke more air holes! Water your soil with distilled water, or you will burn the roots of your carnivorous plants.  Trim your plants if they crowd your TAC.
2. If you run out of fruit flies, place a few slices of banana or melon in an aluminum cup or milk jig lid at the bottom of a soda bottle (which has the top half cut off). Invert the top half and place it upside down into the bottom part so it looks like a funnel and seal with tape so the flies can’t escape.  Make a hole in the cap small enough so only one fly can get through. The speed of a fruit fly’s life cycle (10-14 days) depends on the temperature range (75-80 degrees). Transfer the flies to your TAC. If you have too many fruit flies, discard the fruit by putting it outside (away from your trash cans) or flush it down the toilet.
3. You can’t feed a praying mantis too much, and they must have water at all times. You can place 2-3 baby mantises in a TAC at one time with the fruit flies breeding below. When a mantis molts, it can get eaten by live crickets, so don’t feed if you see it begin to molt. When you see wings develop, they are done fully mature. Adult mantises will need crickets, houseflies, and roaches in addition to fruit flies.
4. Baby triops will hatch in your TAC aquarium. The first day they do not need food. Crush a green and brown pellet and mix together. Feed your triop half of this mixture on the 2^nd and the other half on the 4^th day (no food on day 3). After a week, feed one pellet per day, alternating between green and brown pellets. You can also feed them shredded carrot or brine shrimp to grow them larger. If you need to add water (or if the water is too muddy), you can replace half the water with fresh, room temperature distilled water. You can add glowing beads when your triop is 5 days old so you can see them swimming at night (poke these through the access hole).

Exercises

1.  What three things do plants need to survive?
2.  What two things do animals need to survive?
3.  Does salt affect plants? How?

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It drives me crazy it when my store-bought tomatoes go straight from unripe to mush. After talking with local farmers in my area, I discovered a few things that might help you enjoy this fruit without sacrificing taste and time.

Grocery store owners know that their products are very perishable. If the tomatoes arrive ripe, they might start to rot before they can get on the shelf for the customer. Ripe tomatoes are near impossible to transport, which means that farmers often pick unripe (green and therefore very firm) tomatoes to put on the truck. Grocery stores prefer hard, unripe tomatoes so their customers can get them home safely.

The problem is, how do you enjoy a tomato if it’s not ready?

Scientists and food experts ripen tomatoes quickly with ethylene while they are in storage. As the gas surrounds the green tomato, it chemical reacts to speed up the ripening process, causing the tomato to soften and change color to red or orange.

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The color change in this video is subtle – can you tell the difference between the beginning and end?

Another hormone involved in plants is ethylene. Ethylene is an unusual hormone because it is a gas. What does this mean? Find out using a fruit with plenty of ethylene, a ripe banana.

Materials:

• green banana
• very ripe banana
• paper bag

Experiment:

1. Place one green banana in a paper bag.
2. Place another green banana in a paper bag, along with a very ripe banana.
3. Make daily observations about each banana.
4. What’s causing the differences you see? (Hint: Think about ethylene and how it can travel.)

What’s Happening: In the bag with two bananas, the gas travels from one to the other, ripening it.

Ethylene, a hydrocarbon gas like propane and butane, is generated by other fruits like bananas. When you store a banana next to a tomato, the banana’s gas triggers the ripening process in the tomato. Scientists have found that tomatoes ripened this way keep longer, but farmers and customers have found that these tomatoes have less flavor and mushier texture.

If you’ve noticed the recent vine-ripened tomato trend at the grocery store, it’s because those tomatoes tend to have more flavor than the green ones picked from the vine and stored in a room of ethylene gas.

When you’re at home, keep fully ripe tomatoes out of the refrigerator, as they are best kept at room temperature on your counters. If you stick a tomato in the fridge, you’ll find it less flavorful and starting to have a starchier texture.

Experiment:

1. Place a green tomato in a bag with a banana.
2. Make daily observations about the tomato and banana.
3. How did the banana take to ripen?

The bottom line? Use the banana-gas trick for tomatoes you cook or bake with, and enjoy your fresh tomatoes straight from the vine and stored on your countertop.

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Birds, people, plants, and microscopic organisms need to know where they are as well as where they want to be. Birds migrate each year and know which way is south, and plants detect the sun so they can angle their leaves properly. People consult a map or GPS to figure out where they are.

Magnetotactic bacteria orients itself along magnetic field lines, whether from a nearby magnet or the Earth’s magnetic field. It’s like having a built-in internal compass.

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Discovered in 1975, scientists noticed that certain bacteria seemed to move to the same side of the microscope slide. After placing a magnet near the slide, they were able to determine these bacteria contain tiny bits of iron (magnetic crystals, to be exact). The bacteria place the iron (which act like magnets) in a line to make one long magnet, and use this magnet to align to the earth’s magnetic field, just like a compass.

Bacteria move away from oxygen and toward areas with low (or no) oxygen. In water, oxygen levels decrease with depth, so you’ll find magnetotactic bacteria in the deeper parts. These bacteria use their internal compass to figure out which way is deeper.

Since the Earth’s geomagnetic north pole actually points at an angle, the “north-seeking” bacteria aligned to the field lines are also pointing down. When the bacteria move north along the field lines, they are moving into deeper water (with less oxygen). On the flip side (Southern Hemisphere), magnetotactic bacteria must be “south-seeking” in order to go deeper. Of course, at the equator, there’s a mixture of north-seeking and south-seeking bacteria.

Since the magnetic crystals are found in the organisms, even dead cells will align themselves!

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Fungi and protists, including mold, moss, yeast, and mushrooms, are found all around us. One common group of fungi is mold. Mold, like all fungi, are heterotrophs, which means they rely on other living things for their energy. This is different than an autotroph like a plant, which gets its energy from the sun.

Mold commonly grows on bread, getting food from this source. What do you think makes mold grow? Being in a dark place? Being exposed to moisture? Something else? The scientific method is a series of steps some scientists use to answer question and solve problems. To conduct an experiment based on the scientific method, you must have a control sample, which has nothing done to it, and several experimental samples, which have changes made to them. You can then observe results in the experimental sample to see how your changes to them affect results.

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Materials:

• water
• paper towel
• slices of bread
• plastic wrap
• pie dish or plate
• microscope with slides and coverslips (optional)

Here’s what you do:

1. Place a wet paper towel on the bottom of a pie tin
2. Add a slice of bread
3. Cover with plastic wrap and place in a dark place for three days
4. Take the pie tin out and make observations
5. What organisms do you think you see?

In the dark environment, mold grows on the bread. The exact type of mold will be different depending on the type of bread. Is there a difference between white and wheat? Organic and Wonder Bread? Now let’s take this a step further:

1. Take five pieces of bread. Place one in a pie tin and leave it on the kitchen counter. This is your “control” bread.
2. Place the other pieces of bread in pie tins and do something you think will help make mold grow. These are experimental samples.
3. Every day, observe each slice of bread and take notes.
4. What made the mold grow fastest? Did anything slow down mold growth, and form less mold than the control?
5. What does this tell us about food storage?

You probably found that mold grows well in the dark, and warm conditions. So, if you want to make your bread last longer, keep it cool and out of the dark.

Build an Ecosystem

Protists can be classified as animal-like, plant-like, and fungus-like. Animal-like protists are able to move and are heterotrophic, relying on other organisms for food. Many protozoa live in grasses, especially those found in lakes, rivers, and streams, where they are able to get the nutrients they need to survive. Create your own mini-ecosystem of these remarkable creatures in the activity below.

Materials:

• grass
• clean, empty glass jar
• microscope with slides (optional)

Experiment:

1. Add water and a handful of grass to the jar
2. Put the lid on the jar but don’t seal it all the way
3. Keep the jar in a dark area for three days
4. Take it out and make observations. If possible, observe the organisms under a microscope.

Protozoa and other protists live of the grass, and increase in number after the jar is in the dark for several days.

Fun with Yeast

There are over 1,500 species of yeast currently discovered, and scientists estimate that this is only 1% of all yeast species. Most reproduce by budding, although a few use mitosis. Most yeasts are single-celled, although the multicellular varieties use a string to connect budding cells (pseudohyphae or false hyphae). Yeast is a fungus used in cooking many products, including bread. Why is yeast important in the baking process? Let’s find out!

Materials:

• yeast
• zipper-type sandwich bag
• warm water
• sugar

Experiment:

1. Put about a teaspoon of yeast into a sandwich bag.
2. Add about three spoons of sugar and about half a cup of very warm water. If you stick your finger into the water, it should feel warm but comfortable.
3. Squeeze out as much air as you can and then seal the bag. Place it in a warm spot
4. After about 5 minutes, you should start to see tiny bubbles forming. After 15 minutes, you should see quite a few more bubbles. After an hour, the bag should be inflated quite a bit.

Imagine that the yeast is inside some bread dough instead of the bag. As it changes the flour into sugar and consumes it, it gives off carbon dioxide and alcohol. Your bread will not be alcoholic, but when the alcohol cooks away, it leaves behind flavors that add to the taste of the bread.

More Ideas!

What happens if you place leftover food in three different cups and placed one of the cups on a sunny windowsill, another cup in the refrigerator, and a third cup in a dark cupboard? What if you use a magnifier? How does light or temperature affect the mold’s growth? Are the molds all the same color, or are they different?

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If your kitchen is like most kitchens, you probably have cabinets for cups and pots and pans, along with drawers for silverware and cooking utensils.  You might also have a drawer you call the “junk drawer.”  The things in this drawer aren’t actually “junk.”  If they were, you’d throw them away.  Instead, things usually get put here because they just don’t fit anywhere else.

You might be surprised to learn that the system for classifying organisms has its own “junk drawer.”  It’s called the protist kingdom.  Its members, like the contents of your kitchen junk drawer, are important, but don’t fit nicely in one of the other kingdoms.

Broadly, protists can be classified as animal-like, plant-like, or fungus-like.  It is important to remember that being “animal-like” does not make a protist an animal.  Such and organism, like plant-like or fungus-like protists, are members of an entirely different group of living things.

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Amoeba are protists that walk using a method called a false foot, or pseudopodia. The amoeba extend a “false foot” and then pull the rest of their body along with them.

Animal-like protists are called protozoa. Like animals, protozoa can move on their own and are heterotrophic. Some protozoa eat by wrapping their bodies around their prey, creating a “food storage compartment.” Toxins are then produced which paralyze the prey, and food moved into the waiting protist.

Other protozoa have flagella, or tails, that assist in feeding. The flagella whip back and forth creating a current that brings food to the protist. Still other protozoa are parasites, and get nutrients from a host organism, harming the host in the process.

Animal-like protists can be classified, or placed into groups, based on how they move. Some move with the aid of a flagellum (that’s the singular form of flagella.) Others have many small tail-like structures called cilia which they move back and forth to get around. Still others have what is known as a “fake foot” or pseudopodia. These protozoa have a part of their cell stretch out, which pulls the rest of the organism along. The amoeba is a common example of this type of protozoan. Finally, some protozoa don’t move at all.

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This type of slime Physarum Polycephalum is called the “many-headed slime”. This slime likes shady, cool, moist areas like you’d find in decaying logs and branches. Slime (or slime mold) is a word used to define protists that use spores to reproduce. (Note: Slime used to be classified as fungi.)

Real slime lives on microorganisms that inhabit dirt, grass, dead leaves, rotting logs, tropical fruits, air conditioners, gutters, classrooms and laboratories. Slime can grow to an area of several square meters.

Slime shows curious behaviors. It can follow a maze, reconnect itself when chopped in half, and predict whether an environment is good to live in or not. Scientists have battled with the ideas that at first glance, slime appears to be simply a “bag of amoebae”, but upon further study, seem to behave as if they have simple brains, like insects.

Slime can be either a plasmodial slime, a bag of cytoplasm containing thousands of individual nuclei, or a cellular slime which usually stays as individual unicellular protists until a chemical signal is released, causing the cells to gather and acts as one organism.
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Slime feeds by surrounding its food completely and secreting enzymes to digest it. If the slime dries out before its finished eating, it will form a hard tissue shell to protect the dormant slime until the weather turns wet again. The cool part is that the slime will continue searching for food once it hydrates and softens up. When slime can’t find food, it will begin the reproductive phase. Spores form from the mitosis phase and are spread by wind currents. Spores can remain formant for years if the conditions are unfavorable.

Scientist have discovered that physarum polycephalum (orange slime) seems just as intelligent as some insects! A team researchers set up a maze (made of agar) and found that the slime found the shortest possible path to the food.

Another team of scientists are working on bio-computing devices, which use slime instead of semiconductors. The scientists found that slime reacts consistently to certain stimuli. (If they poke it here, it moves to the left…) This team is also figuring out how to precisely point and steer slime using light and food sources.

What this means is that you’ve got a creature that will always emerge from a maze the same way when dropped in at random, is direction-controllable, and always reacts to stimuli the same way. Sounds like the inner workings of a computer, doesn’t it?
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All living things need a way to get energy. Bacteria get their food and energy in many ways. Some bacteria can make food on their own, while others need other organisms.

Some bacteria help other living things as they get energy, others hurt them while they get energy, and still others have no affect on living things at all.
Some living things, or organisms, are able to make their own food in a process called photosynthesis.

In this process, the organism turns energy from the sun into energy that can be used for energy. Organisms that get their energy from photosynthesis are called autotrophs. Some bacteria get their energy this way.

Some bacteria, called chemotrophs, get their energy by breaking down chemical compounds in the environment, including ammonia. Breaking down ammonia is important because ammonia contains the element nitrogen.

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All organisms need nitrogen to survive, and the nitrogen released by bacteria is crucial to these living things’ survival. Clearly, chemotrophs are very important and beneficial to other living things. Living things that cannot get their energy through photosynthesis or from breaking down chemical compounds have to get their energy from other living things. Some bacteria, called decomposers, get their energy by breaking down dead organisms or waste products into simple nutrients and energy.

Pseudomonas bacteria are decomposers found in the soil, where they recycle dead plant material. The last groups of bacteria get energy from organisms that are still alive, and depend on these organisms to survive.
Mutualistic bacteria get their energy in ways that help another organism. For example, some bacteria live in the roots of legumes, including pea plants. The bacteria make the nitrogen the pea plants need and the pea plants provide a place for the bacteria to live. Other bacteria, called parasitic bacteria, hurt the organism they are getting help from. For example, some bacteria cause illness. We will talk about ways bacteria can be helpful or harmful a little later.

All living things reproduce. This is the only way to ensure the organisms continued survival. Bacteria reproduce asexually. This means that a single “parent” organism produces offspring on their own. In the case of bacteria, a process called binary fission is used. In binary fission, the DNA in the nuceleoid region and plasmids double, and the bacterium splits into two identical copies. If everything happens the way it’s supposed to, the two new bacteria will be identical to the original bacterium. These bacteria can then split again to increase the number of bacteria in the population. Through binary fission, bacteria reproduce very quickly. Some populations can double their size in less than ten minutes!

How to Grow Your Own Bacteria

Although we often think of bacteria as things that cause disease, some bacteria are very helpful. In fact, if you like to eat yogurt, you are eating helpful bacteria all the time! See for yourself in these two activities:

Materials:

• clean plastic cup
• yogurt
• dropper or toothpick
• microscope with slides and coverslips

1. Place a very small portion of plain yogurt onto the slide, and add one drop of water. Place the coverslip on top.
2. Under low power, find a section where the yogurt is pretty thin; this is where you will find the bacteria.
3. Switch to high power (400X for most microscopes) for a better view of the bacteria.
4.  Make a sketch of your view under different magnifications.

Finding Bacteria in Yogurt

Materials:

• clean plastic cup
• yogurt
• toothpick
• water
• microscope with slides and coverslips

1. Clean a small plastic cup. Make sure ALL soap is completely rinsed off.
2. Put a small amount of yogurt in the cup, and put it aside in a dark, relatively warm area. Leave undisturbed for at least 24 hours.
3. After the time has past, take a small sample with a toothpick and place on a slide. If the sample seems too thick, dilute with a drop of water. Next, place a cover slip on top.
4. First observe the bacteria at low power 100X to find a good place to start looking. The diaphragm setting should be very low (small) because these bacteria are nearly transparent.
5. Switch into the highest power to identify the bacteria according to arrangement.
6. From here you can identify any bacteria you might find. For example, a common inhabitant of yogurt is a paired, round bacteria or diplococcus (see list below)
7. Did you observe more bacteria in part 1 or 2? Why do you think this is?
8. Do you want to take it a step further? Think about all the kinds of yogurt out there. There are different flavors, different brands, some that are non-fat, and much more. Do some types have more bacteria than others? This is a great question to investigate using the scientific method. So come up with a specific question, write a hypothesis, grab some yogurt, and get experimenting!

Bacteria are classified as follows:

First observe the way the bacteria are arranged:

• paired = diploe
• chained = streptose
• clusters = staphyle

Next observe the shape of the bacteria:

• round = coccus
• rod = bacillus
• spiral = spirillum

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If you have a backyard garden, be sure to give it plenty of sunshine, water, and garbage.

Wait… garbage?  Yes, you read that right.

Garbage like rotting food and coffee grounds, made into compost, can be highly beneficial to garden plants.  Why? It all has to do with nitrogen.

Plants need nitrogen in order to survive.  There is plenty of nitrogen in the atmosphere; the problem is that plants can’t use it in the form found in the atmosphere.  For this, bacteria are needed.  Bacteria “fix” nitrogen, meaning that they change it into a usable form.

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This is where the garbage comes in.  Bacteria break down the garbage by eating it.  When other organisms living in the soil, particularly worms, eat the bacteria, the nutrients they have stored up are released.  The result is soil far more rich in nutrients.

So, how do you create your own compost pile to create plenty of garbage for your garden’s bacteria to enjoy?  Well, you already have the garbage, which is a good first start.  Next, you’ll want to get a compost bin.  Garden supply stores sell bins, although you could also make one with wood and chicken wire.  For even simpler compost bins, a pit in the ground or plastic garbage bag with holes in it will work, although you’ll need to be sure to air out the plastic bag every couple days.

Fill your bin with 1/3 brown material (dead leaves or plants are good), 1/3 vegetation, and 1/3 soil.  Then, pile on the garbage!  Add kitchen waste, grass clippings, dry leaves, dead plants, shredded newspaper, lint from your clothes dryer, and pet hair.  The ideal compost heap will have a 25 to one ratio of things like dead leaves and newspapers, which are high in carbon to grass and other plants, which are high in nitrogen.  Adding cattle, horse, or chicken manure is a great idea.  Trash to avoid are bones, meat, and fat (all of which can attract pests), human or pet waste (which can spread disease), and weeds or diseased plants (which can re-introduce the weed or disease into your garden.)

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Keep your compost heap moist, but not soggy and turn it with a pitchfork or spade to add air into the mix.  Once your compost bin is going strong, you can add it to your garden for improved plant growth!

Plants need light, water, and soil to grow. If you provide those things, you can make your own greenhouse where you can easily observe plants growing. Here’s a simple experiment on how to use the stuff from your recycling bin to make your own garden greenhouse.

We’ll first look at how to make a standard, ordinary greenhouse. Once your plants start to grow, use the second part of this experiment to track your plant growth. Once you’ve got the hang of how to make a bottle garden, then you can try growing a carnivorous greenhouse.
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Materials:

• 2 liter bottle
• scissors or razor
• gravel or sand
• spanish moss
• dish or plate
• seeds of your choice

Experiment:

1. Using an exacto knife or scissors, cut the label from the soda bottle. Carefully cut the bottle in half so that the bottom (container) piece is deep enough to hold soil and plants. Poke a few holes into the bottom of the container for drainage.
2. Fill the bottom of the bottle with a half cup of sand or gravel to provide drainage. Use playground sand, aquarium gravel or small stones picked up from a hike. If sand or gravel isn’t available, crush an old clay pot and use that. (Let an adult crush the pot.)
3. Place a 1-inch layer of Spanish or Spaghnum moss in the mini greenhouse to keep the soil from mixing with the rock layer. Place a thick layer of potting soil on top of the moss, at least 4 inches deep or 1 inch from the top. Tamp down lightly with your finger
4. Put the top half of the soda bottle back on, tucking inside the edges of the container. If necessary, you can cut small slits into the upper portion to make it fit. Leave the cap on.
5. Place atop a waterproof plate in a sunny spot and water sparingly. The lid retains moisture and heat, so your seeds should sprout quickly. Because the plastic is clear, you’ll be able to see the roots beneath the surface of the soil. If the greenhouse gets too steamy, you can remove the lid once in a while. When your seedlings get big enough, transplant to the garden, and plant a new crop!

Tracking Plant Growth

You know that plants grow… but when a plant grows, is the entire stem getting longer, like rolling dough, or is only the tip growing, like squeezing the end of a toothpaste tube?

This simple experiment can give you the answer. Ready?

1. Tie string around the edge of a plants stem, between the last leaf at the end, and the next leaf.
2. Make observations as the plant grows.

What’s going on? If the entire stem grows, your string will always stay at the end. If just the tip grows, the string will become further and further from the edge. Which is it? Are you surprised?

Carnivorous Greenhouse

Was the last activity too tame for you? You’ll need to order carnivorous plant seeds. Carnivorous plants are heterotrophs. As you learned, this means they must get their energy from other organisms instead of the sun. Such plants are good at catching small animals, such as insects, to eat. Used the video below to learn how to plant the seeds that will produce these carnivores, and how to care for them once they have sprouted.

Download Student Worksheet & Exercises

Exercises

1. What is a carnivorous plant?
2.  What is another name for a carnivorous plant?
3.  What does a carnivorous plant need to thrive?
4.  Should we fertilize a carnivorous plant? Why or why not?

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What grows in the corner of your windowsill? In the cracks in the sidewalk? Under the front steps? In the gutter at the bottom of the driveway? Specifically, how  doe these animals build their homes and how much space do they need? What do they eat? Where do fish get their food? How do ants find their next meal?

These are hard questions to answer if you don’t have a chance to observe these animals up-close. By building an eco-system, you’ll get to observe and investigate the habits and behaviors of your favorite animals. This column will have an aquarium section, a decomposition chamber with fruit flies or worms, and a predator chamber, with water that flows through all sections. This is a great way to see how the water cycle, insects, plants, soil, and marine animals all work together and interact.

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Here’s what you need:

• four (or more) 2-liter soda bottles, empty and clean and with caps
• scissors
• tape
• razor with adult help
• ruler
• soil
• water
• plants or seeds
• compost or organic/food scraps
• spiders, snails, fruit flies, etc

Here’s what you do:

Download Student Worksheet & Exercises

You can easily incorporate the Water Cycle Column, the Terraqua Column, the Predator-Prey Column, Worm Column, and the Fruit Fly Trap into your Eco-Column. If you want to make your Eco-Column more permanent, seal it together with silicone sealant, making sure you have enough drainage holes and air holes in the right places first.

Exercises

1. What are parts of the eco system?

2. Give an example of each.

3. What do decomposers do?

4. How do fruit flies breed?

5. How does the precipitation funnel function in this eco column?

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The way animals and plants behave is so complicated because it not only depends on climate, water availability, competition for resources, nutrients available, and disease presence but also having the patience and ability to study them close-up.

We’re going to build an eco-system where you’ll farm prey stock for the predators so you’ll be able to view their behavior. You’ll also get a chance to watch both of them feed, hatch, molt, and more! You’ll observe closely the two different organisms and learn all about the way they live, eat, and are eaten.

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This experiment comes in two parts. The materials you need for both parts are:

• four 2-liter soda bottles, empty and clean
• 2 bottle caps
• one plastic lid that fits inside the soda bottle
• small piece of fruit to feed fruit flies
• aluminum foil
• plastic container with a snap-lid (like an M&M container or film can)
• scissors and razor with adult help
• tape
• ruler
• predators: spiders OR praying mantis OR carnivorous plants (if you’re using carnivorous plants, make sure you do this Carnivorous Greenhouse experiment first so you know how to grow them successfully)
• soil, twigs, small plants

Fruit Fly Trap

In order to build this experiment, you first need prey. We’re going to make a fruit fly trap to start your prey farm, and once this is established, then you can build the predator column. Here’s what you need to do to build the prey farm:

Download Student Worksheet & Exercises

Did you know that fruit flies don’t really eat fruit? They actually eat the yeast that growing on the fruit. Fruit flies actually bring the yeast with them on the pads of their feet and spread the yeast to the fruit so that they can eat it. You can tell if a fruit fly has been on your fuit because yeast has begun to spread on the skin.

When you have enough fruit flies to transfer to the predator-prey column, put the entire fruit fly trap in the refrigerator for a half hour to slow the flies down so you can move them.

If you find you’ve got way too many fruit flies, you might want to trap them instead of breed them. Remove the foil buckets every 4-7 days or when you see larvae on the fruit, and replace with fresh ones and toss the fruit away. Don’t toss the larvae in the trash, or you’ll never get rid of them from your trash area! Put them down the drain with plenty of water.

Predator-Prey Column

You can use carnivorous plants, small spiders, or praying mantises. If you use plants, choose venus flytraps, sundews, or butterworts and make sure your soil is boggy and acidic. You can add a bit of activated charcoal to the soil if you need to change the pH. Since the plants like warm, humid environments, keep the soil moist enough for water to fog up the inside on a regular basis. You know you’ve got too much moisture inside if you find algae on the plants and dirt. (If this happens, poke a couple of air holes.) Don’t forget to only use distilled water for the carnivorous plants!

Keep the column out of direct sunlight so you don’t cook your plants and animals.

Exercises

1. What shape is the head of the mantis?
2.  How many eyes does a praying mantis have?
3.  How else has the mantis head evolved to stalk their prey?
4.  How does a praying mantis hold its food?
5.  Do fruit flies eat fruit?
6.  How do predators and prey change over time?

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If you’ve ever eaten fruits or vegetables (and let’s hope you have), you have benefited from plants as food.  Of course, the plants we eat have been highly modified by growers to produce larger and sweeter fruit, or heartier vegetables.

There are three basic ways to create plants with new, more desirable traits:

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Grafting

Grafting takes advantage of the fact that trees have the ability to heal themselves.  In this method, a branch of a tree is cut off and replaced with the branch of a different tree.  Wait a season and, voila, a new tree with the traits of the branch that was added on, or grafted, is growing on the original tree.

There are many reasons for grafting.  First, it allows growers to produce a tree with more than one type of fruit.  Peaches, plums, and apricots can all be found on the same tree after grafting has occurred.  Grafting of the same fruit can also beneficial.  Sweet oranges are preferred for taste, but trees that produce these types of oranges are at greater risk for disease.  Also, sweet oranges often have no seeds, making it impossible for them to reproduce naturally.  By grafting sweet oranges onto sour orange trees, both problems can be avoided.

 Hybridization

You’ve probably noticed that children look like their parents, and that brothers and sisters tend to look alike as well.  We share more traits with the people we are most closely related to.  This is the basic idea of the branch of science called genetics.  It’s not just true with people, though.  Plants will share traits with their offspring.

Breeders have been using the ideas of genetics for years.  They have been forcing plants with traits people find desirable to breed, hoping that the offspring will share those traits.  Traits such as resistance to disease, large size, and sweetness, are bred for.  When breeders began doing this, they didn’t know about genes, the factors that carry traits from parents to offspring.  As this became known, breeders became better at making crosses that would produce the traits they were looking for.

Transgenics

Every living thing has a genome.  A genome is the complete sequence of genes the organism has.  The genes of each organism are different, which is why a bacterium is different than, say, a tomato.  For the most part, that’s a good thing.  We wouldn’t want our tomatoes to be much like bacteria.  But what if we did?  At least a little.  If there was something in bacteria that would be helpful to tomatoes, would there be a way to add the bacteria gene to the tomato genome?  It turns out that the answer is yes, and transgenics refers to the process of adding something helpful to another organism’s genome.

In the case of the bacteria and the tomato, some bacteria have a gene that would give tomatoes resistance to disease.  This gene has been placed in many tomatoes.  Some people have concerns about transgenics, worrying that adding to genomes could have unintended consequences.  Nevertheless, this process has become very common.

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