The young of kangaroos (joeys) remain in the mother's pouch, or marsupium, while they develop, and until they are independent enough to live outside the pouch.
A microorganism or microbe is a microscopic organism that comprises either a single cell (unicellular), cell clusters, or no cell at all (acellular). The study of microorganisms is called microbiology, a subject that began with Anton van Leeuwenhoek's discovery of microorganisms in 1675, using a microscope of his own design.
Microorganisms are very diverse; they include bacteria, fungi, archaea, and protists; microscopic plants (green algae); and animals such as plankton and the planarian. Some microbiologists also include viruses, but others consider these as non-living.Most microorganisms are unicellular (single-celled), but this is not universal, since some multicellular organisms are microscopic, while some unicellular protists and bacteria, like Thiomargarita namibiensis, are macroscopic and visible to the naked eye.
Microorganisms live in all parts of the biospherewhere there is liquid water, including soil, hot springs, on the ocean floor, high in the atmosphere and deep inside rocks within the Earth's crust. Microorganisms are critical to nutrient recycling in ecosystems as they act as decomposers. As some microorganisms can fix nitrogen, they are a vital part of the nitrogen cycle, and recent studies indicate that airborne microbes may play a role in precipitation and weather.
Microbes are also exploited by people in biotechnology, both in traditional food and beverage preparation, and in modern technologies based on genetic engineering. However, pathogenic microbes are harmful, since they invade and grow within other organisms, causing diseases that kill people, other animals and plants.
__Types of microorganisms
__Importance of microorganisms
-Use in food-
Main article: Fermentation (food)
Microorganisms are used in brewing, winemaking, baking, pickling and other food-making processes. They are also used to control the fermentationprocess in the production of cultured dairy products such as yogurt and cheese. The cultures also provide flavour and aroma, and inhibit undesirable organisms.
-Use in water treatment-
Main article: Sewage treatment
Specially-cultured microbes are used in the biological treatment of sewage and industrial waste effluent, a process known as bioaugmentation.
-Use in energy-
Main articles: Algae fuel, Cellulosic ethanol, and Ethanol fermentation
Microbes are used in fermentation to produce ethanol,and in biogas reactors to produce methane.Scientists are researching the use of algae to produce liquid fuels,and bacteria to convert various forms of agricultural and urban waste into usable fuels.
-Use in science-
Microbes are also essential tools in biotechnology, biochemistry, genetics, and molecular biology. The yeasts (Saccharomyces cerevisiae) and fission yeast (Schizosaccharomyces pombe) are important model organisms in science, since they are simple eukaryotes that can be grown rapidly in large numbers and are easily manipulated.They are particularly valuable in genetics, genomics and proteomics.Microbes can be harnessed for uses such as creating steroids and treating skin diseases. Scientists are also considering using microbes for living fuel cells,and as a solution for pollution.
-Use in warfare-
Main article: Biological warfare
In the Middle Ages, diseased corpses were thrown into castles during sieges using catapults or other siege engines. Individuals near the corpses were exposed to the deadly pathogen and were likely to spread that pathogen to others.
Do you know? The first antibotic was developed by Alexandar Flemming. He discovered that fungi produced a type of chemical calledpenicillin. Penicillin is used to cure diseases caused by certain bacteria.
Garlic contains a substance that has powerful antibotic and anti-fungal properties.Garlic has been used as food and medicine for many years.It is claimed to prevent heart disease,high cholesterol, hypertension,fight cold,improve immune system and also protect against cancer.
Sharks do not have a single bone in their bodies. Instead they have a skeleton made up of cartilage; the same type of tough, flexible tissue that makes up human ears and noses.
Some sharks remain on the move for their entire lives. This forces water over their gills, delivering oxygen to the blood stream. If the shark stops moving then it will suffocate and die.
Sharks have outstanding hearing. They can hear a fish thrashing in the water from as far as 500 metres away!
If a shark was put into a large swimming pool, it would be able to smell a single drop of blood in the water.
Although most species of shark are less than one metre long, there are some species such as the whale shark, which can be 14 metres long.
A pup (baby shark) is born ready to take care of itself. The mother shark leaves the pup to fend for itself and the pup usually makes a fast get away before the mother tries to eat it!
Not all species of shark give birth to live pups. Some species lay the egg case on the ocean floor and the pup hatches later on its own.
Great whites are the deadliest shark in the ocean. These powerful predators can race through the water at 30 km per hour.
Unlike other species of shark, the great white is warm-blooded. Although the great white does not keep a constant body temperature, it needs to eat a lot of meat in order to be able to regulate its temperature.
A shark always has a row of smaller teeth developing behind its front teeth. Eventually the smaller teeth move forward, like a conveyor belt, and the front teeth fall out.
Enjoy this simple melting chocolate experiment for kids. You've no doubt experienced chocolate melting on a hot day, so let's do some experiments to recreate these conditions as well as a few others before comparing results and coming to some conclusions. At what temperature does chocolate gofrom a solid to a liquid ? Is it different for white and dark chocolate? Give this fun science experiment a try and find out!
What you'll need:
♦ Small chocolate pieces of the same size (chocolate bar squares or chocolate chips are a good idea) ♦ Paper plates ♦ Pen and paper to record your results
Instructions:
① Put one piece of chocolate on a paper plate and put it outside in the shade. ② Record how long it took for the chocolate to melt or if it wasn't hot enough to melt then record how soft it was after 10 minutes. ③ Repeat the process with a piece of chocolate on a plate that you put outside in the sun. Record your results in the same way. ④ Find more interesting locations to test how long it takes for the chocolate pieces to melt. You could try your school bag, hot water or even your own mouth. ⑤ Compare your results, in what conditions did the chocolate melt? You might also like to record the temperatures of the locations you used using a thermometer so you can think about what temperature chocolate melts at.
What's happening?
At a certain temperature your chocolate pieces undergo a physical change, from a solid to a liquid (or somewhere in between). On a hot day, sunlight is usually enough to melt chocolate, something you might have unfortunately already experienced. You can also reverse the process by putting the melted chocolate into a fridge or freezer where it will go from a liquid back to a solid.
The chocolate probably melted quite fast if you tried putting a piece in your mouth, what does this tell you about the temperature of your body?
For further testing and experiments you could compare white choclate and dark chocolate, do they melt at the same temperature?
How about putting a sheet of aluminium foil between a paper plate and a piece of chocolate in the sun, what happens then?
