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Archive for March 9th, 2017

Here are some nice fact extracted from http://primaryhomeworkhelp.co.uk/adaptations/penguins.htm:

How are penguins adapted so they can swim fast?

Penguins have webbed feet for powerful swimming. Their bodies are streamlined to reduce drag in water. Their wings, shaped like flippers, also help them “fly” underwater at speeds up to 15 mph.

How do penguins keep warm?

Penguins have to keep high body temperatures to remain active. They have thick skin and lots of fat (blubber) under their skin to keep warm in cold weather.

They also huddle together with their friends to keep warm. Emperor penguins have developed a social behaviour that when it gets cold, they huddle together in groups that may comprise several thousand penguins.

The dark coloured feathers of a penguin’s back surface absorb heat from the sun, so helping them to warm up too.

What is the job of penguins feathers?

Penguins tightly packed feathers overlap to provide waterproofing and warmth. They coat their feathers with oil from a gland near the tail to increase impermeability. Waterproofing is critical to penguins’ survival in water, Antarctic seas may be as cold as -2.2°C (28°F) and rarely get above +2°C (35.6°F).

(-2°C is the freezing point of sea water, below zero because of the salt).

How do penguins stay under water?

Penguins don’t have all the extra airspaces in their bones that normal birds have. Their heavy, solid bones act like a diver’s weight belt, allowing them to stay underwater.

 

coagulate – cause (a fluid) to change to a solid or semisolid state

Here is a good experiment on growing mould on bread:

Directions:

  • SAMPLE 1:  Take a piece of bread and slice it in half (it can be a few days old, but ensure it isn’t too stale).  Seal one half in saran wrap and expose the other to air.
  • SAMPLE 2:  Take another piece of bread and slice it in half.  Leave one half in the dark (a paper bag or cupboard) and the other half in strong light (sunlight works)
  • SAMPLE 3:  Take a third piece of bread and slice it in half.  Keep one half very dry and put about 1 tsp of water on the other half.  (Spritz the wet piece with a few drops of water each day).
  • SAMPLE 4:  Take a fourth piece of bread and put half of it someplace warm, in the dark (on top of the fridge in a paper bag) and the other half someplace cold in the dark (the refrigerator).
  • Examine the samples each day with your naked eye or a magnifying glass and record any changes in appearance.

 

What happened:

Molds will develop on some of the samples.

Molds grow best in warm, dark and moist conditions.

In the first sample, the sealed bread should develop mold more slowly than the unsealed bread.

In the second sample, the bread kept in darkness should develop mold more quickly than the bread kept in light.

In the third sample, the moist bread will develop mold more quickly than the dry bread.

In the fourth sample, the mold in the warm place should develop mold more quickly than the bread in the cold place.

Reference: http://www.kidzone.ws/science/mold.htm


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