Thursday, March 12, 2009

Sperm and Egg

On the left is a human egg gamete and on the right is a sperm on the surface of one the eggs.





















These things go together and make a zygote which then develops into a huan body of extremely specialized cells.
Here is a rap explaining how that is done.


Tuesday, March 10, 2009

Karyogram

Male Karyogram


Female Karyogram

Humans have 46 Chromosomes 23 pairs called homologous pairs.
You can count them in this karyogram,
which is done during cell division so that the Chromosomes are fully formed.

Notice at the bottom right
that the female has 2 x's and male has 1 x and 1 y












Monday, March 9, 2009

Flipbooks and Science

Today we are making Mitosis & Mieosis flipbooks, I don't have any examples yet but here is a cool dodecahedral star flipbook.





Leftovers from Evolution


I was thinking about the Kakapo (a flightless parrot) today like we all do from time to time and it reminded me about all the leftovers from evolution and how confusing they can be for some people to understand how or why they came about.



How come a bird lost the ability to fly?
How could that benifit it in terms or evolution?
Well the Kakapo found itself on an island without predators, so rather than eat a little bit then fly away to a perch the Kakapo really tucked in to a meal knowing it wasn't in any danger of having to fly away at the spur of the moment. The birds that ate more couldn't fly but had more energy and were naturally selected for.



Our bodies have several, here are a few :

  1. The Appendix a sac that other animals have which helps them handle a really high plant diet.
  2. Goose Bumps which used to be used for raising hair follacles, ever make a cat mad or watch a bird in the sun?
  3. Wisdom Teeth were used for mashing up lots of veggies.

None of these things are essential for living and can be removed without slowing you down at all.

What you need to remember is that there is no pressure against these vestigal features forcing them to disappear.

For example goose bumps certainly don't help us in anyway but more importantly they don't hurt us in any way.