Assignment Part 3

1. Why does the sun make your skin dark but your hair light?
I know that our hair is dead and our skin is alive. So the skin will absorb the heat and therefore it will be darker. Like baking a cake. The dough is first yellow or white but upon heating in the oven the dough will eventually turn brown!! FNN student mah..

2. If vegetables have no fat, why is vegetable oil all fat?
First of all, oil is basically used by plants as a store of energy, just as in animals. But so are various sugars and starches (carbohydrates) - and they tend to be used in more ways than just for fuel (for example, plant cellulose is a form of carbohydrate). So generally fats aren't needed in plants, they can get by with carbohydrates but,Fats and oils hold more energy than a given amount of carbohydrates - about double the energy. In plants weight doesn't matter much except in the seed - it takes a lot of energy to grow the seed and space (and weight) in a seed is at a premium, so oil is the most efficient storage. That's why oils are usually made from vegetable seeds ... excepting a few anomalous plants like the avocado, which stores oils instead of sugar or starch in the fruit.

3. Cockroaches are one tough animal. If you cut the head off of a cockroach, it could live for a month without it. And don't try drowning it. The cockroach can hold its breath for 40 minutes!
Find out why & how does the cockroach do that!

Well, i do not know how to summarize but, It cant reattach its head.But, it can still survive.
A cockroach can live a week (or) upto a month ( only if conditions are cold ) without its head. The roach only dies because without a mouth, it can't drink water and dies of thirst.

The reason why cockroaches and many insects in general dont die are :

(1) Cockroaches breath through spiracles which are in each body segment and the blood does not carry oxygen to the tissues. The spiracles deliver air to each cell of the body through a set of tubes called tracheae. The brain does not control the breathing through the spiracles.

(2) The cockroach does not have blood pressure the way a mammal does and so cutting off the head does not lead to uncontrolled bleeding.

3) The cockroach is a poikilotherm or cold blooded animal. They need much less food and a one day meal would be enough to last them a whole month as long as they were not extremely active. Without a head the cockroach would just sit around without doing anything much.

All this along with a cool temperature could allow the cockroach to last about a month without need for their head, as long as they did not get infected with a mold, bacterium or virus, which could kill them prematurely.



By Amin (30)