Analogy of The Animal Cell

1A) I'm comparing the animal cell to a restaurant.
The administrative office stores important information such as recipes of food and investment plans of the restaurant. It performs daily supervision of the operation of the restaurant so that it can function properly. Other than that, it decides when to expand the restaurant or when to set up a branch (Like the division of a cell). The Administrative office is the place where the manager works. He is in charge of employing and training chefs. The chefs are supposed to cook delicious foods (proteins) for the customers. The waiters put the food on trays, which are then placed on special carts. They will either be served to the customers or be sent them to the packaging department. In the packaging department, the workers pack the foods into containers for easier delivery. In order to deliver the food to the customers, the deliverymen have to pass through the security guards that guard the door and ensure that no troublemakers are allowed into the restaurant. Throughout the day, the cleaners will throw away all the rubbish and unwanted stuff left behind by the customers. The power supply provided all the energy needed in the restaurant, just like the mitochondria in the cell.
Nucleus:
Controls all the activities of the cell & essential for cell Division-- administrative office
Nucleolus:
Produces Ribosomes -- Manager
Ribosomes:
Produces Proteins that is used inside/outside the cell-- Chefs
Rough endoplasmic Reticulum:
Transports the proteins made by the Ribosomes to the Golgi apparatus-- Waiter
Golgi Apparatus:
stores and modifies the substances made by the ER & packages them into vesicles for secretion out of the cell-- Packaging Department
Lysosomes:
Vesicles that contain digestive enzymes &Break down engulfed bacteria/virus and worn out organelles -- Cleaners
Plasma membrane:
a partially permeable membrane that only allows some substances to pass through and not others-- Security Guards
Mitochondria:
Performs aerobic respiration-- Power Supply

From: http://plantphys.info/Plants_Human/unitlife.html

B) What are the advantages and disadvantages of animal cells only having a cell membrane (Compared to a cell wall found in plants)?

Advantages: Without the Cell Walls, we can move our bodies freely without feeling constricted, unlike plants which have to be rooted stiff to one place. The flexibility of the cell makes it easy to contract or expand easily to make very complicated and delicate movements ( such as a simple smile).

Disadvantages: Without a cell wall, the cell is too soft to keep in shape. Animals need special structure, like the skeletal system or exoskeleton , to support their bodies. When the water potential outside a cell is higher than the inside, Osmosis will occur. Unlike the plant cell, the animal cell does not have the cell wall to support and protect them, thus it will swell and even burst. Also, if the water potential outside is lower, the animal cell crenates when it becomes dehydrated and will eventually die, while the plant cell will just be plasmolysed.
Without the protection of the cell wall, animal cells are easier to be destroyed or injured.

Can Animals Sense Earthquakes?

For centuries, people have believed that animals can predict earthquakes, as some animals behave differently a few days before an earthquake occurs, such as, catfish moving violently, chickens that stop laying eggs and bees leaving their hive in a panic..

Animals are known to have keen senses that help them avoid predators or locate prey. So it is thought that these senses might also help them detect pending disasters.

A research on this was made by Sheldrake, and in all cases, there were reports of animals displaying peculiar behaviour beforehand, such as dogs howling in the night mysteriously, caged birds becoming restless, and nervous cats hiding. Overall, his report showed comparable patterns of animal behavior prior to earthquakes all over the world.

Other than this, in September 2003, a medical doctor in Japan made headlines with a study that indicated erratic behavior in dogs, such as excessive barking or biting, could be used to forecast quakes.

Despite all these reasearches, a real connection between a specific behavior and the occurrence of an earthquake has not been made. Some scientist believe that with their finely tuned senses, animals can often feel the earthquake at its earliest stages before the humans can, and they have two theories as to how animals may be able to detect earthquakes. One theory is that animals sense the earth's vibrations. While another is that they can detect changes in the air or sense gases released by the earth.

A few others disagree, saying that animals also change their behavior for many reasons such as changes in weather, being hungry, defending their territories, mating, predators. And given that an earthquake can shake millions of people, it is likely that a few of their pets will, by chance, be acting strangely before an earthquake.

Although scientists disagree as to whether animal behavior can be used to predict earthquakes and natural disasters, they all agree that it is possible for animals to sense changes in the environment before humans.



From:http://news.nationalgeographic.com/news/2003/11/1111_031111_earthquakeanimals.html#main