Aristotle's Work

The Greek philosopher Aristotle advised a way classifying animals and plants. He grouped plants and animals into three: the plants which have vegetative souls, animals with both vegetative and animals souls, and human beings, who have vegetative, animal and rational souls as manifested by their reasoning ability and intellectual pursuits.

Among organisms, those that could move by themselves (e.g animals) and those that could not move by themselves (e.g plants) where good separately. Those that could move by themselves were further grouped according to their habitat, whether they were land-dwellers, water-dwellers, or air dwellers. Those in the second group were classified according to size.

In the 16th and 17th centuries, geographical studies led to the discovery of new species of plants and animals. Scholars then classified plants into three groups: trees, shrubs, and herbs.

Aristotle's scheme of classification was not always applicable. Take the case of the turtles. They stay underwater to get food, but stay to the land to lay their eggs. Are turtles water-dwellers or land-dwellers? Baby frogs or baby toad stay in water. As they mature, they can live on land. Aristotle's scheme, therefore, did not encompass all organisms.

Aristotle's attempts to classify organisms prompted other scientists to find better ways or classifying organisms. Some worked on determining more reliable ways of looking at how organisms are related to each other.

Energy Requirements of Humans

Food is a basic need of all living things. Food contains nutrients that provide the body with energy. Sixty-five percent of the human body is water. The rest is fat, protein and carbohydrates.

The energy provided by these nutrients is expressed in units called calories. This unit is used to express the heat output of the organism or the energy value of food. You will find that some product labels indicate how many calories their product contain. For example, a cup of dried buttermilk has 465 kilo- calories, a cup of roasted peanuts has 840 kilo calories, and 10 pieces of vanilla and wafer cookies have 185 kilo calories.

There are several factors that influence calorie intake. Nutritionists and dietitians have conducted studies to show how sex, age, physical activity, health, and climatic conditions affect calorie intake.

Generally, growing individuals or those who are engaged in strenuous activities, and those living in warm to hot places should take in food with high calorie value. For individuals with special health concerns, it is suggested that they consult a doctor or a nutritionist.

Cytoskeletons

Cytoskeletons are the "bone and muscle" of the cell. There are three main types of cytoskeletons namely: microtubules, intermediate filaments, and microfilaments.

Microtubules are the skeletons of the cells. Generally, these are not attached to the membrane. Centrioles and spindle fibers are microtubules that play an important role during cell division. These microtubules help provide anchorage for organelles in the cell. They also act as tracks which the organelles, like ribosomes can move along in the cytoplasm. Locomotion of unicellular organisms like paramecium and euglena are made possible by the microtubules in the cilia and flagella, respectively. Cilia and flagella are the structures for locomotion that protrude from some cells. Cilia usually occur in large numbers on the cell surface. Flagella are usually limited to just one or a few per cell. The human sperm cell uses its flagella to swim.

Intermediate Filaments give support to the cytoplasm of cells. These are biochemically distinct from the microtubules, and microfilaments. Biological tests are done on the intermediate filaments to detect some disorders.

Microfilaments are the muscle of the cells. These are finger than microtubules and are generally attached to the membrane. Microfilaments give shape to the cell and are involved in the constriction of cytoplasm during mitosis.

Red and Think

The Tragical History of the Life and Death of Doctor Faustus
Early in the Play, Dr. Faustus, contracts his soul to the devil for special powers of the mind. Now facing death, he makes a desperate attempt to repent and save his soul. Now hast thou but one bare hour to live and then thou must be damned perpetually. Stand still, you ever moving spheres of heaven.

The Energy Pyramid

In a food web, the producer has the greatest amount of energy. At the consumer level, only 10% of absorbed nutrients are used to make a new body tissues. This represents the food available for the following level. The rest of the energy is lost as heat. Thus, the amount of usuable energy per unti mass decreases as the feeding level goes higher.

Herbivores, primary consumers, acquires only 10% of the total energy of the producers. Only 10% of the hervivores' energy goes to the animal in the next trophic level, so that the latter acquires 1/100th of the total producer's energy.

Harvesting

Most farm products are perishable. A single day's delay in marketing harvested products may result to serious deterioration especially during hot weather. Delay in harvesting also reduces the yield caused by many factors.

Crop products are harvested in different stages depending on the purpose. Leafy and fruit and vegetables are harvested while they are fresh, tender and green. Some vegetable crop possess better quality when they are harvested while dry. Rice and corn for human and animals consumption are best harvested when the grains are at their hard dough stages. Corn for boiling is harvested at the early stage of the fruit. On the other hand, root crops are harvested before they fully mature and become fibrous. Others are harvested when the leaves are dry.