OLD AND ACTIVE
It is a well-known fact that Japanese people have a longer life expectancy than the population of most other countries. They also expect to (26) _____ healthier for longer.
Scientists are trying to work out what keeps elderly Japanese people so healthy, and whether there is a lesson to be learnt from their lifestyles. Should we make any changes to our eating habits, for instance? Are there (27) _____ secret ingredients in the Japanese diet that are particularly (28) _____ for the human body?
(29) _____ the prospect of a longer, healthier life is a good thing for the individual, it can actually create a social problem. The number of people over the age of 65 in the population has doubled in the last 50 years. Japan could soon be facing an economic problem: there are more elderly people (30) _____ need to be looked after, and relatively fewer younger people working and paying taxes to support them.

Genetic modification of foods is not a new practice. It has been practiced for thousands of years under the name of “selective breeding”. Animals and plants were chosen because they had traits that humans found useful. Some animals were larger and stronger than others, or they yielded more food, or they had some other traits that humans valued. Therefore, they were bred because of those traits. Individuals with those traits were brought together and allowed to breed in the hope that their offspring would have the same traits in greater measure.
Much the same thing was done with plants. To produce bigger or sweeter fruit, or grow more grain per unit of land, strains of plants were combined and recombined to produce hybrids, or crossbreeds that had the desired traits in the right combinations. All the while, however, biologists wondered: is there a more direct and versatile way to change the traits of plants and animals? Could we rewrite, so to speak, the heredity of organisms to make them serve our needs better?
In the 20th century, genetic modification made such changes possible at last. Now, it was possible to alter the genetic code without using the slow and uncertain process of selective breeding. It even became possible to blend plants and animals genetically: to insert animal genes into plants, for example, in order to give the plants a certain trait they ordinarily would lack, such as resistance to freezing. The result was a tremendous potential to change the very nature of biology.

In the history of technology, computers and calculators were innovative developments. They are essentially different from all other machines because they have a memory. This memory stores instructions and information. In a calculator, the instructions are the various functions of arithmetic, which are permanently remembered by the machine and cannot be altered or added to. The information consists of the numbers which are keyed in.
An electronic pocket calculator can perform almost instant arithmetic. A calculator requires an input unit to feed in numbers, a processing unit to make the calculation, a memory unit, and an output unit to display the result. The calculator is powered by a small battery or by a panel of solar cells. Inside is a microchip that contains the memory and processing units and also controls the input unit, which is the keyboard, and the output unit, which is the display.
The input unit has keys for numbers and operations. Beneath the key is a printed circuit board containing a set of contacts for each key. Pressing a key closes the contacts and sends a signal along a pair of lines in the circuit board to the processing unit, in which the binary code for that key is stored in the memory. The processing unit also sends the code to the display. Each key is connected by a different pair of lines to the processing unit, which repeatedly checks the lines to find out when a pair is linked by a key.
The memory unit stores the arithmetic instructions for the processing unit and holds the temporary results that occur during calculation. Storage cells in the memory unit hold the binary codes for the keys that have been pressed. The number codes, together with the operation code for the plus key, are held in temporary cells until the processing unit requires them.
When the equals key is pressed, it sends a signal to the processing unit. This takes the operation code - for example, addition - and the two numbers being held in the memory unit and performs the operation on the two numbers. After the addition is done, the result goes to the decoder in the calculator's microchip. This code is then sent to the liquid crystal display unit, which shows the result, or output, of the calculation.