Taste-buds

Explanation text with the answer : Taste-buds

 Taste-buds

The sense of taste is one of a person's five senses. We taste with the help of taste-buds in the tongue.

There are four main kinds of taste: sweet, sour, salty, and bitter. All other tastes are just mixtures of two or more of these main types.

The surface of the tongue has more than fifteen thousand taste-buds (or cells). These are connected to the brain by special nerves which send the so-called 'tastes messages.

When the tongue comes into contact with food of any kind, the taste-buds will pick up the taste. The nerves then send a message to the brain. This will make us aware of the taste. All this happens in just a few seconds.

There are four kinds of taste-buds, each of which is sensitive to only a particular taste. These four groups are located in different parts of the tongue.

The taste-buds for salty and sweet tastes are found round the tip of the tongue and along its sides. Sour tastes can be picked up only at the sides of the tongue. The taste-buds of the bitter taste are found at the innermost edge of the tongue. There are taste-buds at the center of the tongue.

The senses of smell and sight can affect taste. The good smell of food increases its taste. Similarly, attractive colors can make food appear tastier and more delicious. If food does not smell good or is dull-colored, it will look tasty and may not taste good at all.

Very hot or cold sensations can make the taste-buds insensitive. Food that is too hot or too cold, when placed in the mouth, will have no tastes at all.

1.      We can taste any kind of food because of ....

A.  the good smell of food                                                     D. the four main kinds of taste

B.   the taste-buds in the tongue                                             E. the senses of smell and sight

C.   the taste-buds round the tip of the tongue

2.      When we eat very hot or cold food ....

A.  the food will lose its taste                                                 D. the food won't smell good

B.   the taste of the food increases                                          E. the taste-buds will be sensitive

C.   the taste-buds will be very, responsive

3.      The senses of smell and sight ....

A.  increase the taste of the food                                            D. affect the taste of the food

B.   make food more delicious                                                E. make the food look good

C.   make the food attractive

Biodiesel

Explanation text with the answer : Biodiesel
                                                                             Biodiesel

Biodiesel is a clean burning substitute for petroleum based diesel fuel. Biodiesel is made of vegetable oil.

To make or manufacture Biodiesel, you must first start with raw materials. The raw materials needed in the production of Biodiesel are a small amount of methanol and a ready supply of vegetable product. One of the most common vegetables used in the production of Biodiesel is corn, although depending on the geographic location of the manufacturing facility many other plants are used as well (rapeseed, soybeans, flax seed, etc.). The first step is to use the raw vegetable product to make vegetable oil. Vegetable oil by itself will not be what you need to power a car, from here it has to be processed into Biodiesel.

The process for converting vegetable oil into Biodiesel is sometimes called ester interchange. To complete this process the vegetable oil has to be combined with a smaller amount of methanol and then put in the presence of a small quantity of an alkaline catalyst (for example, 5% to 1% sodium hydroxide). Vegetable oil is made up of so-called triglycerides, which is a compound of the trivalent alcohol glycerin with three fatty acids. The goal of ester interchange is to separate the glycerin molecule from the three fatty acids and replace it with three methanol molecules. This process then yields roughly 90% Biodiesel and 10% of a glycerin by product. The glycerin byproduct can be used in a number of other chemical processes for different industries.

1.      What is the text about?

A.the process of making biodiesel.                                       

B.  the advantage of using the biodiesel.                                 

C. the benefit of producing the biodiesel.

D. the development of the biodiesel product.

E.  the use of the biodiesel

2.      What are interchanged in the process of ester interchange?

A.  the three fatty acids with the glycerin molecules.              

B.   the glycerin molecule with three methanol molecules.      

C.  methanol and alkaline catalyst.

D.   methanol with the three fatty acids.

E. vegetable oil with methanol

3.      According to the text, one of the advantages in using biodiesel is…

A.  it is cheap.                                                                        

B.   it uses replaceable materials.                                              

C.  it can be done in small industry.

D.   it gives less pollution than petroleum.

E.  it only uses vegetable oil

4.      “The process for converting vegetable oil…”(Paragraph 3)

              The underline word is closest in meaning to…

A.  producing                                                                         D. separating

B.   Attaching                                                                          E. processing

C.   changing