Read the text and answer the questions



Living organisms are made up of chemical substances. An element is a substance that cannot be broken down into simpler substances by normal chemical reactions. Four basic elements, carbon, hydrogen, oxygen and nitrogen, make up 96% of an organism's body.

Atoms are the simplest units of elements. Atoms are composed of protons, neutrons and electrons. Different atoms are joined by chemical bonds to form compounds. Compounds are divided into two main types: inorganic and organic compounds.


Inorganic compounds

They do not have a carbon skeleton. Water and minerals are inorganic compounds. Water is the most important inorganic compound. The chemistry of life is the chemistry of water. Without water, life cannot exist. All life processes require water.

Minerals are needed for normal growth and development. Calcium and potassium are minerals needed for bone growth.


Organic compounds

Carbon is the central component of all organic compounds. They are mainly 6 made up of carbon, hydrogen, oxygen, and nitrogen, and sometimes sulfur and phosphorus. The major groups of biologically important organic compounds are carbohydrates, proteins, lipids, vitamins, enzymes, hormones, and nucleic acids.


They are the primary energy source for all organisms. Carbohydrates are divided into many types. Some are called sugars. The most important sugar is glucose, because it is very important for brain cells. Mostly we get carbohydrates from plants.

Lipids or fats

They are the secondary source of energy for organisms. They also have protective and supportive functions in organisms. Plant and animals contain fat.

In the human body, excess fat can cause some disorders, such as arteriosclerosis, which is the accumulation of fat molecules on the walls of blood vessels.

Arteriosclerosis blocks the blood flow and may cause heart attack and even death.



They have many vital roles in an organisms' body. They are part of many other organic molecules or structures. They are the structural compounds for all organisms. Hair and fingernails are made up of a protein called keratin. They are also used as an energy source. Antibodies, which kill microbes, are also made up of protein.


They are regulator molecules. They regulate normal growth and development.

Vitamin A regulates normal eye function, vitamin D regulates normal growth of bone, and vitamin C is needed for immunity or body defense. They do not provide energy.


They are biological catalysts. Enzymes speed up biochemical reactions.

Without enzymes life processes would be very slow. There are many enzymes in our body, such as pepsin, which acts in protein digestion in the stomach.



They are chemical messengers in organisms. They carry messages from one organ to another organ, or to all of the body's organs. Hormones regulate normal body functions. Insulin is a hormone that carries a message from the pancreas to body cells in order to balance the glucose level in the blood.



Nucleic acids

They are master or director molecules. They control all life activities in the cell.

DNA and RNA are the nucleic acids found in the cells. DNA functions like a director, and RNA like a vice-principal.


Answer the questions.

1. What is an element?

2. What are the basic elements that make up 96% of an organism body?

3. What are atoms?

4. What are atoms composed of?

5. How many types are compounds divided into?

6. Do inorganic compounds have a carbon skeleton?

7. What is the most important inorganic compound?

8. What do all life processes require?

9. What minerals are needed for bone growth?

10. What is the central component of all organic compounds?

11. What are the major groups of biologically important organic compounds?

12. What do sugars refer to?

13. What are the primary energy sources for all organisms?

14. Why is glucose important?

15. What are the secondary sources of energy for organisms?

16. What functions do lipids or fats have?

17. What is arteriosclerosis?

18. Why is arteriosclerosis harmful?

19. Do proteins have important roles in organisms’ body?

20. How is protein which makes up hair and fingernails called?

21. What are antibodies made of?

22. What compounds speed up biochemical reactions?

23. What are DNA and RNA?



Дата добавления: 2018-04-04; просмотров: 104;