What is the most common inorganic substance on earth? The composition and structure of cells The most common inorganic substance in a living organism

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Biology test The chemical composition of the cell for students in grade 6 with answers. The test consists of 2 options, each with 11 tasks.

1 option

1. The most common inorganic substance found in living organisms is

1) water
2) calcium salt
3) table salt
4) carbon dioxide

2. The main organic matter of a cell is

1) water
2) protein
3) starch
4) calcium salts

3. Sucrose, or beet sugar, which we eat every day, is

1) protein
2) fat
3) carbohydrate
4) nucleic acid

4. The significance of fats in the body of a seal lies in the fact that they

1) form a skeleton
2) are involved in muscle contraction
3) store hereditary information
4) prevent heat loss

5. The main role of nucleic acids in the body is associated with

1) storage of hereditary information
2) power generation
3) oxygen transport
4) the formation of wood

6.

A. The composition of the chemical elements that form the cells of all living organisms is similar.
B. Only animal organisms are made up of cells.

1) only A is true
2) only B is true
3) both statements are correct
4) both judgments are wrong

7. Are the following statements true?

A. There are chemical elements that are found only in living organisms and are absent in inanimate nature.
B. Most of the chemical elements are found in the cell in the form of chemical compounds.

1) only A is true
2) only B is true
3) both statements are correct
4) both judgments are wrong

8. Are the following statements true?

A. Water helps to remove harmful substances from the body.
B. The main function of carbohydrates in the cell is energy.

1) only A is true
2) only B is true
3) both statements are correct
4) both judgments are wrong

9. Review the diagram. Specify the chemical compound, the content of which in the cell is 70-80%.

1) water
2) proteins
3) carbon dioxide
4) mineral salt

10. Establish a correspondence between chemical compounds and the group of substances to which they belong.

Chemical compounds

1. Proteins
2. Fats
3. Water
4. Mineral salts

Substance group

A. Organic matter
B. Inorganic substances

11.

Answer the questions.

1. Specify the chemical elements that form the basis of the cell.
2. What is the importance of calcium salts in wildlife?

Option 2

1. Most of the chemical reactions that take place in a cell require an environment.

1) alcohol
2) water
3) air
4) fatty

2. The most common salt in living organisms

1) magnesium salt
2) sodium salt
3) phosphorus salt
4) lithium salt

3. The starch found in potato tubers is

1) protein
2) fat
3) carbohydrate
4) nucleic acid

4. The main source of substances in the cell are

1) proteins
2) carbohydrates
3) mineral salts
4) nucleic acids

5. The transmission of hereditary traits from parents to children is

1) fats
2) carbohydrates
3) nucleic acids
4) mineral salts

6. Are the following statements true?

A. Living organisms are made up of cells.
B. The chemical element carbon is widely distributed in wildlife.

1) only A is true
2) only B is true
3) both statements are correct
4) both judgments are wrong

7. Are the following statements true?

A. The percentage of different chemical elements in the cell is different.
B. Chemical elements found in living nature are widely distributed in inanimate nature.

1) only A is true
2) only B is true
3) both statements are correct
4) both judgments are wrong

8. Are the following statements true?

A. Proteins make up about half of all organic substances of the cell.
B. Fats are part of the bodies of inanimate nature.

1) only A is true
2) only B is true
3) both statements are correct
4) both judgments are wrong

9. The figure shows a clam shell. Indicate the chemical compound that is part of the shell.

1) fats
2) proteins
3) calcium salts
4) nucleic acids

10. Establish a correspondence between chemical compounds and the group of substances to which they belong.

Chemical compounds

1. Carbohydrates
2. Water
3. Mineral salts
4. Nucleic acids

Substance group

A. Organic matter
B. Inorganic substances

11. Analyze tabular data.

The prevalence of chemical elements in inanimate nature

Answer the questions.

1. Are there chemical elements that are found only in living organisms?
2. What chemical element is widespread in inanimate and living nature?

The answer to the biology test The chemical composition of the cell
1 option
1-1, 2-2, 3-3, 4-4, 5-1, 6-1, 7-2, 8-3, 9-1
10-AABB
11.
1. O, C, H, N - together they make up 98% of the contents of the cell.
2. They are part of the bone tissue and shells of mollusks.
Option 2
1-2, 2-2, 3-3, 4-2, 5-3, 6-3, 7-3, 8-1, 9-3
10-ABBA
11.
1. No. Elements that are found in living nature are also found in inanimate nature.
2. Oxygen.

Plants and animals are different from each other. And yet there are signs common to the cells of all organisms.

Organic and mineral substances of the cell

It includes organic and inorganic (mineral) substances. Organic substances are formed in the cells of living organisms. These include proteins, fats and carbohydrates. Inorganic substances are widely distributed in inanimate nature. The most common inorganic substance is water. It is necessary for all cells and makes up about 70% of the mass of the cell. Water is a direct participant in many life processes: growth, nutrition, excretion, movement of substances in the cell and body. Mineral salts (for example, table salt) are dissolved in water.

Squirrels

Proteins are complex organic compounds. The bodies of living organisms are built from proteins. They are involved in all life processes. Vegetable proteins play an important role in the nutrition of animals and humans. Most proteins are found in plant seeds. Among animal proteins, you are well aware of the protein contained in a chicken egg. The diversity of proteins in the cells of one organism can reach several thousand species.

Carbohydrates

Carbohydrates are essential for all living organisms as a source of energy. These include glucose, sucrose, starch and other substances. Starch accumulates in potato tubers, bananas, wheat seeds. In many animals, carbohydrate glycogen is stored in the liver and muscles. Carbohydrates give strength to many parts of organisms, for example, they are part of wood. The carbohydrate chitin forms the outer covering of insects and crustaceans.

Fats

In the cells of living organisms, fats serve as a reserve source of energy and water. They are especially important for animals hibernating (bears, gophers) or living in the desert (camels). Large reserves of fat are found in the seeds of plants such as sunflower and flax.

General features of the structure of cells of all organisms

The cell is made up of interconnected parts. Each of them has a special structure and purpose. Outside, any cell is covered with a plasma membrane. The main role of the membrane is to protect the cell from external influences. The membrane has pores through which the contents of one cell communicate with the contents of other cells. Nutrients and water pass through the membrane into the cell, and waste products are removed from it.

Inside the cell is the cytoplasm - a viscous semi-liquid substance that is constantly moving. Various processes take place in the cytoplasm that ensure the vital activity of the cell. It serves as an internal environment in which cellular structures are located that perform certain functions - organelles.

The most important and largest organelle of the cell is the nucleus. However, the cells of not all organisms contain it. The cells of bacteria, the most ancient organisms on Earth, are most simply arranged. In their cytoplasm there is a nuclear substance that has not yet been formed into a nucleus. These organisms are called prenuclear (prokaryotes). The cells of fungi, plants and animals contain a nucleus and have a more complex structure. Such organisms are called nuclear (eukaryotes). According to scientists, hundreds of millions of years ago, life on Earth was represented exclusively by non-nuclear organisms, and only much later did nuclear organisms arise.

Water* The most common inorganic compound in living organisms is water. Its content varies widely: in the cells of the enamel of the teeth, water is about 10%, and in the cells of the developing embryo - more than 90%. On average, in a multicellular organism, water makes up about 80% of body weight.

The role of water in the cell is very great. Its functions are largely determined by the chemical nature. The dipole nature of the structure of molecules determines the ability of water to actively interact with various substances. Its molecules cause the splitting of a number of water-soluble substances into cations and anions. As a result, ions quickly enter into chemical reactions. Most chemical reactions are interactions between water-soluble substances.

Thus, the polarity of molecules and the ability to form hydrogen bonds make water a good solvent for a huge amount of inorganic and organic substances. In addition, as a solvent, water provides both the influx of substances into the cell and the removal of waste products from it, since most chemical compounds can only penetrate the outer cell membrane in dissolved form.

No less important is the purely chemical role of water. Under the action of certain catalysts - enzymes - it enters into hydrolysis reactions, i.e. reactions in which OH "or NH groups of water are added to the free valences of various molecules. As a result, new substances with new properties are formed.

To a certain extent, water is a heat regulator; due to good thermal conductivity and high heat capacity of water, when the ambient temperature changes, the temperature inside the cell remains unchanged or its fluctuations are much lower than in the surrounding cell -. environment.

mineral salts. Most of the inorganic substances of the cell are in the form of salts - either dissociated into ions, or in a solid state. Among the former, K + cations are of great importance. Na + , Ca 2+ , which provide such an important property of living organisms as irritability. In the tissues of multicellular animals, calcium is part of the intercellular "cement", which determines the adhesion of cells to each other and their orderly arrangement in tissues. The buffer properties of the cell depend on the concentration of salts inside the cell.

amino acid molecules form bonds between acidic carbon and nitrogen main groups. Such bonds are called covalent, and in this case - peptide connections:

The combination of two amino acids into one molecule is called dipeptide, three amino acids tripeptide etc., and a compound consisting of 20 or more amino acid residues - polypeptide.

Amino acids have a common structural plan, but differ from each other in the structure of the radical (R), which is very diverse. For example, the amino acid alanine has a simple radical - CH3, the cysteine ​​radical contains sulfur - CH 2 SH, other amino acids have more complex radicals.

Proteins isolated from living organisms of animals, plants and microorganisms include several hundred and sometimes thousands of combinations of 20 basic amino acids. The order of their alternation is the most diverse, which makes possible the existence of a huge number of protein molecules that differ from each other. For example, for a protein consisting of only 20 amino acid residues, theoretically about 2x10 variants are possible, differing in the alternation of amino acids, and hence in the properties of various protein molecules. The sequence of amino acids in a polypeptide chain is called the primary structure of a protein.

However, a protein molecule in the form of a chain of amino acid residues connected in series by peptide bonds is not yet capable of performing specific functions. This requires a higher structural organization. By forming hydrogen bonds between the residues of the carboxyl and amino groups of different amino acids, the protein molecule takes the form spirals (a- structure) or a sweet accordion layer (/? - structure). This is the secondary structure of the protein (Fig. 3.1, 3.2).

Buffering is the ability of a cell to maintain a slightly alkaline reaction of its contents at a constant level. Buffer solutions are characterized by the fact that the introduction into them or the formation in the process of metabolism of small amounts of acid or alkali does not affect the pH values ​​due to the formation of compounds with carbonates, phosphates or organic molecules. Inside the cell, buffering is provided mainly by H2PO4 anions. "In the extracellular fluid and in the blood, H2CO3" and HCO3 "play the role of a buffer. Anions of weak acids and weak alkalis bind hydrogen ions (NH) and hydroxyl ions (OH"), due to which reaction inside cells remain virtually unchanged.

Insoluble mineral salts, such as calcium phosphate, are part of the intercellular substance of bone tissue, in mollusk shells, ensuring the strength of these formations.