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Elements that build organisms

All substances are made up of atoms. If the substance consists of identical atomsatomatoms, which are not permanently bonded to each other, it is called a chemical elementchemical elementchemical element.

Let us trace the content of some elements in the human body. On average, one kilogram of the human body contains 650 g of oxygen, 180 g of carbon, 100 g of hydrogen and 30 g of nitrogen. These four elements are the basic components of living matter. If we add further elements to them: phosphorus (10 g) and sulphur (3 g) – we obtain a group of so‑called biogenic elementsbiogenic elementsbiogenic elements. Without them, life on Earth would not exist.

Further elements in the sample analysed are 15 g of calcium, 4 g of potassium, 2 g of sodium, 1 g of magnesium and 1 g of chlorine. Together with the biogenic elements, they are called macroelementsmacroelementsmacroelements, because their amount in organisms is large enough to be easily determined by weight. The remaining elements are the so‑called microelementsmicroelementsmicroelements, i.e. elements occurring in trace amounts, each of which constitutes less than 0.01% of dry matterdry matterdry matter. They are as important for the development and functioning of organisms as macroelements. These include, among others, iron, iodine, copper, zinc, fluorine and silicon.

Chemical compounds present in organisms

Organisms are composed of the same basic chemical compoundschemical compoundchemical compounds, but in different proportions. The human body consists on average of 65% of water and 2% of other inorganic compoundsinorganic compoundinorganic compounds. The rest, i.e. about 33%, are molecules of organic compounds composed of numerous elements, the most important of which is carbon. Carbon is distinguished by its ability to form long chains of various shapes. They constitute the “backbone” to which other elements can be added. This results in creation of complex molecules of compounds such as proteinsproteinsproteins, carbohydratescarbohydratescarbohydrates, fatsfatsfats and nucleic acidsnucleic acidsnucleic acids. They build bodies of organisms, are a source of energy for their functioning and regulate processes occurring in them. Organic compounds also include vitamins responsible for the proper course of life processes.

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Ilustracja przedstawia schemat składników chemicznych, budujących organizm. Podzielono je na pierwiastki i związki organiczne. U góry są pierwiastki, które dzielą się na mikroelementy i makroelementy. U dołu znajduje się podział związków chemicznych na nieorganiczne i organiczne. Nieorganiczne to woda i związki mineralne. Organiczne to tłuszcze, węglowodany, białka, kwasy nukleinowe i inne. The illustration shows a schematic of chemical components that build the body. They were divided into elements and organic compounds. At the top are elements that are divided into microelements and macronutrients. At the bottom is the division of chemical compounds into inorganic and organic compounds. Inorganic is water and mineral compounds. Organic are fats, carbohydrates, proteins, nucleic acids and others.

Chemical composition of organisms (in%):

Biological function of water

WaterwaterWater is one of the most common substances on Earth. Without it, life would not exist. It is found in cells and tissue fluids that fill the intercellular spaces and in body fluids (e.g. blood) of animals. It is also found in plant tissues and organs. The average water content in organisms is not the same, it depends on the species and living environment, on the age and condition of the organism, as well as on the type of organ. The chemical structure of a water molecule determines its physical properties, and these affect its biological functions. Water is the environment in which most life processes take place and is a solvent for many chemical compounds. In addition, it enables regulation of the body temperature and influences the size and shape of the cells. The embryos of animals develop in an aquatic environment that provides them with a constant temperature and humidity.

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Plansza przedstawia sześć wykresów, obrazujących zawartości wody w roślinach. Od największej: 95% w płatkach kwiatów, 81% w liściach grochu, 80% w korzeniu buraka, 64% w owocach pomidora, 45% w drewnie, 10% w nasionach soi.

Observation 1

Determination of the water content in leaves. OR What is water content in leaves?

You will need

• a few fresh leaves of different plants,

• burner or candlestick,

• heat‑resistant test tubes,

• test tube holder,

• laboratory scales.

Instruction

1. Weigh all leaves separately.

2. Put each leaf into a different test tube and heat it over the burner until the water evaporates completely.

3. Weigh the dried leaves.

4. Calculate the percentage content of water in each leaf.

5. Open and fill in the attachment.

6. Use the following formula to calculate the percentage of water in the leaves:

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Ilustracja przedstawia sposób obliczania zawartości wody w liściach. Wynik odejmowania świeżej masy lisci i suchej masy liści mnoży sie przez 100, a wynik dzieli przez masę świeżych liści.

Summary

Plant leaves differ in their water content.

Conclusion

• Among the elements building organisms, we can distinguish macroelements and microelements.

• The elements without them life would not exist are carbon, hydrogen, nitrogen, oxygen, phosphorus and sulphur.

• Carbon is the main component of organic compounds.

• The specific properties of water make it an essential component of all organisms.

• Proteins, fats, carbohydrates, nucleic acids are the basic organic compounds of the organisms.

• Glucose is the main source of energy in cells.

• Polysaccharides perform building and reserve functions.

• Proteins are the basic building material of cells and regulate the course of life processes of organisms.

• Fats are a source of energy and a reserve material for plants and animals.

• DNA is a carrier of genetic information.

Keywords

inorganic compounds, atom, element, particle

Glossary