Topic: Chemical build of organisms

Author: Elżbieta Szedzianis

Target group

5th grade student of an elementary school.

Core curriculum

Lesson objective

The students talk about chemical compounds which build organisms.

Key Success Criteria

• you will explain what is the difference between an element and a chemical compound;

• you will present the division of the chemical ingredients of organisms;

• you will describe the properties of water and its significance for the functioning of organisms;

• you will create models of selected chemical compounds.

Key Competences

• communicating in the mother tongue;

• communicating in a foreign language;

• mathematical competence and basic competences in science and technology;

• digital competence;

• learning to learn;

• social and civic competences.

Methods/Forms of work

Programmed teaching, work with text, exercises, model making, conducting expreriments.

Individual work.

Teaching measures

• abstract;

• interactive or traditional whiteboard;

• tablets/computers;

• paper plates with a set of colored gummy bears (6 blue ones, 8 red ones and 3 black ones) and 15 toothpicks;

• post‑its.

Lesson plan overview (Process)

Introduction

The teacher tells the topic of the lessons, defines the purpose of the course and gives students the criteria for success. Then, he informs the students about what is planned for this lesson: they will work individually, at their own pace - they will read an abstract, complete exercises and conduct observations. He gives detailed information to his students. He announces that he will supervise their work and help them if necessary.

Realization

1. The students read the fragment titled “Elements that build organisms” twice. They write down the most important notions. If they do not understand some, they check their meaning in the “Glossary”. Next, they analyze the table that presents the meaning of selected elements for the body.

2. The students complete the interactive exercise no. 1, 2, and 3.

3. The students read the fragment titled “Chemical compounds in organisms” twice, write down the most important notions and copy into their notebooks the scheme of how the chemical compounds of organisms are divided.

4. The students complete the interactive exercise no. 4‑9.

5. The students familiarize themselves with the fragment titled “Biological function of water” and look at the interactive illustration presenting the properties of water.

6. They analyze the illustration “Amount of water in plant organs” and complete “Exercise 2” in writing.

7. The students complete the interactive exercise no. 10‑15.

8. The teacher constructs out of gummy bears and toothpicks models of chemical compounds: oxygen, hydrogen, carbon dioxide, water, methane and carbon monoxide. He explains their composition. He explains that elements, forming chemical compounds, connect with each other forming chemical bonds, and their number is a characteristic feature of the element (e.g. carbon and oxygen form 2 or 4 chemical bonds, whereas hydrogen forms only one bond). Next, he gives the students paper plates with a set of colored gummy bears and toothpicks. The students create molecule models out of them, using as a reference the models prepared by the teacher. They write the names of each chemical compound on a post it and stick it next to a correct molecule model.

Summary

The teacher asks the students to answer the following questions:

• How do you assess the degree to which you learnt the material during class?

• What was helpful while studying? What was problematic?

The following terms and recordings will be used during this lesson

Terms

Texts and recordings

Chemical structure of organisms

All substances are made up of atoms. If the substance consists of identical atoms, which are not permanently bonded to each other, it is called a chemical 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 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 macroelements, because their amount in organisms is large enough to be easily determined by weight. The remaining elements are the so‑called microelements, i.e. elements occurring in trace amounts, each of which constitutes less than 0.01% of dry 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.

Organisms are composed of the same basic chemical compounds, but in different proportions. The human body consists on average of 65% of water and 2% of other inorganic 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 proteins, carbohydrates, fats and nucleic 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.

Chemical composition of organisms (in%):

Water 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.

• 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.