Topic: Cellular respiration

Author: Zyta Sendecka

Target group

5th grade student of elementary school.

Core curriculum

I. Organisation and chemism of life. Student:

8. presents aerobic respiration and fermentation as a means of producing life energy
(substrates, products and conditions of processes).

Lesson objectives

Students explain what cellular respiration consists in and what its significance is.

The criteria for success

• you will specify products and substrates for cellular respiration;

• you will explain what for cellular respiration occurs.

Key competences

• communication in the mother tongue;

• communication in foreign languages;

• mathematical competence and basis competences in science and technology; 

• digital competence;

• learning to learn;

• social and civic competences.

Methods/forms of work

Working with the text, working with the film, talk, experiment, alternative observation.

Individual activity and activity in groups.

Teaching aids

• abstract;

• interactive whiteboard or traditional blackboard;

• tablets/computers;

• two identical lighters with lids;

• drink straws;

• large beakers or jars (one per group);

• a large beaker or jar with the words “lime water” written on it (teacher's vessel);

• lime water;

• a clip to a song about photosynthesis from the Internet titled „Piosenka o fotosyntezie w Laboratorium „Runo Leśne”.

Lesson plan overview

Introduction

1. The teacher displays a clip to the song about photosynthesis. The students write equation of this process on the board.

2. The teacher presents a lighter with a lid. The teacher lights it up and closes it. The teacher asks the students why the flame goes out when the lid is closed. The teacher gives the volunteer two identical lighters, one with fuel and the other without fuel. The student tries to light up the lighter without fuel and indicates the difference between the lighters (lack of fuel in the second lighter). The teacher asks the student to summarize the presentation and to explain what determines the combustion process. Then, the teacher tells the students that they will learn during the classes about a combustion‑like process that takes place in the cells of all organisms.

3. The teacher specifies the subject and the objective of the lesson as well as the criteria for success.

Realization

1. Students read the first four paragraphs of the abstract (extract “Cellular respiration”) and answer the following questions:

• What is contained in the nourishment?

• What do organisms use energy for?

• Where is the energy contained in the nourishment released?

• From which chemical compounds is energy released?

2. The teacher writes down the cellular respiration equation under the photosynthesis equation. Students compare the equations, paying attention to the substrates and products of energy conversion. They explain where glucose and oxygen come from and what happens to energy, water and carbon dioxide.

3. The teacher discusses the difference between cellular respiration and gas exchange.

4. Students do interactive exercise no. 1.

5. The teacher divides the students into groups. Each group receives a vessel with lime water, and each student receives a drink straw. The teacher presents his/her lime water vessel and says it becomes opaque when exposed to carbon dioxide. The teacher asks the students how to find out if carbon dioxide is produced in their cells, i.e. cellular respiration takes place. When the correct answer is given, the students blow the air into the vessels using straws. Then they compare the appearance of the lime water in their vessels and in the teacher’s vessel to which no carbon dioxide has been introduced.

6. The students prepare the documentation of the experiment: they write down the hypothesis, the research and control sample, the observations and conclusions in their notebooks.

Summary

1. The teacher displays on the screen a diagram showing the use of energy by organisms. A volunteer or the student indicated by the teacher discusses the illustration in the classroom.

2. The teacher asks the students:

• Is gas exchange similar to cellular respiration?

• Is cellular respiration similar to photosynthesis?

The teacher asks the students to justify their answers.

3. The teacher displays the criteria for success and encourages the students to assess their skills acquired during the classes.

The following terms and recordings will be used during this lesson

Terms

Texts and recordings

Cellular respiration

Respiration is the process that determines life, because it allows the organism to use the energy contained in the nourishment. All beings need energy to perform their vital functions – thanks to it they can move and nourish, excrete, response to stimuli, conduct biochemical processes in cells, reproduce and grow. Birds and mammals also need energy to maintain a constant body temperature, independent of ambient temperature.

Organic compounds contain chemical energy and are therefore nourishment for the organisms. Release of energy from the nourishment takes place in each living cell and is called cellular respiration. In the cells of eukaryotes, this process takes place in mitochondria – structures whose function can be compared to that of a power plant. They contain enzymes capable of conducting this process.

Sugar – glucose is an organic compound which is an energy source. When there is no glucose in the organism, the reserve substances are broken down. Mainly other sugars and fats, and when these reserves are exhausted, even proteins are broken down. The use of proteins as “fuel” is a result of prolonged hunger and, for example, in animals, it leads to muscle atrophy.

In the respiration process, chemical energy is converted. A significant part of it is dissipated in the form of heat, while the rest is stored in molecules of a chemical compound called ATP. It can be transported throughout the cell and then used where there is a demand for energy.

During respiration, sugars and fats are broken down into carbon dioxide and water. As a result of the decomposition of proteins, compounds containing nitrogen – ammonia and urea are additionally produced, and in the ammonia conversion process produced is also uric acid. These products are toxic for animals and must be removed from the organism. Plants do not get rid of nitrogen compounds, because they use them to produce their own amino acids and proteins.

Anaerobic respiration is the main source of energy for organisms living in environments with little or no oxygen. This is how some bacteria, fungi and intestinal parasites, sometimes also muscle cells, respire. Anaerobic respiration takes place in the cytoplasm and is called fermentation. The best known is the alcoholic fermentation carried out by the yeast. As a result of it, sugar is broken down into ethyl alcohol and carbon dioxide, and energy is obtained.

Respiration and photosynthesis are interdependent processes. During photosynthesis, plants produce organic compounds and oxygen, which are essential both for them and for heterotrophic organisms to release energy during the respiration process. Products of respiration – carbon dioxide and water – are substrates of the photosynthesis process. Plants respire continuously during the day and at night. During the day, carbon dioxide produced during respiration is used by plants for photosynthesis. However, its amount is not sufficient, so plants additionally take up this gas from the environment. These organisms use only a small proportion of the oxygen produced by photosynthesis to respire, the rest being released into the atmosphere. It is worth knowing that at night, when photosynthesis stops, plants - like other organisms - consume oxygen and produce carbon dioxide.

• Aerobic respiration is the process of obtaining energy through the decomposition of sugars and is carried out according to a simplified scheme:

• Aerobic respiration is more energy efficient than anaerobic respiration.

• Substrates of respiration are products of photosynthesis, and the products of photosynthesis are substrates of the cellular respiration process.

• Gas exchange is the process accompanying aerobic respiration.

• Anaerobic respiration is a type of cellular respiration that occurs without oxygen; the type of anaerobic respiration is fermentation.