Title: Diploid and haploid cells

Target Group

A pupil of the 8th grade of elementary school.

Core Curriculum

General requirements

I. Knowledge of biological diversity and basic biological phenomena and processes. Pupil:

2) explains biological phenomena and processes occurring in selected organisms and in the environment.

Specific requirements

V. Genetics. Pupil:

4) presents the biological significance of mitosis and meiosis, distinguishes between haploid and diploid cells.

Lesson aim

Students characterize haploid, diploid and poliploid cells.

Criteria for success

• you'll explain why gametes have about half the number of chromosomes than somatic cells;

• you characterize haploid, diploid and polyploid cells;

• You'll explain why human gametes and gametes of many other organisms are haploid;

• you will calculate the number of chromosomes present in the somatic cells of a given organism, knowing the number of chromosomes in the gametes of the parent animals;

• you will provide examples of the economic use of species and varieties by humans based on a natural or artificial increase in the number of chromosomes in the cell (polyploidization).

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:

Mini lecture, presentation, didactic discussion, subject exercises.

Individual and collective work.

Teaching measures:

• abstract;

• interactive whiteboard or traditional blackboard;

• tablets/computers;

Lesson phases

Introduction

1. The teacher determines the purpose of the lesson and informs the students about its planned course. Presents the criteria for success.

2. The teacher gives the topic of the lesson, the students write it in their notebooks.

Realization

1. The lecturer explains the concept of haploidity and diploidy on the example of a human being. He also discusses the reasons why the gametes of the diploid organism are haploid cells.

2. The teacher presents an interactive illustration regarding haploidity, diploidy and polyploidy in nature. He presents examples of cells of each type and examples of animal and plant organisms, in particular those that are used economically by humans (arable crops, ornamental plants, farmed fish). He explains that some of these organisms have multiplied their set of chromosomes in a natural and accidental way, making them more attractive to humans as a source of food (eg wheat, carp). Some were created due to intentional breeding operations.

3. The teacher initiates a class discussion on the benefits of some organisms having a multiplication of chromosomes and the role of polyploidization in the emergence of new species and their varieties.

4. Students independently perform interactive exercises, the aim of which is to repeat the messages acquired during the lesson and to check the level of their mastery. The teacher monitors students' progress on an ongoing basis and helps them in case of difficulties.

Summary

Students ask questions, ask for additional explanations and complete the notes.

Homework

1. Listen to the abstract recording at home. Pay attention to pronunciation, accent and intonation. Learn to pronounce the words learned during the lesson. 2. Imagine that you have the opportunity to interview an academic - a specialist in the field of today's lesson. What questions would you like to ask him? Write them down.

The following terms and recordings will be used during this lesson

Terms

Texts and recordings

Diploid and haploid cells

In the somatic cells of animals and vascular plants chromosomes form pairs. Each pair consists of two similar chromosomes that contain information about the same body characteristics. Such chromosomes are called homologous. In human somatic cells there are 46 chromosomes (23 pairs). Cells that contain such a double set of chromosomes are called diploid cells and is displayed as 2n. Human gametes have 23 chromosomes, i.e. a single set of chromosomes. Such cells are called haploid cells and means 1n. Because the sperm and egg cell are haploid, as a result of fertilization, a diploid cell develops, and the child receives from each parent one set of chromosomes.

• Diploid cells contain a double set of chromosomes, and haploid cells – a single one.