1.1 Description of the scientific concept (according to Wynne Harlen, 2015)

Living things produce offspring of the same kind, but offspring are not identical with each other or with their parents. Plants and animals, including humans, resemble their parents in many features because genetic information is passed down from one generation to the next. Other features, such as skills and behavior, are not passed on in the same way and have to be learned. Organisms that arise through asexual reproduction, such as by pullulation, are genetically identical to the parent organism. In the case of sexual reproduction, half of the genetic information comes from one parent. Many of the characteristics of organisms are influenced by external conditions, e.g. from the amount of available food or weather. This results in differences between the generations even with asexual reproduction. In humans, apart from other external conditions, learning processes are an important factor that affects a person›s characteristics.


Inside the nucleus of animal and plant cells are structures called chromosomes which hold large complex molecules of DNA1). When cells divide the information that is needed to make more cells is in the form of a code represented in the way that the parts of the DNA molecule are put together. A gene is a length of DNA; and hundreds or thousands of genes are carried on a single chromosome. In the human body most cells contain 23 pairs of chromosomes with a total of about twenty thousand genes. The total set of 46 chromosomes is also called a double set of chromosomes because each chromosome is present twice (one from the father and one from the mother).

When the organism grows or dead cells are replaced, the cells divide and the genetic information is copied. Then each new cell carries a replica of the parent cell. Sometimes there are errors in copying. This is called mutation. This may or may not be damaging to the organism or it will be completely ineffective. Changes in genes can also be caused by environmental conditions, such as radiation and chemicals or occur spontaneously during cell division. These changes can affect the individual but only affect the offspring if they occur in sperm or egg cells.

Sexual and asexual reproduction

During sexual reproduction, a sperm cell from a male unites with an egg cell from a female. Sperm and eggs are specialized cells. They only have one of the two versions of each gene carried by the parent, i.e. a simple set of chromosomes. When a sperm and egg combine a half of the genetic material in the fertilized egg is from the sperm cell and a half from the egg cell. As the fertilized egg divides time and time again this genetic material is duplicated in each new cell. In this type of reproduction, the genetic material is reorganized. This leads to new gene and trait combinations. There are many possible combinations that are then inherited from one generation to another. Organisms that are best suited to an environment with their gene combination often inherit this combination. In this way, adaptations to a specific habitat occur. This process is called natural selection.

During asexual reproduction, which occurs naturally in a wide range of organisms including some bacteria, insects and plants, identical genetic information is passed on. The biotechnology has made possible the production of genetically identical organisms through artificial cloning in a range of species including mammals.

The Genome

The overall sequence of genes of an organism is known as its genome. Researchers have learned a lot about genetic information by mapping the genomes of different kinds of organisms. When sequences of genes are known genetic material can be artificially changed to give organisms certain features. In gene therapy, special techniques are used to cure diseases by altering human genes.

Genetic information in a cell is held in the chemical DNA. Genes determine the development and structure of organisms. In asexual reproduction all the genes in the offspring come from one parent. In sexual reproduction half of the genes come from each parent.

1.2 What are elementary students able to understand? (according to Wynne Harlen, 2015)

Elementary school students are already able to experience and understand the following part of this “Big Idea”:

Living creatures produce offspring of the same kind. However, these offspring are not identical. Siblings are similar, but they are not the same. Children resemble their parents, but also they are not equal. Plants and animals, including humans, resemble their parents in many features. These similarities are passed down from one generation to the next by genetic information (also genes or DNA). Other characteristics, such as skills and behavior, are not passed on in the same way – they have to be learned.