Noadswood Science, 2011

To know there are two types of reproduction, and the difference between them

Tuesday, April 18, 2023

Order the following in terms of their size: -

During reproduction genetic information is passed from parents to their offspring

There are two distinct methods for this to occur: - Asexual reproduction Sexual reproduction

Asexual reproduction only needs one parent, unlike sexual reproduction, which needs two parent

Since there is only one parent, there is no fusion of gametes and no mixing of genetic information – as a result, the offspring are genetically identical to the parent and to each other (clones)

Some plants produce side branches with plantlets on them (e.g. Busy Lizzy)

Other plants produce runners with plantlets on them (e.g. strawberries)

Asexual reproduction in plants can take a number of forms

Many plants develop underground food storage organs that later develop into the following year’s plants (e.g. potato plants and daffodil plants)

Daffodil bulb at start of season

Daffodil bulb at end of season

Sexual reproduction happens when a male gamete and a female gamete join - this fusion of gametes is called fertilisation

Sexual reproduction allows some of the genetic information from each parent to mix, producing offspring that resemble their parents, but are not identical to them

In this way, sexual reproduction leads to variety in the offspring

Each pair of genes affects a different characteristic – the genes in the pair can come in different forms

These different versions of the same gene are called alleles

Offspring inherit a random mixture of thousands of alleles from their parents, which is why offspring do not look exactly like either parent

Why have sexual reproduction – surely it is easier to simply have asexual reproduction?!

Sexual reproduction leads to variety – this is critical for a species survival as the greater the variety within the individuals the more likely that at least a few of them will have the ability to survive difficult conditions

Young plants and animals resemble their parents, showing similar characteristics

However, young plants and animals can also differ from their parents and each other – these similarities and differences lead to variation within the same species

There are two causes of variation: - Genetic variation (slightly different genes) Environmental variation (upbringing)

Environmental variation in plants is much greater, as they are strongly affected by: - Temperature Sunlight Moisture levels Soil composition