Download File

Noadswood Science, 2011
Thursday, July 6, 2017

To know there are two types of reproduction, and the
difference between them

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