5 (a) Organisms can be classified by the five kingdom or three domain method - Edexcel - GCSE Biology - Question 5 - 2019 - Paper 1

In a chloroplast, oxygen is produced as a result of photosynthesis. This process involves sunlight being absorbed by chlorophyll, which is the green pigment present in chloroplasts, allowing plants to convert light energy into chemical energy.

The three domain method of classification has been suggested to reflect the fundamental differences in the biochemistry and genetics of organisms, particularly distinguishing between bacteria, archaea, and eukaryotes. This approach provides a more accurate representation of evolutionary relationships among different life forms.

To calculate the actual diameter of the cyanobacterium, divide the measured diameter by the magnification factor. If the measured diameter is 2 cm, the calculation would be:

$\text{Diameter} = \frac{\text{Measured Diameter}}{\text{Magnification}} = \frac{2cm}{50000} = 0.00004cm = 0.4µm$

1. Bacterial cells have a cell wall, which provides structural support and protection.
2. They possess ribosomes for protein synthesis, which are smaller than those in eukaryotic cells.
3. Bacterial cells often contain a nucleoid region, where the genetic material (DNA) is located, as they lack a defined nucleus.

The human insulin gene can be inserted into a plasmid using recombinant DNA technology. First, the insulin gene is isolated using restriction enzymes, which cut DNA at specific sequences. The plasmid is also cut open with the same enzymes to create complementary ends. Then, the insulin gene is ligated into the plasmid using ligase enzymes, creating a recombinant plasmid that can be introduced into bacterial cells through transformation.