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, where sunlight is absorbed by chlorophyll to convert carbon dioxide and water into glucose and oxygen.

The three domain system has been suggested to reflect the genetic and biochemical diversity among living organisms, emphasizing the fundamental differences between bacteria (Archaea and Bacteria) and the more complex eukaryotic organisms.

To calculate the actual diameter of the cyanobacterium, use the magnification factor:

ext{Actual diameter} = rac{ ext{Measured diameter}}{ ext{Magnification}}

In this case, if the measured diameter is X micrometres and the magnification is 50000:

ext{Actual diameter} = rac{X}{50000}

Please substitute the measured value for X to get the actual diameter in micrometres (µm).

1. Cell wall: Bacterial cells have a rigid cell wall that provides structure and protection.
2. Nucleoid region: Bacteria do not have a defined nucleus; instead, their genetic material is located in a nucleoid region where the DNA is present in a circular form.
3. Ribosomes: Bacterial cells contain ribosomes that are essential for protein synthesis, smaller than those in eukaryotic cells.

To insert the human insulin gene into a plasmid, one generally follows these steps:

1. Isolation: The human insulin gene is isolated from human DNA using restriction enzymes that cut the DNA at specific sequences.
2. Preparation of Plasmid: The plasmid, also cut with the same restriction enzymes, creates complementary ends (sticky ends) for ligation.
3. Ligation: The insulin gene is then inserted into the plasmid using DNA ligase, which facilitates the joining of the DNA fragments. The recombinant plasmid can then be introduced into bacterial cells via transformation.