Natural selection and genetic modification Revision Notes

Development of Stone Tools Over Time

Early stone tools, such as Oldowan choppers (around 2.6 million years ago), were simple, made by striking one stone against another to create a sharp edge. Over time, tools became more sophisticated. Acheulean hand axes (around 1.7 million years ago) demonstrated bifacial flaking and greater symmetry, indicating more complex planning. Later tools, like Mousterian tools (around 300,000 years ago) used by Neanderthals, involved prepared core techniques, allowing for the creation of more varied flake tools. Upper Palaeolithic tools (around 40,000 years ago) included blades, scrapers, and points, some hafted onto handles, showing advanced craftsmanship and specialisation.

Dating Stone Tools from Their Environment

The age of stone tools is determined by dating the geological layers (strata) in which they are found. Relative dating methods involve observing the position of tools within stratified layers; tools found in deeper layers are generally older than those in shallower layers. Absolute dating methods provide numerical ages. Radiometric dating, such as potassium-argon dating, measures the decay of radioactive isotopes in volcanic rocks associated with the layers. Carbon-14 dating can be used for organic materials alongside tools, though its range is limited to approximately 50,000 years. Palaeomagnetism, which records changes in Earth's magnetic field over time, can also help date sedimentary layers. These methods collectively establish a chronological framework for tool development.

What Culture Dish Is Used For

Culture Dish is practical apparatus for handling cultures during microbiology practical work. In GCSE or introductory practical science, the annotated diagram helps connect the apparatus to the method, measurement, or observation being tested.

How To Use It In An Exam Answer

Use the marker labels to name the apparatus first, then say why it is suitable. A strong answer links culture dish to handling cultures during microbiology practical work, rather than only saying that it is used in a lab.

Syllabus Link

Primary private mapping: EDEXCEL GCSE combined-science 1SC0, Natural selection and genetic modification.

Common Trap

Do not describe apparatus by appearance only. Marks usually come from explaining its function in the practical method.

What Culture Dish Bottom Is Used For

Culture Dish Bottom is practical apparatus for handling cultures during microbiology practical work. In GCSE or introductory practical science, the annotated diagram helps connect the apparatus to the method, measurement, or observation being tested.

How To Use It In An Exam Answer

Use the marker labels to name the apparatus first, then say why it is suitable. A strong answer links culture dish bottom to handling cultures during microbiology practical work, rather than only saying that it is used in a lab.

Syllabus Link

Primary private mapping: EDEXCEL GCSE combined-science 1SC0, Natural selection and genetic modification.

Common Trap

Do not describe apparatus by appearance only. Marks usually come from explaining its function in the practical method.

What Culture Dish Lid Is Used For

Culture Dish Lid is practical apparatus for handling cultures during microbiology practical work. In GCSE or introductory practical science, the annotated diagram helps connect the apparatus to the method, measurement, or observation being tested.

How To Use It In An Exam Answer

Use the marker labels to name the apparatus first, then say why it is suitable. A strong answer links culture dish lid to handling cultures during microbiology practical work, rather than only saying that it is used in a lab.

Syllabus Link

Primary private mapping: EDEXCEL GCSE combined-science 1SC0, Natural selection and genetic modification.

Common Trap

Do not describe apparatus by appearance only. Marks usually come from explaining its function in the practical method.