Inheritance
Cells
New cells are needed for-
- Growth- as an organism grows it needs more cells
- Repair- cells become damaged due to wear and tear
- Replacement- cells wear out and die
so each cell has to be able to make copies of itself.
The instructions for doing this are contained in the chromosomes within the nucleus of each cell
Each characteristic has it’s own set of instructions called a gene
These are found in the chromosomes
In humans each cell has 46 chromosomes (23 pairs one of each pair coming from each parent)
Mitosis
Mitosis
In this process exact copies of each cell are made
This process happens all the time and is used for growth, repair and asexual reproduction in which the offspring are identical to the parent
Stages of mitosis
- The cell makes copies of all the chromosomes
- The cell then divides into 2 each having one set of chromosomes.
Skin is an example of a tissue that needs to be constantly doing this
Each cell then can only make copies of itself ie skin cells only make skin cells and muscle cells only make muscle cells
After fertilisation of an egg by a sperm there is just 1 cell and this needs to develop into a complete organism that contains many different tissues and so many types of cell
Stem cells
This is possible because the early embryo contains stem cells and these cells have the capacity to turn into any type of cell (They are unspecialised or undifferentiated)
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Peer Reviews
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Quality of writing
The report is well written, with a few minor grammatical and spelling errors. They have kept a good, formal tone throughout, as is suitable for the target audience. The report is split into sections on key topics, indicated by sub-headings. This makes it very easy to read and thus mark. They have used many relevant scientific terms, only once conflating 'molecules' with 'bases' - it is a good idea to learn definitions of difficult terms in order to avoid getting things confused. Their quality of written communication is generally very good, and the report therefore is easy to read and shows off their scientific understanding and vocabulary.
Level of analysis
They have discussed genetic inheritance in detail, and explained about dominant and recessive genes, and the probabilities of a child having a particular characteristic given their parents' genes are also described in detail. However, they have not mentioned key topic within genetic variation - for example Darwin's theory of evolution (although Mendal's theories are described briefly) and the effects of mutations (these are not always pathogenic, and cause new genes to be introduces to a population). They have also failed to take opportunities to develop their analysis further by discussing the impacts of some technology (for example the ability for parents to test their genes to discover if their child is likely to suffer from a genetic disorder) on society, and the moral conflicts surrounding them - they have only briefly mentioned the use of forensic analysis in crime investigations. They have described all the science well, for example meiosis, which shows a thorough understanding of the topic. However, they have included many diagrams within the coursework, which are clearly copied from books or the internet, but not referenced them. This is an example of plagiarism. Although in this case, it appears to be accidental, this can lead to disqualification. Diagrams can be copied from books and the internet, as long as their original source is quoted and clearly stated, but it is a good idea to do this only if you also include some of your own writing to summarise the image and thus show you understand it. Despite this, they have shown a thorough understanding of the topic and analysed data and ideas well.
Response to question
The candidate has written a detailed report on genetic inheritance and cell mitosis, and included examples of genetic inheritance of certain characteristics, and how they may be caused depending on whether their parents were homozygous of heterozygous for that particular trait, particularly focussing on generically inherited diseases. They have included good descriptions of cell division and replication, including the mitosis and meiosis processes. They have mentioned genetic inheritance in plants, as well as comparing the undifferentiated plant cells to animal cells, which are differentiated from birth. However, they have rarely referred directly back to the question - for example adding 'this increases genetic variation in species' after some sentences, which would help to pull the report together.
Quality of writing
The report is well written, with a few minor grammatical and spelling errors. They have kept a good, formal tone throughout, as is suitable for the target audience. The report is split into sections on key topics, indicated by sub-headings. This makes it very easy to read and thus mark. They have used many relevant scientific terms, only once conflating 'molecules' with 'bases' - it is a good idea to learn definitions of difficult terms in order to avoid getting things confused. Their quality of written communication is generally very good, and the report therefore is easy to read and shows off their scientific understanding and vocabulary.
Level of analysis
They have discussed genetic inheritance in detail, and explained about dominant and recessive genes, and the probabilities of a child having a particular characteristic given their parents' genes are also described in detail. However, they have not mentioned key topic within genetic variation - for example Darwin's theory of evolution (although Mendal's theories are described briefly) and the effects of mutations (these are not always pathogenic, and cause new genes to be introduces to a population). They have also failed to take opportunities to develop their analysis further by discussing the impacts of some technology (for example the ability for parents to test their genes to discover if their child is likely to suffer from a genetic disorder) on society, and the moral conflicts surrounding them - they have only briefly mentioned the use of forensic analysis in crime investigations. They have described all the science well, for example meiosis, which shows a thorough understanding of the topic. However, they have included many diagrams within the coursework, which are clearly copied from books or the internet, but not referenced them. This is an example of plagiarism. Although in this case, it appears to be accidental, this can lead to disqualification. Diagrams can be copied from books and the internet, as long as their original source is quoted and clearly stated, but it is a good idea to do this only if you also include some of your own writing to summarise the image and thus show you understand it. Despite this, they have shown a thorough understanding of the topic and analysed data and ideas well.
Response to question
The candidate has written a detailed report on genetic inheritance and cell mitosis, and included examples of genetic inheritance of certain characteristics, and how they may be caused depending on whether their parents were homozygous of heterozygous for that particular trait, particularly focussing on generically inherited diseases. They have included good descriptions of cell division and replication, including the mitosis and meiosis processes. They have mentioned genetic inheritance in plants, as well as comparing the undifferentiated plant cells to animal cells, which are differentiated from birth. However, they have rarely referred directly back to the question - for example adding 'this increases genetic variation in species' after some sentences, which would help to pull the report together.
