• Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

GCSE: Variation and Inheritance

Browse by
4 star+ (21)
3 star+ (27)
Word count:
fewer than 1000 (55)
1000-1999 (54)
2000-2999 (14)
3000+ (8)
Submitted within:
last 6 months (1)
last 12 months (3)

Meet our team of inspirational teachers

find out about the team

Get help from 80+ teachers and hundreds of thousands of student written documents

  • Marked by Teachers essays 12
  • Peer Reviewed essays 17
  1. 1
  2. 2
  3. 3
  4. 4
  5. 5
  1. Marked by a teacher

    Embryo Screening. The embryo screening, also referred as PGD (preimplantation genetic diagnosis), is a procedure tested on an embryo to identify any unwanted diseases that is found in the genes of the embryo.

    5 star(s)

    "PGD involves extracting a single cell from an eight-cell embryo, created via in vitro fertilization, and analyzing the DNA of that single cell for the presence of one or more disease-associated genetic alterations." [6] Then the embryos that are free from diseases are put inside the uterus of the mother which then grows into a fetus. Preimplantation genetic engineering allows couples to have a chance to fix an innocent child's life, enabling them to live a healthy lifestyle. It allows couples at jeopardy of transmitting a genetic disease leave their future generations unaffected.

    • Word count: 1722
  2. Marked by a teacher

    Biology Case Study

    4 star(s)

    Little do you know about where the drug comes from and how the doctors know it's safe to use. The drugs go through 2 stages before being licensed and deemed safe to use. The first phase is in a lab. And the second is on an actual human being. A drug trial is the development and testing of a new medicine. Laboratory Tests The disease needs to be studied and must be understood on how it makes people ill. This helps to understand what would be needed to treat it. Example in cancer there is a fault in the cells, so to treat cancer you would destroy the faulty cells.

    • Word count: 1976
  3. Marked by a teacher

    Evolution, what, and any evidence is there?

    4 star(s)

    Discoveries of early geneticists were difficult to reconcile with gradual evolution and the mechanism of natural selection. The synthesis reconciled the two schools of thought, while providing evidence that studies of populations in the field were crucial to evolutionary theory. It drew together ideas from several branches of biology that had become separated, particularly genetics, cytology, systematics, botany, morphology, ecology and paleontology. Summary of the modern synthesis The modern synthesis bridged the gap between experimental geneticists and naturalists, and between both and paleontologists.

    • Word count: 5177
  4. Marked by a teacher

    Gregor Mendel

    4 star(s)

    It was at the monastery where he was introduced to a diverse and intellectual community. However, in 1850, Mendel failed an exam introduced through new legislation for teacher certification and was sent to the University of Vienna for two years to benefit from a new program of scientific instruction. Mendel devoted his time at Vienna to physics and mathematics, working under Austrian physicist Christian Doppler and mathematical physicist Andreas von Ettinghausen. He also studied the anatomy and physiology of plants and the use of the microscope under botanist Franz Unger, an enthusiast for the cell theory and a supporter of the developmentalist (pre-Darwinian)

    • Word count: 726
  5. Marked by a teacher

    Antibiotic Resistant Bacteria

    4 star(s)

    Some organisms are resistant to all antibiotics and can be only treated with experimental or potentially toxic drugs. There is an alarming increase in the amount of resistant bacteria's, especially in the staphylococci and pneumococci (Streptococcus pneumoniae), which are common causes of disease and death. What happened before antibiotics where invented? And who invented them? Before antibiotics were invented there use to be no cure for many diseases and many people died because of this reason. It was not until 1940 when the first safe and used antibiotic was invented called "Penicillin" Alexander flaming was the one who invented it.

    • Word count: 882
  6. Marked by a teacher


    4 star(s)

    Mutation is the only variation that occurs in asexual reproduction, unless mutation occurs all the members of clones share the same genetic constitution. s****l reproduction involves the fusion of gametes, this is known as fertilisation. The genetic material from two different individuals is mixed and combined to produce an individual that is genetically different from either parent. All individuals, unless they are identical twins are genetically unique, this process produces variation within the population. Many organisms that carry out asexual reproduction also carry out s****l reproduction at some stage in their lifecycle, hardly any animal species use it as their only means of reproduction.

    • Word count: 1224
  7. Marked by a teacher

    Evaluating the risks and benefits of GM crops.

    4 star(s)

    Under the new law, all foods with more than 0.9% genetically modified content will have to be labelled. This aspect of the labelling has also angered consumer groups who say that consumer can't express their free will to avoid GM products, as those with less than 0.9% are classified as non-GM. Though essentially carried out for the same purposes, to remove or improve particular characteristics of crops, conventional plant breeding and genetic engineering differ greatly. There are many conventional plant-breeding methods used. Crossing involves the removal of male pollen from one superior plant to the stigma of another superior plant, in the hope that the offspring from this process will possess the preferred characteristics of both its parents.

    • Word count: 2041
  8. Marked by a teacher

    The role of DNA in protein synthesis

    4 star(s)

    > a phosphate group (H3PO4) > an organic nitogenous base - adenine, guanine, thymine or cytosine -the organic base present in nucleotides are either pyrimidines, which have a single-ring structure, or purines with a double ring structure. Pyrimidines - single rings each with six sides. e.g. cytosine (C) and thymine (T) purines - double rings comprising of a six-sided and five-sided ring. e.g. adenine (A) and guanine (G) Condensation reactions join the nucleotides together, the reaction between the nucleoside and phosphoric acid. A phosphodiester bridge is formed between the 3 carbon atom of one pentose sugar and 5 carbon atom of another sugar.

    • Word count: 699
  9. Marked by a teacher

    Research in Genetic Engineering Should Be Halted. Discuss

    3 star(s)

    In order to fully understand this issue, it is important to look at both views in this controversy. One must believe that those who do not know their opponent's arguments do not completely understand their own. When the opinion of others is known one can then become a more "intelligent and discriminating consumer of information in our media-centered culture" (Dudley 9). What are the benefits of genetic engineering? For one thing, chronic and fatal diseases can be avoided before they strike. Many lives, as well as medical dollars, could be saved if doctors could identify individuals that have a likelihood of developing heart disease, cancer, and other fatal diseases.

    • Word count: 2923
  10. Marked by a teacher

    Biology - Cloning. In this case study I shall explain the divisive subject of cloning, I shall endeavour to give an insight into the many factors of cloning, a detailed explanation to what it is and why we do it. I will include what the experts and the pu

    3 star(s)

    His experiments involved sea urchins because they have large embryo cells and grow independently. And then in 1951, scientists cloned a frog egg from the research and experiments from the 1800's. They cloned the frog egg cell using modern methods of nuclear transfer. And then finally, the most famous mammal cloned, Dolly the Sheep, cloned in 1996 from the unknown adult ewe that died before dolly had been fully grown. Natural genetic reproduction is the genetic information that's carried in chromosomes from both parents; it is then combined to form a fertilized egg. As soon as the chromosomes of a male and a female combine, the cells start to divide and create an individual.

    • Word count: 1812
  11. Marked by a teacher

    Cloning. Should it be banned? I will explain all the different types of cloning and I will be researching the scientists evidence behind each method and evaluating whether or not it is reliable

    the female body, this then turns into a clonal zygote and then into a clonal embryo, this then produces a clonal baby Types of Asexual reproduction There are 8 types of asexual reproduction; Binary fission, Budding, Vegetative reproduction, Spore formation, Fragmentation, Parthenogenesis, Agamogenesis, and Apomixis and nucellar embryony. One of the main types of asexual reproduction is Binary fission - Binary fission begins with DNA replication. DNA replication starts from an origin of replication, which opens up into a replication bubble.

    • Word count: 3672
  12. Peer reviewed

    Why is s****l reproduction so common in nature?

    5 star(s)

    Asexual spores and meiosis-bypassing apomixis appears much more efficient. Thirdly, s****l species can not perpetuate what are often fitness-improving types (eg: triploids, aneuploids). Finally, the actual physical contact between organisms/gametes entails risks separate from those that are maintained by s****l competition. One of the primary costs of initial contact is the risk of disease or parasite transmission. Another significant cost associated with fertilisation is the eminent wastage of gametes, or more appropriately in some cases, a waste of effort transmitting gametes. Given all of these costs, we would expect natural selection to favour asexual reproduction in wild populations, however, it generally does not: s****l reproduction is widespread throughout the animal and plant kingdoms.

    • Word count: 1962
  13. Peer reviewed

    Cloning pros and cons

    5 star(s)

    It raises the possibility of breeding many identical copies of animals including transgenic animals, showing desirable features. One of the ethical concerns is that the techniques could be applied to humans, although such work is currently banned. (1) The cloning of sheep at Roslin Institute near Edinburgh was thus a highly significant biological departure, and one of the most momentous scientific events of the 1990s. In 1995, Ian Wilmut, Keith Campbell, and their colleagues cloned Megan and Morag from cultured embryo cells; and in July 1996, Dolly, produced from cultured adult cells, was born.

    • Word count: 1073
  14. Peer reviewed

    Genetically modified crops - Do we know all the answers?

    5 star(s)

    This is because genetic modification is more specific in changing a particular gene, rather than cross-pollinating, as this changes another 30,000 - 40,000 random genes, creating an entire new variation. Under his hypothesis, GM technology is much safer, economically, and environmentally, he believes the ease of changing and modifying just one gene in a genetic sequence is far less complicated and bordering on the unknown than traditional methods. The insertion of Vitamin A into the genetic structure of rice has meant that 2-4 billion people across the third world have had their chances of becoming blind reduced many times over4, this is just one example of where GM technology has been beneficial to consumers.

    • Word count: 1087
  15. Peer reviewed

    Ganetics, Inheritance and Cells.

    4 star(s)

    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) As the embryo develops some of the genes within a cell are switched off and the cell can no longer turn into other types of cell (It has become specialised or is differentiated)

    • Word count: 1169
  16. Peer reviewed

    Cloning means making a living thing from another living thing such as a plant or animal. The process uses the genes of the first so they both have identical DNA.

    4 star(s)

    And identical twins are naturally-occurring clones of each other even though they're genetically different from their parents. In the last few decades scientists have been trying to clone animals. They transplant DNA (the gene pattern which makes living things unique) from the cell of one animal into the cell of another which has had its DNA taken out. Now scientists in America have announced that they have created a clone of a human embryo. In 1997 Dolly the sheep became the first ever cloned mammal.

    • Word count: 475
  17. Peer reviewed

    Asexual reproduction and cloning

    4 star(s)

    Artificial cloning Artificial cloning of animals is now commonplace in laboratories. The most famous example of animal cloning is Dolly the Sheep, born in the UK in 1996 using a technique called embryo transplanting. Here's how it was done: 1. An egg cell was removed from the ovary of an adult female sheep, and the nucleus removed. 2. Using micro-surgical techniques, the empty egg cell was fused with DNA extracted from an udder cell of a donor sheep 3. The fused cell now began to develop normally, using the donated DNA.

    • Word count: 543
  18. Peer reviewed

    Cellular Reproduction

    4 star(s)

    Interphase is broken up into three phases, G1, S, and G2. During the G1 phase, the cell increases in mass except for the chromosomes, which stay the same, uncoiled. Protein synthesis is also occurring rapidly in this phase. If a cell doesn't divide further, it remains permanently in the G1 phase. Next is the S phase, in which the mass of the cell continues to increase, and DNA is duplicated, and then the chromosomes divide to form identical sister chromatids attached by a centromere. (Harold, 45). During the G2 phase of Interphase, the cell becomes double its mass at birth, the chromosomes begin to shorten and coil, and the centrioles appear, the cell is now ready to enter into mitosis.

    • Word count: 2664
  19. Peer reviewed

    The structure of nucleic acid chains (or DNA).

    4 star(s)

    This "counting system" allows the strand of nucleic acid to be oriented: the 5' end of the molecule always ends with a phosphate and the 3' end of the strand always ends with a sugar. You may be wondering why we don't just call the 5' end the "top" of the DNA or RNA molecule and the 3' end the "bottom" of the molecule. But in order to name something the "top", we're assuming that that end of the molecule is "up".

    • Word count: 1190
  20. Peer reviewed

    Is Cloning Ethical?

    4 star(s)

    Biomedical Cloning, better known as Therapeutic cloning is the third process. In the beginning this process is identical to Reproductive Cloning, but the stem cells are removed from the pre-embryo in order to produce tissue or an organ to transplant back into the patient whose DNA was used. This procedure is used for the purpose of producing a healthy replica of an organ for transplant back into the person. Many people are in favour of this as it would mean no waiting lists for organ transplants, no risk of a new organ being rejected and it would have the patients original DNA (2).

    • Word count: 1487
  21. Peer reviewed

    Debate on Genetically Modified Food.

    4 star(s)

    For example, GM Soya has been modified using genes that will make it resistant to certain herbicides, such as 'roundup'. Although this may seem like a good thing on the surface, what happens when the pollen from these GM foods is passed on to native species? Aspects like this seem to have been overlooked. It is also a worry, because genetic engineering can be very unpredictable and the damaging effects of GM foods irreversible; if left unconfined it could get out of control.

    • Word count: 690
  22. Peer reviewed

    Agricultural Issues: Genetic Modification.

    4 star(s)

    Throughout the world there are drastic inequalities in food supply with the emergence of areas of surplus and famine. The cause of such inequalities vary from physical to human and political. Most of the responses to these problems have been driven by high income, high technology MEDC's or trans-national companies. The impacts of the Green Revolution, intensification of farming and the development of genetically-modified foods have varied. Some are economic while others have been social or environmental: some have brought benefits, while others have created problems and some may be focused upon the environment e.g., organic farming.

    • Word count: 430
  23. Peer reviewed

    The potential benefits and risks of genetically modifying food.

    4 star(s)

    Of course, not everyone fits into a single one of these categories, for example many people are on the fence about the issue, there are people who just don't care about the issue, and there are those who cross between the groups. There are some genuine Health risks that could arise from extensive genetic modification of foods, these risks include; New toxins and allergens in foods, Other damaging effects on health caused by unnatural foods, The creation of herbicide-resistant weeds, The spread of diseases across species barriers, Loss of bio-diversity in crops, The disturbance of ecological balance, Artificially induced characteristics and inevitable side-effects will be passed on to all subsequent generations and to other related organisms.

    • Word count: 880
  24. Peer reviewed

    Natural variation

    3 star(s)

    I also think that the length of their foot will depend on their inherited genes. Probably the older they are the larger their foot. 2 Materials and methods Equipment used: A4 blank paper- to measure the foot Tape measure- to measure heights of the children (to see if there is a correlation between height and foot size) Ruler- to measure the foot size marked by the paper (for precision) Questionnaire- I used figure 1 as my basis for the report to look for genetic or environmental influences. * I went to my local community centre and I asked if I could use six year old children, for an investigation.

    • Word count: 1682
  25. Peer reviewed

    Effects of Genetic Engineering

    3 star(s)

    Each of these views is correct in certain ways. Genetic engineering could be used to enhance people's lives, but it could also be used to harm people's lives. Discussion Genetic modification is a significant issue that involves the whole community because of the mass amount of genetically enhanced foods being produced and consumed on a daily basis. Many buyers are unaware of the fact that if the food they are consuming does not say "organic" it means that there are at least 70% genetically modified foods inside of that product.

    • Word count: 768

Marked by a teacher

This document has been marked by one of our great teachers. You can read the full teachers notes when you download the document.

Peer reviewed

This document has been reviewed by one of our specialist student essay reviewing squad. Read the full review on the document page.

Peer reviewed

This document has been reviewed by one of our specialist student document reviewing squad. Read the full review under the document preview on this page.