thebiotutor.com 5D Cloning Time: 54 minutes Total marks available: 54 Total marks achieved: Andy Todd

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1 thebiotutor.com 5D Cloning Time: 54 minutes Total marks available: 54 Total marks achieved:

2 Q1. The photograph shows a Siberian tiger. Siberian tigers are very rare and are in danger of becoming extinct. Scientists hope to use cloning as a method to increase the number of Siberian tigers. The passage below describes the process of cloning. Complete the passage by writing a suitable word on each dotted line. A nucleus is taken from a body... of an adult Siberian tiger. (6) This nucleus is put into an enucleated... cell, a cell that has had its nucleus removed. The cell is given a mild electric shock to help it divide by a type of cell division called.... A ball of cells is produced called an.... The ball of cells is placed into the... of a female Bengal tiger.

3 This female tiger is called a... mother. (Total for question = 6 marks)

4 Q2. Describe the stages in the production of cloned mammals such as Dolly the sheep. (5) (Total for question = 5 marks)

5 Q3. The diagram shows one side of an organ donor card. (a) The table lists different human illnesses. Complete the table by giving the donated organ named on the card needed to cure each illness. The first one has been done for you. (5) (b) Describe the role of the liver in digestion. (2)

6 (c) There is a shortage of people willing to donate their organs. Scientists hope to create cloned organisms to solve this problem. (i) What is a cloned organism? (ii) Suggest two advantages of using cloned organisms to provide organs rather than relying on people to donate organs. (2) (2) (Total for question = 11 marks

7 Q4. Read the passage below. Use the information in the passage and your own knowledge to answer the questions that follow.

8 (a) Explain what is meant by the term gene (line 3).

9 (b) Suggest what is meant by the term superovulate (line 2). (2) (1) (c) In which part of the surrogate mother are the embryos implanted (lines 6 to 7)? (d) Name the human behaviour that can lead to emphysema (line 11). (1) (1) (e) What percentage of eggs produced by Tracy were known to contain transgenic DNA (lines 13 to 14)? (f ) (i) To be able to work, the blood clotting factors must be extracted from the milk. Suggest why drinking milk containing blood clotting factors will not help to clot blood (line 17). (ii) Suggest why it is an advantage to increase the ability of cattle to digest cellulose (line 22). (g) Suggest the benefits of producing transgenic hearts. (1) (1) (2) (3)

10 (Total for question = 12 marks)

11 Q5. (a) Describe how micropropagation (tissue culture) can be used to produce large quantities of identical plants. (b) Explain what is meant by the term genetic modification (GM) and suggest why a farmer might want to grow a GM crop. (6) (3) (Total for question = 9 marks)

12 Q6. Read the passage below. Use the information in the passage and your own knowledge to answer the questions that follow. (a) Name one base found in DNA (line 3). (1) (b) Suggest why explants are sterilised (line 4). (2)

13 (c) Suggest why amino acids are provided in the growth medium (line 5). (d) What is meant by the term pathogen (line 10)? (1) (1) (e) Suggest two reasons why growers prefer to use micropropagation rather than sexual methods of reproduction to produce good quality flowers (lines 11 to 14). (f ) Suggest what is meant by the term sustainable energy source (lines 19 and 20). (g) The destruction of habitat can lead to extinction of species. Give three other disadvantages of deforestation. (3) (2) (1) (Total for question = 11 marks) Q1. This question tested understanding of the cloning process. Despite its apparent simplicity, the question discriminated very well. The most common error was naming meiosis as the cell division, rather than mitosis. Candidates are advised to use technical terms correctly, so only the term 'surrogate' was accepted in the final sentence.

14 Q2. This question was a good discriminator. Some excellent, very detailed answers were seen. However, weaker students were confused about the roles of the egg cells and the body cells involved. Many poor answers contained information about genetic engineering and gave hybrid answers often implying a role for restriction enzymes in transferring DNA to eggs. A surprising number of students believe that the adult nucleus is obtained from Dolly. Q3. Candidates were shown a donor card and asked, in (a), to match the illness with the organ named on the card. Most gained full marks but some confused hepatitis and diabetes and others did not name the organ on the card. In (b), most could describe the liver as producing bile and its role in emulsifying fat and neutralising stomach acid. In (c), most could describe a clone as being genetically identical and suggest two advantages of using cloned organisms to provide transplant organs. Q4. (a) The concept of a gene being a section of DNA that codes for a protein was known by the more able candidates. The idea that genes determine characteristics was also credited as an alternative to coding for a protein. Many answers simply discussed the fact that they are inherited or made loose references to chromosomes or nuclei. (b) The examiners were looking for answers that expressed the idea that superovulation would result in a greater quantity of eggs than normal. Many appreciated this and gained the mark. However, there were an abundance of answers that showed that the word 'super' was not understood and nor was the process of 'ovulation'. Poor answers simply reiterated information from the comprehension. (c) Most candidates recalled that the uterus is the place where embryos would implant in the surrogate mother, though a variety of other named female organs were named in the poorer answers. The non-technical term 'womb' was credited. (d) Most candidates were aware of the link between smoking and emphysema. Weaker answers showed no understanding of emphysema and tended to describe general aspects of human behaviour or make reference to AAT. (e) The correct answer of 50% was seen in most scripts. (f) (i) There were some very good answers that were able to make a link between what might happen in the gut of a person which would not assist

15 the clotting of blood. The passage stated that 'human proteins could be made in other mammals and extracted from their milk' so the examiners were looking for a comment that made it clear that the blood clotting factors (protein) would not be able to enter the bloodstream because they would be digested. Many candidates got close to being credited by making it clear that the blood clotting factors would not be able to get into the blood but then failed to say why. Many candidates simply repeated the wording of the question stating that blood clotting factors have to be extracted before being used, and many simply noted that blood clotting factors are needed to clot blood. (ii) Candidates described the role of cellulose as roughage to help peristalsis in the gut. This suggests that candidates should be encouraged to read questions carefully. The question required an appreciation that cellulose is made from glucose which is used in respiration and could help to increase cattle growth or milk and meat production. A surprising number of candidates seem to think that cellulose has a role in immunity. (g) Many candidates appreciated that producing transgenic hearts would increase availability for transplantation which would save lives, and also that the transgenic hearts are less likely to be rejected by the host. This question discriminated well with the better candidates making reference to at least three of these points and the weaker candidates only referring to one or none.

16 Q5. There were many excellent answers to part (a) by students who knew all the salient facts about tissue culture, notably the use of explants to culture on nutrient agar under sterile conditions, combined with the further use of plant growth regulators and the provision of sensible abiotic factors. Weaker candidates merely repeated the stem of the question and gained little credit with the rest of their answer. Most often they would confuse tissue culture with some other biological process, often selective breeding. Part (b) was more accessible with most appreciating that the process of genetic modification involved the transfer of genes using enzymes and vectors to produce plants with desirable qualities, most often named as high yielding or pest resistant. Again, weaker candidates wrote about selective breeding and lost credit as a result. They also rephrased the stem of the question and stated that the term genetic modification means that genes are modified. Candidates need to be more aware that rephrasing the stem of a question will not gain credit. Q6. This question this year explored the use of micropropagation in modern day biology. All the questions were attempted by students showing that they were able to access the content of the comprehension. Most were able to name one of the bases found in DNA though the spellings were often rather disappointing. In part (b) many appreciated that sterilising kills bacteria that otherwise might cause disease or have a detrimental effect on the growth of the explants. Most students appreciated that amino acids are fundamental in the manufacture of proteins. There were a lot of answers that gained no credit because they simply rephrased the stem of the question stating that amino acids are needed for growth. Many students know that pathogens are disease causing microorganisms, but many lost credit by being too vague. For example, stating that pathogens are organisms that cause harm or illness is not sufficient. It was pleasing to note that most were able to suggest a meaningful definition of a sustainable energy source, with most using the phrase 'never runs out'. Some students wrote about the ecological benefits of sustainable energy sources but this was not credited. Answers to part (g) were pleasing with most answers making reference to leaching, soil erosion and global warming. Many had failed to read the question carefully and wrote about the consequences of habitat destruction and extinction.

17 Q1. Q2.

18 Q3. Q4.

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20 Q5. Q6.

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