Microsoft word - life sciences paper 1 memorandum _web_.doc

LIFE SCIENCES PAPER MEMORANDUM 1
Tissues, cells & molecular studies and Life Systems

SECTION A: QUESTION 1

1.1.1 C
1.1.2 D√√ 1.1.3 A√√ 1.1.4 A√√ 1.1.5 C√√ 1.2.4 bivalent or homologous chromosomes √ 1.2.5 amniocentesis 1.3.3 B√ 1.3.4 A√ 1.3.5 D√ 1.4.1 C,E, D, B, F, A √ mark each 1.4.2 crossing over increases variation√ in the gametes or offspring√ 1.4.4 In anaphase I chromosomes are double stranded√. The chromosomes shown moving to the poles in √ and nitrogenous wastes e.g. urea √ 1.5.3 The branched arrangement gives a large surface area. √√ The barrier between the foetal blood and
the placenta is very thin for diffusion.√√ (4) (7)
√ by looking to see the time period between maximum LH (or oestrogen) levels √ 1.6.2 A high level of LH causes ovulation√. After ovulation the corpus luteum forms and it begins secreting 1.6.3 If cows are in calf, they continue producing milk: allowing the farmer to make money OR If the
farmer is a beef farmer, he/she may want to increase the herd size to make more money √ it is possible that the hormone can cross the placenta √ and have unwanted effects on the foetus √ OR Yes √ it may cause women to produce more milk than usual during lactation √ and their baby
would grow well √ Or any suitable argument
TOTAL SECTION A: 50

SECTION B: QUESTION 2

2.1.1 A – pentose sugar
B-phosphate group
C-nitrogenous base √
D- hydrogen bond
2.1.2 A nucleotide is made up of a nitrogenous base attached to 1 pentose√, ribose sugar√ bonded to a 2.1.3 Table outlining the differences between DNA and RNA DNA RNA
the sugar is deoxyribose
molecule consists of a double strand of nucleotides allowing RNA with its single strand it to unzip HAS thymine Any 3 differences 3 x 2 = 6 marks Draw table with rows and columns = 1 mark phenotype: haemophiliac male x normal female carrier √√√ 50% chance of third son being haemophiliac √ TOTAL QUESTION 2 = 30
QUESTION 3
3.1.1 Process N is transcription √.
DNA molecule unwinds and hydrogen bonds break, under the control of RNA polymerase √. As the DNA strands separate, bases of free RNA nucleotides line up opposite exposed complementary bases on the coding strand √; temporary hydrogen bonds form between bases √. Adjacent RNA nucleotides join together to form a strand of mRNA √. Hydrogen bonds between complementary bases break √and the mRNA strand is free to leave the nucleus. Max 4 for this part. 3.1.3 P is the organelle at which the mRNA “docks” to have the codons read √. Each tRNA √one brings its appropriate amino acid from the amino acid pool √ to the mRNA where the anticodon of a tRNA lines up with the codon on mRNA √ to get the appropriate order of amino acids √ Parents may have the choice whether to abort the foetus or not OR counselling may give the parents the coping skills to manage the affected child. They cane only be seen with a microscope √ (1) It ensures that genetic material is exchanged√ resulting in variation√. (2) Chromosome drawn √ Chromosome has shaded and unshaded part in the correct proportion√

3.4.1 The older the woman √the less viable her eggs are because her hormone levels have dropped√ (2)
3.4.2 IVF should not be given to all couples who request it as the older the woman the less chances she
has of having a successful pregnancy√ the data shows that the most successful women only have 28% success rate√ Argument must reflect the data for max marks data must be given TOTAL QUESTION 3 = 30
QUESTION 4

4.1.1 15% √
4.1.2 The percentage of men with low sperm counts has increased√ from 1951 to 2000 compared to the percentage of men with high sperm counts has decreased √ from 1951 to 2000. 4.1.3 The reason for the decline could be related to levels of pollution√ in the water or possibly diet Graph illustrating the comparision between
percentage of men with high sperm counts and
low sperm counts between 1951 to 2000
Time period (years)
(11) (16)
4.2.1 Flow diagram to show how genetic engineers transfer genes 2 and 3 into Agrobacterium tumefaciens√ √ vertical + fits on one page√ + 6 content Gene 2 is cut out from a daffodil Gene 3 is cut from Erwinia (using enzymes as chemical scissors)√ (using enzymes as chemical scissors)√ Both genes are inserted√ into small loops of DNA/plasmids in Agrobacterium tumefaciens√ The rice embryo is infected with the bacterium√ In the process the genes for making beta-carotene√ are transferred into the white rice cells√ This produces yellow kernels rich in beta carotene √ 4.2.2 The 4 strategies must be clear strategies and be well worded e.g.  Subsidise the price of yellow rice seeds.  Educate farmers.  Run workshops at clinics and schools.  Offer financial incentives for processing the rice.  Any other logical answer that meets the criteria of the question The four descriptions must match the strategies and give sufficient information to make sense of
how the strategy would be implemented.
 Subsidise the price of yellow rice seeds so that they are affordable to rural farmers and selected
in preference to the cheaper white rice seeds.  Educate farmers about the value of yellow miracle rice over white rice as it would save them money having healthy families/bring them greater income as the demand for this type of rice would increase.  Run workshops at clinics and schools to encourage women and children to opt for yellow miracle rice over white rice. Show the huge health benefits. They are the main purchase market and need to understand the benefits.  Offer financial incentives such as free fertilizer or milling facilities for farmers who grow surplus yellow miracle rice. The farmers would want to switch the yellow miracle rice for this reason as well as the health reasons.  Any other logical answer that meets the criteria of the question. Four arguments against the project. The answers must be clearly stated and relate to the
information provided:
 Government funding is limited and cannot be used to subsidise yellow rice seed due to costs of
 People are bound by traditional ways and see this “new” rice as foreign…a preference for yellow rice over rides the education process.  The concern that there may be long term side affects that might impact health/environment of  The fact that seeds have to be obtained/bought each year means that there is a cost involved that diminishes profit. This is not the case when growing white rice.  Any other logical argument against the project. TOTAL QUESTION 4: 40
TOTAL: 150

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