AQA AS Level Biology Paper 1 June 2018 Exam: Practice Questions and Answers, Exams of Advanced Education

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AQA AS LEVEL BIOLOGY PAPER 1 JUNE

2018 EXAM

Name the blood vessels that carry blood to the heart muscle. [1 mark] - - coronary arteries What is a monomer? (1 mark) - -the smaller/ repeating unit from which larger molecules/polymers are made Following digestion and absorption of food, the undigested remains are processed to form faces in the parts of the intestine below the ileum. The faeces of people with constipation are dry and hard. constipation can be treated by drinking lactulose. Lactulose is soluble, but not digested or absorbed in the human intestine. Use your knowledge of water potential to suggest why lactulose can be used to help people suffering from constipation. (2 marks) - -(lactulose) lowers water potential in the faeces water enters due to osmosis and softens the faeces Give two features of DNA and explain how each one is important in the semi- conservative replication of DNA. (2 marks) - -Weak / easily broken hydrogen bonds between bases allow two strands to separate / unzip; Two strands, so both can act as templates; Complementary base pairing allows accurate replication;

What is meant by a hierarchy? [2 marks] - -smaller groups within larger groups and no overlap Use Figure 6 D. erecta and D. willistoni are closely related species but different species. Describe evidence from Figure 6 that supports this statement. - -both sine song is very similar but pulse song have different peaks When two females were together, their songs did not lead to any attempt to mate. Use information from Figure 6 to suggest why the two females did not attempt to mate. Use information from Figure 6 to suggest why the two females did not attempt to mate. [2 marks] - -3 peaks in pulse song occur at the same time since both are female so normal male song to stimulate/ cause mating What is the proteome of a cell? [1 mark] - -the full range of different proteins that a cell is able to produce Give two structural differences between a molecule of messenger RNA (mRNA) and a molecule of transfer RNA (tRNA) [2 marks] - -1. mRNA does not have hydrogen bonds / base pairing, tRNA does; OR

mRNA is linear / straight chain, tRNA is cloverleaf;

2. mRNA does not have an amino acid binding site, tRNA does;
3. mRNA has more nucleotides;
4. (Different) mRNAs have different lengths, all tRNAs are similar / same length;
5. mRNA has codons, tRNA has an anticodon; Starting with mRNA in cytoplasm, describe how translation leads to the production of a polypeptide. Do not include descriptions of transition and splicing in your answer. [5 marks] - -1. mRNA associates with a ribosome / ribosome attaches to mRNA;
6. Ribosome moves to / finds the start codon / AUG;
7. tRNA brings / carries (appropriate / specific) amino acid;
8. Anticodon (on tRNA complementary) to codon (on mRNA);
9. Ribosome moves along to next codon; OR Ribosome 'fits' around two codons / can fit two tRNAs;
10. (Process repeated and) amino acids join by peptide bonds / condensation reaction (to form polypeptide);

OR

(Process repeated and) amino acids joined using (energy from) ATP (to form polypeptide); State and explain the property of water that can help to buffer changes in temperature. [2 marks] - -1. (water has a relatively) high (specific) heat capacity;

2. Can gain / lose a lot of heat / energy without changing temperature; OR Takes a lot of heat / energy to change temperature; Describe the pathway taken by an oxygen molecule from an alveolus to the blood [2 marks] - -across alveolar epithelium and across capillary endothelium Explain one feature of an alveolus allows efficient gas exchange to occur. [ mark] - -(the alveolar epithelium is) one cell thick creating a short diffusion pathway The Crohn's disease symptoms of swelling of the lining of the intestines could be triggered by pathogenic bacteria in the intestines. suggest how. [3 marks] - -
3. (Presence of) antigen of the (pathogenic) bacteria;
4. (Causes) more T cells produced / faster T cell production;
5. Against (the pathogen and) normal bacteria;
6. (Long lasting as) cells do not die / live for longer;
7. (More) cytokines / chemicals causing swelling are produced;

Suggest the meaning of 'a genetic tendency to Crohn's disease' [2 mark] - - (some people) have a mutation that increases the chances of having a large T cell response Suggest why 5-ASA is only effective in controlling the swelling of the lining of the intestine in some people with Crohn's disease. [2 marks] - - Suggest why 6-MP can be used to control the symptoms of Crohn's disease. Do not include details of enzyme inhibition or protein synthesis in your answer. [ marks] - -