A-level BIOLOGY Paper 1

Biology Salters Nuffield Edexcel A Level: Topic 4 QUESTIONS WITH ANSWERS SOLVED. 3 phase testing of drugs on humans - CORRECT ANSWER1. healthy, small sample to test for side effects, low concentrations to measure tolerance, ill people not used because they could potentially become more ill 2. small number of patients, measuring efficacy - how well the drug works at lowest concentrations possible 3. large group of patients - efficacy and value in comparison to current '...

AQA biology a-level paper 2 actual exam questions with solved lation of DNA - CORRECT ANSWERacetyl groups added to histones, so DNA is less tightly wound round it, making it easier for RNA polymerase and transcriptional factors to bind, so transcription can occur. allopatric speciation - CORRECT ANSWERWhen populations of a species become geographically isolated. Gene flow between them ceases (reproductive isolation). the new environment will trigger a change in the gene pool due...

AQA A-level Biology paper 1 Actual Exam Questions with solved answers. A experiment is reproducible if.... - CORRECT ANSWER....the results/pattern of your data matches the data of others A vaccine can be used to produce immunity. Describe how memory cells are important in this process. (3) - CORRECT ANSWERimportant because when individual is in contact with virus again, antibodies can be produced at a faster rate in a secondary immune response, and so the pathogen can be...

What's starch made from - amylose and amylopectin amylose estruture - alpha helix 1,4 compact good for storage amylopectin structure - alpha helix 1,4 and 1,6 (slightly branched) - glucose can be released quickly Glycogen structure - alpha glucose, branched Structure of cholesterol - hydrocarbon ring structure with OH group attached to hydrocarbon tail Conjugated protein - Protein with a non-protein group attached How do enzymes work - Lower the activation energy by creating...