B1H Edexcel PiXL Mark Scheme November 2014 Question 1 (a) 1 (b) 1 (c) 1 (d) (i) 1 (d) (ii) 1 (e) 2 (a) (i) 2 (a) (ii) 2 (b) 2 (c) Answer B alleles (1) Variation caused by genes (1) (inherited) from parents (1) 23 (1) T t t Tt tt t Tt tt 3 (b) 3 (c) 1 mark for parents 1 mark for offspring Parents can be either way round If more than one 50% or ½ or 1 in 2 or 2 in 4 or 2:2 or 1:1 (1) probability is given and any are incorrect, the mark is negated Accept correct alternative Breathing difficulties (1) and weight loss (1) and higher level responses (Total for Question 1 = 9 marks) A chemical (1) that changes the way the body works (1) C addicted (1) Score 0 marks if more than one box is crossed Alcohol is a depressant (1) so slows down the activity of neurones in the brain (1) Short-term effects, any 2 from: Maximum of 2 marks for short-term effects Reduces negative feelings/makes you feel happier Ignore references to Lower inhibitions/take greater risks reaction time as this is Blurred vision Affect co-ordination/difficult to do simple mental or mentioned in the stem of the question physical tasks Vomiting Unconsciousness (2) Maximum of 2 marks for Long-term effects, any 2 from: long-term effects 3 (a) Additional Guidance Score 0 marks if more than one box is crossed Liver cirrhosis Affecting learning/memory in the brain Blood clot in the brain Addictive (2) (Total for Question 2 = 9 marks) Score 0 marks if more A tears (1) than one box is crossed Chemical substances (1) that kill microorganisms outside the body (1) Antibiotics can only kill/stop the growth of bacteria (1) 3 (d) Any 4 from: Some bacteria are more resistant to antibiotics than others Susceptible bacteria are killed by the antibiotic The more resistant bacteria are still there/continue to cause infection if the patient stops taking the antibiotics These resistant bacteria reproduce and spread to other patients This causes an infection that cannot be treated now with that specific antibiotic (4) 3 (e) 4 (a) (i) 4 (a) (ii) Wash hands/use alcohol gel (1) (Total for Question 3 = 9 marks) 0.6 on its own = 2 marks 104 2.4 x 4 x 106 x 100 (1) 0.6 (1) Any 2 from: Accept correct alternative or higher level responses reflected not absorbed or misses chloroplasts / chlorophyll photosynthesis inefficient some lost through respiration / as heat (from respiration) (2) 4 (a) (iii) Any 2 from: Ignore just ‘cell walls’ Cellulose cell walls Multicellular Autotrophic Complex cell structure Has a nucleus (2) 4 (b) Energy lost via faeces / not digested / waste / excreted (of insect-eating birds) (1) Energy loss via respiration / movement / muscle contraction / heat (by insect-eating bird) (1) Some of (insect eating) bird not eaten but all / most / more of insect is eaten (1) (Total for Question 4 = 9 marks) 5 (a) Any 2 from: Chemical messengers Released by (endocrine glands) That travel in the blood (2) *5 (b) Indicative content: Mark the answer according to the levels below. Identify the level first of all, then award the top of the mark band if the student’s literacy is generally good or the bottom if there are many literacy errors. Lowering blood glucose Insulin is released From the pancreas Glucose is converted into glycogen In the liver Blood glucose levels fall Accept higher level answers and a well annotated diagram covering the level description. Rising blood glucose Level 0 1 Glucagon is released From the pancreas Glycogen is converted into glucose In the liver Blood glucose levels rise Level Description No relevant answer. A simple explanation of how hormones raise or lower blood glucose levels Marks 0 1-2 or 2 Mention that insulin decreases and glucagon increases blood glucose levels. A simple explanation of how hormones raise and lower blood glucose levels 3-4 or 5 (c) (i) A detailed explanation of how hormones raise or lower blood glucose levels. A detailed explanation of how hormones raise and lower blood glucose levels. Correct scientific terminology is used and the candidate’s answer flows well in a clear logical order. 86.7 / (1.72) (1) 5 (c) (ii) 30 (1) Any 1 from: 3 5-6 30 on its own = 2 marks Accept correct alternative wording, such as ‘eating too much saturated fat’ Lack of exercise High-fat diets Ageing Genetics (1) 5 (d) 6 (a) 6 (b) 6 (c) 6 (d) D homeostasis (1) Score 0 marks if more than one box is crossed (Total for Question 5 = 12 marks) Score 0 marks if more B auxin (1) than one box is crossed Score 0 marks if more D positive gravitotropism (1) than one box is crossed Auxins cause cell elongation (1). Auxins move to shaded side of the shoot (1) when light is coming from one direction (1). Cells on the shaded side elongate more (1). Indicative content: Mark the answer according to the levels Selective weedkillers below. Identify the level first of all, then award the top of the mark band if the Use artificial auxin student’s literacy is It only makes plants with broad leaves generally good or the These grow out of control and die bottom if there are many Farmers can kill all the weeds in a field of e.g. literacy errors. wheat without affecting their crop Making seedless fruit Accept higher level answers. Some seedless fruits are made using plant hormones The flowers are sprayed with plant hormones causing fruits to develop only (not the seeds) Naturally seedless fruits are sprayed with gibberellins to make them bigger Fruit ripening Level 0 1 2 Plant hormones can be sprayed onto fruit trees to increase their speed of ripening and make them all ripe at the same time Plant hormones can be sprayed onto fruit trees to stop fruit falling off and allow them to increase in size Plant hormones can be sprayed onto unripe fruit to make them ripe just in time for purchase Level Description No relevant answer. A simple explanation of one of: selective weedkillers, making seedless fruit and fruit ripening as plant hormone uses. A simple explanation of two of: selective weedkillers, making seedless fruit and fruit ripening as plant hormone uses. or A detailed explanation of one of: selective weedkillers, making seedless fruit and fruit ripening as plant hormone uses. Marks 0 1-2 3-4 3 A detailed explanation of selective weedkillers, making 5-6 seedless fruit and fruit ripening as plant hormone uses. Correct scientific terminology is used and the candidate’s answer flows well in a clear logical order. (Total for Question 6 = 12 marks) TOTAL FOR PAPER = 60 MARKS