AQA GCSE COMBINED SCIENCE: TRILOGY 8464/B/2H Biology Paper 2H Version: 1.0 Final *JUN238464B2H01* IB/M/Jun23/E7 8464/B/2H QUESTION PAPER & MARKING SCHEME/ [MERGED] Marl( scheme June 2023

GCSE COMBINED SCIENCE: TRILOGY 8464/B/2H Biology Paper 2H Version: 1.0 Final *JUN238464B2H01* IB/M/Jun23/E7 8464/B/2H For Examiner’s Use Question Mark 1 2 3 4 5 6 TOTAL Friday 9 June 2023 Afternoon Time allowed: 1 hour 15 minutes Materials For this paper you must have: • a ruler • a scientific calculator. Instructions • Use black ink or black ball-point pen. • Pencil should only be used for drawing. • Fill in the boxes at the top of this page. • Answer all questions in the spaces provided. • If you need extra space for your answer(s), use the lined pages at the end of this book. Write the question number against your answer(s). • Do all rough work in this book. Cross through any work you do not want to be marked. • In all calculations, show clearly how you work out your answer. Information • The maximum mark for this paper is 70. • The marks for questions are shown in brackets. • You are expected to use a calculator where appropriate. • You are reminded of the need for good English and clear presentation in your answers. Please write clearly in block capitals. Centre number Candidate number Surname Forename(s) Candidate signature I declare this is my own work. GCSE COMBINED SCIENCE: TRILOGY Higher Tier Biology Paper 2H H 2 *02* IB/M/Jun23/8464/B/2H There are no questions printed on this page DO NOT WRITE ON THIS PAGE ANSWER IN THE SPACES PROVIDED Do not write outside the box 3 *03* Turn over ► IB/M/Jun23/8464/B/2H Do not write outside the 0 1 Sexual reproduction in humans involves the production of egg cells and sperm cells. box 0 1 . 1 Name the type of cell division that produces egg cells and sperm cells. [1 mark] 0 1 . 2 Sexual reproduction produces offspring that are genetically different from each other. Give two reasons why sexual reproduction causes variation in the offspring. [2 marks] 1 2 Question 1 continues on the next page 4 *04* IB/M/Jun23/8464/B/2H Do not write outside the Polydactyly is an inherited disorder. box The allele for polydactyly is dominant, D. A person with two copies of the allele d will not have polydactyly. 0 1 . 3 A person with the genotype DD is homozygous. What word describes the genotype Dd? [1 mark] 0 1 . 4 A person with the genotype Dd and a person with the genotype dd plan to have a child. Determine the probability that the child will have polydactyly. You should: • complete the Punnett square diagram • identify any offspring genotype that would have polydactyly. [5 marks] Probability that the child will have polydactyly = 5 *05* Turn over ► IB/M/Jun23/8464/B/2H Do not write outside the box 11 0 1 . 5 Embryos can be screened for the alleles that cause inherited disorders. Give two advantages of embryo screening. [2 marks] 1 2 Turn over for the next question 6 *06* IB/M/Jun23/8464/B/2H Do not write outside the 0 2 box It is estimated that 99.9% of all species that have ever existed are now extinct. 0 2 . 1 Why is the percentage of species that are extinct only an estimate? [1 mark] Tick () one box. All individuals of one species have the same genes. Extinction is always caused by humans. Humans have not found evidence of every species. 0 2 . 2 What evidence is used to study species that have become extinct? [1 mark] 7 *07* Turn over ► IB/M/Jun23/8464/B/2H Do not write outside the box 8 0 2 . 3 A bacterium called Clostridioides difficile (C. difficile) can infect the human digestive system. C. difficile can multiply and produce toxins. The toxins cause diarrhoea. Doctors are concerned that new strains of C. difficile may evolve. Antibiotics may not be able to kill these new strains. Explain how the evolution of antibiotic resistant C. difficile can be slowed down. [6 marks] 8 *08* IB/M/Jun23/8464/B/2H Do not write outside the 0 3 box Figure 1 shows a river next to a field. Figure 1 0 3 . 1 Describe a method to investigate how the distance from the river affects the number of different plant species in the field. You should explain how to use a transect in your method. [4 marks] 9 *09* Turn over ► IB/M/Jun23/8464/B/2H Do not write outside the 0 3 box . 2 Students used a valid method to investigate how the distance from the river affects the number of different plant species in the field. Figure 2 shows the results. Figure 2 What is shown by the data in Figure 2? [1 mark] Tick () one box. Fewer different species are always recorded nearer to the river. The mean value students can be most certain about is 5 metres from the river. The number of species recorded 6 metres from the river is anomalous. Question 3 continues on the next page 10 *10* IB/M/Jun23/8464/B/2H Do not write outside the Cows walk on the ground near the river more than they walk on the ground further box from the river. 0 3 . 3 Which is an abiotic factor that could affect the number of different plant species found near the river? [1 mark] Tick () one box. Microorganisms near the roots Moisture levels in the soil Oxygen concentration in the air Primary consumers in the field 11 *11* Turn over ► IB/M/Jun23/8464/B/2H Do not write outside the box 12 0 3 . 4 Increasing numbers of cows are being farmed across the world. Explain the environmental implications of increasing numbers of cows being farmed. [6 marks] Turn over for the next question 12 *12* IB/M/Jun23/8464/B/2H Do not write outside the 0 4 Sea lice are small animals that feed on the skin and blood of box salmon fish. Figure 3 shows sea lice attached to the skin of a salmon, Oncorhynchus keta. Figure 3 0 4 . 1 What is the genus name of salmon? [1 mark] 0 4 . 2 Which domain are sea lice classified in? [1 mark] 13 *13* Turn over ► IB/M/Jun23/8464/B/2H Do not write outside the 0 4 box . 3 Some salmon have genes that result in fewer sea lice attaching to the skin. Describe how fish farmers can selectively breed salmon that sea lice cannot attach to. [3 marks] 0 4 . 4 Explain the advantages to salmon farmers of producing salmon that do not have sea lice attached to their skin. [3 marks] Question 4 continues on the next page 14 *14* IB/M/Jun23/8464/B/2H Do not write outside the box 10 0 4 . 5 Explain the disadvantage of selectively breeding salmon. Do not refer to cost or to time in your answer. [2 marks] 15 *15* Turn over ► IB/M/Jun23/8464/B/2H Do not write outside the 0 5 box In Vitro Fertilisation (IVF) can be used to treat infertility. 0 5 . 1 Which hormones are given to women having IVF trea