BiologyPast paper questions
- Figure 1 shows the structure of a fatty acid molecule and the structure of a glycerol molecule. On Figure 1, draw a circle around the part of the fatty acid molecule and the part of the glycerol molecule that is removed to form a bond in a triglyceride molecule. Name the bond formed between a fatty acid and glycerol…2024 · Paper 1 · Question 1 · 8 marks
- Describe the processes of facilitated diffusion and active transport. Facilitated diffusion Active transport What are microvilli? Vitamin A is a fat-soluble substance. Micelles are involved in the process of vitamin A absorption. Describe the process of vitamin A absorption into cells lining the ileum.2024 · Paper 1 · Question 2 · 7 marks
- Describe how we breathe in. A scientist prepared alveolar tissue to view using an optical microscope. The scientist cut very thin slices of the alveolar tissue. Explain why the scientist used very thin slices of alveolar tissue with the optical microscope. Figure 2 is an image of the lung tissue observed using an…2024 · Paper 1 · Question 3 · 10 marks
- Give the number of different types of monosaccharides present in molasses. A student used the biochemical test for reducing sugars on a clear sample of molasses. Describe the biochemical test for a reducing sugar. Explain the result expected from the test on the sample of molasses. Description of biochemical test…2024 · Paper 1 · Question 4 · 10 marks
- Describe the appearance and behaviour of chromosomes during prophase and during anaphase of mitosis. Prophase Anaphase A scientist used an optical microscope to determine the mitotic index in cells at different distances from the tip of onion roots. Figure 4 shows the results. Complete the word equation used to…2024 · Paper 1 · Question 5 · 10 marks
- Give three structural differences between an mRNA molecule and a tRNA molecule. mRNA ______________ tRNA Table 3 shows mRNA codons and the amino acid coded by each codon. Figure 5 shows the mRNA base sequence produced when part of a gene coding for an enzyme is transcribed. UUU CGG GCG Use Table 3 to give the amino…2024 · Paper 1 · Question 6 · 8 marks
- In the box labelled Figure 8, design a suitable results table. • Enter the student's results into the table. • Calculate the mean results and include these in the table. • Use 1 decimal place for both mean results. Figure 8 Suggest and explain why the results for variety D are different from the results for variety E.…2024 · Paper 1 · Question 7 · 9 marks
- Give two structural features of an aorta wall and explain how they are related to the function of an aorta. 1 2 Small tears may occur in the layers of tissue in an aorta wall. These tears weaken the wall without bursting the aorta. Scientists: • measured the aorta diameter (d) in a large population of people over 60…2024 · Paper 1 · Question 8 · 8 marks
- There were 800 males in the control population. Each male made one type of call. Use this information and Table 6 to calculate the number of males making mating calls in the control population. Answer ______________ males Suggest one change the scientists could make to both frog populations to increase the number of…2024 · Paper 1 · Question 9 · 6 marks
- Describe and explain how you would use cell fractionation and ultracentrifugation to obtain a sample of nuclei from muscle tissue. Describe the role of organelles in the production and release of enzymes by animal cells. Do not include details of transcription in your answer. Describe the structure of ATP. Outline how…2024 · Paper 1 · Question 10 · 15 marks
- Name the parts labelled A to D. A B C D Following the release of acetylcholine into a neuromuscular junction, a muscle contraction occurs. Describe the sequence of events, following the release of acetylcholine, that leads to stimulation of this contraction. Do not include in your answer the events following the…2024 · Paper 2 · Question 1 · 8 marks
- Use the information provided to calculate the length of the myofibril after contraction. Give your answer in mm and in standard form. Show your working. Answer ______________ mm Which statement correctly describes the changes in length in a sarcomere when a myofibril contracts? Tick (✓) one box. ☐ H-zone decreases,…2024 · Paper 2 · Question 2 · 7 marks
- Using Figure 3, what can you conclude about the relationship between: the percentage of light absorbed and the rate of photosynthesis the colour of light and the rate of photosynthesis Give three environmental factors that should be controlled when measuring the rate of photosynthesis in this investigation. Do not…2024 · Paper 2 · Question 3 · 7 marks
- Explain how you would determine if the genotype of a grey fly is homozygous or heterozygous for body colour. A cross between a grey-bodied male fly and a black-bodied female fly produced some black-bodied females. Explain how this shows that the gene for body colour is not sex-linked. A population of fruit flies…2024 · Paper 2 · Question 4 · 8 marks
- Describe how you could estimate the number of fat hen plants in a field. Use the information provided to explain why. In your answer, name the type of competition occurring between fat hen plants and potato plants. Calculate the maximum mass, in kg, of viable fat hen seeds on this farm after a growing season. Show…2024 · Paper 2 · Question 5 · 10 marks
- Describe the myogenic stimulation of the heart and how the regular contraction of the atria and ventricles is coordinated. Do not include the autonomic nervous system in your answer. Atrial fibrillation (AF) is a condition that causes an irregular heart rate. Scientists used a statistical test to investigate the…2024 · Paper 2 · Question 6 · 8 marks
- Complete Figure 5 to show the relative positions of the bands following electrophoresis in experiments 1 and 2. Suggest how you could determine the size of the different DNA fragments produced in these experiments. How many DNA fragments would be produced in experiment 2 if the original DNA molecule was a plasmid?…2024 · Paper 2 · Question 7 · 7 marks
- Use the information provided to explain the relationship between IAA concentration, cell wall plasticity and mean growth of the stem segments. Use Figure 6 to calculate the percentage increase in mean growth of the stem segments when the IAA concentration was increased from 10–8 mol dm–3 to 10–5 mol dm–3 Give your…2024 · Paper 2 · Question 8 · 10 marks
- Give two reasons why a weight-loss programme could be used to treat type II diabetes but not type I diabetes. 1 2 The design of this investigation helps to support the validity of any conclusions obtained. Suggest and explain three features of this investigation that justify this statement. 1 2 3 Use the information…2024 · Paper 2 · Question 9 · 11 marks
- The wall gecko shows phenotypic diversity (lines 1–2). Suggest two factors that have resulted in this phenotypic diversity. 1 2 The ability of diurnal geckos to change skin colour (lines 7–8) is advantageous. Explain why. The scientists concluded that it was probable that disruptive selection was leading to sympatric…2024 · Paper 2 · Question 10 · 15 marks
- In the following passage, each numbered space can be filled with a biological term. Each type of cell has specific molecules on its (1) that identify it. An antibody is a (2) with two (3) binding sites. Antibodies are made and released by (4) cells. Vaccines can provide protection for individuals and populations…2024 · Paper 3 · Question 1 · 6 marks
- Other than those stated, suggest two variables the student should have kept constant in this investigation. 1 2 Describe how the student used the apparatus in Figure 1 to reset the drop of coloured liquid back to the right-hand end of the tubing. The student also set up a control experiment. Suggest a suitable control…2024 · Paper 3 · Question 2 · 8 marks
- Describe and explain the relationship between surface area to volume ratio of the human body and metabolic rate. The surface area of a person is estimated using the following formula: Surface area in m2 = √(height in cm × mass in kg / 3600) The volume of a person is estimated using the following formula: Volume in m3…2024 · Paper 3 · Question 3 · 8 marks
- Describe how the scientists determined the median of the stiffness scores. Using all the information, evaluate the use of pralnacasan as an effective treatment for OA in humans.2024 · Paper 3 · Question 4 · 6 marks
- Name one type of SURF1 gene mutation and explain how this mutation could lead to production of a shorter polypeptide. Type of mutation Explanation Globally, the frequency of LS is 1 in 40 000 In the Faroe Islands, which are 18 isolated islands, the frequency of LS is 1 in 1700 The population of the Faroe Islands is 49…2024 · Paper 3 · Question 5 · 10 marks
- Define the biological term population. Ecologists monitored the biodiversity of birds in a protected woodland. They recorded the number of bird species breeding in the woodland on the same day, every year for a 30-year period. Which statement correctly represents the species richness of the woodland? Tick (✓) one box.…2024 · Paper 3 · Question 6 · 15 marks
- Phosphorus-containing substances and their importance in biological systems. The mechanisms and importance of transport within organisms.2024 · Paper 3 · Question 7 · 50 marks
- Give the three structural features found in all virus particles and describe the function of one of these features. 1 2 3 Function of one named feature Explain why viruses are described as acellular and non-living. Give one reason why antibiotics are not effective against viruses.2023 · Paper 1 · Question 1 · 5 marks
- Chitin is a polysaccharide. The chitin monomer is a β-glucose molecule with one OH group replaced by an NHCOCH3 group. NHCOCH3 can be represented by N(Ac). Figure 1 shows the monomer that forms chitin and the chitin polymer. Chitin has a similar structure to cellulose. Use Figure 1 to describe three ways the structure…2023 · Paper 1 · Question 2 · 8 marks
- Other than the Golgi apparatus, name one structure in Figure 2 which shows that P. vivax is a eukaryote. Describe two functions of the Golgi apparatus in a eukaryotic cell. 1 2 P. vivax evolved from a common ancestor in Africa. As humans migrated around the world, new strains of P. vivax evolved. P. vivax is now…2023 · Paper 1 · Question 3 · 9 marks
- Explain why the damage to the cells lining the ileum reduces absorption of the products of digestion and why this reduces absorption of water. Not all patients in hospital with C. difficile develop diarrhoea. Scientists measured the anti-toxin antibody concentration in hospital patients with and without C. difficile…2023 · Paper 1 · Question 4 · 9 marks
- The student added 100 mm3 of each bacterial culture from its glass bottle onto a separate agar plate. She spread each bacterial culture evenly over the agar using a spreader. Describe the aseptic techniques she should use. On each agar plate, the student cut a well (a hole) in the agar. The well had a diameter of 6…2023 · Paper 1 · Question 5 · 10 marks
- Define genome and proteome. Genome Proteome The classification system used in the early 20th century grouped different species of bacteria according to the position and shape of flagella on bacterial cells and by the number of flagella per cell. These were observed using an optical microscope. Each species of…2023 · Paper 1 · Question 6 · 8 marks
- Carbon monoxide (CO) is released during incomplete combustion of fossil fuels. Figure 7 shows the dissociation curve for oxyhaemoglobin when: • not exposed to CO • exposed to CO such that 50% of the oxygen binding sites are occupied by CO (50% COHb). Using Figure 7, what can you conclude about how exposure to CO…2023 · Paper 1 · Question 7 · 6 marks
- The cells in drawing A can be identified as those treated with MiTMAB. Explain why. MiTMAB acts as a non-competitive inhibitor of an enzyme called dynamin. Suggest how MiTMAB can cause dynamin to become inactive. When active, dynamin has two functions: • it stimulates cytokinesis • it inhibits cell death. The…2023 · Paper 1 · Question 8 · 10 marks
- Suggest what is on the test at line T and explain what causes the line to appear in a positive test. A line at C shows that the test has worked. Suggest one reason why a line at C shows the test has worked. Figure 12 shows a flowchart of how the anti-human antibodies with enzyme attached are produced. Suggest why the…2023 · Paper 1 · Question 9 · 6 marks
- A student used chromatography to separate the different photosynthetic pigments in a chlorophyll solution. She had the following materials. Chromatography paper A ruler and pencil Suitable glassware A solvent (solvent A) 2 cm3 of the chlorophyll solution Describe how she could use these materials to separate the…2023 · Paper 2 · Question 1 · 6 marks
- Explain how ziconotide reduces severe, constant pain. Suggest two reasons why the patients had ziconotide injected into their cerebrospinal fluid rather than taking a pill containing the drug. 1 2 Ziconotide was injected at 3 ng kg–1 h–1 for 8 days into each patient. 1 ng = 1 × 10–9 g Calculate the total mass in grams…2023 · Paper 2 · Question 2 · 11 marks
- Calculate in teragrams the difference in the supply of phosphorus to the soil from the two stores shown in Figure 1. Show your working. Answer ______________ Tg Using all the information, evaluate the effectiveness of using mycorrhizae to increase crop production under conditions of water shortage and no water…2023 · Paper 2 · Question 3 · 11 marks
- Name the type of interaction between the two genes affecting fur colour. What phenotype would a cat with the following genotype have? XGXBff Complete the genetic diagram to show all the possible genotypes and the ratio of phenotypes expected in the offspring of this cross. Phenotypes of parents XGXGFf x XBYff…2023 · Paper 2 · Question 4 · 7 marks
- Figure 3 shows the wavelengths of light absorbed by three types of photoreceptor found in the human retina. Use Figure 3 and your knowledge of colour vision to explain how an orange colour is seen at 600 nm Which of the following statements is associated with high sensitivity to light in the retina? Tick (✓) one box.…2023 · Paper 2 · Question 5 · 9 marks
- Describe and explain how three features of the cells in the proximal convoluted tubule allow the rapid reabsorption of glucose into the blood. 1 2 3 Antidiuretic hormone (ADH) binds to V receptors found in cell-surface membranes in two parts of a nephron. Name the two parts of a nephron where V receptors are found. V…2023 · Paper 2 · Question 6 · 9 marks
- In the following passage, the numbered spaces can be filled with biological terms. An ecosystem supports a certain size of population of a species, called the (1) capacity. There are often numerous habitats within an ecosystem. Within a habitat, a species occupies a (2) governed by an adaption to both (3) and biotic…2023 · Paper 2 · Question 7 · 7 marks
- Suggest and explain how an alteration in the KRAS gene can cause a tumour to develop. Using the information provided, what can you conclude about the effects of type II diabetes and the different drug treatments on the survival time of CRC patients?2023 · Paper 2 · Question 8 · 8 marks
- Describe how STRs could be removed from a sample of DNA. Genetic fingerprinting using STRs requires amplification of the STRs using the polymerase chain reaction (PCR). The short base sequences either side of a specific STR are known. Explain the importance of knowing these base sequences in PCR. A single STR molecule…2023 · Paper 2 · Question 9 · 8 marks
- ATP is essential for muscle contraction (line 1). Describe the roles of ATP in muscle contraction. Calculate how long maximum exercise would last if ATP was not resynthesised (lines 3–4). Answer ______________ s Describe and explain how taking creatine supplements (lines 5–6) and 'carbohydrate loading' (lines 6–7) can…2023 · Paper 2 · Question 10 · 15 marks
- Describe how stimulation of a Pacinian corpuscle produces a generator potential. Scientists investigated the stimulation of a Pacinian corpuscle in the skin of a fingertip. The scientists applied two different pressures to the fingertip and recorded the changes in membrane potential of the Pacinian corpuscle's sensory…2023 · Paper 3 · Question 1 · 6 marks
- Other than those stated, suggest two variables the student needed to keep constant in her investigation. 1 2 Figure 3 shows the result she obtained for yeast in glucose solution. Use Figure 2 and Figure 3 to calculate the rate of carbon dioxide production in mm s–1 for yeast in glucose solution. Give your answer in…2023 · Paper 3 · Question 2 · 9 marks
- Below are four statements about the structure of prokaryotic cells. 1. No prokaryotic cell has DNA that is associated with proteins. 2. No prokaryotic cell has membrane-bound organelles. 3. All prokaryotic cells have one or more flagella. 4. All prokaryotic cells have smaller ribosomes than eukaryotic cells. Which…2023 · Paper 3 · Question 3 · 6 marks
- Suggest how SCFR is destroyed by a lysosome. After a heart attack, cardiomyocytes (cardiac muscle cells) die, and become infarcted tissue. Infarcted tissue cannot contract. Stem cells in bone marrow cannot move to the infarcted tissue and differentiate into cardiomyocytes. Scientists used laboratory rats to…2023 · Paper 3 · Question 4 · 10 marks
- The scientists used the following formula to calculate the index of diversity (d) of fish. d = N (N–1) / Σn (n–1) where N = total number of fish of all species and n = total number of fish of each species In some years, the values were N = 624 and Σn (n–1) = 64 792 Which years had these values? Use Figure 8 and the…2023 · Paper 3 · Question 5 · 7 marks
- Give two types of cell that can stimulate an immune response. 1 2 An autoimmune disease causes the immune system to attack healthy body tissues. Scientists investigated the immune responses of healthy mice and mice with autoimmune disease. The chemical OXA causes an immune response in mice and can make their skin…2023 · Paper 3 · Question 6 · 15 marks
- The importance of interactions between organisms and their environment. The importance of membranes in the functioning of cells.2023 · Paper 3 · Question 7 · 50 marks
- Describe the structure and function of the nucleus. Name the main polymer that forms the following cell walls. Plant cell wall Fungal cell wall Scientists investigated the effect of the number of fungal species in soil on the diversity of plant species. Table 1 shows their raw data for soil containing 14 fungal…2022 · Paper 1 · Question 1 · 10 marks
- Explain how the use of antibiotics has led to antibiotic-resistant strains of bacteria becoming a common cause of infection acquired when in hospital. Scientists suggested that factors, other than antibiotic use, led to the increase in antibiotic-resistant C. difficile infections. One suggested factor is people eating…2022 · Paper 1 · Question 2 · 10 marks
- Give two features of all prokaryotic cells that are not features of eukaryotic cells. 1 2 This AP has a secondary structure in a helical shape. Tick (✓) the box to show which type of bond maintains the helical structure of the polypeptide. ☐ Disulfide ☐ Hydrogen ☐ Ionic ☐ Peptide The amino acids on one side of each AP…2022 · Paper 1 · Question 3 · 11 marks
- Describe viral replication. Complete Table 2 by putting a tick (✓) where the feature is part of a cell cycle involving mitosis or a cell cycle involving binary fission. Figure 6 represents a cell undergoing meiosis. It shows the chromosomes in the parent cell and in the two cells formed after the first meiotic…2022 · Paper 1 · Question 4 · 9 marks
- Define the quaternary structure of a protein. Explain how two enzymes with different amino acid sequences can catalyse the same reaction. Scientists investigated the effect of pH 8.4 and pH 7.5 on the activity of enzymes P and Q. Figure 8 shows their results. Describe what the scientists should place in the control…2022 · Paper 1 · Question 5 · 9 marks
- Explain the rate of transpiration between 5 am and midday shown in Figure 9. Use Figure 9 to calculate the percentage increase in the rate of transpiration from 1 pm to 2 pm. Percentage increase in rate of transpiration ______________ % The higher rate of transpiration at high tide shows that the mangrove tree is…2022 · Paper 1 · Question 6 · 10 marks
- Complete Table 3 to give three differences between DNA molecules and tRNA molecules. The scientists broke open the cells to produce a suspension of cell contents. Describe how the scientists would remove large organelles from this suspension of cell contents. Explain the position of the bands of ribosomes in tubes A…2022 · Paper 1 · Question 7 · 8 marks
- To observe the fish gills with the optical microscope, the scientists used two different stains. The first stain binds to DNA; the second stain binds to the red blood cells. Explain why a second stain would be needed to stain the red blood cells. Suggest which molecule the stain could bind to in the red blood cells.…2022 · Paper 1 · Question 8 · 9 marks
- Describe the transport of carbohydrate in plants. Compare and contrast the structure of starch and the structure of cellulose. Describe the complete digestion of starch by a mammal.2022 · Paper 1 · Question 9 · 15 marks
- In the following passage the numbered spaces can be filled with biological terms. During photosynthesis, plants produce (1) compounds which contain carbon, such as carbohydrates, lipids and proteins. Most of the sugars synthesised by plants are used by the plant in (2). The rest are used to make other groups of…2022 · Paper 2 · Question 1 · 8 marks
- Put a tick (✓) in the box next to the equation that shows how the net production of consumers, N, can be calculated where I represents the chemical energy store in ingested food F represents the chemical energy lost to the environment in faeces and urine R represents the respiratory losses to the environment. ☐ N = (I…2022 · Paper 2 · Question 2 · 6 marks
- Apart from temperature and pH, give two variables the scientist would have controlled when preparing the liquid medium cultures. 1 2 A student concluded that this investigation showed that ammonia inhibits nitrogenase activity in nitrogen-fixing bacteria. Use all the information to evaluate the student's conclusion.…2022 · Paper 2 · Question 3 · 7 marks
- Put a tick (✓) in the box next to the process that occurs in anaerobic respiration but does not occur in aerobic respiration. ☐ Formation of acetyl coenzyme A from pyruvate ☐ Reduction of NAD ☐ Reduction of pyruvate ☐ Oxidation of triose phosphate During the 48 hours, the coloured liquid moved to the left. Explain…2022 · Paper 2 · Question 4 · 10 marks
- Using Figure 2, give three conclusions you can make about the distribution of these lemur species. 1 2 3 Using all the information, suggest how speciation happened to produce two species of lemur. The scientists used the mark-release-recapture method to determine the number of lemurs in one area of forest. They…2022 · Paper 2 · Question 5 · 10 marks
- Give the genotypes of the ABO blood groups for individuals 1 and 2. Do not include the genotypes for the Rhesus blood groups in your answer. 1 2 Explain one piece of evidence from Figure 3 that the allele for Rhesus positive is dominant. Calculate the probability of individuals 1 and 2 producing a Rhesus positive son…2022 · Paper 2 · Question 6 · 10 marks
- Give two reasons why transmission across a cholinergic synapse is unidirectional. 1 2 Figure 4 shows the changes in membrane potential in a postsynaptic neurone after repeated stimulation from a single presynaptic neurone. Name and explain the type of summation shown in Figure 4. Suggest and explain how MG can weaken…2022 · Paper 2 · Question 7 · 9 marks
- Calculate how many grams of STZ should be injected into a rat with a mass of 230.45 g. Show your working. Give your answer in standard form. Answer ______________ g Suggest and explain why STZ was injected per unit of body mass. The scientists concluded that group B rats could be used for studying type II diabetes in…2022 · Paper 2 · Question 8 · 10 marks
- Name the part of the body which releases antidiuretic hormone (ADH) into the blood. Alcohol decreases the release of ADH into the blood. Suggest two signs or symptoms which may result from a decrease in ADH. 1 2 Describe the effect of ADH on the collecting ducts in kidneys.2022 · Paper 2 · Question 9 · 6 marks
- BRCA1 and BRCA2 are human genes that code for tumour suppressor proteins. Mutations in BRCA1 and BRCA2 can cause cancer (lines 1–2). Explain how. Genetic testing, using DNA from saliva, can screen for all known harmful mutations in both genes (lines 5–6). Describe how this DNA could be screened for all known harmful…2022 · Paper 2 · Question 10 · 15 marks
- Use Table 1 to identify the three different amino acids used to make the polypeptide shown in Figure 1. Left amino acid Middle amino acid Right amino acid Table 2 shows three statements and names of four biological molecules. Put a tick (✓) in each box where the statement is true for the biological molecule. Figure 2…2022 · Paper 3 · Question 1 · 10 marks
- Name the structures labelled P, Q and R shown in Figure 4. P Q R Two students (A and B) investigated reaction time in response to touch. • Student A sat with her eyes shut and her forearm resting on a worktop so that her hand was over the edge. • Student B held a ruler vertically between student A's thumb and first…2022 · Paper 3 · Question 2 · 9 marks
- Suggest why the student soaked the root tips in hydrochloric acid in step 2. Pressing the coverslip downwards enabled the student to observe the stages of mitosis clearly. Explain why. Figure 6 shows the student's drawing of one field of view. Name the stage of mitosis shown in cell G. Explain the appearance of this…2022 · Paper 3 · Question 3 · 9 marks
- Complete the following definitions. The genome is The proteome is Recombinant DNA technology can involve the transfer of fragments of human DNA into bacteria. The bacteria are then used to produce human proteins. Give two reasons why bacteria are able to use human DNA to produce human proteins. 1 2 Suggest and explain…2022 · Paper 3 · Question 4 · 10 marks
- Calculate the total uptake of carbon dioxide between 11.40 and 13.15 hours in trees exposed to full sun in a forest that is 12 000 m2 in area. Give your answer in standard form. Show your working. Answer ______________ µmol Figure 8 shows there is a small difference in the mean uptake of carbon dioxide between 08.30…2022 · Paper 3 · Question 5 · 15 marks
- The uses and importance of ATP in organisms. The importance of cycles in biology.2022 · Paper 3 · Question 6 · 50 marks
- Describe the induced-fit model of enzyme action and how an enzyme acts as a catalyst. Scientists investigated the action of the enzyme ATP synthase. They made reaction mixtures each containing: • ATP synthase • buffer (to control pH) • substrates. One of the substrates required in these reaction mixtures is inorganic…2021 · Paper 1 · Question 1 · 8 marks
- Explain the advantage for larger animals of having a specialised system that facilitates oxygen uptake. Figure 2 shows two models of oxygen uptake found in animals. Suggest how the environmental conditions have resulted in adaptations of systems using Model A rather than Model B. Figure 3 shows changes in…2021 · Paper 1 · Question 2 · 11 marks
- Describe how one amino acid is added to a polypeptide that is being formed at a ribosome during translation. Crystallin is a structural protein found in the human eye. An inherited disease that leads to blindness is caused by changes in properties of crystallin. The replacement of the amino acid Arg with the amino…2021 · Paper 1 · Question 3 · 7 marks
- Suggest two ways the student could improve the quality of his scientific drawing of the blood vessels in this dissection. 1 2 Identify the type of blood vessel labelled as X and the type of blood vessel labelled as Y in Figure 4. Describe one feature that allowed you to identify the blood vessels. Blood vessel X Blood…2021 · Paper 1 · Question 4 · 6 marks
- Describe how a sample of chloroplasts could be isolated from leaves. Scientists grew two groups of plants: • control plants with all the inorganic ions needed • iron-deficient plants with all the inorganic ions needed but without iron ions. After 1 week, the scientists measured the mass of protein and the mass of…2021 · Paper 1 · Question 5 · 10 marks
- Calculate the rate of movement of the centromeres during phase E. Give your answer in μm minute–1 and to 3 decimal places. ______________ μm minute–1 Name the three phases of mitosis shown by C, D and E on Figure 7. Describe the role of the spindle fibres and the behaviour of the chromosomes during each of these…2021 · Paper 1 · Question 6 · 7 marks
- Use your knowledge of phagocytosis to describe how an ADC enters and kills the tumour cell. Some of the antigens found on the surface of tumour cells are also found on the surface of healthy human cells. Use this information to explain why treatment with an ADC often causes side effects. Scientists investigated…2021 · Paper 1 · Question 7 · 10 marks
- Describe how a triglyceride molecule is formed. Table 5 shows some properties of four fatty acids. Figure 10 shows diagrams of these fatty acids. Put a tick (✓) in one box that contains correct information about one of these fatty acids. ☐ Caprylic acid is an unsaturated fatty acid represented by diagram L. ☐ Linoleic…2021 · Paper 1 · Question 8 · 10 marks
- Complete Table 7 with ticks (✓) to show which elements are found in the following biological molecules. After Watson and Crick proposed the model of DNA structure, scientists investigated the possible mechanisms for DNA replication. Two scientists grew a bacterial population, providing them with a nitrogen source…2021 · Paper 1 · Question 9 · 7 marks
- Describe the structure of DNA. Name and describe five ways substances can move across the cell-surface membrane into a cell. Figure 14 shows transmission electron micrographs of two cells, one animal cell and one prokaryotic cell. Contrast the structure of the two cells visible in the electron micrographs shown in…2021 · Paper 1 · Question 10 · 15 marks
- Describe the process of glycolysis. Malonate inhibits a reaction in the Krebs cycle. Explain why malonate would decrease the uptake of oxygen in a respiring cell.2021 · Paper 2 · Question 1 · 6 marks
- Explain how a resting potential is maintained across the axon membrane in a neurone. Explain why the speed of transmission of impulses is faster along a myelinated axon than along a non-myelinated axon. A scientist investigated the effect of inhibitors on neurones. She added a respiratory inhibitor to a neurone. The…2021 · Paper 2 · Question 2 · 9 marks
- Use your knowledge of indoleacetic acid (IAA) to explain the growth curvature shown in Figure 1. Using the procedure in Figure 2 and the calibration curve in Figure 3, describe how you could compare the IAA concentration in shoot tips from two different plant species. In your answer you should refer to all the…2021 · Paper 2 · Question 3 · 10 marks
- Male fruit flies are more likely than female fruit flies to have white eyes. Explain why. A female fruit fly with white eyes was crossed with a male fruit fly with red eyes to produce a large number of offspring. Tick (✓) one box next to the statement which correctly describes the phenotypes produced from this cross.…2021 · Paper 2 · Question 4 · 9 marks
- Neonatal diabetes is a disease that affects newly born children. The disease is caused by a change in the amino acid sequence of insulin. This change prevents insulin binding to its receptor. Explain why this change prevents insulin binding to its receptor. A decrease in the activity of PI3K can cause type II…2021 · Paper 2 · Question 5 · 8 marks
- For some patients, HSCT is an effective treatment for MDS. Explain how. MDS can develop from epigenetic changes to tumour suppressor genes. In some patients, the drug AZA has reduced the effects of MDS. AZA is an inhibitor of DNA methyltransferases. These enzymes add methyl groups to cytosine bases. Suggest and…2021 · Paper 2 · Question 6 · 10 marks
- HBV infects a liver cell. The liver cell is 25 µm in diameter. Use Figure 7 to calculate how many times larger in diameter this cell is than HBV. You should use the lipid layer to measure the diameter of HBV. One method of transferring RNAi molecules into cells involves combining these molecules with a lipid. Suggest…2021 · Paper 2 · Question 7 · 8 marks
- Describe and explain how the polymerase chain reaction (PCR) is used to amplify a DNA fragment. Explain the shape of the curve in Figure 9.2021 · Paper 2 · Question 8 · 6 marks
- Describe a method that could be used to determine the mean percentage cover of algae on a coral reef. Do not include information on the difficulties of using your method underwater. Explain how succession results in a wide variety of fish living on coral reefs. Do not describe the process of succession in your answer.…2021 · Paper 2 · Question 9 · 10 marks
- Lake Malawi in East Africa has more species of fish than any other lake in the world (line 1). Suggest and explain how this speciation may have occurred. The percentage of forest cover in Malawi decreased between December 1990 and December 2016 (lines 9–10). Calculate the mean loss of forest cover in km2 per week…2021 · Paper 2 · Question 10 · 15 marks
- In a population of 34 S. carolinensis, 2 had black fur. Use the Hardy–Weinberg equation to estimate how many squirrels in this population had brown-black fur. Show your working. Answer ______________ The actual number of squirrels in this population that had brown-black fur was 16. Use all of the information to…2021 · Paper 3 · Question 1 · 9 marks
- Describe how the human immunodeficiency virus (HIV) is replicated once inside helper T cells (TH cells). HIV-1 is the most common type of HIV. HIV-1 binds to a receptor on TH cells called CCR5. Current treatment for HIV-1 involves the use of daily antiretroviral therapy (ART) to stop the virus being replicated. Only…2021 · Paper 3 · Question 2 · 9 marks
- Name the type of behaviour shown by beetles G, J, P and R, and suggest one advantage to adult beetles of the type of behaviour shown. Behaviour ______________ Advantage ______________ At higher temperatures and higher light intensities, adult pine beetles normally • move more • fly rather than walk. When preparing to…2021 · Paper 3 · Question 3 · 5 marks
- Use your knowledge of NPP to explain why freshwater marshes have a high CUE and the advantage of this. Do not refer to abiotic factors in your answer. Explanation ______________ Advantage ______________ Freshwater marsh soils are normally waterlogged. This creates anaerobic conditions. Use your knowledge of the…2021 · Paper 3 · Question 4 · 8 marks
- The changes that occur as a result of ageing may be categorised as physiological or pathological. A physiological change due to ageing is one that will occur in all individuals. A pathological change is one that is not inevitable; it is caused by disease or ill health. State why each of the following changes is a…2021 · Paper 3 · Question 5 · 7 marks
- The scientists used a radioactively labelled DNA probe to show that the cells of tobacco plant leaves contained the SUT1 gene. Describe how they would do this. Do not include PCR in your answer. To study the role of SUT1 in tobacco plants, scientists reduced the expression of the SUT1 gene. When the SUT1 gene is…2021 · Paper 3 · Question 6 · 15 marks
- The importance of complementary shapes of molecules in organisms The importance of ions in metabolic processes2021 · Paper 3 · Question 7 · 50 marks
- The action of the carrier protein X in Figure 1 is linked to a membrane-bound ATP hydrolase enzyme. Explain the function of this ATP hydrolase. The movement of Na+ out of the cell allows the absorption of glucose into the cell lining the ileum. Explain how. Describe and explain two features you would expect to find in…2020 · Paper 1 · Question 1 · 10 marks
- Use your knowledge of lipid digestion to explain the differences in the results for samples A and B shown in Table 1. You should assume that no absorption had occurred. After collecting the samples, the scientist immediately heated them to 70 °C for 10 minutes. Explain why. Describe the role of micelles in the…2020 · Paper 1 · Question 2 · 8 marks
- At P on Figure 3, the pressure in the left ventricle is increasing. At this time, the rate of blood flow has not yet started to increase in the aorta. Use evidence from Figure 3 to explain why. At Q on Figure 3 there is a small increase in pressure and in rate of blood flow in the aorta. Explain how this happens and…2020 · Paper 1 · Question 3 · 7 marks
- When making up extraction solvent E, the student used a volume ratio of 70:30:1 ethanol:water:acid. Tick (✓) one box that shows the most appropriate volumes she would use to make up 100 cm3 of extraction solvent E. ☐ 63.6 cm3 ethanol, 27.3 cm3 water, 9.1 cm3 acid ☐ 69.3 cm3 ethanol, 29.7 cm3 water, 1.0 cm3 acid ☐ 70.0…2020 · Paper 1 · Question 4 · 10 marks
- Describe the role of DNA polymerase in the semi-conservative replication of DNA. Figure 5 shows the percentage of rat cells undergoing DNA replication. Some cells contained a protein called cyclin D and some cells did not contain cyclin D. All cells were in early interphase at time 0 It took less time for 25% of cells…2020 · Paper 1 · Question 5 · 8 marks
- Explain why death of alveolar epithelium cells reduces gas exchange in human lungs. Scientists grew alveolar epithelium cells and exposed the epithelium cells to different concentrations of particulate matter. They calculated the percentage of these alveolar epithelium cells that died after 24 hours of exposure to…2020 · Paper 1 · Question 6 · 5 marks
- Alpha-gal is a disaccharide found in red meat. Alpha-gal is made of two galactose molecules. Galactose has the chemical formula C6H12O6 Give the chemical formula for the disaccharide, alpha-gal, and describe how it is formed from two galactose molecules. Formula Description Some people eat red meat for many years…2020 · Paper 1 · Question 7 · 10 marks
- Complete Table 2 to show three differences between DNA in the nucleus of a plant cell and DNA in a prokaryotic cell. 1 2 3 Scientists investigated the genetic diversity between several species of sweet potato. They studied non-coding multiple repeats of base sequences. Define 'non-coding base sequences' and describe…2020 · Paper 1 · Question 8 · 8 marks
- Calculate the mean stomatal density in the three fields of view in Figure 9. Give your answer as number of stomata per mm2 Show your working. Stomatal density ______________ per mm2 The scientists used leaves from individual trees that had grown in different areas of the world in different years. Each tree had grown…2020 · Paper 1 · Question 9 · 10 marks
- Describe how mRNA is formed by transcription in eukaryotes. Describe how a polypeptide is formed by translation of mRNA. Define 'gene mutation' and explain how a gene mutation can have: • no effect on an individual • a positive effect on an individual.2020 · Paper 1 · Question 10 · 15 marks
- Suggest and explain how the interaction between the muscles labelled in Figure 1 could cause the pupil to constrict (narrow). The fovea of the eye of an eagle has a high density of cones. An eagle focuses the image of its prey onto the fovea. Explain how the fovea enables an eagle to see its prey in detail. Do not…2020 · Paper 2 · Question 1 · 10 marks
- Steroid hormones are hydrophobic. Explain why steroid hormones can rapidly enter a cell by passing through its cell-surface membrane. In the cytoplasm, testosterone binds to a specific androgen receptor (AR). An AR is a protein. Suggest and explain why testosterone binds to a specific AR. The binding of testosterone…2020 · Paper 2 · Question 2 · 9 marks
- Other than the thermometer, explain how two features of the calorimeter shown in Figure 2 would enable a valid measurement of the total heat energy released. 1 2 A 2 g sample of biomass was fully combusted in a calorimeter. The volume of water in the calorimeter was 100 cm3 The increase in temperature recorded was…2020 · Paper 2 · Question 3 · 10 marks
- Explain the banding pattern shown in Figure 3. Use the information provided to describe how you could produce a calibration curve for creatinine. Do not include details on the use of glassware in your answer. Describe how you would determine the concentration of creatinine in a urine sample using your calibration…2020 · Paper 2 · Question 4 · 9 marks
- Mutation is one cause of genetic variation in organisms. Give two other causes of genetic variation. 1 2 Name the relationship between the two alleles that code for flower colour. A dwarf, pink-flowered plant was crossed with a heterozygous tall, white-flowered plant. Complete the genetic diagram to show all the…2020 · Paper 2 · Question 6 · 8 marks
- Calculate how many times greater the mean growth rate per day was using 37.5 g potassium nitrate than using 37.5 g ammonium sulfate. Assume the mean biomass of the spinach plants at the start of the investigation was 0.5 g per pot. Using all the information, evaluate the effect on plant growth of adding the different…2020 · Paper 2 · Question 7 · 8 marks
- Suggest how AS could cause proteinuria. AS results from a sex-linked mutation. In a male with AS, where would the sex-linked mutation be located? Tick (✓) one box. ☐ Autosome ☐ X chromosome ☐ Y chromosome ☐ Mitochondrial DNA Using all the information, evaluate the use of stem cells to treat AS in humans. The…2020 · Paper 2 · Question 8 · 9 marks
- Describe how enzymes could be used to insert the GH gene into a plasmid. Microinjection of DNA into fertilised egg cells is a frequent method of producing transgenic fish. However, the insertion of the transferred gene into nuclear DNA may be delayed. Consequently, the offspring of transgenic fish may not possess the…2020 · Paper 2 · Question 9 · 8 marks
- Black bears can hibernate for up to 7 months without food or water (lines 1−2). Suggest and explain how. During hibernation, the heart rate and the metabolic rate of black bears decrease (lines 3−5). Use your knowledge of the nervous control of heart rate to describe how these are linked. In many mammals, 'uncoupling…2020 · Paper 2 · Question 10 · 15 marks
- Suggest three possible limitations of this investigation. 1 2 3 Guppies with large brains are better at identifying predators. The scientists found that only female guppies with large brains were attracted to male guppies bright in colour. Suggest and explain the advantage of this behaviour to the population of…2020 · Paper 3 · Question 1 · 9 marks
- Name the type of competition between livestock and ibex. Answer ______________ Livestock will outcompete ibex if they: • are in the same habitat • eat a similar diet. Scientists investigated this conflict of interests. Table 1 summarises some of the scientists' findings. There must be a balance between the need for…2020 · Paper 3 · Question 2 · 4 marks
- Suggest and explain how the viruses became able to infect other species of frog. Name two techniques the scientists may have used when analysing viral DNA to determine that the viruses were closely related. 1 2 Determining the genome of the viruses could allow scientists to develop a vaccine. Explain how. Describe how…2020 · Paper 3 · Question 3 · 8 marks
- A journalist studied the data in Table 2. She made the following suggestion. 'If an adult takes the maximum number of tablets allowed for either of the medicines, then the person would have more than the RDA of sodium.' The RDA (recommended daily allowance) of sodium for an adult human is 2.4 g per day. Is the…2020 · Paper 3 · Question 4 · 9 marks
- In the UK in 2016, there were 525 048 deaths. Cancer caused 30.4% of all deaths. Throat cancer caused 5% of all deaths from cancer. Calculate the mean number of people who died of throat cancer per month in 2016. Show your working. Answer ______________ people per month Increased methylation of the promoter region of…2020 · Paper 3 · Question 5 · 8 marks
- Describe the advantage of the Bohr effect during intense exercise. A cyclist completed a fitness test on an exercise bike. The intensity of the exercise was increased every 10 seconds. The test finished when he was unable to cycle any further. The partial pressure of oxygen (pO2) and of carbon dioxide (pCO2) in air…2020 · Paper 3 · Question 6 · 15 marks
- The functions of enzymes and their importance in organisms. The causes and importance of variation and diversity in organisms.2020 · Paper 3 · Question 7 · 50 marks
- Describe how a non-competitive inhibitor can reduce the rate of an enzyme-controlled reaction. Pectin is a substance found in some fruit and vegetables. A scientist investigated the effect of pectin on the hydrolysis of lipids by a lipase enzyme. His results are shown in Figure 1. The scientist concluded that pectin…2019 · Paper 1 · Question 1 · 8 marks
- Complete Table 1 by putting a tick (✓) where a cell wall component is present. Cell walls make up much of the fibre that people eat. Scientists investigated the relationship between the mass of fibre people ate each day and their risk of cardiovascular disease (CVD). They gathered data from a large sample of people…2019 · Paper 1 · Question 2 · 9 marks
- What data would the students need to collect to calculate their index of diversity in each habitat? Do not include apparatus used for species sampling in your answer. Give two ways the students would have ensured their index of diversity was representative of each habitat. 1 2 Modern farming techniques have led to…2019 · Paper 1 · Question 3 · 6 marks
- Use Figure 5 to explain how human mass at birth is affected by stabilising selection. The scientists studied the effect of one form, KIR2DS1, of the human KIR gene on mass at birth. In the following passage the numbered spaces can be filled with biological terms. KIR2DS1 is an (1) of the KIR gene, found at a (2) on…2019 · Paper 1 · Question 4 · 10 marks
- Describe the structure of the human immunodeficiency virus (HIV). A test sample of 500 mm3 of blood is taken from an HIV controller to determine the viral load. Tick (✓) one box that shows the number of virus particles that would be present in a test sample of blood taken from an HIV controller with the median viral…2019 · Paper 1 · Question 5 · 8 marks
- Describe and explain the data in Table 4. The scientists determined the percentage of heart cells undergoing DNA replication by using a chemical called BrdU. Cells use BrdU instead of nucleotides containing thymine during DNA replication. Describe how BrdU would be incorporated into new DNA during semi-conservative…2019 · Paper 1 · Question 6 · 10 marks
- Unlike plants, Ulva lactuca does not have xylem tissue. Suggest how Ulva lactuca is able to survive without xylem tissue. Ulva lactuca has a haploid and a diploid form. Figure 7 shows the life cycle of Ulva lactuca. On Figure 7 complete each box with an appropriate letter to show the type of cell division happening…2019 · Paper 1 · Question 7 · 5 marks
- The scientists needed solutions of known water potential to generate their calibration curve. Table 5 shows how to make a sodium chloride solution with a water potential of −1.95 MPa Complete Table 5 by giving all headings, units and volumes required to make 20 cm3 of this sodium chloride solution. Table 6 shows some…2019 · Paper 1 · Question 8 · 10 marks
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