Biology questions and solutions
Browse original practice and official past-paper questions. Each question has its own link, with its source and worked solution.
385 questions · Page 3 of 17
- Q12 · 2024 QCAA · Paper 1 · 1 markFunctioning ecosystems and successionQUESTION 12 The diagram shows key processes in the nitrogen cycle. Atmospheric nitrogen (N2) lightning Animals Plants denitrifying bacteria III Decomposers nitrifying bacteria I II nitrogen-fixing nitrifying bacteria bacteria Which option correctly identifies I, II and III? I II III − ) − ) + ) (A) nitrites (NO2 nitrates (NO3 ammonium (NH4 − ) + ) − ) (B) ni…
- Q13 · 2024 QCAA · Paper 1 · 1 markFunctioning ecosystems and successionQUESTION 13 The role and space that an organism fills in an ecosystem is referred to as its (A) niche. (B) ecoregion. (C) environment. (D) microhabitat.
- Q14 · 2024 QCAA · Paper 1 · 1 markBiodiversity and populationsQUESTION 14 Compared to K-strategists, species classified as r-strategists tend to (A) have more offspring. (B) have longer lifespans. (C) reach sexual maturity later. (D) live in more stable habitats.
- Q15 · 2024 QCAA · Paper 1 · 1 markBiodiversity and populationsQUESTION 15 Which graph best illustrates exponential growth? (A) (B) Population Population Time Time (C) (D) Population Population Time Time
- Q16 · 2024 QCAA · Paper 1 · 1 markFunctioning ecosystems and successionQUESTION 16 The diagram shows feeding relationships for an ecosystem where tiger sharks are a keystone species. Tiger shark Spotted wobbegong Giant triton Trout Octopus Starfish Turtle Jellyfish Butterfly fish Crab Coral Seagrass Plankton Which species is most likely to experience an increase in predation if tiger sharks are removed? (A) trout (B) starfish…
- Q17 · 2024 QCAA · Paper 1 · 1 markGenetics and heredityQUESTION 17 Which genetic tool is not required to make recombinant DNA? (A) DNA ligase (B) plasmid vectors (C) restriction enzymes (D) transcription factors
- Q18 · 2024 QCAA · Paper 1 · 1 markGenetics and heredityQUESTION 18 Karyotypes for two human gametes are shown. 1 2 3 4 5 1 2 3 4 5 6 7 8 9 10 11 12 6 7 8 9 10 11 12 13 14 15 16 17 18 13 14 15 16 17 18 19 20 21 22 X X 19 20 21 22 X If the two gametes produced a zygote, the resulting embryo would be (A) male, with trisomy. (B) female, with trisomy. (C) male, with monosomy. (D) female, with monosomy.
- Q19 · 2024 QCAA · Paper 1 · 1 markContinuity of life on EarthQUESTION 19 Which diversification pattern involves the independent development of similar structures in two species with no recent common ancestor? (A) coevolution (B) parallel evolution (C) divergent evolution (D) convergent evolution
- Q20 · 2024 QCAA · Paper 1 · 1 markContinuity of life on EarthQUESTION 20 The graph shows the number of nucleotide differences observed in the cytochrome c gene of 10 species and their time since divergence. 120 100 Nucleotide differences 80 60 40 20 0 0 20 40 60 80 100 120 140 Time (millions of years) Cytochrome c genes from two new species were compared and found to have 60 nucleotide differences. Based on this infor…
- Q21 · 2024 QCAA · Paper 1 · 7 marksBiodiversity and populationsQUESTION 21 (7 marks) In 2014, a group of scientists surveyed a plant community and determined Simpson’s diversity index (SDI) to be 0.84. They returned to the same site in 2024 and collected this data. Species Number of individuals A 133 B 96 C 256 ∑ ( 1) n n − a) Calculate SDI in 2024 using the formula Show your working. 1 SDI = − [2 marks] (…
- Q22 · 2024 QCAA · Paper 1 · 4 marksContinuity of life on EarthQUESTION 22 (4 marks) The graph shows the effect of a selection pressure on the body length of a fish population. 0.18 Key 0.16 before selection 0.14 pressure 0.12 30 generations later Frequency 0.10 0.08 0.06 0.04 0.02 0.00 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Body length (cm) a) Determine which type of phenotypic selection has occurred. [1 mark]…
- Q23 · 2024 QCAA · Paper 1 · 3 marksGenetics and heredityQUESTION 23 (3 marks) In rabbits, black fur is dominant to white fur. A male that is heterozygous for black fur is crossed with a female with white fur, producing 12 offspring. Predict the number of offspring with white fur. Justify your response using a Punnett square.
- Q24 · 2024 QCAA · Paper 1 · 3 marksGenetics and heredityQUESTION 24 (3 marks) The diagram shows a process that occurs during meiosis. a) Identify the process. [1 mark] b) Explain how this process contributes to genetic variation in the genotypes of offspring. [2 marks]
- Q25 · 2024 QCAA · Paper 1 · 2 marksBiodiversity and populationsQUESTION 25 (2 marks) Describe what is meant by an interspecific hybrid, using an example.
- Q26 · 2024 QCAA · Paper 1 · 6 marksFunctioning ecosystems and successionQUESTION 26 (6 marks) The diagram shows energy flow through an ecosystem. Values are in kJ m−2 year−1. Shaded boxes represent gross productivity. Respiration and heat 55 000 9500 1100 Producers Primary consumers Secondary consumers Sun 92 000 16 000 1700 Decomposers a) Calculate the efficiency of energy transfer between primary and secondary consumers. Sho…
- Q27 · 2024 QCAA · Paper 1 · 2 marksBiodiversity and populationsQUESTION 27 (2 marks) M n × To determine the reliability of the capture–recapture technique and the Lincoln index , N = m two researchers collected data on a mouse population from the same site at the same time. Researcher Number of mice Number of mice in Number of marked in first capture second capture mice in second capture I 160 140 80 II 100 60 ? If the…
- Q1 · 2024 QCAA · Paper 2 · 3 marksContinuity of life on EarthQUESTION 1 (3 marks) This cladogram shows the development of key features in species A to G. A B C D E F G hair postorbital bone amniotic egg four limbs bony skeleton backbone a) Identify the most distant relative of species C. [1 mark] b) List all the features you would expect to observe in the most recent common ancestor of species C and F. [1 mark] c)…
- Q2 · 2024 QCAA · Paper 2 · 3 marksFunctioning ecosystems and successionQUESTION 2 (3 marks) a) Define carrying capacity. [1 mark] b) Identify two factors that affect the carrying capacity of plant species in an ecosystem. [2 marks]
- Q3 · 2024 QCAA · Paper 2 · 2 marksBiodiversity and populationsQUESTION 3 (2 marks) The table shows data for a population in 2023. Starting Births Deaths Immigration Emigration population 4000 835 324 34 65 Calculate the population growth rate. Show your working.
- Q4 · 2024 QCAA · Paper 2 · 6 marksGenetics and heredityQUESTION 4 (6 marks) a) Describe the roles of helicase and DNA polymerase in DNA replication. [2 marks] b) Explain two ways the structure of DNA allows helicase and DNA polymerase to carry out their roles. [2 marks] c) Explain how errors during DNA replication can lead to point and frameshift mutations. [2 marks]
- Q5 · 2024 QCAA · Paper 2 · 3 marksContinuity of life on EarthQUESTION 5 (3 marks) a) Describe a population bottleneck. [1 mark] b) Explain why populations affected by bottlenecks face increased risk of extinction. [2 marks]
- Q6 · 2024 QCAA · Paper 2 · 4 marksContinuity of life on EarthQUESTION 6 (4 marks) Sickle-cell anaemia is an autosomal recessive condition that reduces the ability of red blood cells to carry oxygen. This is usually considered detrimental; however, individuals who are heterozygous for the trait may be less prone to the infectious disease malaria. These maps show the distribution of malaria and frequency of the sickle-…
- Q7 · 2024 QCAA · Paper 2 · 4 marksContinuity of life on EarthQUESTION 7 (4 marks) a) Explain how habitat fragmentation can lead to speciation. [3 marks] b) Identify the type of speciation that occurs due to habitat fragmentation. [1 mark]
- Q8 · 2024 QCAA · Paper 2 · 6 marksFunctioning ecosystems and successionQUESTION 8 (6 marks) The table shows data from a transect study along a sand dune. Zone A B C D Distance from sea (m) 0–100 >100–150 >150–250 >250–300 Age of dune (years) 0–50 >50–100 >100–125 >125–150 pH of soil 8.4 7.4 6.9 6.0 Organic matter in soil (%) 1 2.5 5 30 Number of grass species 2 4 6 2 Number of tree species 0 1 3 8 a) Contrast species richness…