Cambridge & Pearson Edexcel Past Paper Questions
Browse 35,704 questions from Cambridge O-Level & A-Level and Pearson Edexcel IGCSE & IAL exams. Click any question to practice.
During which phase of the cell cycle does DNA replication take place?
Human body cells in interphase have 46 chromosomes. What is correct about the number of telomeres present in prophase of a human body cell?
Sometimes hydrogen bonds form temporarily between the bases of two strands of RNA. How many hydrogen bonds form when guanine and uracil each bind t...
The table shows all the possible DNA triplet codes for some amino acids. amino acid: cysteine, DNA triplet code: ACA amino acid: cysteine, DNA trip...
Which row is correct for transpiration?
Which features of companion cells and xylem vessel elements make them suitable for their function?
The diagram shows some root cells. [Figure 28.1 (diagram of root cells with water pathway indicated)] Which statement is correct for the pathway sh...
The graph shows the diameter of a tree trunk at different times. [Figure 29.1 (graph of diameter of tree trunk vs time of day, with points J, K, L)...
The plan diagrams of transverse sections of two plant organs are shown. These are not drawn to scale. [Figure 30.1 (plan diagrams of plant organs w...
The diagrams show three types of blood cells, which are all drawn to the same scale. [Figure 31.1 (diagrams of three blood cells X, Y, Z, with nucl...
The graph shows oxygen dissociation curves for three animals. The shape of each curve is influenced by respiration rate and the affinity of haemogl...
Which statements about a mammalian heart are correct? 1 The right atrium and right ventricle contain deoxygenated blood going to the lungs. 2 The l...
How is most carbon dioxide transported in the blood?
Which row shows the tissues that are present in the wall of the trachea and the wall of the bronchus?
Which factors maintain the diffusion gradient for carbon dioxide at the surface of the alveoli? 1 blood flow around the alveoli 2 breathing movemen...
A student made notes about two diseases: hand, foot and mouth disease (HFMD) and Lyme disease. HFMD is caused by a viral pathogen and is transmitte...
Which statements explain why antibiotics may not treat cholera successfully? 1 The infectious organism has developed resistance to the antibiotic. ...
The statements describe the phagocytosis of a bacterium by a macrophage. 1 Digestive enzymes break down the bacterium. 2 Lysosome fuses with the va...
Amylose and the triglyceride stearin are macromolecules. Students used the enzyme maltase extracted from the fungus Aspergillus oryzae to investiga...
In mammals, the small intestine is the main site of absorption of the products of digestion. Fig. 2.1 is a transmission electron micrograph of a lo...
Scientists investigated the progress of reactions catalysed by two enzymes: dopa oxidase and neutrase. The reactions catalysed by these enzymes res...
Cells of the immune system have cell surface receptors that detect molecules made by pathogens. One of these cell surface receptors is known as TLR...
Phosphate ions are absorbed from the soil solution by roots and are needed for cellular processes throughout plants. Scientists investigated the mo...
Fig. 6.1 is a ribbon model of a molecule of haemoglobin. The effect of the partial pressure of oxygen (pO2) and the effect of the partial pressure ...
Root hair cells are specialised plant cells located in the outer layer of young roots of plants. Root hair cells have an essential role in the upta...
The transport of respiratory gases involves blood plasma and red blood cells. Red blood cells contain the globular protein, haemoglobin.
Carrots are root vegetables of the carrot plant. The carrot plant is an important food crop that is grown throughout the world. Carrots have a swee...
Tuberculosis (TB) is an infectious disease that is caused by a bacterial pathogen. The pathogen has mechanisms to avoid digestion by phagocytes. Ma...
There is a global shortage of blood for transfusions. Researchers can culture bone marrow stem cells in the laboratory to manufacture red blood cel...
Horseradish peroxidase (HRP) is an enzyme that can be extracted from the roots of the horseradish plant, Armoracia rusticana. HRP is used extensive...
Ranunculus is a group (genus) of dicotyledonous plants that includes more than 1600 species. (a) Fig. 1.1 is a photomicrograph of a transverse sect...
Bees are insects that produce venom as a means of self-defence. Melittin is a polypeptide present in the venom of bees.
Staphylococcus epidermidis is a species of bacterium that lives on human skin. Staphylococcus aureus is a pathogenic bacterium that can infect humans.
Lysosomes are membrane-bound organelles found in mammalian cells.
Telomeres are lengths of DNA that consist of repetitive nucleotide sequences. Telomeres are present in eukaryotic chromosomes.
Monoclonal antibodies can be used in the treatment of disease.
Invertase is an enzyme that catalyses the breakdown of sucrose into glucose and fructose. Invertase can be extracted from yeast cells. You will inv...
When plant tissue is placed into a solution of sodium chloride, water moves between the sodium chloride solution and the cells in the plant tissue....
L1 is a slide of a stained transverse section through a plant organ. [Figure 2.1] is a diagram of a stage micrometer scale that is being used to ca...
Organisms need a source of energy for many cellular processes. Respiration involves the release of energy from energy-rich molecules for the synthe...
A respirometer can be used to investigate how temperature affects the rate of respiration of woodlice. Woodlice are small invertebrate animals. Fig...
Porphyria is a group of rare genetic diseases in which molecules called porphyrins accumulate in the body. Three examples of porphyria are: • X-lin...
Scientists have invented a way of producing food by artificial photosynthesis. • Solar panels convert sunlight energy into electricity. • The elect...
The Galápagos is a group of islands with a high biodiversity.
In the kidney, various molecules move between the blood and the kidney nephron. Table 6.1 describes the movements of molecules at three regions of ...
Insulin is an example of a cell-signalling molecule of the endocrine system.
The presence of gibberellins in a plant cell leads to the expression of genes involved in stem elongation. Describe how gibberellin causes stem elo...
A species is classified into one of three domains.
During the course of an action potential, the potential difference across a neurone membrane changes. Table 10.1 shows the potential difference acr...
Fig. 1.1 is a diagram of part of the inner membrane of a mitochondrion. [Figure 1.1]