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.
Galactogen is a storage polysaccharide in some animal species. It is a branched polymer that is formed from ẞ-galactose monomers. Which comparison ...
Which levels of protein structure are always involved in forming the active site of an enzyme?
Catalase is an enzyme that breaks down hydrogen peroxide into water and oxygen. Catalase was added to a solution of hydrogen peroxide and the oxyge...
Succinic dehydrogenase is an enzyme that catalyses the conversion of succinate to fumarate in aerobic respiration. Malonate is a reversible inhibit...
The diagram shows the dimensions of two blocks of agar. The diagram has been drawn to scale. [Figure 16.1] The blocks of agar were stained pink wit...
The graph shows how the rate of facilitated diffusion of substance X across a cell surface membrane changed as the concentration of substance X inc...
Which molecule forms a bilayer in the cell surface membrane of a bacterial cell?
A nucleus in a body cell of a species of fruit fly has 8 chromosomes. How many strands of DNA are present in the nucleus at the end of interphase?
The photomicrograph shows plant cells in different stages of the mitotic cell cycle. Four of the cells are labelled with a number to identify them....
Which percentage of the chromosomal DNA present in a cell during G₁ is present in the same cell later in the same mitotic cell cycle during prophas...
The statements are about two genes and their protein products that can have a role in tumour formation. • The protein coded for by the PTEN gene pr...
Telomerase is an enzyme that prevents the shortening of telomeres. It is not present in most normal cells, but is active in an estimated 85% to 95%...
Which diagram correctly represents one of the base pairs of DNA?
The diagram represents the process of transcription of a gene in the nucleus of an animal cell. [Figure 25.1] Which row correctly identifies P, Q a...
Which row correctly describes the role of growing leaves as sources or sinks for amino acids and sucrose?
Which row correctly matches each description to cilia or root hairs?
Which changes occur as amino acids are moved into phloem sieve tubes at a source?
The graph shows the dissociation curves for haemoglobin at two different partial pressures of carbon dioxide. Which labelled point on the oxygen di...
Which statements about the transport of carbon dioxide in the blood are correct? 1 Carbonic anhydrase catalyses the reaction of carbon dioxide and ...
What happens as a result of the blood pressure in the left ventricle becoming higher than the blood pressure in the left atrium?
The scanning electron micrograph shows the inner surface of a human trachea. [Figure 32.1] What is the identity of the part of the electron microgr...
Which rows correctly summarise the typical distribution of cartilage and smooth muscle within different parts of the gas exchange system of humans?
A molecule of oxygen diffuses from the air in an alveolus to haemoglobin in a red blood cell. Assuming that the molecule crosses cellular layers by...
Which row shows the type of pathogen that causes cholera and its mode of transmission?
Which statement about tuberculosis (TB) is not correct?
More cases of malaria are being reported in Europe. Other diseases, formerly confined to tropical countries and transmitted in the same way as mala...
The diagrams show three different bonds. [Figure 38.1] Which bonds are found in an antibody molecule?
Specific monoclonal antibodies can be used to treat some forms of cancer. One example is trastuzumab, which can be used in the treatment of tumours...
The HIV virus causes illness by infecting and destroying T-helper cells. This leads to AIDS and an inability to produce an effective immune respons...
Smilax china is a herbaceous plant. Fig. 1.1 shows part of a transverse section of a root of S. china with root hair cells visible. [Figure 1.1]
Fig. 2.1 is an incomplete diagram of the structure of an α-glucose molecule. Complete Fig. 2.1 to show the structure of an α-glucose molecule.
Fig. 3.1 and Fig. 3.2 are diagrams of transverse sections of the human heart during different stages of the cardiac cycle. The sections pass throug...
State why some diseases are described as infectious.
Eukaryotic cells and prokaryotic cells contain DNA. Complete the passage about DNA in eukaryotic cells and prokaryotic cells, using the most approp...
Fig. 6.1 shows photomicrographs of individual cells from the root tip of an onion, Allium sp., at different times in the mitotic cell cycle. [Figur...
Different types of respiratory substrate can have different energy values and therefore release different quantities of energy when they are respir...
The orca, Orcinus orca, has the largest distribution of all aquatic mammals and is found in nearly all seas and oceans. Orca are social mammals tha...
Gentamicin is an antibiotic used to treat severe bacterial infections in children. (a) Some children have a genetic mutation in the gene MT-RNR1. I...
The HFE gene codes for the HFE protein, which has a role in the regulation of iron absorption by the body. Iron is an essential mineral that can be...
[Figure 5.1] shows a photomicrograph of a single plant cell in a stage of meiosis. Describe the stage of meiosis shown in Fig. 5.1.
[Figure 6.1] outlines part of the control mechanism that regulates blood glucose concentration.
The Sumatran tiger, Panthera tigris sumatrae, is classified as critically endangered on the International Union for Conservation of Nature (IUCN) R...
(a) In the link reaction, a two-carbon acetyl group is produced from pyruvate. The acetyl group is transferred to coenzyme A to form acetyl coenzym...
The chloroplasts of leaves of tobacco plants, Nicotiana sp., contain chlorophyll a and chlorophyll b. (a) Describe the role of chlorophyll b in pho...
(a) Fig. 10.1 shows chemoreceptor cells in a taste bud. Two of the chemoreceptor cells have formed synapses with sensory neurone dendrites. [Figure...
Sand dunes are important ecosystems that are found in many regions of the world. Sand dune ecosystems can be damaged by natural events, such as ext...
Nagarahole National Park in southern India is a forest ecosystem that is important for the conservation of large mammals such as the Asian elephant...
Type 1 diabetes is a disease that occurs when the pancreas stops producing insulin. Type 1 diabetes occurs most commonly in children and is often t...
The diagram shows a section through a type of epithelium. [Figure 1.1] Where is this type of epithelium found in the respiratory system?
Which statement is an example of epidemiological evidence linking smoking to lung cancer?