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.
The diagram shows a tripeptide molecule. [Diagram of a tripeptide molecule with points 1, 2, 3, 4 indicated] At which two points will hydrolysis oc...
Which combination of procedures would not be used in a food test?
HIV-1 protease is an enzyme produced by the HIV virus. Two identical chains of 99 amino acids form the enzyme. In each chain, amino acids 25, 26 an...
Which features of collagen result in it having high tensile strength? 1 covalent bonds form between adjacent molecules 2 each three-stranded molecu...
The diagram shows a red blood cell and the concentrations of ions, in mmol dm⁻³ in and in the cell. [Diagram of a red blood cell showing ion concen...
Diagrams 1 and 2 show how the transverse section through a leaf changes when one solution W to a different solution Y. [Diagram 1 showing a cell in...
In an experiment, 5 cm³ of 1% salivary amylase are added to 100 cm³ of different concentrations of starch. Which graph shows the results of plottin...
Cystic fibrosis is a disease where Cl¯ ions are unable to be transported into cells. Which structure in the cell surface membrane is faulty? [Diagr...
Cancer cells divide out of control, forming tumours. Which statement describes the difference between a cancer cell and a normal cell?
Which statement describes a cell that is capable of reproduction and belonging to a haploid organism?
During which stage of the mitotic cell cycle is DNA replicated?
The following statements describe events that take place during DNA replication and transcription. Which statement is not correct?
Which diagram shows the semi-conservative replication of a section of a molecule of?
What is the sequence of events in the translocation of assimilates?
Which description states some of the features of xylem vessels?
The diagram shows the changes in pressure potential (Ψp), solute potential (Ψs) and water potential (Ψ) when a plasmolysed plant cell is placed in ...
The graph shows the percentage saturation of haemoglobin with oxygen at din pressures of oxygen. [Graph of % saturation of haemoglobin with oxygen ...
When stained, which features, visible under the light microscope, are part of the cells of the plant tissues listed in the table?
A disease damages alveoli. Which effect does this have on the gas exchange surface area and volume of the lungs?
An oxygen molecule diffuses directly from the air in an alveolus to haemoglobin in a red blood cell. What is the minimum number of cell surface mem...
What would be seen in an electron micrograph of a bronchus wall? 1 cartilage cells 2 ciliated cells 3 exocytotic vesicles
Below are correct statements comparing blood, tissue fluid and lymph in a capillary bed. • W lacks large plasma proteins and red blood cells and ha...
After an immune response, memory cells remain in the blood for a long time. What is the function of memory cells?
What are produced by B-lymphocytes?
Scientists are concerned that avian (bird) flu caused by the H5N1 virus, could infect humans and cause a pandemic. If this occurs, which factors co...
A country has fewer than 2.5 deaths per 100 000 people from TB in one year and the next year this rose to 25 deaths per 100 000. What may have cont...
The diagram shows an arctic ecosystem. [Diagram of an arctic food web] How many trophic levels are represented?
A tree carries out photosynthesis and provides organic compounds for other organisms in a forest. It takes carbon dioxide from and returns oxygen t...
In an investigation, discs of 2.5 cm diameter were cut from leaves. Fifty discs were p identical bags with different net sizes and buried in newly ...
Which steps are needed to find the actual width of a xylem vessel viewed in transv using a ×40 objective lens? 1 Convert from mm to µm by multiplyi...
A specimen is viewed under a microscope using green light with a wavelength of 510nm. If the same specimen is viewed under the same conditions, but...
Which cell organelle does not contain nucleic acid?
The diameter of living cells varies considerably. The typical diameters are a eukaryote, such as a white blood cell 1.5 × 10¹ μm a prokaryote, such...
Cells consist of a number of different components. Which row shows the components present (✔) in both a prokaryotic and eukaryotic cell? lysosomes ...
The diagram shows part of a carbohydrate molecule. [Figure 6.1] If all the 1,4 glycosidic bonds in this molecule are hydrolysed, how many water mol...
A peptide bond is formed between atoms of which two elements?
An amino acid can be represented as [Figure 9.1 showing a central carbon atom bonded to N, H, C(=O)OH, and R] where R represents a variable side ch...
When red cells leave the lungs, haemoglobin is 98% saturated. How many molecules of oxygen will be carried by the majority of haemoglobin molecules?
A fixed volume of the enzyme catalase was added to a fixed volume of hydrog solution. The diagram shows how the rate of the reaction changed over t...
The diagram shows the transport of ions across the cell surface membrane. Inside is a low concentration of sodium ions (Na+) and a high concentrati...
Plant cells were immersed in solutions of different water potential and left for one hour. Which row shows the effect of the different solutions on...
Which molecules, found in cell surface membranes, contribute to cell recognition? 1 glycolipids 2 glycoproteins 3 phospholipids
In which process does mitosis not have an important role in living things?
The diagram shows the chromosomes of a typical plant cell at the metaphase stage [Figure 18.1 showing chromosomes arranged at metaphase plate]. Whi...
The table shows the percentages of bases in DNA from various types of cell. [Table showing percentages of adenine, guanine, thymine, cytosine for c...
Which row shows the correct combination? triplet code codon anticodon
A culture of bacteria had all its DNA labelled with the heavy isotope of nitrogen (15N). A sample was taken and spun in a centrifuge. The diagram s...
S and T are products of a biochemical pathway. A different enzyme, coded for specific genes, catalyses each step in the pathway. [Figure 22.1 showi...
Which processes are involved in transpiration? 1 the diffusion of water vapour from stomata 2 the mass flow of water through the xylem 3 the evapor...
What is the main function of a companion cell in mature phloem tissue?