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.
Which row describes a triglyceride?
The diagrams show the amino acid serine. Which circled area is different in all other amino acids?
Which statements describe some enzyme actions? 1 Enzymes hold reacting molecules in such a way that their reactive groups are brought close togethe...
The diagram shows the mass of product formed over time in three reactions using the same substrate and enzyme. The volumes of substrate, enzyme and...
Tyrosinase is an enzyme that catalyses the conversion of the amino acid tyrosine into the black pigment melanin. It is responsible for the black fu...
Which descriptions are correct for transport across cell surface membranes?
The stages of an investigation using plant tissue are listed below. • A freshly cut slice of plant tissue was rinsed in distilled water, dried and ...
What explains the effect on a red blood cell of being placed into pure water?
Which statements about a diploid cell are correct? 1 can divide by mitosis to repair itself 2 has two complete sets of chromosomes 3 can undergo a ...
What occurs during DNA replication and transcription and translation? 1 ATP provides energy. 2 Condensation reactions occur to form a polymer. 3 Hy...
Ricin is a toxic protein which inactivates ribosomes. Which effect will this have on protein synthesis?
Which row shows two pairs of nucleotide bases in a molecule of DNA?
What is the role of the Casparian strip?
Sucrose is loaded into companion cells and phloem sieve tube elements by active transport and diffusion using transport proteins and plasmodesmata....
Which changes to the water potential and the volume of liquid in the phloem occur when sucrose is transferred from leaves into phloem sieve tubes t...
Which components of blood are found in tissue fluid?
Which reactions take place in a capillary in an active tissue? 1 carbon dioxide and water are formed from hydrogencarbonate ions and hydrogen ions ...
What happens to the atrioventricular valves and to the semilunar valves during atrial systole and ventricular systole?
Red blood cells may contain a molecule known as 2,3-bisphophoglycerate (2,3BPG). When 2,3BPG binds to haemoglobin a higher partial pressure of oxyg...
Which row about the human gas exchange system is correct?
Which of the effects are caused by breathing in both carbon monoxide and nicotine from cigarette smoke? 1 increased heart rate 2 increased risk of ...
Why is it necessary for a person with a bacterial infection to take antibiotics at evenly spaced time intervals?
Which statement is correct for a neutrophil?
What describes artificial passive immunity?
Which group could be a population?
The diagram shows the flow of energy through a food chain. [Figure 39.1] What percentage of the energy is used by the green plants for photosynthesis?
Anaerobic bacteria are found in large numbers in waterlogged soils. Which effect does this have on soil fertility and why?
Until recently, the typical viruses known to science were 20 – 150 nm in size. In 2003, the Mimivirus was discovered with a size of approximately 6...
This electron micrograph of a section of a leaf has a magnification of × 210. What is the actual length along the line X-Y? [Figure 2.1]
What is the correct order in which organelles function to make and secrete an enzyme?
The diagram shows a stage micrometer scale, with divisions 0.1 mm apart, viewed through an eyepiece containing a graticule. What is the area of the...
Which is a correct comparison between a typical prokaryotic cell and a typical eukaryotic cell?
The diagrams show four monosaccharides with the formula C₆H₁₂O₆. Which diagrams do not show glucose molecules? [Figure 7.1]
Which statements about a triglyceride molecule are correct? 1 It always contains unsaturated hydrocarbon tails. 2 It is formed using ester bonds. 3...
The table shows some features of collagen and haemoglobin. Which row is collagen?
The ring structure of sugars can also be represented as a linear structure, as shown in the diagram. Which of the sugar molecules could be represen...
What is the minimum number of carbon atoms in an amino acid?
The graph shows the results of an investigation into the effect of amylase on starch at three different temperatures. Which statements are correct ...
Substances called furanocoumarins are found in some fruits, where they act as inhibitors of the enzyme CYP3A4. This enzyme is needed to break down ...
Which observations support a link between active transport and ATP production? 1 Active transport occurs only in living cells. 2 The rate of active...
The stalk of a dandelion flower is a hollow tube. Pieces of the stalk are cut as shown and placed in sucrose solutions of different water potential...
Three of the molecules found in prokaryotes are listed below. 1 phospholipid 2 protein 3 peptidoglycan Which of these molecules are found in prokar...
Which row correctly shows the behaviour of the nuclear envelope, the centrioles and the spindle during a stage of mitosis?
Which group of cells can all divide by mitosis?
Which row represents the correct features of the nitrogenous base cytosine? key: ✓ = true, X = false
Bacteria were grown in a medium containing ¹⁵N. After several generations, all of the DNA contained ¹⁵N. Some of these bacteria were transferred to...
Which processes are involved in the mass movement of water through xylem vessels? 1 hydrogen bonding between water molecules 2 cohesion between wat...
The diagram shows a model to demonstrate mass flow. In a plant, what are the structures W, X, Y and Z and what is the direction of flow of solution...
Which blood vessels carry blood into the atria of the heart?
Which statement describes the effect of increased carbon dioxide concentration on the oxygen dissociation curve of human haemoglobin and its signif...