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.
A section of a DNA molecule has the coding sequence: AGGCAATGGC. Which statements are correct? 1 This coding sequence contains 3 pyrimidines. 2 The...
XNA is a laboratory-made nucleic acid made of nucleotides in which one component has been replaced by chemical X. The chemical X is not found in na...
Which statements about tRNA are correct? 1 Hydrogen bonds between bases temporarily hold tRNA against mRNA. 2 The base sequences in the tRNA molecu...
What is the role of ATP in a companion cell when sucrose is loaded into a sieve tube element?
A potometer was used to measure the transpiration rate of a leafy shoot. What could be the correct units?
The diagrams show transverse sections of parts of a plant. [Figure 29.1] Which structures, labelled 1 to 4, transport water and sucrose?
Which statement explains why the ventricles contract after the atria?
If the left atrioventricular valve in the heart does not close completely it results in blood flowing back into the atrium during ventricular systo...
The graph shows two oxygen dissociation curves, one for a tissue at rest and one for the same tissue during exercise. [Figure 32.1]
Which of these statements about the formation of haemoglobinic acid are correct? 1 It can only occur with the dissociation of oxygen from haemoglob...
Which of these structures contain cartilage and cilia? 1 bronchi 2 bronchioles 3 trachea
What correctly describes the effect of carcinogens on lung tissue that causes a tumour to develop?
Which row identifies both the type of pathogen that causes cholera and the way in which cholera is transmitted from person to person?
Why do people with HIV/AIDS have a higher occurrence of malaria than people without HIV/AIDS?
How many variable regions are there on a typical Y-shaped antibody molecule?
Where are antigens found?
When an organ is transplanted from one person to another, rejection of the non-self organ must be avoided. At the same time, the immune system of t...
Fig. 1.1 is a transmission electron micrograph of a cell from the root of thale cress, Arabidopsis thaliana. [Figure 1.1]
Sucrose is a disaccharide. Fig. 2.1 shows how sucrose is broken down in a reaction with hydrochloric acid. [Figure 2.1]
Researchers isolated a sucrase enzyme from the bacterium Bacillus subtilis. They immobilised the enzyme in alginate beads. The researchers investig...
Fig. 4.1 is a ribbon model of a molecule of haemoglobin. [Figure 4.1]
The toxins released by some pathogenic bacteria can be altered chemically so that they are harmless. These harmless toxins are called toxoids. Toxo...
Water absorbed by plant roots travels by different pathways from root hairs to the xylem. Fig. 6.1 shows these pathways in the root of Ranunculus a...
Fig. 1.1 is a drawing of a photomicrograph of a spongy mesophyll cell from a leaf. [Figure 1.1]
In 1953, James Watson and Francis Crick published details about the structure of DNA. They used experimental results from other scientists to help ...
Bacteria may be classified according to differences in cell wall structure. The differences are shown by using the Gram stain. • A Gram-positive ba...
Fig. 4.1 is a photomicrograph showing some cells in interphase and some cells in stages of mitosis. [Figure 4.1]
When tobacco smoke is inhaled, chemicals such as nicotine and carbon monoxide enter the circulatory system through the gas exchange system. Tar bui...
Enzyme inhibitors and monoclonal antibodies can be used in the treatment of disease.
Fig. 1.1 is a photomicrograph of root tip meristem. Different stages of the cell cycle are visible. Some cells are in the same stage of the cell cy...
Adipose tissue, which is composed of cells known as adipocytes, stores large quantities of triglycerides and functions as an energy storage tissue....
Nerium oleander is a xerophytic plant. A photomicrograph of a section through the leaf of N. oleander is shown in Fig. 3.1. [Figure 3.1]
Oxygen enters the blood stream from the alveoli in the lungs and carbon dioxide leaves the bloodstream to enter the alveoli. Most of the oxygen is ...
The fig tree, Ficus carica, and the papaya tree, Carica papaya, produce a milky-looking fluid known as latex. The latex is released when plant tiss...
(a) Fig. 6.1 is a list of infectious diseases. Each of the statements A to D describes a feature that applies to one or more of these diseases. [Fi...
Milk contains proteins which are used to make cheese. During cheese making, bacteria are added to the milk. The bacteria change the pH of the milk ...
J1 is a slide of a stained transverse section through a plant leaf. You are not expected to be familiar with this specimen. (a) The specimen on J1 ...
You are required to investigate the effect of concentration of hydrochloric acid (independent variable) on the rate of diffusion. The investigation...
M1 is a slide of a stained transverse section through a plant leaf. You are not expected to be familiar with this specimen. Use a sharp pencil for ...
Fruit growers need to know the concentration of sugars, such as sucrose, in the fruit so that it can be picked at the best time. As the fruit matur...
K1 is a slide of a stained transverse section through a plant stem. You are not expected to be familiar with this specimen.
The Sumatran orangutan, Pongo abelii, is found only on the island of Sumatra, Indonesia. Fig. 1.1 shows a Sumatran orangutan. [Figure 1.1] (a) The ...
Scientists have found very little evolutionary change in populations of two Australian songbirds, the zebra finch, Taeniopygia guttata castanotis, ...
3 (a) The lac operon is a section of DNA present in the genome of the bacterium Escherichia coli. The structural genes of the operon are only fully...
4 Domestic goats, Capra hircus, show a wide range of coat patterns and colours. One gene involved in coat colour and pattern has multiple alleles. ...
5 (a) Pigs are farm animals used for livestock in some parts of the world. The first genetically modified (transgenic) pigs were produced in 1985. ...
6 (a) Fig. 6.1 shows a transmission electron micrograph of a section through a mitochondrion. [Figure 6.1] Fig. 6.1 Table 6.1 sho...
7 (a) Fig. 7.1 outlines the process of non-cyclic photophosphorylation in the chloroplast of a leaf mesophyll cell. [Figure 7.1]
8 (a) In mammals, the nervous system and the endocrine system coordinate responses to the changes in internal and external environments.
The Sumatran tiger lives on the island of Sumatra, Indonesia. Fig. 1.1 shows a Sumatran tiger.