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.
Cyclin-dependent kinases (CDKs) are enzymes that regulate the cell cycle.
DNA and RNA are polynucleotides.
Plasmolysis may be seen in onion cells that have been put into a sodium chloride solution. Plasmolysis occurs when water moves out of the cells and...
Many plants store starch in their roots. The amount of starch present in roots can vary with the seasons. In the summer months, when plants are act...
Some fruits contain protease enzymes. These enzymes can denature the proteins in milk, causing the milk to clot. You will investigate the effect of...
K1 is a slide of a stained transverse section through a plant leaf.
Yeast cells contain enzymes that catalyse the breakdown of sugars, such as glucose and sucrose, to produce ethanol and carbon dioxide. As the sugar...
L1 is a slide of a stained transverse section through a plant stem.
Oxygen is needed for aerobic respiration in cells. In eukaryotic cells, the mitochondrion is the organelle used for aerobic respiration.
Coordination in humans involves two main systems: the nervous system and the endocrine system. Paracrine cell signalling is a third way in which co...
Stomata in leaves respond to changes in environmental conditions by opening and closing. This regulates carbon dioxide uptake and water loss.
White-clawed crayfish, Austropotamobius pallipes, live in rivers and lakes in Europe. In the 1850s, the North American signal crayfish, Pacifastacu...
Photosynthesis is the energy transfer process that occurs in chloroplasts. Fig. 5.1 shows some biochemical events that occur in a chloroplast durin...
Many different genes are involved in the production of pigments in mammals. One example is the TYR gene.
It has been hypothesised that the mutation rate of an animal species may affect how fast animals of that species age and how long they live (lifesp...
Bears are several species of mammal in the family Ursidae. Climate change and loss of habitats due to human activity have reduced the size of some ...
The harlequin ladybird, Harmonia axyridis, is an insect that shows discontinuous variation in colour pattern and continuous variation in body size.
Humans detect the sweet taste of sucrose sugar using chemoreceptor cells in taste buds on the tongue. The red admiral butterfly, Vanessa atalanta, ...
Osmoregulation is the control of the water potential of body fluids such as blood.
Variation exists in populations of a species and this may provide the opportunity for evolution to occur.
The tortoise beetle, Chelymorpha alternans, is an insect found in Panama that has several different colour patterns. [Figure 3.1] Researchers have ...
Genes have a role in determining the overall phenotype of an organism.
The gene BRCA1 is expressed in breast tissue and in several other tissues of the body. BRCA1 codes for a tumour suppressor protein. This protein is...
[Figure 6.1] is a diagram of part of a mitochondrion.
A student investigated the effect of temperature on the rate of photosynthesis at two different light intensities. The rate of photosynthesis was d...
[Figure 8.1] is a diagram of a sensory neurone.
The Asian common toad, Duttaphrynus melanostictus, arrived accidentally in eastern Madagascar in 2010 on a ship. [Figure 9.1] shows an Asian common...
In mammals, blood glucose concentration is maintained around a set point so that the mammal can function efficiently. This is an example of homeost...
Fig. 1.1 outlines the effect of antidiuretic hormone (ADH) on the cells of the collecting duct. The cell-signalling mechanism of ADH is similar to ...
Phenotypic variation exists in many forms. (a) Some examples of phenotypic variation in plants and animals are described in Table 2.1. Complete Tab...
In plants and humans, the phenotype of an organism is determined by the genotype and the environment. (a) Plants from the genus Primula have differ...
Genetic engineering is a technique used to modify the genetic material of a specific organism to change a characteristic.
BRCA2 is a tumour-suppressor gene. Its gene product, BRCA2, is involved in DNA repair. If the DNA cannot be repaired, BRCA2 has a role in causing t...
In plants, stomata open and close in response to changes in environmental conditions. Explain why stomata need to open and close according to envir...
(a) Experiments were carried out to determine the effect of light intensity on the rate of photosynthesis of a species of the unicellular protoctis...
(a) Fig. 8.1 is a diagram of a mitochondrion. [Figure 8.1]
(a) Fig. 9.1 shows how the mean global atmospheric carbon dioxide concentration has changed over the 800000 (800 ×103) years leading up to the year...
(a) Fig. 10.1 is a diagram of part of a neurone membrane while the resting potential is maintained. [Figure 10.1]
A student investigated the effect of wind speed on the rate of transpiration. The student used the flowering plant Japanese spiraea, Spiraea japoni...
The responses of plant species to water stress can be classified as either isohydric or anisohydric. • Isohydric plant species close stomata during...
Female mosquitoes feed on human blood. Some species of mosquitoes are vectors of human pathogens. For example, female mosquitoes of the species Aed...
Tree plantations are areas where trees are planted for a particular purpose. Some tree plantations increase the supply of wood for construction and...
Tumours may be described as benign or malignant. Malignant tumours can lead to greater complications for the person with the tumour. Early identif...
Blood vessels must be able to withstand and maintain varying blood pressures. There are several methods that could be used to determine the strengt...
Gibberellins are a group of plant hormones that are involved in the elongation of plant stems. A student investigated the effect of two different c...
Which row shows possible uses of an eyepiece graticule?
Which statement about a light microscope is correct?
The electron micrograph shows a cell. [Electron micrograph of a cell] What is the actual maximum length of the cell?
The table compares some biochemical molecules of P, Q, R and S. Which row correctly identifies P, Q, R and S?
Which cell structures contain enzymes and are enclosed by a double membrane? 1 nucleus 2 mitochondrion 3 chloroplast