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.
Telomeres are lengths of DNA that consist of repetitive nucleotide sequences. Telomeres are present in eukaryotic chromosomes.
Monoclonal antibodies can be used in the treatment of disease.
Invertase is an enzyme that catalyses the breakdown of sucrose into glucose and fructose. Invertase can be extracted from yeast cells. You will inv...
When plant tissue is placed into a solution of sodium chloride, water moves between the sodium chloride solution and the cells in the plant tissue....
L1 is a slide of a stained transverse section through a plant organ. [Figure 2.1] is a diagram of a stage micrometer scale that is being used to ca...
Organisms need a source of energy for many cellular processes. Respiration involves the release of energy from energy-rich molecules for the synthe...
A respirometer can be used to investigate how temperature affects the rate of respiration of woodlice. Woodlice are small invertebrate animals. Fig...
Porphyria is a group of rare genetic diseases in which molecules called porphyrins accumulate in the body. Three examples of porphyria are: • X-lin...
Scientists have invented a way of producing food by artificial photosynthesis. • Solar panels convert sunlight energy into electricity. • The elect...
The Galápagos is a group of islands with a high biodiversity.
In the kidney, various molecules move between the blood and the kidney nephron. Table 6.1 describes the movements of molecules at three regions of ...
Insulin is an example of a cell-signalling molecule of the endocrine system.
The presence of gibberellins in a plant cell leads to the expression of genes involved in stem elongation. Describe how gibberellin causes stem elo...
A species is classified into one of three domains.
During the course of an action potential, the potential difference across a neurone membrane changes. Table 10.1 shows the potential difference acr...
Fig. 1.1 is a diagram of part of the inner membrane of a mitochondrion. [Figure 1.1]
When organisms reproduce, they pass on their alleles to the next generation. There are many factors that can affect how allele frequencies change o...
Rice, Oryza sativa, is an important grain crop. A rice grain is a seed and can have a structure known as an awn, which projects from the tip of the...
Sexual reproduction in plants and animals involves: the formation of gametes as a result of meiosis the process of fertilisation.
A number of diseases in humans can be treated using recombinant human proteins. These are produced by recombinant DNA technology.
Guard cells are located in the epidermis of the leaves of most plants. When environmental conditions change, this causes changes in guard cells tha...
An axon membrane is described as being at its resting potential when an action potential is not occurring.
A lichen describes a mutually beneficial association of a fungus with an organism termed a photobiont. An example of a photobiont is the green alga...
The biodiversity of an area can be assessed using a variety of sampling methods.
The grey seal, Halichoerus grypus, is an aquatic mammal that lives in the North Atlantic Ocean. It feeds on fish, which it hunts at depths of up to...
Fig. 1.1 is a diagram of part of a liver cell. [Figure 1.1]
Natural selection and selective breeding (artificial selection) are processes that result in changes in the gene pool of a population. Natural sele...
An operon is a section of DNA found in prokaryotes.
The Grand Canyon is located in Arizona, USA. It is estimated to have formed over five million years ago as the Colorado River began to create a dee...
Recombinant DNA technology is used to make recombinant human proteins. Two of the available methods to obtain the gene of interest are: • cutting t...
The kidneys have a role in excretion and in osmoregulation. Excretion is the removal of the waste products of metabolism or the removal of substanc...
A chloroplast is composed of many structures, each with a different function. Several chloroplast structures are listed. stroma lamellae thylakoid ...
The Boelen's python, Simalia boeleni, is a non-venomous snake found only on the island of Papua New Guinea. Fig. 8.1 shows a Boelen's python. [Figu...
Most carnivorous mammals need to move to hunt their prey.
The golden poison dart frog, Phyllobates terribilis, lives in the Colombian rainforest ecosystem. Fig. 10.1 shows golden poison dart frogs. [Figure...
Pepsin is an enzyme that is present in gastric juice. Gastric juice is secreted into the stomach of humans and many other animals. Pepsin catalyses...
Golden orb weaver spiders, Nephila pilipes, are found in East Asia, South-east Asia and Australia. They are active in the day and at night. Golden ...
Phosphatases are enzymes that catalyse the removal of phosphate from other molecules, releasing inorganic phosphate (P₁). A phosphatase can be extr...
Sponges are immobile, aquatic animals that live on rocks and sediment at the bottom of salt water environments. [Figure 2.1] Fig. 2.1 shows an ex...
Drosophila melanogaster is a species of fruit fly. [Figure 1.1] shows a female fruit fly and a male fruit fly. A typical fruit fly is 3 mm in lengt...
Echidnas are mammals that live in Australia and New Guinea. [Figure 2.1] shows an echidna. Scientists analysed the milk produced by female echidnas...
Which cell structure can be seen only with an electron microscope?
Which is a feature of all prokaryotic cells?
A lymphocyte has a diameter of 1 × 10¯² millimetres (mm). What is the diameter in nanometres (nm)?
Which plan diagram of a transverse section of a leaf correctly shows the position of xylem and phloem as well as the fact that the palisade mesophy...
The photomicrograph of a cell has a 2 cm scale line labelled 5 µm. [Photomicrograph of a cell with a 5 µm scale line] What is the magnification of ...
What is a function of the smooth endoplasmic reticulum?
Which combination of bond types correctly shows the weak and strong bonds that hold a molecule of protein in shape?
Which statement is true for cellulose, but not true for protein?
The diagram shows a triglyceride molecule that has been partially hydrolysed. [Diagram of a partially hydrolysed triglyceride molecule] What will b...