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Cells and Chemistry. Find past papers and mark schemes. Find past papers and mark schemes for your exams, and specimen papers for new courses.

Find past papers and mark schemes

Can’t find your papers? Some question papers are not available online and older question papers and mark schemes are removed from our public website and Secure Key Materials (SKM) after three years because of copyright restrictions (except for Maths and Science).Not sure which exams you're taking? Ask your school or college.Following consultations with a cross section of teachers across subjects, we will now make all papers and mark schemes available on the AQA website free of charge from about 10 months after the exam (see what's available when). Students may find our Preparing for your exams webpages useful for their revision and exams. Teachers can get past papers earlier, starting 10 days after the exam, from Secure Key Materials. Sciences. GCSE Bitesize - Science. Biology. Clam FAQ!! - The Reef Tank. Phyto and Clams: In the first post of this thread it was suggested that Phyto be fed to Maxima clams,..

Clam FAQ!! - The Reef Tank

But it is a long held hobby myth that any clam under 3" should be fed Phyto, by means of the boal feeding method, or by puting a container over the clam and injecting phyto into the container,.. or more simply feeding it directly to the tank. There are certainly plenty of phyto supplements out there,.. and it is proven that clams do eat phyto, but do they need it? Why do we care? Top Shelf Aquatics. Aquarium Fish: Tropical Freshwater Fish and Saltwater Fish for Home Aquariums. Biology videos. Biology Topics. A. Base pairs and H bonds in DNA. Cell Biology. Chemistry. Chapter 2: Water. Chapter 5: Organic chemistry. Chapter 2: Rocks and Building Materials. Chapter 6: Plant Oils. Chapter 5: Products from Oil. Chapter 4: Crude Oil and fuels. Chapter 7: Our Changing Planet. Chapter 1: Fundamental Ideas. Chapter 1: The Periodic Table. Atoms. Elementary particle. In particle physics, an elementary particle or fundamental particle is a particle whose substructure is unknown, thus it is unknown whether it is composed of other particles.[1] Known elementary particles include the fundamental fermions (quarks, leptons, antiquarks, and antileptons), which generally are "matter particles" and "antimatter particles", as well as the fundamental bosons (gauge bosons and Higgs boson), which generally are "force particles" that mediate interactions among fermions.[1] A particle containing two or more elementary particles is a composite particle.

Elementary particle

Everyday matter is composed of atoms, once presumed to be matter's elementary particles—atom meaning "indivisible" in Greek—although the atom's existence remained controversial until about 1910, as some leading physicists regarded molecules as mathematical illusions, and matter as ultimately composed of energy.[1][2] Soon, subatomic constituents of the atom were identified.

Overview[edit] Atomic orbital. The shapes of the first five atomic orbitals: 1s, 2s, 2px, 2py, and 2pz.

Atomic orbital

The colors show the wave function phase. These are graphs of ψ(x, y, z) functions which depend on the coordinates of one electron. To see the elongated shape of ψ(x, y, z)2 functions that show probability density more directly, see the graphs of d-orbitals below. Each orbital in an atom is characterized by a unique set of values of the three quantum numbers n, ℓ, and m, which correspond to the electron's energy, angular momentum, and an angular momentum vector component, respectively.

Any orbital can be occupied by a maximum of two electrons, each with its own spin quantum number. Atomic orbitals are the basic building blocks of the atomic orbital model (alternatively known as the electron cloud or wave mechanics model), a modern framework for visualizing the submicroscopic behavior of electrons in matter. Electron properties[edit] Proton. Neutron. The neutron is a subatomic hadron particle that has the symbol n or n0.


Neutrons have no net electric charge and a mass slightly larger than that of a proton. With the exception of hydrogen-1, the nucleus of every atom consists of at least one or more of both protons and neutrons. Protons and neutrons are collectively referred to as "nucleons". Since interacting protons have a mutual electromagnetic repulsion that is stronger than their attractive nuclear interaction, neutrons are often a necessary constituent within the atomic nucleus that allows a collection of protons to stay atomically bound (see diproton & neutron-proton ratio).[4] Neutrons bind with protons and one another in the nucleus via the nuclear force, effectively stabilizing it. Atomic nucleus. A model of the atomic nucleus showing it as a compact bundle of the two types of nucleons: protons (red) and neutrons (blue).

Atomic nucleus

In this diagram, protons and neutrons look like little balls stuck together, but an actual nucleus (as understood by modern nuclear physics) cannot be explained like this, but only by using quantum mechanics. In a nucleus which occupies a certain energy level (for example, the ground state), each nucleon has multiple locations at once.

Build an Atom. Reactions. Chapter 3: Energy calculations. Chapter 3: Electrical Energy. Science Glossary. Physics. Chapter 5: Waves. Chapter 6: Electromagnetic Waves. Chapter 4: Generating Electricity. Calculating Speed and Velocity. Chapter 2: Using Energy. Chapter 1: Energy Transfer by Heating. GCSE Bitesize - Electronics. R.E. Buddhism. Buddhism (pronunciation: /ˈbʊdɪzəm/ or /ˈbuːdɪzəm/) is a religion[3] and dharma that encompasses a variety of traditions, beliefs and spiritual practices largely based on teachings attributed to the Buddha.


Buddhism originated in India sometime between the 6th and 4th centuries BCE, from where it spread through much of Asia, whereafter it declined in India during the middle ages. Two major extant branches of Buddhism are generally recognized by scholars: Theravada (Pali: "The School of the Elders") and Mahayana (Sanskrit: "The Great Vehicle"). Buddhism is the world's fourth-largest religion, with over 500 million followers or 7% of the global population, known as Buddhists. [web 1][5] Mahayana, which includes the traditions of Pure Land, Zen, Nichiren Buddhism, Shingon and Tiantai (Tendai), is found throughout East Asia.

Life of the Buddha "The Great Departure", relic depicting Gautama leaving home, first or second century (Musée Guimet). Buddhist concepts Dukkha Rebirth Saṃsāra. Geography. Tourism. Population. Course Information. Coasts. AQA Exam Board. GCSE Bitesize - Geography. GCSE Restless Earth. Glaciation. Languages. GCSE Bitesize - Spanish. Maths. GCSE. Average Speed, What is Average Speed, Average Speed Formula. A Man is traveling in his car from city A to city B and back.

Average Speed, What is Average Speed, Average Speed Formula

In the journey from city A to city B, he is traveling with the constant speed of 40 kmph, and he is traveling with the 45 kmph while he is coming back. The total journey took 3 hours to complete. Find the average speed of the car for the whole journey? As you can see that we are provided with the speed in both the direction, one can directly calculate the average speed by averaging the two speeds, but it is the wrong approach. Let us assume that the distance between two cities is D.Time taken is equal is 3 hours to complete the round trip journey.

Now, the correct approach for finding average speed is as follows, first find the distance in both the direction.DAB = 40 \times tDBA = 45 \times (3 - t) Now we will find the distance between the city A to B isD_{AB} = S_{AB} \times tD_{AB} = 40 \times 1.59 = 63.53 kmsSo, the average speed of the round trip journey isS_{AVG} = \frac{(D_{AB} + D_{BA})}{(T_{AB} + T_{BA})} GCSE Bitesize - Maths. All Subjects - Revision. English. GCSE - English. Unit 1 - Understanding and producing non-fiction texts. GCSE English Revision – Focussed Learning for Year 10 and Year 11. GCSE Bitesize - English. GCSE - English Literature.