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165 results for “nucleus”
…them. No chemical reaction causes this. No heating, cooling or crushing changes it. The instability is in the nucleus, and it is the nucleus that this whole sub-strand is about. Nuclear vocabulary Nucleon - a particle in…
What the nucleus contains, what it does, and why a red blood cell is the famous exception. Plant and animal cells in detail. You can already point to the nucleus on a drawing. Biology 1.3 Cell Structure and Specializatio…
…ns without it. The cytoplasm. Integrated Science 2.1 The Cell The dark round spot in your onion cells was the nucleus. It is the smallest part you could see clearly, and it is in charge of everything the cell does. The n…
…s the point of this lesson. Biology asks what is living in the slide. Chemistry is the iodine that stains the nucleus so you can see it. Physics is the glass lenses and the reason you still cannot see ribosomes, however …
Almost all the mass is in a tiny nucleus; almost all the volume is empty. Where the three particles sit. Chemistry 1.2 The Atom If atoms were solid balls packed together, your desk would be a continuous block of matter. …
The nucleus at the centre holds protons and neutrons and nearly all the mass. Electrons stay on shells. Carbon-12: 6 protons, 6 neutrons, electrons 2.4. Charge, place and mass of proton, neutron and electron. Integrated …
… the electron shells. If it did, the atom would just be ionised, and Z would not change. It is created in the nucleus when a neutron changes into a proton. Beta-minus particle A beta particle (β−) is a fast electron emit…
…and it takes place deep inside the ovary, out of sight. Fertilisation Fertilisation is the fusion of the male nucleus from the pollen grain with the female nucleus in the ovule. The result is a zygote. The four steps 1. …
A five-step Bohr diagram: nucleus labels, then electrons on shells. Electron arrangements of the first twenty. Chemistry 1.2 The Atom An arrangement such as 2,3 is a sentence. A Bohr diagram is the picture of that senten…
…ater than Z. Extra neutrons dilute the proton–proton repulsion without adding extra charge. Off the band, the nucleus decays towards it. Beyond Z = 83 (bismuth) the band ends: there is no stable nuclide at all. Too many …
…ton repulsion. The neutron-to-proton ratio. Physics 2.2 Radioactivity and Stability of Isotopes Two protons a nucleus apart repel each other millions of times more strongly than gravity pulls them together. Something els…
…on, and it is where a new individual begins. Fertilisation and the zygote Fertilisation is the joining of the NUCLEUS of a sperm cell with the NUCLEUS of an egg cell. The single cell that results is called a ZYGOTE. The …
Energy level diagrams in this course use dots, not crosses. Draw the nucleus, concentric shells, then place electron dots on the rings. Sodium 2.8.1 is the worked method. Arrangements of C, O, Na and Cl. Integrated Scien…
…chnology, and the reason it is treated with such caution. Nuclear fission Fission is the splitting of a heavy nucleus into two lighter nuclei, with the release of neutrons and a large amount of energy. It is usually trig…
No mass, no charge, A and Z unchanged; the most penetrating emission. Beta particles from the nucleus. Physics 2.2 Radioactivity and Stability of Isotopes After an alpha or beta decay the new nucleus is often still “exci…
… keeps and what it loses Keeps: a thin layer of cytoplasm, the cell membrane, and the sieve plate. Loses: the nucleus, most organelles, and a large vacuole. Losing the nucleus leaves space for flow. Keeping cytoplasm and…
A biconcave disc with no nucleus, packed with haemoglobin, built to carry oxygen. Specialised cells (overview) and the nucleus lesson. You know why losing a nucleus is a trade-off. Biology 1.3 Cell Structure and Speciali…
An electron has charge -1, occupies shells around the nucleus, and has tiny relative mass (about 1/1840). Lithium shows two inner electrons and one outer. Proton and neutron in the nucleus. Integrated Science 1.1 Structu…
A neutron has charge 0, sits in the nucleus, and has relative mass about 1. It adds mass without adding charge. Hydrogen has no neutron; helium has two. The proton: positive, nucleus, mass about 1. Integrated Science 1.1…
A proton has charge +1, sits in the nucleus, and has relative mass about 1. The proton count tells you which element you have. Atom, element and particle. Integrated Science 1.1 Structure of the atom Inside every atom is…
A helium nucleus: charge, mass, range, and what it does to A and Z. The strong force and why large nuclei fail. Physics 2.2 Radioactivity and Stability of Isotopes When a heavy nucleus is too large, it often throws out a…
A bacterium is one cell with no true nucleus. Binary fission, Kenyan diseases, and why antibiotics can work. The overview of bacteria, fungi and viruses, and that antibiotics target bacterial structures. General Science …
…ttle tops, seeds, wire, clay. A model you can hold is how many learners finally stop putting electrons in the nucleus. It is also how you see that the model is a lie about scale. Build one atom well 1. Choose an element …
…SAME in both CELL MEMBRANE — chooses what enters and leaves. CYTOPLASM — where the chemical reactions happen. NUCLEUS — the control centre. ### Only in the PLANT cell CELL WALL — so plant cells have a fixed box shape. CH…
…y shells of different energy; the first four matter for the first twenty elements. Electrons live outside the nucleus, not in it. Chemistry 1.2 The Atom Electrons are not sprinkled like sugar. They occupy energy levels, …
…ence corrects itself. Rutherford did not insult Thomson; he did a new experiment. Bohr did not throw away the nucleus; he added shells. The lithium diagram in lesson 1 is a Bohr picture sitting on a Rutherford nucleus. D…
… Chemistry is the reactions. Physics is the energy change and the surfaces those reactions need. Control: the nucleus The nucleus holds DNA - the instructions for proteins the cell will make, and for when the cell divide…
… column of living cells with perforated end walls called sieve plates. The cells have little cytoplasm and no nucleus. Beside each element sits a companion cell, which has a nucleus and dense cytoplasm. It keeps the siev…
…t all of an atom is empty space, with a dense centre and a lot of nothing around it. The centre is called the nucleus. It holds two kinds of particle. Moving around the nucleus, much further out, are electrons. The three…
…ell enough to stop. Bacteria Bacteria are single-celled organisms with a cell wall and cytoplasm, but no true nucleus - their DNA lies free in the cytoplasm as a loop. They are extremely small, typically about 1 to 5 mic…
Writing down what a decay does to a nucleus, and measuring how fast a sample disappears. The previous lesson. Physics 2.2 Radioactivity and Stability of Isotopes A nucleus that emits an alpha particle is no longer the sa…
…ygen to form oxyhaemoglobin. Shape. Biconcave discs, which give a large surface area for taking up oxygen. No nucleus. In mammals they lose the nucleus, leaving more room for haemoglobin. Number. About five million per c…
Neutrons add mass and help hold the nucleus together, without changing the element. The proton as the identity particle. Chemistry 1.2 The Atom If protons were the only heavy particles, every nucleus of the same element …
…nd. Physics 2.2 Radioactivity and Stability of Isotopes Almost all the mass of an atom sits in a tiny central nucleus. The rest of the atom is empty space with a few orbiting electrons. Radioactivity is a nuclear event. …
…protons is the one number that decides which element you have. Inside the atom: you know a proton sits in the nucleus and carries charge +1. Chemistry 1.2 The Atom Cut a carbon atom in any way you like and you still have…
Irregular cells with a nucleus, specialised to defend the body against pathogens. Red blood cell. You can already contrast a cell that carries oxygen with one that keeps a nucleus. Biology 1.3 Cell Structure and Speciali…
1. State two functions of the nucleus. 2. What does the nucleolus make? 3. Name one human cell that has no nucleus when mature, and give one advantage and one disadvantage of that. 4. Why does iodine make the onion nucle…
1. Describe the appearance of the nucleus on a stained slide. 2. Give three functions of the nucleus. 3. What are chromosomes, and how many are in a human body cell? 4. Why is the nucleus often at the edge of a plant cel…
…tation. The menstrual cycle. General Science 1.3 Human Reproduction Fertilisation is the joining of the sperm nucleus and the egg nucleus to form a zygote. The zygote then divides and settles in the uterus lining, in a p…
Fungal cells have a true nucleus. They grow as hyphae or as yeasts, spread by spores, and need antifungals not antibiotics. Bacterial structure, and that fungi were named as a third group in the opening lesson. General S…