Unit 0 - Basic Skills
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List and describe the characteristics of living organisms
Movement - ability to move Respiration - organisms taking in oxygen and giving out carbon dioxide. The release of energy from the chemical breakdown of glucose. Glucose reacts with O2 to make ATP. Sensitivity - can sense the organism’s surroundings. Circulation - Able to move food, gasses, and wastes around their body. eg circulation of blood Growth - Getting bigger (more matter) Reproduction - cells and offspring Excretion - getting rid of waste products Nutrition - need nutrition to function.
What are living organisms made of?
Cells
Draw and describe the structure of a palisade cell and an animal cell (liver) as seen under a light microscope
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Describe functions of structures of palisade and liver cell as seen under a microscope.
Palisade: Cell wall - strengthens the cell. Helps the plant stay stiff. Turgid. *Cell membrane - controls the entry and exit of chemicals into the cell. Nucleus - contains genetic material which controls the cell’s activities Chloroplast - contains chlorophyll which absorbs light energy for photosynthesis ()Vacuoles - contains chemicals/liquid. *Cytoplasm - Most chemical reactions take place here, controlled by enzymes. Stores organelles. *Mitochondria - most energy is released by respiration here. Liver cell: Ribosome - protein synthesis happens here. Parts with an * is also present in animal cells.
How to calculate magnification and size of specimens using millimetres as units
Magnification = eyepiece x * lens x eg eyepiece = 10x, lens = 40x, total magnification = 400x Size of real specimen = measured length / magnification eg measured specimen = 260mm = 260,000 um. 260,000 / 900 = 2888.89 um um = micrometre
List the chemical elements that make up carbohydrates, fats and proteins
Carbohydrates = hydrogen, carbon and oxygen Fats = hydrogen, carbon, oxygen. Same as carbohydrates Proteins = Nitrogen. Some may contain sulphur.
Describe the structure of large molecules made from smaller basic units
Simple sugars to starch and glycogen Amino acids to proteins Fatty acids and glycerol to fats and oils
Describe tests for starch, reducing sugars, protein and fats
Starch - add iodine. Positive = turns purple/black Reducing sugars - Benedict’s solution. Blue -> orange/green/red. Protein - Biuret solution. Blue -> purple. Fats - Sodium hydroxide and shake. Cloudy suspension. Or smear on paper towel. Or add ethanol.
List the principal sources of, and describe the importance of carbohydrates, fats, proteins, vitamins (C and D only), mineral salts (calcium and iron only), fibre (roughage), water.
Carbohydrates: Sugars (glucose, fructose), starches (potatoes, rice, bread), cellulose (vegetable, fruits, wood. Supplies about 60% of our energy. Cannot be used by the body, helps food push through. If we don’t get it: lack of energy, lose weight, body processes slow. Fats: Oils, meat, dairy, nuts. Stored by the body, they provide a store of energy. Supply about 25% of our energy. Insulation. If we don’t get it: lose weight. Proteins: Eggs, meat, fish. Muscles and ligaments/tendons, Hair/skin are made of proteins. Supplies materials for muscles. If we don’t get it: Bad hair/skin/injuries Vitamin C: Citrus fruits. For eyesight, skin, hair, immune system. Vitamin D: Sunlight. For enhancing absorption of calcium and phosphate. Calcium: from cheese, milk, yoghurt. For growth and maintenance of healthy teeth and bones. Iron: liver, vegetables, blood. To make blood. Fibre: Vegetables, whole grains. For healthy bowels. Water: tap. For body temperature regulation, cushions and lubricates joints, nourishes and protects the brain, removes waste through perspiration, bowel movements and regulation. Our bodies are composed mostly of water - about 60%.
Describe the use of microorganisms in the manufacture of yoghurt.
The souring of milk is a fermentation process, as it takes place better when oxygen is absent. Fresh milk contains sugars and some bacteria. the bacteria feed on the sugars in the milk. The main sugar in milk is called lactose. Lactose is converted into lactic acid by bacterial fermentation, the increased acidity sours and thickens the milk.
Describe the deficiency symptoms for vitamins C & D, mineral salts (calcium and iron)
Vitamin C: Anemia (low red blood cell count). Easy fatigue and loss of energy, dizziness, shortness of breath. Scurvy: general weakness, anemia, gum disease, skin haemorrhages. Vitamin D: Soft bones (rickets). Bone pain and muscle weakness. Calcium: Osteoporosis (fragile bones), rickets (softening of bones) Iron: Anaemia (low red blood cell count). Tiredness and lack of energy.Dizziness. Coldness in hands and feet.
Define “atom” and “molecule”
Atom: The smallest stable unit of matter. Molecule: 2 or more atoms chemically joined together.
State the distinguishing properties of solids, liquids and gases
Solids: Particles are tightly packed, usually in a regular pattern. Retains a fixed volume and shape (rigid particles locked into place) Cannot be compressed Does not flow easily (rigid particles can’t move/slide past one another) Dense Liquids: Particles are close together with no regular arrangement. Assumes shape of container (particles slide past one another) Not easily compressible Definite volume Most liquids expand with an increase of temperature and constant air pressure Dense Gases: Particles are well separated with no regular arrangement. Assumes shape and volume of its container (particles have enough energy to overcome attractive forces) The volume of a quantity of gas is dependent on its temperature and the surrounding pressure. Compressible Flows easily Have no definite shape or volume If unconstrained the gases will spread out indefinitely Low density.
Describe qualitatively the molecular structure of solids, liquids and gases.
Solids: Closely packed. Regular pattern Liquids: Close together with no regular pattern Gases: Particles well separated with no regular arrangement
Relate the properties of solids, liquids and gases to the forces and distances between molecules and to the motion of the molecules.
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Describe the structure of an atom
A nucleus containing protons and neutrons surrounded by a cloud of electrons
State the charges and masses of protons, neutrons and electrons
Protons: Positive. Heavy Neutrons: Neutral. Heavy Electrons: Negative. Light.
Define PROTON NUMBER and NUCLEON NUMBER
Proton number: the number of protons in an atom Nucleon number: the number of protons AND neutrons.
Describe the build-up of electrons in “shells” and understand the significance of the noble gas electronic structures and of valence electrons
Electron arrangement: 1st shell: 2 2nd shell: 8 3rd shell: 8 4th shell: an amount. Nobel gases have a full outer electron shell so they do not react. Valence shell: outermost shell
Use the proton number and the simple structure of atoms to explain the layout of the periodic table with reference to the elements of proton number 1 to 20.
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Identify physical and chemical changes, and understand the differences between them.
Physical - changes form but keeps its same chemical composition (reversible) Chemical - when a substance’s composition has been changed.
Difference between elements, compounds and mixtures
Elements only contain one type of atom and cannot be broken down into a simpler type of matter by either physical or chemical means and can exist as either atoms or molecules. Compounds consist of two or more DIFFERENT elements bound together. Can be broken down into a simpler type of matter by chemical means. Has properties that are different from its component elements. Always contains the same ratio of its component elements. Mixtures consist of two or more different elements and/or compounds PHYSICALLY mingled. Can be separated into its components by physical means and often retains many of the properties of its components. Eg powdered iron and powdered sulphur can be separated using a magnet.
Describe methods of separation and purification: filtration, crystallisation, distillation, fractional distillation.
Filtration - separates insoluble solids from liquids Crystallisation - copper sulfate. A saturated solution warmed and cooled so crystals will start to grow. Distillation - removes souvent from solute, but then condenses it back into liquid. Fractional distillation - Fractional distillation differs from distillation only in that it separates a mixture into a number of different parts, called fractions. A tall column is fitted above the mixture, with several condensers coming off at different heights. The column is hot at the bottom and cool at the top. Substances with high boiling points condense at the bottom and substances with low boiling points condense at the top. Like distillation, fractional distillation works because the different substances in the mixture have different boiling points. Eg oil fractions
Describe paper chromatography
Used to separate and identify components of a mixture. Identify colouring agents for example in food or ink.