form 1 science notes

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FORM 1 SCIENCE NOTES What is Science? 1. Science is a systematic study of nature and how it affects our lives and the environment. 2. Natural phenomena are events that happen around us. 3. Example of natural phenomena : - Growth of a baby into an adult - An object falling to the ground - Melting of ice - Volcano eruptions, earthquakes and tsunami - Thunderstorm, snow and lightning 4. Science is important to us because it - Enables us to understand ourselves and our surrounding environment - Solves mysteries of science through the systematic investigation - Contributes to new discoveries inventions and knowledge gained - Improve our standard of living and quality of our environment - Creates science-based job opportunities Hazard Warning Symbols 1. Flammable substances y May become hot and finally ignite in contact with air y White phosphorus, yellow phosphorus, petrol, kerosene, ethanol, methylated spirit 2. Explosive substances y May explode under the effect of a flame or if subjected to shocks or friction y Sodium, potassium, mixture of hydrogen and air, hydrazoic acid, hydrazine, diazo 3. Corrosive substances y May destroy or burn living tissues on contact with them y Hydrogen peroxide, concentrated hydrochloric acid, concentrated sodium hydroxide 4. Poisonous or toxic substances y May cause immediate or long term health risks and even death if inhaled, ingested or absorbed into the skin y Mercury, bromine, lead, sodium cyanide, chlorine, hydrogen sulphide, benzene 5. Irritating or harmful substances y May cause discomfort or inflammation to the body y Ammonia, chloroform, bromine vapour, chlorine 6. Radioactive substances y May cause cell mutation y X-ray, uranium, plutonium, thorium, radium The steps in a scientific investigation Identifying the problem Forming a hypothesis Planning the experiment y Identifying variables y Determining apparatus and materials y Determining the procedure to carry out the experiment y Determining method to collect and analyses data Controlling the variables Collecting data Analyzing and interpreting data Drawing a conclusion Writing a report Physical quantities and their units 1. Five physical quantities which can be measured - Length - Mass - Time - Temperature - Electric current 2. Physical quantities can be measured in systeme international dunites (SI) units. Physical quantity SI Unit Symbol Length Metre m Mass Kilogram Kg Time Second s Temperature Kelvin K Electric current Ampere A Prefix Symbol Numerical value Mega M 1000000 Kilo K 1000 Centi C 0.01 Milli M 0.001 Micro 0.000001 Weight and Mass Mass 1. Mass is the amount of matter in an object. 2. The more the matter in an object, the bigger is its mass. 3. SI Unit kilogram (kg) 4. Mass can measured in gram (g) and milligram (mg). 5. Mass can be measured by beam balance and lever balance. I kg = 1000 g 1g 1000 mg Weight 1. Weight is the gravitational force acting on an object. 2. The greater the force pulling the object towards centres of Earth, the heavier the object. 3. Weight is measured in Newton (N). 4. Compression balance and spring balance is used to measure weight. Cell as a unit of life 1. A cell is the basic unit of living things which can function on its own. 2. Cells are microscopic and cannot be seen with naked eye. General structures and functions of animal cells and plant cells Most cells consist of protoplasm which is surrounded by cell membrane. Structures Characteristics Function Nucleus - Is dense and spherical structure. - Is surrounded by a nuclear membrane. - Contain chromosomes which carry genetic materials that determine the characteristics of organisms. It is the control centre of the cell because it controls all chemical reactions in the cell. Cytoplasm - Is a flexible, colorless, jelly-like substance. - Is surrounded by a cell membrane. - Contains water and chemical substances such as proteins, stored food and minerals. Acts as the medium for chemical reactions of the cell. Cell membrane - Is a thin, elastic layer on the outer surface or animal cells. - Contains fats and proteins. - Is partially permeable. This means that it allows certain substances to pass through. Controls the movement of substance in and out the cell. Cell wall - Is a thick and rigid layer on the outer surface of plant cells. - Is mainly composed of tough substance called cellulose. It gives the cell a definite shape. Chloroplasts - Are tiny, oval structures found inside the cytoplasm of most They enable green plants to manufacture their won food. 1 N = 0.1 kg 1 kg = 10 N plant cells. - Contain a green pigment called chlorophyll. - Absorbs light energy and uses it to make food. This process is called photosynthesis. Vacuoles - Is a fluid-filled sac found in the cytoplasm. - Is surrounded by a membrane and is filled with cell sap. - Contains of a solution of sugars, proteins, minerals. The vacuole acts as a store of various substances such as water, food, pigments, enzymes, and waste products. Unicellular organisms - Are simple organisms that are made up of only one cell - In animal kingdom: Amoeba and Paramecium - In plant kingdom: Pleurococcus, Euglena, Chlamydomonas and yeast. Multicellular organisms - Are organisms which have more than one cell - In animal kingdom: mammals, amphibians, reptiles, birds, dish, and Hydra - In plant kingdom: mosses, algae (Chondrus, Spirogyra), ferns. Life processes of unicellular and multicellular organisms 1. Unicellular organism - Can grow - Sensitive to light, chemical substances, and sharp objects - Main food is bacteria - Its excretory organ is the vacuole - Moves by extending pseudopodium - Breathes through cell membrane - Reproduces asexually 2. Multicellular organism - Main food is zooplankton - Excretes through its excretory pores - Moves by means of its tail and fins - Can grow - Sensitive to light and vibrations in water - Reproduces sexually - Breathes through gills Cell organization in the human body 1. Types of cells found in human body : a.) Nerve cells conducts nerve impulses b.) Red blood cells transport oxygen from lungs to all cells c.) White blood cells d.) Skeletal muscle cells controls movement of bones and organs of body e.) Reproduction cells f.) Epithelial cells controls exchange of substances g.) Bone cells functions in the support system of the body 2. Types of tissue a.) Epithelial tissue protects the tissues beneath it b.) Connective tissue connects one tissue to another tissue , supports organs in the body c.) Muscle tissue enables the movement of body parts d.) Nerve tissue enables body to respond to stimuli e.) Carries nerve impulses from one part of the body to another 3. Types of systems a.) Excretory system discards toxic waste products produced by the body cells b.) Reproductive system produces offspring c.) Respiratory system inhales oxygen and exhales carbon dioxide d.) Lymphatic system defends the body against disease e.) Skeletal system provides support and protection to soft internal organs f.) Blood circulatory system transport food substances, oxygen, hormones, and others to the entire body g.) Endocrine system produces hormones that control the bodys responses toward stimuli h.) Nervous system coordinates and controls all bodily activities related to impulses and reactions i.) Muscular system helps in movement of the body j.) Digestive system breaks down complex food into simple substances for easy absorption by body cells 4. Cells, tissues, organs and systems can be interconnected by the following chart : Cells Tissue Organ System Organism 5. The importance of organization of cells : a.) Enables body to perform life processes simultaneously b.) Ensure life processes function efficiently and smoothly What is matter? Everything that has mass and occupies space is called matter. The states of matter 1. Matter is made up of tiny particles which are separate. 2. These particles can be composed of atoms or molecules 3. An atom is the smallest particle of matter and cannot be further divided. 4. A molecule is made up of two or more atoms 5. Proofs that matter is made up of tiny and discrete particles - Dissolving copper (II) sulphate crystals in water - Diffusion of gas Arrangement of particles in matter Matter exists as solids, liquids and gases. 1. Arrangement of particles in solids : a.) Are arranged close together and in a regular pattern b.) Are very small spaces between particles of a solid c.) Cannot be compressed d.) Volume of a solid is definite 2. Arrangement of particles in liquids : a.) Are arranged closer but not in a regular pattern b.) Spaces between the particles of a liquid are bigger c.) Cannot be compressed d.) Shape is not definite e.) Known as fluids because of its flowing property 3. Arrangement of particles in a gas : a.) The particles of a gas are far apart and are not arranged in a regular pattern b.) Does not have define shape or volume c.) Large spaces d.) Volumes of a gas increases when the particles move apart e.) Can be compressed f.) Known as fluids because of their flowing property 4. Free motion or Brownian motion is the movement of particles in all directions at high speeds. The concept of density Density and buoyancy 1. Density of a substance is the mass per unit volume Formula: mass gvolume cm 2. The SI Unit for density is kg/m or kg m-. 3. The density of a substance depends on two factors : a.) Mass - The bigger its mass, the bigger is its density. b.) Volume - The bigger its volume, the smaller is its density. 4. Buoyancy of a matter refers to whether the matter floats on or sinks in another matter. 5. A solid that has a lower density than the density of a liquid will float on the surface of the liquid 6. A solid that has a higher den