Science Grade 9 - Applications of Micro-organisms, Eye and Ear, Nature and Properties of Matter, Force, Pressure, Human Circulatory System, Plant Growth Substances, Support and Movements of Organisms, and The Evolutionary Process

Science Notes - Grade 9, Part I

General Information

• Electronic textbooks are available at www.edupub.gov.lk.

• First Print: 2017, Second Print: 2018, Third Print: 2019.

• ISBN: 978-955-25-0162-3.

Messages and Foreword

• Message from the Minister of Education (Akila Viraj Kariyawasam):

  • Focus on adapting to rapid changes in technology and IT.

  • Importance of education in determining the future of the country.

  • Curriculum changes to suit the technological world.

  • Aim to become productive citizens and give proper value to the government's investment in education.

• Foreword (W. M. Jayantha Wickramanayaka, Commissioner General of Educational Publications):

  • Educational objectives are becoming more complex with global development.

  • Textbooks are designed to include subject-related information aligned with syllabus objectives.

  • Textbooks contribute to higher education, conduct, values, and learning experiences.

  • Maximize the use of provided textbooks.

Applications of Micro-organisms

• Micro-organisms: Unicellular or multicellular organisms not clearly visible with the naked eye.

  • Live in our environment and body.

  • Most are favorable, some are harmful.

  • They grow fast and have a high rate of reproduction.

  • Adaptable to different environmental conditions and modes of nutrition.

  • Categorized into bacteria, fungi, algae, and protozoa. Viruses are studied under micro-organisms as well.

• Table 1.1 - Characteristics of different micro-organism categories and examples for them

  • Bacteria:

    • Unicellular and microscopic with different body shapes.

    • Found in every type of environment on Earth. Example: Lactobacillus bulgaricus, Bacillus anthracis, Acetobacter aceti, Vibrio cholerae.

  • Fungi:

    • Unicellular or multicellular, some reproductive organs visible to the naked eye (e.g., mushroom).

    • Thrive on moist surfaces. Examples: Mucor, Saccharomyces.

  • Protozoa:

    • Unicellular and microscopic, use cilia, pseudopodia, and flagella for locomotion.

    • Live in aquatic environments and other organisms. Examples: Amoeba, Paramecium, Euglena, Plasmodium.

  • Algae:

    • Unicellular or multicellular, filamentous or thallus body forms.

    • Microscopic algae floating on water surfaces are called phytoplanktons.

    • Possess chlorophyll and can perform photosynthesis. Example: Ulva, Chlamydomonas, Spirogyra, Diatoms.

  • Viruses:

    • Electron microscopic, display living and non-living characteristics.

    • Multiply only inside living cells; no cellular organization.

    • Do not show respiration and growth. Examples: Influenza virus, HIV, Ebola virus, Dengue virus.

• Environments and Substrates:

  • Live within all ecosystems on Earth, including soil, water, and up to 6 km of the atmosphere.

  • Specific substrates include meat, fish, fruits, vegetables, human skin, mouth, alimentary canal, and urinary tract.

  • Can survive under extreme conditions like hot water springs, salt marshes, and liquids such as petrol and diesel.

• Effects of Micro-organisms:

  • Used in agriculture, medicine, environmental conservation, and various industries.

• Beneficial Effects:

  • Agriculture:

    • Gene technology used to enhance crop harvest by producing drought-resistant and pest-resistant crops with high nutrients and taste.

      • Example: Golden rice enriched with vitamin A using Erwinia uredovora genes.

      • Example: Zea maize genome muted with Bacillus thuringiensis genes to produce toxins to crop pests.

    • Nitrogen fixation: Rhizobium bacteria in legume nodules absorb atmospheric nitrogen.

      • Azotobacter, a free-living nitrogen-fixing bacteria, is added to cultivation lands as bio fertilizers.

    • Producing compost by rapid decomposition of organic matter.

    • Bio-pesticides: Micro-organisms used to control insect pests e.g., Alternaria fungus to combat aquatic weed, salvinia.

  • Medicine:

    • Used to produce antibiotics, vaccines, and anti-toxins.

    • Antibiotics are chemicals produced by microbes to destroy other micro-organisms.

      • Examples: Penicillin, Amoxicillin, Tetracycline, Erythromycin (against bacterial infections), Griseofulvin (against fungal infections).

      • Penicillin discovered by Alexander Fleming from Penicillium notatum fungus.

    • Vaccines contain an agent that resembles a disease-causing micro-organism.

      • Examples of vaccines made from weakened microbes: Polio, Tuberculosis, Measles

      • Examples of vaccines made from killed microbes: Cholera, Influenza, Typhoid.

      • Examples of vaccines made from toxins of microbes: Tetanus, Diphtheria

      • Examples of vaccines made from body parts of microbes using genetic engineering: Hepatitis B

    • Anti-toxins: Synthesized using toxins by removing its toxic components e.g., Tetanus vaccine.

  • Industries:

    • Dairy products (yoghurt, curd, cheese, butter): Lactobacillus bulgaricus, Streptococcus thermophilus.

    • Biogas: Methanococcus, Methanobacterium.

    • Metal extraction: Acidithiobacillus ferrooxidans, Thiobacillus ferrooxidans. Bio-leaching technology.

    • Products based on plant fibers: Bacillus corchorus, Bacillus comesii.

    • Alcohol: Saccharomyces cerevisiae.

    • Vinegar: Acetobacter aceti.

    • Bakery industry: Saccharomyces cerevisiae.

    • Milk based products: Lactobacillus and Streptococcus used to turn Lactose into Lactic acid creating an acidic medium and retard growth of other micro-organisms.

    • Products based on plant fibers: Pectinase enzyme produced by bacteria helps to separate fibers by digesting pectate.

  • Environmental Conservation:

    • Bio-remediation: Technology used to remove environmental pollutants using micro-organisms.

      • Microbes decompose organic waste matter in polluted water.

      • Pseudomonas decompose oil layers on the ocean.

      • Heavy metals such as Chromium (Cr), Lead (Pb), and Mercury (Hg) are removed using bacteria in towers.

      • Producing bio-degradable plastics.

• Favorable Impacts for Large-Scale Productions:

  • Rapid biological processes due to high growth and metabolic rates.

  • Various strains of microbes can act on various substances.

  • Simple genes make them easily used for genetic engineering.

  • Low-cost or free availability from the environment.

  • Low energy requirements compared to other industries.

  • Minimal environmental damage.

• Adverse Effects:

  • Causing diseases in humans, plants, and animals.

  • Food spoilage.

  • Economical damage to non-living surfaces.

  • Use as biological weapons.

  • Causing Diseases:

    • Bacteria, viruses, fungi, and protozoa are the groups that cause diseases.

    • Pathogen: A micro-organism that can cause a disease.

    • Vectors: Mosquitoes and flies that carry pathogens to the host.

    • Host: An organism that provides its body as the substrate to growth of the pathogen.

    • Table 1.2 - Information of diseases caused by micro-organisms to human

      • Viruses:

        • Cold (spread by air through the respiratory system).

        • Dengue (spread by mosquito vectors through skin).

        • AIDS (spread by blood and other fluids through sexual contacts or blood transfusion).

      • Bacteria:

        • Tuberculosis (spread by air through the respiratory system).

        • Typhoid fever (spread by polluted food and vectors through the digestive system).

      • Protozoa:

        • Malaria (spread by mosquito vectors through skin).

        • Amoebic dysentery (spread by polluted water and food through the digestive system).

        • Leishmaniasis (spread by vectors such as sandfly through open wounds).

      • Fungi:

        • Pityriasis (spread by contact through skin).

        • Rashes (spread by contact through skin).

    • Diseases caused by micro-organisms to plants

      • Powdery mildew disease: Affected leaves, stem, flowers and fruits. White or gray powdery material appears.

      • Late blight: Brown spots appears on potato plant.

      • Wilting: Xylem vessels are affected which transports water throughout the tree.

  • Food spoilage caused by micro-organisms

    • Micro-organisms convert or add toxic materials to food, changing its physical and chemical nature.

    • Physical changes: Food becomes soft, change of color, taste, and odor.

    • Chemical changes: Fermentation of carbohydrates, putrefaction of proteins, rancidity of lipids.

    • Internal factors: Amount of nutrients, moisture, biological structure of food.

    • External factors: Environmental temperature and humidity, gases available in atmosphere.

  • Applications of micro-organisms as biological weapons

    • Toxins produced by microbes or harmful pathogenic bacteria or viruses used for military purposes.

    • Bacillus anthracis, the causative agent of Anthrax disease, is considered the most harmful biological weapon.

The Eye and Ear

• 2.1 Structure and function of the human eye

  • The eye is the optical sensory organ.

  • Eyes are located inside the orbits of the skull and fixed with six eye muscles.

  • The eye ball can move in vertical, horizontal, and circular planes.

  • This allows for a “widening of the optic region.

  • Table 2.1 - Information about the major parts of the human eye

    • Sclerotic Layer: Tough, white, outer layer. Light does not penetrate.

    • Cornea: Thin, transparent front part of the sclerotic layer.

    • Choroid: Inside the sclerotic layer, supplies blood to the eye.

    • Retina: Inside the choroid layer, contains light-sensitive rod and cone cells.

    • Aqueous Humor: Transparent watery liquid between the lens and cornea.

    • Lens: Transparent biconvex lens that can change curvature to focus images on the retina.

    • Iris: Controls the amount of light entering the eye.

    • Pupil: Hole in the center of the iris that allows light to enter.

    • Ciliary Muscle: Holds the lens and helps change its curvature.

    • Vitreous Humor: Transparent jelly-like substance that maintains the spherical shape of the eye.

    • Fovea/Yellow Spot: The sensitive part of the retina where sharp images form.

    • Blind Spot: Area of the retina without light-sensitive cells.

    • Optic Nerve: Connects the eye to the brain, conveying visual stimulus for image interpretation.

  • To see clearly, light rays enter the eye, refract through the lens, and converge on the retina, forming an inverted image.

  • Nerve endings on the retina send the message to the brain via the optic nerve, which interprets it as an upright image.

  • Convex Lens: Parallel beam of light converges after refraction to the focal point.

  • Focal Length: Distance between the lens and the focus.

  • Concave Lens: Parallel beam of light diverges after refraction; rays appear to come from a point called focus.

  • Image formation: Close object forms an image farther from the lens, while a far object forms an image closer to the lens.

  • The curvature of the eye lens adjusts:

    • Reduced for a distant object.

    • Increased for a close object.

  • Ray diagram for a far object: Parallel rays converge onto the retina to form an image

  • Ray diagram for a close object: Diverged rays converge onto the retina forming an image.

• 2.2 Defects of Vision

  • Long Sight (Hypermetropia):

    • Far objects seen clearly, close objects blurred.

    • Caused by inability to increase eye lens curvature or short eye ball.

    • Corrected using a convex lens.

    • Light rays from nearby objects do not focus on the retina, forming behind it.

  • Short Sight (Myopia):

    • Close objects seen clearly, distant objects blurred.

    • Caused by inability to reduce eye lens curvature or elongated eye ball.

    • Corrected using a concave lens.

    • Rays from distant objects focus in front of the retina.

  • Binocular Vision and Stereoscopic Vision:

    • Eyes located in front of the skull (humans, monkeys) allow seeing the same area with both eyes.

    • Binocular Vision: Ability to maintain visual focus on an object with both eyes creating a single visual image.

    • Stereoscopic Vision: Ability to determine the depth or height of an object.

• 2.3 Eye Diseases

  • Cataract:

    • Cloudiness or opacity in the crystalline lens due to protein denaturing.

    • Prevents proper focusing on the retina, causing blurred vision.

    • Occurs with age, genetic factors, and potentially UV rays.

  • Glaucoma:

    • Gradually reduces visual range and leads to blindness due to optic nerve damage.

    • Usually results from high blood pressure inside the eye.

    • Damage is irreversible.

  • Eye infections

    • Reddening of the eye and secretion of tears are a symptom.

    • The disease spreads through insects and by contact.

  • Precautionary measures:

    • Protect eyes from harmful rays.

    • Avoid looking directly at the sun during a solar eclipse.

    • Use safety glasses when welding.

    • Do not use eye drops without medical advice.

    • Care for personal hygiene.

    • Do not watch television continuously.

• 2.4 Structure and Function of the Human Ear

  • The ear is the audio sensory organ.

  • Figure 2.28 Diagram of the human ear

  • Area Part of the organ Information

    • Pinna/ear lobe cartilaginous organ Directs sound waves to auditory canal

    • External Auditory Canal Directs the sound to tympanic membrane

    • Tympanic Membrane Vibrates in response to sound wave and acquires auditory senses

    • Ossicles 3 bones named malleus, incus and stapes Transmit sound related vibration to the cochlea

    • Eustachian Tube An open tube connected to pharynx Controls the pressure on either sides of the tympanic membrane

    • Cochlea The nerve ending of the auditory nerve is connected   transmit auditory senses to auditory nerve

    • Auditory Nerve Transmit auditory senses for sound interpretation

    • Semi-circular Canals Contribute to maintain the balance of body

• 2.5 Defects of Ear

  • Disorders: Impaired hearing, deafness, hardening of ossicles.

  • Hearing aids can be used as a remedy for loss of hearing.

  • Audible range of the human ear: 20 Hz - 20,000 Hz.

  • Precautions to protect the ear:

    • Avoid inserting foreign objects.

    • Refrain from loud noises.

    • Avoid diving in deep waters.

Nature and Properties of Matter

• Matter is classified into pure substances and mixtures with examples such as air, drinking water, aluminum, silver, copper, salt solution, distilled water, carbon, sulphur, zinc, copper sulphate, sodium chloride.

• Pure substances: aluminum, silver, copper, distilled water, carbon, sulfur, zinc, copper sulphate, sodium chloride.

• Mixtures: air, drinking water, salt solution.

• Pure substances are composed of elements and compounds and mixtures contain two or more constituents.

• Elements: sulfur, chlorine, silver, zinc and copper.

• Compounds: glucose, sodium chloride, copper sulphate.

• Symbols for Elements based on english and latin names Ex: Carbon (C), Oxygen (O), Sulphur (S), Chlorine (Cl) Calcium(Ca) Magnesium (Mg) Aluminium(Al) Sodium (Na) - Natrium, Copper(Cu) - Cuprum, Lead(Pb) - Plumbum, Gold(Au) - Aurum, Mercury(Hg) - Hydrargyrum, Iron(Fe) - Ferrum, Silver (Ag) - Argentum.

• Atoms: Smallest, indivisible particles from which matter is made.
  * Coined by John Dalton (1766-1844). Atoms of different elements differ from each other for example iron atoms, and aluminium atoms.

• Molecules: Units formed by the combination of one or more atoms of the same type or one or more atoms of different types.

  • Element oxygen exists as oxygen molecules Ex: Element Oxygen (O), Nitrogen (N), Chlorine (Cl), Hydrogen (H), Fluorine (F). Since above molecules are formed by the atoms of the same elements they are known as homo-atomic molecules.

  • Subatomic Particles according to Ernest Rutherford: Electrons, Protons & Neutrons. Protons and Neutrons: found in nucleus at the center of the Atom. Electrons are moving around the nucleus. Electrons: relative mass 1/1840 , relative charge -1. Protons have +1 charge, Neutrons have no charge, electrons have -1 charge. relative mass 1.

• Atomic Number (Z) The number of Protons in the nucleus

  • Mass Number (A) Sum of protons and neutrons. Symbol is top left and atomic is bottom left of the element.

• Compounds: Pure substances formed by chemical combination of two or more elements. hetero-atomic molecules. Ex: hydrogen atom plus chlorine atom forms hydrogen chloride. an oxygen atom plus two hydrogen atoms form water molecule. glucose or acetic acid formed from C, H and O.
  chemical formula, ex, water is H2O.
  elements in the smallest unit doesn't possess characteristics of that compound.

• Mixtures

  • Two or more pure substances mixed together. Constituents can be separated by physical methods.

  • Separation methods: panning, winnowing, floating, sifting, evaporation, fractional distillation, steam distillation, crystallization, magnets.

  • Homogenous vs Heterogenous. Ex salt solution is homogenous. muddy water, ice cream, fruit salad is heterogeneous.

  • Homogeneous: Uniform composition throughout.

  • Heterogeneous: Non-uniform composition throughout.

Basic Concepts Associated with Force

• Force: A pull or a push with example as pulling or pushing the object.. Examples, force to book on table, moving faster by kicking. A single person may not move a bus. Sometimes we can move an object and sometimes not.

  • Force Types: moving an object.

    • Force stops things, changes direction and speed, changes shape, pushes and pulls.

  • Magnitude, Direction, Point of Application.

• Magnitude of force- hitting slightly moves slowly while hitting fast the object moves fast. Measured with spring balance. unit in Newtons (N).

• Direction of force & point of application: Direction of hit decides the direction of motion. Opening a drawer needs it to be pulled, closing it needs to push. so not only magnitude but direction matters. Results changes according to where applied, ex: top or bottom. POint of application of force.
  *. Quantities with magnitude and direction are known as vector quantities.
  *. Graphical Representation of force with a segment of straight line with magnitude by lenght, direction by arrow and point by the dot.

Pressure Exerted by Solid

• If strap is narrow it is uncomfortable to the area. The force of the school bag distributes to area of connection.
  *Pressure is a factor of force but the greater contact of force is distributed to a larger area. In this instance, it is useful
  to know the force exerted over a unit area. The force exerted over a unit area is known as the pressure.
  Factors: thin wire has higher pressure and easy to cut, higher the surface area, lower the pressure and L SHAPED FRAME is used to put against surface of the wood
  ie Pressure (P) =
  Perpendicular force (F)
  Surface area on which the force is acting (A)
  Units of Pressure:
  Pressure =
  Perpendicular force
  Surface area on which the force is acting
  Pressure = N/m2 = N m-2 or Newton per square meter.
  1 N m-2 = 1 Pa Pasqual.
  example 1: 300 N surface area on 2m2 = 150Pa
  Example 2: weight 400N box on horizontal plane.
  Pressure 200 Pa. Area=? pressure = force/area, == area= force/pressure. 400/200 is 2m2.
  Factors with Sharp edge is easy to put pressure. trucks can cause pressure and damage. increasing contact reduce pressure and damage to road.

The Human Circulatory System

*Transportation of blood throughout. Closed system. Pumping of blood from heart into blood vessels.
. Heart has 4 chamber which are upper chambers called atria and lower chambers called ventricles. Valves between atria and ventricles are bicuspid and tricuspid.
*Two main arteries connected to ventricles: Aorte to the left and pulmonary to the right. Main veins are connected to artria including superior ana inferior.

• Arterioles, Venules and capillaries.
  Pulmonary arteries starting from lungs take it to the left atrium.
  Tough walls in arteries can withstand lots of pressure, vein walls are thinner. Valves in veins opening to heart prevent backflow. Capillaries are just single layer to diffuse nutrients, co2 from cells from the capillary walls

*Components of blood: 55% liquid in plasma.
45% in solid form into Corpuscles.
Water, substance. Soluble and insoluble in water.
Erythrocytes, Leucocytes, platelets.
Red Blood cells contain red pigment for haemoglobin for O2 from lungs carries it to the cells (erythrocytes.
White blood cell for defence by desotryoing pathogens to produce antibodies.
Platelets which are cell fragments to clot the blood. ex: Dengue causes decline in platelet percentages.
*Plasma carry substances and transports the products of cell, hormones enzymes and gases throughoout body.
*Blood Transfusion from one individual to another. Donar & recipient must need blood compability in blood groups. types are A, B, AB and 0. 0 Group is universal donar, AB is universal acceptor. Must ensure Rhesus factor compatibility.
*Agglutination is clumping of tranfused blood. Blood clotting is a mechanism that prevent over bleeding.

*Habits to maintain blood good mental health, exercise, good BMI, good diet, reduce salt and fatty foods, refrain smoking. If you have family history.

Plant Growth Substances

• Air, water, light and minerals are essential for growth. Stem goes up while roots done and plants are stimulated in apex tips.
  . Plant without apex doesnt grow.

• Chemical compounds regulare the gorwth, some promote and some inhibit growht. Apex does growht. ex cutting top of leaves. Plants dont grow properly without apex.
  Promote: Auxin, Gibberellins, Cytokinis.
  *Auxin. Growth promoting hormone tips on roots, stimualtes cell elangation.
  stem apex turn toward light due to dissimilar cell elognation.
  Auxins, IAA, diffuse downwards.

• Auxin concentration more when where luminosity is low with dark and cause the growth. Positive photography movement. Auxin inhibits growth of lateral buds.
  gibberlins promote mainly elognation and rowth of fruits. Cabbage plant
  cytokinins: accelarates cell division. Flowers leave and fruits, Stimulate seed germination and cell division and delat aging.

• Absics acid to control stroma acid.
  ethene produces for ripening and conver starch for store platnts.
  Growth inhibtors in agri purposes for 2,4 -DPA herbicide for paddy fields for braod leaf weedicide. To induce formation of stem

Support and Movements of Organisms

• .1 Living Organisms change location or body part in response to stimulus known as movement as seen via Video clips with snail, earth worm, praw frog, crow, fish.
  each is movement is a feature of living organism. Plants also show movement!
  Amoeba false feet and Euglena, Paramecium uses cilia, people use limbs, dolphin use flippers. earthworm does not have, crow/toad does not have. use movemtns.

• Muscle cells have muscle fibers, that can contract, relax to go back to orgiinal. hard wooden peices attached
  with cardboaod.
  mucse bicepts causehands to bend and lift up while tricepts are hand stretches.

• Plant tissue have mecahnical support. non woodsy plants have low water, if high causes it to benid.
  woodsy plants have percentage, wood with cellulose and lignin.
  movenmts planst are growth or changes

• Trophic: grothw due to stimulus. Can be postiive or negative.
  Positive geotroph is grows toward ground and negative is going other way. Stem moves away. hydro: mvoes totwrdas. chemolitho and positive thermotropism.
  Hapotonastic movment with leaf stimulus..
  *Nastic are where repsonse of stimulus direction doesn't depend EX: legumee, paranchyma ceells, turn pressure with leages Kathurmunga, tamarind leaf is shrink on touch.
  A pulvina help leaves shrink based on sunlight.
  *Tactic is the orgnaism respodns like algel chlamydomonas. They ca locommot like algel.
  Pflants grow well when needed and conserve themselv to avoid external haxaard and prtoce thse in their insitu conservation.

The Evolutionary Process

• Universe origin about 4.5 billion ages ago. Nebula to Earth. Big bang to enrgy with giant explosion into galaxy. solar in way Milky.
  lots of heat and valotacnic activity. Earth has oxygen, metal, silicion and water which condence and forms rain. Mneral riches and eatern for oceans.

• Life Orgini: has many beliefs, 3.5 billion history on earth.
  Theory: Super Natural Power, Spontaneous - things generated spontatensouly . This disporbed by Louis pasture with nutritional media sterilize with swan neck and broken flask after broken flask .
  Cosmozic- living fall from space. Bio Chemicals. that start gases react each other and creatied life.
  elctric discharge via volcanoes. from 1st form on, life to form unicellur algae. unicellular organisms were botn
  cnidarians, fish were vertebrate. REptiies and mammals.
  s evolution took abobut 12 years agio wiht modern 5 yeras ago. with plan photo synthetic alge to non flowering to flowering.
  This to understand process to several cahgems. life exsietns via ocntnuous changes from living organim to natural environmental.
  These changes occr gradually from simple orgaism to cpmpmes. fossil records reveal changes. Part of animal or plant. skeleton to sludge rocks . some deacyed which removes material but remains shaepd . extreme conidtiosn are fossli.
  Living fossil survive even today retaining porpeies unchanged Ex coalacthan fish (foundin souttth africa 1930s). dragon fly, crocach, ling. Rocks are in layers with differnt organisms and animal fossil with bio evoolion.
  C14 carbon is uisotoip used with evolution. Horse has 54min years ago changes of location and feeding. with vertical position.