Comprehensive University Study Notes: Grade 11 Science

BIOLOGY: LIVING TISSUES

• Definition of Tissue: A group of cells with a common origin, organized to perform a specific function in a multicellular organism.

• Plant Tissues: Plant tissues are categorized based on their ability to divide into two main groups: Meristematic tissues and Permanent tissues.

• Meristematic Tissues: Tissues composed of undifferentiated cells that actively undergo mitotic division to create new cells.

  • Characteristics:
    • Living cells with thin cell walls.
    • Lack or have very small vacuoles.
    • Contain large, prominent nuclei.
    • Possess a high density of mitochondria.
    • Absence of intercellular spaces.
    • Lack chloroplasts.
  • Types of Meristems:
    • Apical Meristem: Found at the tips of shoots and roots. Responsible for increasing the height/length of the plant through primary growth.
    • Intercalary Meristem: Located at the bases of nodes/internodes (especially in grasses). Responsible for lengthening the internodes.
    • Lateral Meristem: Located parallel to the long axis of the stem and root. Responsible for increasing the girth/thickness of the plant (secondary growth). Example: Vascular cambium in dicotyledonous plants.

• Permanent Tissues: Tissues that have lost the power of division and have specialized for a particular function.

  • Simple Permanent Tissues: Made of cells of the same type.
    • Parenchyma: Spherical/isodiametric living cells with thin cellulose walls and large central vacuoles. Functions include photosynthesis (if they contain chloroplasts), food storage (in tubers like potato), and water storage (in succulents).
    • Collenchyma: Living, elongated cells with unevenly thickened corners (thickened with pectin and cellulose). Provides mechanical strength and flexibility to non-woody plants.
    • Sclerenchyma: Dead cells with heavily thickened lignified walls. No intercellular spaces. Includes fibers (long, narrow) and sclereids (stone cells). Provides rigid mechanical support.
  • Complex Permanent Tissues: Made of several types of cells.
    • Xylem: Conducts water and minerals from roots. Consists of xylem vessels, tracheids (dead), xylem fibers (dead), and xylem parenchyma (living).
    • Phloem: Conducts organic food (sucrose) produced in leaves. Consists of sieve tube elements (living, no nucleus), companion cells (living, control sieve tubes), phloem parenchyma, and phloem fibers.

• Animal Tissues:

  • Epithelial Tissue: Covers internal and external surfaces. Cells are tightly packed on a basement membrane. Provides protection, absorption, secretion, and sensory reception. Types include simple and stratified epithelium.
  • Connective Tissue: Connects and supports other tissues. Cells are embedded in an extracellular matrix. Examples: Bone, Cartilage, and Blood.
    • Blood: A unique connective tissue. Consists of plasma (fluid matrix) and blood cells (RBCs, WBCs, and Platelets). Transports gases, nutrients, and hormones.
  • Muscle Tissue: Specialized for contraction and movement. Responds to stimuli as an effector.
    • Smooth Muscle: Spindle-shaped, uni-nucleated, non-striated, involuntary. Found in walls of internal organs (e.g., digestive tract).
    • Skeletal Muscle: Cylindrical, multi-nucleated, striated, voluntary. Attached to the skeleton. Tires easily.
    • Cardiac Muscle: Branched, uni-nucleated, striated, involuntary. Found only in the heart. Does not tire.
  • Nervous Tissue: Composed of neurons specialized for conducting nerve impulses. A typical neuron consists of a cell body (containing nucleus), axon (long protrusion), and dendrites (branching protrusions).
    • Sensory Neuron: Carries impulses from the receptor to the Central Nervous System (CNS).
    • Motor Neuron: Carries impulses from the CNS to the effector (muscles/glands).
    • Interneuron: Connects sensory and motor neurons within the CNS.

BIOLOGY: PHOTOSYNTHESIS

• Definition: The process by which green plants synthesize organic food (glucose) using inorganic raw materials (carbon dioxide and water) in the presence of sunlight and chlorophyll.

• General Equation:   $6CO_2(g) + 6H_2O(l) \xrightarrow{\text{Light Energy/Chlorophyll}} C_6H_{12}O_6(s) + 6O_2(g)$

• Factors Affecting Photosynthesis:

  • Chlorophyll: Green pigment in chloroplasts that absorbs light.
  • Light Energy: Primarily solar energy. Plants absorb blue and red wavelengths efficiently.
  • Carbon Dioxide: Absorbed from the atmosphere through stomata via diffusion.
  • Water: Absorbed from the soil by root hairs via osmosis.

• Products and Storage:

  • Glucose: Primary product. Temporarily stored as starch in leaves.
  • Oxygen: Byproduct released into the atmosphere.
  • Translocation: Starch converted to sucrose for transport through phloem to storage organs (fruits, roots, tubers).

• Testing for Starch in a Leaf:

  1. Boil the leaf in water (to break cell membranes).
  2. Boil in alcohol using a water bath (to extract chlorophyll/decolorize).
  3. Wash in cold water.
  4. Add Iodine solution. A blue-black color indicates starch presence.

CHEMISTRY: MIXTURES

• Definitions:

  • Mixture: Matter containing two or more substances not chemically combined.
  • Homogeneous Mixture: Uniform composition throughout (e.g., salt solution).
  • Heterogeneous Mixture: Non-uniform composition (e.g., muddy water).

• Solubility:

  • Solvent: Substance present in larger quantity in a solution.
  • Solute: Substance dissolved in the solvent.
  • Factors affecting solubility: Temperature, nature of solute, nature of solvent.
  • Principle: "Like dissolves like." Polar solutes (like salt) dissolve in polar solvents (like water). Non-polar solutes (like grease) dissolve in non-polar solvents (like kerosene).

• Expressing Concentration:

  • Mass Fraction ($m/m$): $\frac{\text{Mass of solute}}{\text{Total mass of mixture}}$
  • Volume Fraction ($v/v$): $\frac{\text{Volume of solute}}{\text{Total volume of mixture}}$
  • Molarity (Concentration $C$): $\text{mol}\,\text{dm}^{-3}$. Formula: $C = \frac{n}{V}$ where $n$ is the number of moles and $V$ is the volume in $\text{dm}^3$.

• Methods of Separation:

  • Filtration: Separates insoluble solids from liquids.
  • Evaporation: Recovers a solute from a solution by boiling off the solvent.
  • Crystallization: Forming pure solid crystals from a saturated solution.
  • Distillation: Separating components based on boiling points. Includes Simple Distillation, Fractional Distillation (for petroleum fractioning), and Steam Distillation (for essential oils).
  • Chromatography: Separation based on the speed of components moving through a stationary phase (e.g., paper) under a mobile phase (solvent).

PHYSICS: WAVES AND OPTICS

• Types of Waves:

  • Mechanical Waves: Require a medium for propagation (e.g., sound, water ripples).
    • Transverse Waves: Particles vibrate perpendicular to the direction of wave travel (e.g., water waves, light).
    • Longitudinal Waves: Particles vibrate parallel to the direction of wave travel (e.g., sound waves, compressions in a spring).
  • Electromagnetic (EM) Waves: Do not require a medium. Speed in vacuum is approximately $3 \times 10^8\,\text{m/s}$.

• Wave Parameters:

  • Amplitude ($A$): Maximum displacement from rest position.
  • Wavelength ($\lambda$): Distance between two consecutive crests or troughs.
  • Period ($T$): Time taken for one complete oscillation.
  • Frequency ($f$): Number of oscillations per second ($s^{-1}$ or $Hz$). $f = \frac{1}{T}$.
  • Wave Equation: $\text{Speed } (v) = f \times \lambda$.

• Electromagnetic Spectrum: Arranged by frequency (low to high): Radio waves, Microwaves, Infrared, Visible light, Ultraviolet, X-rays, Gamma rays.

• Sound:

  • Human hearing range: $20\,Hz$ to $20,000\,Hz$.
  • Infrasound: Below $20\,Hz$.
  • Ultrasound: Above $20,000\,Hz$. Used in SONAR, medical scans, and lithotripsy.
  • Properties: Pitch (depends on frequency), Loudness (depends on amplitude), Quality (depends on wave shape).

• Optics:

  • Reflection: Angle of incidence ($i$) = Angle of reflection ($r$). All rays and the normal lie on the same plane.
  • Lenses:
    • Convex (Converging): Can form real or virtual images. For an object at infinity, image forms at the focus ($F$). As object approaches lens, real image moves further from lens and gets larger. If object is inside $F$, image is virtual, erect, and magnified.
    • Concave (Diverging): Always forms a virtual, erect, and diminished (smaller) image.
  • Refraction: $\text{Refractive Index } (n) = \frac{\sin(i)}{\sin(r)}$.
  • Total Internal Reflection: Occurs when light travels from a dense to a rare medium and the angle of incidence exceeds the critical angle ($c$).

BIOLOGY: HUMAN BODY PROCESSES

• Digestion:

  • Mouth: Amylase (Ptyalin) breaks starch into maltose.
  • Stomach: Pepsin breaks proteins into polypeptides in the presence of $HCl$. Renin coagulates milk (in infants).
  • Small Intestine: Bile (from liver) emulsifies fats. Trypsin (protease), Amylase, and Lipase (fat-splitting) come from the pancreas. Peptidases, Maltase, Sucrase, and Lactase come from the intestinal wall. End products: Glucose, Amino acids, Fatty acids, and Glycerol.
  • Absorption: Small intestine has villi and microvilli to increase surface area for absorption into blood capillaries and lacteals (for fats).

• Respiration:

  • Respiratory Surface: Alveoli in lungs (thin, moist, large surface area, good blood supply).
  • Cellular Respiration:
    • Aerobic: $\text{Glucose} + 6O_2 \rightarrow 6CO_2 + 6H_2O + 38\,ATP$.
    • Anaerobic (Fermentation):
      • Yeast: $\text{Glucose} \rightarrow \text{Ethanol} + CO_2 + \text{Energy}$.
      • Animal Muscle: $\text{Glucose} \rightarrow \text{Lactic Acid} + \text{Energy}$.
  • ATP: High-energy molecule used for muscle contraction, active transport, and synthesis.

• Circulation:

  • Heart: 4 chambers (L/R Atria, L/R Ventricles). Double circulation (Pulmonary and Systemic).
  • Blood Vessels: Arteries (away from heart), Veins (toward heart), Capillaries (exchange).
  • Blood Pressure: Normal is $120/80\,mmHg$ (Systolic/Diastolic).
  • Lymphatic System: Re-collects tissue fluid (lymph) and returns it to blood circulation. Lymph nodes filter pathogens.

• Excretion:

  • Kidneys: Main nitrogenous waste is Urea. The functional unit is the Nephron.
  • Nephron Process:
    1. Ultrafiltration (in Bowman's capsule).
    2. Selective Reabsorption (in tubules for glucose, water, salts).
    3. Secretion (waste ions).

• Homeostasis: Maintaining a constant internal environment ($37^\circ\text{C}$, $0.1\%$ blood glucose).

  • Glucose Control: Insulin (decreases glucose by converting to glycogen), Glucagon (increases glucose by converting glycogen back).

CHEMISTRY: ACIDS, BASES, AND SALTS

• Acids: Produce $H^+$ ions in aqueous solution.
  • Strong Acids: Completely ionized (e.g., $HCl$, $H_2SO_4$, $HNO_3$).
  • Weak Acids: Partially ionized (e.g., $CH_3COOH$, $H_2CO_3$).
• Bases: Produce $OH^-$ ions in aqueous solution. Soluble bases are called alkalis (e.g., $NaOH$, $KOH$).
• Salts: Formed when the hydrogen of an acid is replaced by a metal or ammonium ion.
• Neutralization: $\text{Acid} + \text{Base} \rightarrow \text{Salt} + \text{Water}$. Ionic equation: $H^+(aq) + OH^-(aq) \rightarrow H_2O(l)$.
• pH Scale: Range 0-14. Neutral is 7. Below 7 is acidic, above 7 is basic.

CHEMISTRY: HEAT IN REACTIONS

• Exothermic Reaction: Releases heat energy to the surroundings. Temperature of the system increases ($\Delta H < 0$).
• Endothermic Reaction: Absorbs heat energy from the surroundings. Temperature of the system decreases ($\Delta H > 0$).
• Calculation: $\text{Heat Change } (Q) = mc\Delta\theta$.
  • $m$: mass ($kg$).
  • $c$: specific heat capacity ($J\,kg^{-1}\,K^{-1}$).
  • $\Delta\theta$: temperature change ($K$ or $^\circ\text{C}$).

PHYSICS: ELECTRICITY AND ELECTRONICS

• Power and Energy:
  • $\text{Power } (P) = V \times I$ ($\text{Watts}$).
  • $\text{Energy } (E) = P \times t = V \times I \times t$ ($\text{Joules}$).
  • Electricity Bill Unit: $\text{Kilowatt-hour } (kWh)$. $1\,kWh = 3,600,000\,J$.
• Domestic Wiring: Colors used: Brown (Live), Blue (Neutral), Green/Yellow (Earth). Components include MCB (Miniature Circuit Breaker) to stop overloads and RCCB (Residual Current Circuit Breaker) to prevent electric shock.
• Electronics:
  • Semiconductors: Silicon udoped is intrinsic. Doping with Group V elements creates n-type (extra electrons). Doping with Group III elements creates p-type (extra holes).
  • Diode: Allows current in one direction (forward bias). Used for rectification ($AC$ to $DC$).
  • Transistor: Used as an amplifier or switch. Three terminals: Base ($B$), Emitter ($E$), and Collector ($C$).

ENVIRONMENTAL SCIENCE

• Ecological Hierarchy: Individual $\rightarrow$ Population $\rightarrow$ Community $\rightarrow$ Ecosystem $\rightarrow$ Biosphere.
• Growth Curves: Typical biological population shows an S-shaped (sigmoidal) curve. Human population shows a more rapid J-shaped curve.
• Nutrient Cycles:
  • Carbon Cycle: Photosynthesis fixes it; Respiration/Combustion release it.
  • Nitrogen Cycle: Nitrogen-fixing bacteria (e.g., Rhizobium) convert $N_2$ to nitrates. Lightning also fixes nitrogen. Denitrifying bacteria return $N_2$ to air.
• Environmental Issues:
  • Acid Rain: Caused by $SO_2$ and $NO_x$.
  • Global Warming: Caused by greenhouse gases ($CO_2, CH_4, CFCs$).
  • Ozone Depletion: Caused by $CFCs$; allows harmful $UV$ rays to reach Earth.
  • Sustainable Development: Meeting current needs without compromising future generations' ability to meet theirs (e.g., using 4R: Reuse, Reduce, Replace, Recycle).