Heat Transfer: Conduction, Convection, Radiation

Heat

• A form of energy transferred due to temperature differences.

Temperature

• Measures the average kinetic energy of particles in a substance.

Temperature Scales

• Celsius (°C): Water freezes at 0°C and boils at 100°C.
• Fahrenheit (°F): Water freezes at 32°F and boils at 212°F.
• Kelvin (K): Absolute temperature scale where 0 K is absolute zero (-273.15°C); K = °C + 273.15.

Temperature Gradient

• Temperature change with distance, like a metal rod cooling from the heated end.

Heat Transfer: Conduction

• Heat transfer through direct contact, without particle movement.
• Metals are good conductors; wood and plastic are insulators.

Heat Transfer: Convection

• Heat transfer via fluid (liquids or gases) movement.
• Warm fluids rise, cool fluids sink, creating currents.

Heat Transfer: Radiation

• Heat transfer through electromagnetic waves, even in a vacuum.
• How the sun's energy reaches Earth.

Electromagnetic Spectrum

• Range of electromagnetic waves: radio waves, microwaves, infrared, visible light, UV, X-rays, gamma rays.

Effects of Electromagnetic Radiation

• Positive: Visible light for sight, infrared for warmth, UV for sterilization.
• Negative: Excessive UV exposure causes skin cancer; high-energy radiation harms tissues.

Light

• Visible electromagnetic radiation.

Properties of Light

• Travels in straight lines, creating shadows.
• Can be reflected off surfaces.
• Can be refracted (bends) when passing through different mediums.

Reflection

• Light bouncing off a surface.

Laws of Reflection

• Angle of incidence equals the angle of reflection.
• Incident ray, reflected ray, and normal all lie in the same plane.

Refraction

• Light bending when moving between mediums (e.g., air to water).
• Occurs due to speed of light changing in different mediums.

Atom

• Basic unit of matter

Subatomic Particles

• Protons: Positive charge, in the nucleus
• Neutrons: Neutral charge, in the nucleus
• Electrons: Negative charge, orbit the nucleus in energy levels

Nucleus

• The central part of an atom, containing protons and neutrons.

Atomic Number (Z)

• Equals the number of protons in an atom's nucleus, determines the element.

Mass Number (A)

• Sum of protons and neutrons in an atom's nucleus.

Calculating Neutrons

• Neutrons = Mass number (A) - Atomic number (Z).

Acids

• Release hydrogen ions (H⁺) in water.
• Sour-tasting and corrosive.

Bases

• Release hydroxide ions (OH⁻) in water.
• Bitter-tasting and slippery.

Neutralization

• Reaction between acid and base to produce salt and water.

Salts

• Compounds formed when an acid's hydrogen ion is replaced by a metal or ammonium ion.

Indicators

• Change color depending on acidity or alkalinity.
• Litmus paper: Red in acid, blue in base.
• Universal indicator: Shows a range of colors based on pH.

Litmus Paper

• Turns red in acidic solutions, blue in basic solutions.

Universal Indicator

• Gradual color change indicates pH level.

Everyday Importance

• Acids: Batteries, cleaning products, food processing.
• Bases: Soaps, detergents, antacids.
• Salts: Food flavoring, fertilizers, industrial uses.
• pH control: Important in agriculture and water treatment.

Species

• Group of similar organisms that can interbreed.

Reproduction

Biological process of creating offspring, vital for species survival.

Asexual Reproduction

• Involves one parent, offspring are genetically identical.

Sexual Reproduction

• Involves two parents, offspring have combined genetic material, leading to variation.

Gametes

• Sperm and egg cells containing half the normal chromosome number.

Fertilization

• Fusion of sperm and egg to form a zygote.

Zygote

• Fertilized egg cell that develops into an embryo.

Chromosomes

• Structures containing DNA in a cell's nucleus.

Sex Chromosomes

• Determine an individual's sex; humans have X and Y.
• Females: XX
• Males: XY

Gender Determination

• Egg cell contains X chromosome.
• Sperm can contain X or Y chromosome.
• Sperm with X chromosome results in female (XX).
• Sperm with Y chromosome results in male (XY).

Sepals

• Protect the developing flower bud.

Petals

• Attract pollinators.

Stamen

• Male part of flower
  • Anther: Produces pollen (containing sperm cells).
  • Filament: Supports the anther.

Pistil (Carpel)

• Female part of flower
  • Stigma: Receives pollen.
  • Style: Connects stigma to ovary.
  • Ovary: Contains ovules (containing egg cells).

Ovule

• Develops into a seed post-fertilization.

Ovary

• Develops into a fruit post-fertilization.

Pollination

• Pollen transfer from anther to stigma.

Self-Pollination

• Pollen transfer within the same flower or plant.

Cross-Pollination

• Pollen transfer between different plants of the same species.

Agents of Pollination

- Wind: Small, inconspicuous flowers, large amounts of light, dry pollen.
- Insects: Brightly colored, fragrant flowers with nectar.
- Birds: Red or orange, tubular flowers with lots of nectar.
- Water: (Less common) Small, inconspicuous flowers.

Pre-Fertilization

• Pollen Tube Growth: Pollen grain germinates, grows tube to ovary.
• Sperm Cell Travel: Sperm travels through tube to ovule.

Importance of Pollinators

• Crucial for food production via crop pollination.

Declining Pollinator Populations

• Due to habitat loss, pesticides, climate change.

Solutions

• Protect habitats, reduce pesticide use, promote pollinator-friendly practices.