Biology: Cells and Transport

Biology - Cells and Transport

• Cells are the basic building blocks of all living organisms.

Organelles and their Functions

• Nucleus: Control center containing DNA, dictating everything about the cell.
• Mitochondria: "Powerhouses" of the cell, generating energy through respiration.
• Ribosomes: Tiny structures that make proteins, the workhorses of the cell.
• Cell membrane: Gatekeeper controlling what enters and exits the cell.
• Cytoplasm: Jelly-like substance filling the cell where organelles are suspended and chemical reactions occur.
• Cell wall: Found in plant cells, providing support and protection.

Specialized Cells

• Cells are adapted to perform specific functions.
• Red blood cell: Biconcave disc shape for efficient oxygen transport, lacks a nucleus to maximize space for hemoglobin.
• Root hair cell: Long, thin extension to increase surface area for water and mineral absorption.

Cell Types

• Eukaryotic cells: Complex cells with a nucleus and membrane-bound organelles, found in animals and plants.
• Prokaryotic cells: Simpler cells without a nucleus or membrane-bound organelles, such as bacteria, with DNA floating freely in the cytoplasm.

Osmosis Practical

• Osmosis: Movement of water across a semi-permeable membrane from high to low water concentration.
• Visking tubing: Used as a partially permeable model cell membrane.
• A typical osmosis experiment involves filling Visking tubing with sugar solution, placing it in a beaker of distilled water, and measuring the mass change over time.
• Water moves into the Visking tubing, increasing its mass as water moves from the beaker (high concentration) to the tubing (lower concentration).

Microscopy Practical

• Use a microscope, slides, and coverslips to observe cells up close.
• Prepare a slide by placing a thin tissue sample on the slide, adding water or stain, and covering it with a coverslip.
• Focus correctly by starting with the lowest magnification and slowly adjusting to get a clear picture.
• Store slides in a clean, dry place.

Biological Drawings

• Include neat labels and the magnification used.
• Use what you see under the microscope to make detailed drawings.

Magnification Calculations and Unit Conversions

• Total magnification: Calculated by multiplying the magnification of the eyepiece lens by the objective lens (e.g., 10x eyepiece and 40x objective = 400x total magnification).
• Unit conversions: 1 cm = 10 mm, 1 mm = 1000 µm.

Drawing Graphs

• Label axes clearly with what is being measured, including units.
• Choose an appropriate scale with even increments.

Diffusion, Osmosis, and Active Transport

• Diffusion: Movement of molecules from high to low concentration (e.g., perfume spreading in a room).
• Osmosis: Movement of water across a membrane.
• Active transport: Movement of molecules against a concentration gradient, requiring energy (e.g., absorbing nutrients into the blood).

Chemistry - Atomic Structure

• Atoms: Smallest particles of an element, composed of protons, neutrons, and electrons.
• Protons: Positively charged, found in the nucleus, relative mass of 1.
• Neutrons: Neutral charge, found in the nucleus, relative mass of 1.
• Electrons: Negatively charged, orbit the nucleus, relative mass close to zero.
• Atomic number: Number of protons in an atom’s nucleus, defining the element.
• Mass number: Total number of protons and neutrons in the nucleus.

Periodic Table

• Elements now arranged by increasing atomic number
• Elements in the same group have similar chemical properties due to same number of outer shell electrons

Groups of Periodic Table

• Alkali Metals (Group 1): Highly reactive metals that react violently with water to form alkaline solutions, become more reactive down the group.
• Noble Gases (Group 0 or 8): Unreactive gases with a full outer electron shell.

Separating Techniques

• Filtration: Separates an insoluble solid from a liquid.
• Evaporation: Obtains a soluble solid from a liquid by evaporating the liquid.
• Distillation: Separates liquids with different boiling points by evaporating and condensing them.
• Paper Chromatography: Separates substances that dissolve in a solvent, components travel different distances.

Types of Bonding

• Ionic Bonds: Formed when atoms transfer electrons, typically between metals and non-metals, creating positive (cations) and negative ions (anions).
• Covalent Bonds: Formed when atoms share electrons, usually between non-metals.
• Metallic Bonds: Found in metals, metal atoms share electrons to form a "sea" of delocalized electrons.

Physics - Energy and Heating

Energy Stores

• Kinetic energy: Energy of movement.
• Gravitational Potential Energy: Energy due to height.
• Elastic Potential Energy: Energy stored in a stretched spring or rubber band.
• Thermal Energy: Heat.
• Chemical Energy: Stored in food, fuels, and batteries.
• Nuclear Energy: Stored in the nucleus of atoms.

Energy Transfers

• Energy: Transferred mechanically, electrically, by heating, or by radiation.
• Examples:
  • Car moving downhill: Gravitational potential energy to kinetic energy.
  • Stretched rubber band: Elastic potential energy to kinetic energy.
  • Kettle boiling water: Electrical energy to thermal energy.

Energy Calculations

• Work Done (J) = Force (N) x Distance (m)
• Gravitational Potential Energy (J) = Mass (kg) x Gravitational Field Strength (N/kg) x Height (m)
• Kinetic Energy (J) = 0.5 x Mass (kg) x (Velocity (m/s))^2
• Power (W) = Work done (J) / time (s)
• Elastic Potential Energy (J) = 0.5 x Spring Constant (N/m) x (Extension (m))^2

Efficiency

• Efficiency: (Useful Energy Output / Total Energy Input) x 100%.
• Energy is always "wasted," usually as heat or sound.

Conduction and Insulation

• Conduction: Transfer of heat through a material.
• Conductors: Transfer heat quickly (e.g., metals).
• Insulators: Transfer heat slowly (e.g., wood, plastic).

Designing an Insulation Experiment

• Requires: Beaker, kettle, water, thermometer, stopwatch and insulation/test material,

1. Add not water to beaker
2. Record the temperature
3. Wrap material around the beaker
4. Leave for 10 minutes
5. Record temperature
6. Compare readings

Specific Heat Capacity

• The amount of energy needed to raise the temperature of 1 kg of a substance by 1 degree Celsius (or Kelvin).
• Water has a high specific heat capacity

Cells are the fundamental units of life. Organelles like the nucleus, mitochondria, and ribosomes perform specific functions within cells. Specialized cells, such as red blood cells and root hair cells, are adapted for unique roles.