Keshu

1. Cells: The Building Blocks

The cell is the basic structural and functional unit of all living organisms. If your body were a house, a cell would be a single brick—but a "smart" brick that can breathe, eat, and reproduce.

• Key Characteristics: Every cell contains genetic material (DNA) and organelles (like the mitochondria, which produce energy).

• Specialization: Not all cells look the same. A neuron (nerve cell) is long and wiry to send signals, while a red blood cell is shaped like a disc to carry oxygen.

2. Tissues: The Power of Groups

When a group of similar cells work together to perform a specific job, they form a tissue. In the human body, there are four primary types of tissue:

1. Metals: The Conductors

Metals like aluminum, copper, and iron are used because of their unique atomic bonding (the "sea of electrons").

• Properties:

  • Malleability: They can be hammered into thin sheets (like aluminum foil).

  • Ductility: They can be pulled into wires (like copper wiring).

  • Conductivity: They are excellent at moving heat and electricity.

1. Key Structural Features

What sets a plant cell apart from an animal cell are three main "extras":

• The Cell Wall: A rigid outer layer made of cellulose. It acts like a skeletal system for the plant, providing protection and allowing trees to grow tall without bones.

• Chloroplasts: These are the green "solar panels" of the cell. They contain chlorophyll, which captures light energy to drive photosynthesis.

• Large Central Vacuole: A massive fluid-filled sac that can take up to 90% of the cell's volume. It maintains turgor pressure (internal water pressure), which keeps the plant from wilting.

2. The Internal Machinery (Organelles)

1. Metals

Metals make up about 80% of all known elements. They are typically found on the left and middle sections of the periodic table.

Physical Properties

• State: Mostly solids at room temperature (except for Mercury, which is liquid).

• Lustre: They have a shiny surface when polished.

• Malleability: They can be hammered into thin sheets (Gold is the most malleable).