science 8 test

Six Characteristics of Living Things

• Cells: Composed of one or more cells.

• Metabolism: Use energy for growth and maintenance.

• Adaptation: Can adjust to environmental changes.

• Growth: Change and develop over time.

• Reproduction: Ability to produce offspring.

• Response to Stimuli: React to changes in their surroundings.

Structure vs. Function

• Structure: The physical features of an organism (e.g., the shape of the heart).

• Function: The role or activity of a structure (e.g., the heart pumps blood).

Adaptations

• Structural Adaptations: Physical traits that enhance survival (e.g., camouflage).

• Behavioral Adaptations: Actions taken by organisms to survive (e.g., migration).

Cells

• Cells are the basic unit of life and can be classified into three main types:

  • Blood Cells: Transport oxygen throughout the body.

  • Skin Cells: Protect the body from pathogens.

  • Brain Cells: Send and receive signals, facilitating communication within the nervous system.

How Organs are Formed

• Groups of specialized cells (tissues) combine to form organs.

Animal vs. Plant Cells

• Animal Cells: Lack a cell wall, have a round shape, and contain small vacuoles.

• Plant Cells: Possess a cell wall, are rectangular, have large vacuoles, and contain chloroplasts for photosynthesis.

Unicellular vs. Multicellular Organisms

• Unicellular Organisms: Consist of a single cell (e.g., bacteria).

• Multicellular Organisms: Composed of multiple cells (e.g., humans).

Unicellular Organisms: Advantages & Disadvantages

• Advantages: Simple structure, rapid reproduction, highly adaptable.

• Disadvantages: Limited functions and sensitivity to environmental changes.

Multicellular Organisms: Advantages & Disadvantages

• Advantages: Specialized functions for different cells, generally longer lifespan.

• Disadvantages: More complex structure and longer growth and development time.

Diffusion

• The movement of particles from an area of high concentration to an area of low concentration.

Osmosis

• The movement of water across a semi-permeable membrane.

Types of Osmosis

• Hypertonic: The cell loses water and shrinks.

• Isotonic: Equal concentration inside and outside the cell; no net water movement (cell remains normal).

• Hypotonic: The cell gains water and may swell or burst.

Semi-Permeable Membrane

• A barrier that allows certain substances to pass through while blocking others.

Plant Tissues

• Meristematic Tissue: Responsible for growth.

• Ground Tissue: Functions in storage and photosynthesis.

• Vascular Tissue: Transports water (xylem) and nutrients (phloem).

Main Plant Organs

• Roots: Absorb water and nutrients; anchor the plant.

• Stems: Provide support and transport materials.

• Leaves: The primary site of photosynthesis.