Life on Earth: Biosphere, Conditions & Characteristics

Life on Earth - The Biosphere

• Life exists almost everywhere on Earth, even in extreme environments like Greenland's ice sheet or the Atacama Desert.
• The biosphere encompasses all living things and the physical environment they inhabit.

How is Life on Earth Possible?

• Earth is the only known planet with life due to several factors.
• Optimal distance from the Sun: Earth's distance (150 million kilometers) results in a suitable temperature range for life.
• Presence of Oxygen and Carbon Dioxide: Essential for most living things, with oxygen produced by photosynthesis.
• Presence of Liquid Water: Crucial for all organisms and is the environment for many. The human body is composed of water.
• Protective Atmosphere: Filters harmful UV rays preventing damage and acts as a thermal regulator, preventing drastic temperature changes.

What Makes a Living Thing "Living"?

• Living and non-living things are made of matter, but living things have distinct characteristics.
• These include shared characteristics that differentiate them from the non-living, like minerals or butterflies.

Non-Living Things

• Non-living things are composed of inorganic matter.
• Abundant inorganic elements include Oxygen, Silicon, Aluminum, and Iron.

Living Things

• Living things, or organisms, are made of the same chemical elements.
• These are classified as "bioelements" and include Carbon, Hydrogen, Oxygen, Nitrogen, Phosphorus, and Sulfur.
• These elements make up over 90% of living matter.
• Bioelements combine to form biomolecules through chemical reactions.
• Examples include: inorganic (water, mineral salts) and organic (carbohydrates, lipids, proteins, and nucleic acids)

Functions of Biomolecules

• Water: The site of reactions in organisms.
• Carbohydrates: Provide energy and structure to cells.
• Lipids: Serve as energy reserves and aid in cell structure.
• Proteins: Crucial for growth and maintenance of body structures.
• Nucleic Acids: Carry genetic information.

Functions of Living Things: Nutrition

• Nutrition: Organisms obtain energy for growing and repairing, through autotrophic or heterotrophic means.
• Autotrophic Nutrition: Organisms capture energy from their surroundings to produce organic matter (e.g., photosynthesis in plants, algae, and some bacteria).
• Heterotrophic Nutrition: Organisms cannot produce their own food and rely on other organisms for nourishment (e.g., animals, protozoans, fungi, obtain nutrients from dead organic matter or consume other lifeforms).

Functions of Living Things: Interaction

• Interaction: The ability of organisms to gather information from their environment and respond to stimuli (e.g., temperature change, hunger).
• Stimuli: Changes in the environment or within the organism itself.
• Responses: Adaptations or reactions to stimuli

Functions of Living Things: Reproduction

• Reproduction: The capacity of organisms to produce new, similar individuals.
• Asexual Reproduction: Producing offspring from one parent, resulting in genetically identical individuals.
• Sexual Reproduction: Requires two parents to combine gametes and create genetically unique offspring. -Starfish can reproduce both sexually and asexually.

Cells - The Units of Life

• All living things are composed of cells.
• Cells carry out life functions.
• Cells arise from pre-existing cells.
• Organisms can be single-celled or multicellular.

Types of Cells

• Prokaryotic Cells: Simpler cells without a nucleus (e.g., bacteria).
• Eukaryotic Cells: More complex cells with a nucleus and organelles. (e.g., plants, animals). -There are two main types of eukaryotic cells, animal cells and plant cells.

Explore Earth's biosphere and the conditions that support life. Learn about the optimal distance from the Sun, the presence of oxygen, carbon dioxide, liquid water, and Earth's protective atmosphere. Discover what distinguishes living from non-living things.