Cloning, Stem Cells, Resources, Water, Soil, and Energy
Cloning
Cloning involves obtaining genetically identical copies of DNA molecules, cells, or organisms. It’s a natural process, such as DNA replication or asexual reproduction, but can also be directed purposefully. In labs, DNA is amplified by PCR, cells are cloned by culture, and organisms are cloned by nuclear transfer. Artificial cloning in mammals, like Dolly the sheep, involves transferring a cell nucleus into an enucleated egg. This process bypasses sexual fertilization and allows for obtaining copies of animals with specific traits.
Stem Cells
Stem cells have the ability to multiply and differentiate into specialized cells. There are two types:
- Embryonic Stem Cells: Part of an embryo, capable of generating a complete organism.
- Adult (Somatic) Stem Cells: Present in adults, able to generate specialized cells of different tissues.
Overfishing and Natural Resources
Natural resources are elements from nature used by humans. The Industrial Revolution significantly increased resource exploitation. Renewable resources are inexhaustible (solar, wind). Non-renewable resources are limited (petroleum). Potentially renewable resources depend on the rate of exploitation versus regeneration (livestock, agriculture, fishing).
Water
Water Cycle
The hydrosphere includes seas, rivers, and lakes. Water continuously changes state through the water cycle, driven by solar energy and gravity. Human activities, like building dams, impact this cycle.
Water as a Fragile Resource
Water is essential for life, but unevenly distributed. Consumption is increasing due to population growth and industrial expansion. We must manage water sustainably and reduce consumption.
Soil
Soil Formation
Soil is a vital resource for growing food. Its formation is influenced by original rock, vegetation, land slope, time, and weather.
Living Beings as a Resource
Traditional farming respected the environment. Modern farming and fishing have changed due to technological advancements.
Energy
Non-Renewable Energy
Coal: Cheap but highly polluting, generating greenhouse gases and acid rain.
Oil: Reserves are decreasing, and prices are rising.
Renewable Energy
Solar energy (thermal and photovoltaic), hydropower, and wind power.