Physics Energy Concepts Quiz

Study Notes

Kinetic energy refers to the energy of motion, enabling moving objects to perform work.
Potential energy is stored energy that can be converted into kinetic energy, e.g., a stone on a hillside.
Energy exists in various forms: light, heat, sound, electrical, magnetic, mechanical, chemical, and atomic.
Energy transformation occurs; it cannot be created or destroyed, and is measured in joules (J).

Living organisms require energy to maintain order and prevent disorder, which can lead to death.
Critical functions needing energy include:
- Anabolism: Building larger, more complex substances from smaller ones, essential for processes like DNA replication and protein synthesis.
- Movement: Involves circulation within organisms and locomotion through muscle contractions or cilia/flagella movement.
- Active Transport: Movement of ions and molecules against concentration gradients, e.g., sodium-potassium pump.
- Maintenance: Repair and division of cells and organelles, as well as thermoregulation in birds and mammals.

Energy flow in living systems occurs in three stages:
- Photosynthesis converts sunlight into chemical energy in plants.
- Chemical energy from photosynthesis is used to synthesize ATP.
- ATP powers cellular activities; overall reactions in organisms are known as metabolism.

Metabolism consists of two types:
- Anabolism: Building complex molecules, requiring energy.
- Catabolism: Breaking down complex molecules, releasing energy.
Before chemical reactions can proceed, they require activation energy, which can be lowered by catalysts such as enzymes.

Adenosine triphosphate (ATP) is the primary energy currency in all cells.
Features of ATP:
- Provides immediate energy through one-step reactions.
- Easily hydrolyzed to release energy.
- Can be recycled from adenosine diphosphate (ADP) through phosphorylation.
- Small and water-soluble, allowing easy transport and participation in metabolic reactions.

Three negatively charged phosphate groups in ATP create unstable bonds, making them easy to break and release energy (30.5 kJ/mol for the first two phosphates, 14.2 kJ/mol for the last).
ATP conversion to ADP is reversible, allowing for continual recycling of energy.
A single human utilizes approximately 65 kg of ATP daily, undergoing around 1300 cycles of ATP synthesis and hydrolysis.

Phosphorylation, the process of adding a phosphate group to ADP to form ATP, can occur through:
- Photophosphorylation: In chloroplasts during photosynthesis.
- Oxidative phosphorylation: On mitochondrial membranes during electron transport.
- Substrate-level phosphorylation: In cells when phosphate groups transfer from donor molecules to ADP (e.g., glycolysis).