Biology cie 9700 A level notes on topic 12 ( first topic from A level section)
summary made out of notes from both CIE textbook, classnotes and past papers.
Achieved 91% on my biology A level this june. Prepared for the exam using these notes and past papers.
1. Energy and respiration.
Energy. (What is required to do cellular work)?
ATP is the universal emergency currency as it provides the immediate source of
energy for cellular processes. Its molecules are small, soluble and easily
hydrolyzed to release energy.
Need for energy in living organisms:
All living organisms require a continuous supply of energy to stay alive, to drive
their various activities, either from absorption of light or from chemical potential
energy ( energy stored in nutrient molecules).
Photosynthesis = light energy chemical potential energy
Provides energy supply and usable carbon compounds, all life on earth depends on
photosynthesis directly or indirectly.
An organic compound is a compound including carbon and hydrogen.
Organic molecules can be used as building blocks for complex molecules, or
represent chemical potential energy that can be released by breaking down the
molecules in respiration.
Energy used to do all kinds of work.
Work includes:
1. Anabolic reactions ( synthesis of complex substances form simpler ones.)
eg: synthesis of polysaccharides form monosaccharaides, lipids from
glycerol. ( building up reaction)
2. Protein synthesis (anabolic reaction)
3. DNA replication (anabolic reaction)
4. Active transport of substances against a diffusion gradient, such as the
activity of sodium potassium pump.
5. Mechanical work ( muscle contraction, cellular movements: movement of
vesicles through cytoplasm))
6. Homeostasis, maintenance of body temperature, heat generation.
7. Cellular work : DNA replication, active transport, generating heat.
ATP synthesized and used in cells ,as well as for above:
- oxidative phosphorylation
- substrate level phosphorylation
- photophosphorylation
outline need for energy in living organisms + named ATP
examples (9)
- ATP as universal energy currency - Activate glucose in glycolysis
- Light energy needed for photosynthesis - Active transport
- ATP used t convert GP to TP - Eg: sodium potassium pump
- ATP used to regenerate RUBP - Movement/locomotion.
- Anabolic reactions - Eg: muscle contraction
- Such as: starch formation, protein synthesis - Endocytosis/exocytosis
- Activation energy - Temperature regulation.
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