Study Notes on Plant Respiration

Breathing is essential for life; it provides energy through oxidation of food.
All living organisms, including plants and microbes, require energy for vital activities such as reproduction and movement.

Energy comes from food which is oxidized to release energy.
Green plants and cyanobacteria make their own food via photosynthesis, converting light energy to chemical energy stored in carbohydrates (glucose, sucrose, starch).
Not all plant tissues are capable of photosynthesis; only chloroplast-containing cells do.
Non-green tissues require food that must be transported from green parts.
Animals obtain food heterotrophically—herbivores directly from plants; carnivores indirectly.
All food for respiration originates from photosynthesis.

Cellular respiration is the breakdown of food materials to release energy and synthesize ATP.
Photosynthesis occurs in chloroplasts; respiration processes occur in cytoplasm and mitochondria.
Oxidation of C-C bonds in food compounds releases energy, termed respiration, with compounds used called respiratory substrates.
Carbohydrates are typically oxidized, but proteins, fats, and organic acids can also serve as substrates under certain conditions.
Energy from respiration is released in slow, enzyme-controlled steps, primarily trapped as ATP.
ATP is the energy currency used for various cellular processes.

Plants do breathe, requiring O2 for respiration and producing CO2.
No specialized respiratory organs; gas exchange occurs through stomata and lenticels.
Each plant part manages its own gas exchange needs with minimal transport between parts.
Lower gas exchange demands compared to animals; respiration rates are much lower.
Availability of O2 is generally sufficient during photosynthesis as it is produced by the leaf cells themselves.