Biology: Respiration Overview

Study Notes

Respiration is a continuous life process occurring in all living organisms' cells.
It's a chemical reaction that releases energy from glucose.
This energy powers life processes like movement, growth, and reproduction.
Respiration converts stored chemical energy in glucose into other usable energy forms, and releases some heat.

Humans get oxygen by breathing.
- Inhaled oxygen travels to the alveoli (air sacs) in the lungs.
- Oxygen diffuses from the alveoli into the blood.
- The heart pumps the oxygen-rich blood throughout the body.
Aquatic animals obtain oxygen from water (e.g., fish use gills).
Plants absorb oxygen through stomata (tiny holes) in their leaves.
Single-celled organisms (like bacteria and yeast) absorb oxygen through their cell membranes.
Animals obtain glucose from food.
- Sugary foods provide immediate glucose for respiration.
- Starchy foods require digestion to break down starch into glucose.
- Glucose is absorbed into the blood and transported to cells that require it for respiration.

Factors affecting the rate of respiration include glucose concentration, oxygen concentration, and temperature.
Higher concentrations of reactants (glucose and oxygen) lead to faster reactions.
Higher temperatures provide more energy for molecules to move and react, thus increasing the reaction rate.

Respiration uses oxygen and produces carbon dioxide.
The composition of inhaled air differs from exhaled air. Inhaled air has a higher percentage of oxygen and a lower percentage of carbon dioxide compared to exhaled air.

Plants have special cells (like palisade mesophyll cells in leaves) containing chloroplasts to carry out photosynthesis.
Chloroplasts contain chlorophyll that traps light energy.
Other cells (like root hair cells) absorb water from the soil.
Stomata on leaves allow for gas exchange—carbon dioxide uptake and oxygen release.
Photosynthesis converts light energy into chemical energy.
Word equation: Carbon dioxide + water → glucose + oxygen