Biology: Respiration Overview

Respiration

• 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.

Aerobic Respiration

• Aerobic respiration uses oxygen.
• Word equation: Glucose + oxygen → carbon dioxide + water + energy

Obtaining Respiration Materials

• 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.

Respiration Rate

• 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 and the Air

• 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.

Photosynthesis

• 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

Obtaining Photosynthesis Materials

• Plants obtain water through their roots.
• Plants absorb carbon dioxide from the air through stomata.

Additional Information

• Forests are often called the "lungs of the Earth" because they release oxygen during photosynthesis—essential for respiration by other organisms.