Respiration in Organisms

An athlete needs a lot of energy during the race. To release more energy from food, the muscle cells need more oxygen. Breathing faster and deeper supplies more oxygen to the cells, speeding up the breakdown of food to release the required energy.

Similarities:

1. Both processes break down food to release energy.
2. Both take place inside the cells.

Differences:

Dust-laden air contains smoke, dust, pollen, etc. When we inhale, these particles irritate the lining of the nasal cavity. Sneezing is a reflex action to expel these foreign particles so that clean air enters our body.

Test-tube A will have the highest concentration of CO2.

• Tube A (Snail): Snail breathes out CO2. (High CO2).
• Tube B (Plant): Plant uses CO2 for photosynthesis and releases O2. (Low CO2).
• Tube C (Both): CO2 released by snail is used by plant. (Balanced).

(a) In cockroaches, air enters the body through: (iii) spiracles.

(b) During heavy exercise, we get cramps in the legs due to the accumulation of: (ii) lactic acid.

(c) Normal breathing rate per minute in an average adult person at rest is: (ii) 15-18.

(d) During exhalation, the ribs move: (ii) downwards.

(i) During heavy exercise the breathing rate of a person slows down. (False)

(ii) Plants carry out photosynthesis only during the day and respiration only at night. (False) (Respiration occurs 24x7).

(iii) Frogs breathe through their skins as well as their lungs. (True)

(iv) The fishes have lungs for respiration. (False) (They have gills).

(v) The size of the chest cavity increases during inhalation. (True)

Plants respire through:

1. Stomata: Tiny pores on leaves for exchange of Oxygen and Carbon dioxide.
2. Root Hairs: They take up air trapped between soil particles.
3. Lenticels: In woody stems.

The process of breakdown of food in the cell with the release of energy.

• Aerobic: Breakdown of glucose with use of Oxygen. Releases **More Energy**.
• Anaerobic: Breakdown of glucose without use of Oxygen. Releases **Less Energy**. (e.g. in Yeast).
• Muscle Cramps: When muscles respire anaerobically (during heavy exercise), **Lactic Acid** is produced causing cramps. Hot water bath improves circulation and breaks down lactic acid.

• Inhalation: Ribs move **Up and Out**. Diaphragm moves **Down**. Chest cavity increases. Air rushes in.
• Exhalation: Ribs move **Down and In**. Diaphragm moves **Up**. Chest cavity decreases. Air pushed out.
• Pathway: Nostrils -> Nasal Cavity -> Trachea (Windpipe) -> Bronchi -> Lungs.

• Cockroach (Insects): Have small openings called **Spiracles**. Network of air tubes called **Tracheae** for gas exchange.
• Earthworm: Breathes through its moist and slimy **Skin**.
• Fish: Breathe through **Gills**. Gills are supplied with blood vessels for exchange of gases from water.
• Frogs: Have **Lungs** and also breathe through moist **Skin** (when in water).

• Roots take up air from soil spaces.
• Leaves have **Stomata** for exchange of O2 and CO2.
• Breakdown of glucose is similar to other organisms (Aerobic).

• Aerobic Respiration:
  Glucose + Oxygen -> Carbon dioxide + Water + Energy
• Anaerobic Respiration (Yeast):
  Glucose -> Alcohol + Carbon dioxide + Energy
• Anaerobic Respiration (Muscles):
  Glucose -> Lactic acid + Energy

• Breathing Rate: Number of times a person breathes in a minute. Normal (Rest) = 15-18 times/min. Heavy exercise = up to 25 times/min.
• Yeasts: Single-celled organisms. Used to make wine and beer (alcohol production).
• Smoking: Damage lungs and causes cancer.
• Lime Water Test: Exhaled air turns lime water milky (proves presence of CO2).