Junior Cycle Science Quiz: Respiration & Photosynthesis
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BW7: Respiration and Photosynthesis

BW7: Respiration and Photosynthesis

1. Respiration

What is Respiration?

Respiration is the process by which organisms release energy from food molecules (like glucose) to power cellular activities. It occurs in all living cells.

Types of Respiration:

  • Aerobic Respiration:
    • Requires oxygen.
    • Produces a large amount of energy.
    • Equation: Glucose + Oxygen → Carbon Dioxide + Water + Energy (C6H12O6 + O2 → CO2 + H2O + Energy)
  • Anaerobic Respiration:
    • Does not require oxygen.
    • Produces less energy.
    • By-products include lactic acid (in animals) or ethanol and carbon dioxide (in some microorganisms).

Biological Importance:

Provides energy for growth, repair, and other cellular processes.

2. Photosynthesis

What is Photosynthesis?

Photosynthesis is the process by which plants, algae, and some bacteria use sunlight to produce food (glucose) from carbon dioxide and water. It occurs in the chloroplasts of plant cells.

Equation:

Carbon Dioxide + Water + Sunlight → Glucose + Oxygen (CO2 + H2O + Light → C6H12O6 + O2)

Stages:

  • Light-Dependent Stage: Sunlight energy is captured by chlorophyll, and water is split to release oxygen.
  • Light-Independent Stage: (Calvin Cycle): Carbon dioxide is converted into glucose using the energy captured in the light-dependent stage.

Biological Importance:

Provides oxygen for respiration and produces glucose, which is the basis of the food chain.

3. Factors Affecting Respiration

  • Temperature: Enzymes involved in respiration work best at optimal temperatures. Too high or low temperatures slow down the process.
  • Oxygen Availability: Aerobic respiration requires oxygen; less oxygen reduces energy production.
  • Glucose Availability: Without glucose, cells cannot produce energy.

4. Factors Affecting Photosynthesis

  • Light Intensity: More light increases the rate of photosynthesis, up to a point.
  • Carbon Dioxide Concentration: Higher levels of carbon dioxide increase the rate of photosynthesis.
  • Temperature: Photosynthesis relies on enzymes, which work best within an optimal temperature range.
  • Water Availability: A lack of water slows down or stops photosynthesis.

5. Link Between Respiration and Photosynthesis

Photosynthesis produces glucose and oxygen, which are used in respiration. Respiration releases carbon dioxide and water, which are used in photosynthesis. Together, they form the basis of the energy cycle in ecosystems.

Summary

  • Respiration and photosynthesis are vital biological processes that sustain life.
  • Respiration releases energy, while photosynthesis captures and stores energy.
  • Factors like temperature, light, and resource availability influence both processes, demonstrating their sensitivity to environmental conditions.

Questions:

Q1: What is respiration?
A: Respiration is the process by which organisms release energy from food molecules like glucose to power cellular activities.
Q2: What is the difference between aerobic and anaerobic respiration?
A:
  • Aerobic respiration requires oxygen and produces a large amount of energy.
  • Anaerobic respiration does not require oxygen and produces less energy, with by-products like lactic acid or ethanol.
Q3: Write the equation for aerobic respiration.
A: Glucose + Oxygen → Carbon Dioxide + Water + Energy
C6H12O6+O2→CO2+H2O+Energy.
Q4: What is photosynthesis?
A: Photosynthesis is the process by which plants, algae, and some bacteria use sunlight to produce glucose and oxygen from carbon dioxide and water.
Q5: Write the equation for photosynthesis.
A: Carbon Dioxide + Water + Sunlight → Glucose + Oxygen
CO2+H2O+Light→C6H12O6+O2.
Q6: Where does photosynthesis occur in plants?
A: Photosynthesis occurs in the chloroplasts of plant cells.
Q7: What are the two stages of photosynthesis?
A:
  1. Light-Dependent Stage: Sunlight is captured by chlorophyll, and water is split to release oxygen.
  2. Light-Independent Stage: Carbon dioxide is converted into glucose using the energy captured in the light-dependent stage.
Q8: What factors affect the rate of respiration?
A:
  • Temperature
  • Oxygen availability (for aerobic respiration)
  • Glucose availability
Q9: What factors affect the rate of photosynthesis?
A:
  • Light intensity
  • Carbon dioxide concentration
  • Temperature
  • Water availability
Q10: How are respiration and photosynthesis linked?
A: Photosynthesis produces glucose and oxygen, which are used in respiration. Respiration releases carbon dioxide and water, which are used in photosynthesis. Together, they form the basis of the energy cycle in ecosystems.
Q11: Why is oxygen important for respiration?
A: Oxygen is needed for aerobic respiration to release a large amount of energy from glucose.
Q12: What is the role of glucose in respiration?
A: Glucose is broken down to release energy for cellular activities like growth and repair.
Q13: What happens to plants if there is no sunlight?
A: Without sunlight, photosynthesis cannot occur, so plants cannot produce glucose and oxygen.
Q14: What is the biological importance of photosynthesis?
A: Photosynthesis provides oxygen for respiration and produces glucose, which forms the basis of the food chain.
Q15: What are the by-products of anaerobic respiration in animals?
A: Lactic acid is the by-product of anaerobic respiration in animals.