Respiration and Exercise Quiz 27 March 2024

Anaerobic Respiration in Yeast Cells

• Fermentation in yeast cells produces ethanol and carbon dioxide, used in making bread and alcoholic drinks.
• The word equation for fermentation is: Glucose → ethanol + carbon dioxide.

Photosynthesis

• Plants and algae make their own food through photosynthesis.
• Almost all life on Earth depends on photosynthetic organisms.
• Light provides the energy needed for photosynthesis.
• Water and carbon dioxide are the reactants required for photosynthesis.
• Plants produce carbohydrates in their leaves through photosynthesis and gain mineral nutrients and water from the soil via their roots.
• The products of photosynthesis are oxygen and glucose.
• The word equation for photosynthesis is: carbon dioxide + water → glucose + oxygen.
• Photosynthesis maintains levels of oxygen in the atmosphere.

Leaf Structure and Photosynthesis

• Leaves are the primary site of photosynthesis in plants.
• Chloroplasts in plant cells contain a green pigment called chlorophyll, which uses the energy in light for photosynthesis.
• Leaves have adaptations to carry out photosynthesis effectively, including:
  • Epidermis: thin and transparent to allow more light to pass through.
  • Palisade mesophyll: site of photosynthesis, containing many chloroplasts to absorb maximum sunlight.
  • Spongy mesophyll: contains many air spaces to increase surface area and allow carbon dioxide and oxygen to diffuse easily.

Respiration

• Respiration is a chemical reaction that gives out heat (exothermic).
• All living things respire.
• Respiration is carried out in all cells continuously.
• The purpose of respiration is to release energy for organisms to use.
• Living things need energy for movement, keeping warm, and for other chemical reactions to build molecules.
• The word equation for aerobic respiration is: Glucose + oxygen → carbon dioxide + water.

Respiration and Exercise

• During exercise, cells require a greater rate of respiration to provide more energy for movement.
• Heart rate, breathing rate, and breathing volume all increase during exercise to meet the increased demand for reactants during respiration.

Anaerobic Respiration

• Anaerobic means 'without oxygen'.
• Anaerobic respiration takes place without oxygen and releases less energy than aerobic respiration.
• During intense exercise, if there is not enough oxygen, anaerobic respiration takes place.
• Aerobic respiration uses oxygen and releases more energy than anaerobic respiration.
• Anaerobic respiration in muscle cells causes a build-up of lactic acid, resulting in an oxygen debt.
• The word equation for anaerobic respiration is: Glucose → lactic acid (in animal muscles).