Biology - BIOENERGETICS (B4)

Photosynthesis -

What is the word equation for photosynthesis?

Carbon dioxide + Water → Glucose + Oxygen

Photosynthesis -

What is the balanced symbol equation for photosynthesis?

6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂

Photosynthesis -

Where in a plant cell does photosynthesis take place?

In the chloroplasts, which contain chlorophyll to absorb light energy.

Photosynthesis -

Why is photosynthesis important to life on Earth?

It produces oxygen for respiration + glucose for energy in food chains.

Limiting Factors of Photosynthesis -

What are the three main limiting factors of photosynthesis?

Light intensity, Carbon dioxide concentration, Temperature.

Limiting Factors of Photosynthesis -

How does light intensity affect the rate of photosynthesis?

As light increases, so does the rate - up to a point. After that, another factor becomes limiting.

Limiting Factors of Photosynthesis -

How does temperature affect photosynthesis?

It increases rate until enzymes denature at high temperatures, causing the rate to fall.

Limiting Factors of Photosynthesis -

How does CO2 concentration affect photosynthesis?

More CO2 increases the rate, but eventually levels off when another factor limits the rate.

Limiting Factors of Photosynthesis -

How can farmers increase the rate of photosynthesis in greenhouses?

By using artificial light, heaters, + CO2 enrichment to optimise conditions.

Photosynthesis Required Practical -

What is the dependent variable in the photosynthesis practical?

The number of oxygen bubbles produced (rate of photosynthesis).

Photosynthesis Required Practical -

What is the independent variable?

The distance of the light source from the pondweed.

Photosynthesis Required Practical -

What are the control variables in this experiment?

Temperature, concentration of CO2, amount of pondweed, water volume.

Photosynthesis Required Practical -

Why is sodium hydrogen carbonate added to the water?

To provide a consistent source of carbon dioxide for photosynthesis.

Photosynthesis Required Practical -

What precaution should be taken to ensure valid results in this practical?

Let the pondweed acclimatise to new light distance; repeat the experiment for reliability.

Uses of Glucose in Plants -

What are five ways a plant uses the glucose it produces?

Respiration, Making cellulose for cell walls, Making amino acids (w/ nitrates), Stored as starch, Converted to lipids for storage.

Uses of Glucose in Plants -

Why is starch a better storage molecule than glucose?

It’s insoluble, so it doesn’t affect the water balance/osmosis in cells.

Respiration -

What is respiration?

A chemical process that releases energy from glucose in every living cell.

Respiration -

What is the word equation for aerobic respiration?

Glucose + Oxygen → Carbon dioxide + Water (+ energy)

Respiration -

What is the balanced symbol equation for aerobic respiration?

C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O

Respiration -

Where does aerobic respiration occur in the cell?

In the mitochondria.

Anaerobic Respiration -

What is anaerobic respiration?

Respiration that occurs w/out oxygen, producing less energy.

Anaerobic Respiration -

What is the word equation for anaerobic respiration in muscle cells?

Glucose → Lactic acid.

Anaerobic Respiration -

What is the word equation for anaerobic respiration in yeast (fermentation)?

Glucose → Ethanol + Carbon dioxide.

Anaerobic Respiration -

What is fermentation used for in industry?

Making alcoholic drinks + causing bread to rise.

Response to Exercise & Metabolism -

What changes occur in the body during exercise?

Increased heart rate, Increased breathing rate + depth, More oxygen supplied to muscles.

Response to Exercise & Metabolism -

Why do muscles become fatigued during intense exercise?

Lactic acid builds up from anaerobic respiration, causing muscle fatigue.

Response to Exercise & Metabolism -

What is oxygen debt?

The amount of oxygen required to break down lactic acid after exercise.

Response to Exercise & Metabolism -

What are the three main functions of energy released by respiration?

Building larger molecules from smaller ones, Muscle contraction, Maintaining body temperature.

Response to Exercise & Metabolism -

What is metabolism?

The sum of all chemical reactions in the body, controlled by enzymes.

Response to Exercise & Metabolism -

Give examples of metabolic reactions.

Glucose → starch, glycogen / lipids. Formation of amino acids (glucose + nitrates). Breakdown of excess proteins to form urea. Respiration.