bioenergetics

What is bioenergetics?

The study of energy transfer and transformation in living organisms

What is photosynthesis?

Process plants use to convert light energy into glucose

What is the word equation for photosynthesis?

carbon dioxide + water → glucose + oxygen

What is the symbol equation for photosynthesis?

6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂

Which organelle carries out photosynthesis?

Chloroplast

What pigment absorbs light energy?

Chlorophyll

Why are leaves thin and flat?

To increase surface area for light absorption

Where does photosynthesis occur in a leaf?

Palisade mesophyll cells

Why are stomata important for photosynthesis?

Allow carbon dioxide to enter, oxygen to leave

What factors affect rate of photosynthesis?

Light intensity, carbon dioxide concentration, temperature

What is a limiting factor?

Factor that restricts the rate of a process

What is the effect of increasing light intensity on photosynthesis?

Increases rate up to a point, then plateaus

What is the effect of temperature on photosynthesis?

Rate increases up to optimum, then enzymes denature

What is the effect of increasing CO₂ concentration?

Increases rate up to a point, then other factors limit

What is the test for starch in leaves?

Add iodine, blue-black = starch present

Why is destarching a leaf important in experiments?

Ensures all starch made is from new photosynthesis

How do you destarch a leaf?

Leave plant in darkness for 24-48 hours

Describe a practical to measure rate of photosynthesis.

Count bubbles produced by pondweed in water

What does sodium hydrogencarbonate provide in pondweed experiments?

Extra carbon dioxide

Why use water bath in photosynthesis experiments?

Keep temperature constant

What is respiration?

Process of releasing energy from glucose

Where does aerobic respiration occur?

Mitochondria

What is the word equation for aerobic respiration?

glucose + oxygen → carbon dioxide + water (+ energy)

What is the symbol equation for aerobic respiration?

C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O (+ energy)

What is anaerobic respiration in animals?

Respiration without oxygen producing lactic acid

What is the word equation for anaerobic respiration in animals?

glucose → lactic acid (+ energy)

What is anaerobic respiration in yeast?

glucose → ethanol + carbon dioxide (+ energy)

What is fermentation?

Anaerobic respiration in yeast/plant cells

Name one use of yeast fermentation.

Bread making, alcohol production

What is oxygen debt?

Extra oxygen needed after exercise to break down lactic acid

Why is lactic acid build-up bad?

Causes muscle fatigue and soreness

How do you measure rate of respiration?

Use a respirometer to measure oxygen uptake

What is metabolism?

All chemical reactions in the body

Give examples of metabolic reactions.

Photosynthesis, respiration, breakdown of proteins, synthesis of lipids

What is ATP?

Energy carrier molecule in cells

Why is ATP important?

Provides energy for cellular processes

During what process is most ATP made?

Aerobic respiration

Which cells have lots of mitochondria?

Muscle cells, liver cells

Why do muscle cells need lots of energy?

For contraction and movement

How does exercise affect breathing rate?

Increases to supply more oxygen

How does exercise affect heart rate?

Increases for more oxygen delivery and waste removal

Why do athletes warm up before exercising?

Increase enzyme activity and cardiac output

Why does temperature affect photosynthesis and respiration?

Enzymes work faster at optimum temperature

How is glucose used in plants?

Stored as starch, used for respiration, making cellulose and proteins

What is transpiration?

Loss of water vapor from plant leaves

How does transpiration help photosynthesis?

Brings up water needed for photosynthesis

What is compensation point?

Light intensity at which photosynthesis and respiration rates are equal

What is chlorophyll?

Pigment absorbing light for photosynthesis

Why do leaves turn yellow?

Chlorophyll breaks down, less photosynthesis

How is glucose used in humans?

Energy for respiration, stored as glycogen, making fat, protein synthesis

Why do you pant after exercise?

Increase oxygen intake, repay oxygen debt

What is lactic acid?

Compound produced in anaerobic respiration

Why must lactic acid be removed?

Causes cramp and fatigue

What does a respirometer measure?

Rate of respiration by measuring gas exchange

What affects rate of respiration besides exercise?

Temperature, age, health, activity level

Why is anaerobic respiration less efficient?

Produces less ATP per glucose

How is energy from respiration used?

Muscle contraction, growth, cell division, temperature regulation

Why is anaerobic respiration important in plants?

Allows energy production when oxygen is low (waterlogged soils)

How does light intensity affect plant growth?

Higher intensity increases photosynthesis, growth rate

What is rate calculation?

Rate = amount produced ÷ time taken

How would you test respiration rate in yeast?

Measure CO₂ production in glucose solution

Why use a control in experiments?

To validate results and compare changes

What gas is produced in aerobic respiration?

Carbon dioxide

What gas is produced in photosynthesis?

Oxygen

How do plants store excess glucose?

As starch

Why is starch a good storage molecule?

Insoluble, doesn’t affect water balance

What is the role of enzymes in bioenergetics?

Speed up metabolic reactions

Name a practical to investigate photosynthesis.

Pondweed bubbles / leaf starch test

Name a practical to investigate respiration.

Respirometer, limewater test for CO₂

Why is boiling leaf in ethanol required for starch test?

Removes chlorophyll for clear color test

What safety precautions in ethanol practical?

Use water bath, avoid flames

How do you calculate mean rate?

Mean rate = total amount ÷ number of measurements

What is oxidation?

Gain of oxygen / loss of electrons

Why is water important for bioenergetics?

Solvent for reactions, needed in photosynthesis

What effect does CO₂ level have on plant growth?

Higher CO₂ increases photosynthesis until another factor limits

Why do plants need nitrogen?

For amino acids and proteins

What nutrient increases chlorophyll production?

Magnesium

What deficiency causes yellow leaves?

Magnesium deficiency

What occurs during light-dependent reaction?

Light energy splits water, produces ATP and oxygen

What occurs during light-independent reaction?

Uses ATP to convert CO₂ to glucose

What is photolysis?

Splitting water with light energy

What enzyme controls metabolism?

Many – each reaction has a specific enzyme

Why does respiration release energy?

Breaks down glucose’s chemical bonds

Which direction does oxygen move in respiration?

Into cells from blood

Which direction does carbon dioxide move after respiration?

Out of cells into blood

What is glycolysis?

First stage of respiration – glucose broken to pyruvate

What is Krebs cycle?

Second stage – pyruvate processed to release energy

What type of organism carries out photosynthesis?

Plants and algae

What type of organism carries out respiration?

All living things

Why do seeds respire at night?

No sunlight = no photosynthesis, still need energy

How does pH affect bioenergetic enzymes?

Each has optimum pH; extremes denature enzyme

Why does heart rate rise during exercise?

More oxygen needed, more waste (CO₂) to remove

Why do plants need glucose?

Fuel for energy, making substances like cellulose, starch, proteins

What is aerobic respiration’s main output?

ATP energy, CO₂, water

How does energy transfer in photosynthesis differ from respiration?

Photosynthesis stores energy; respiration releases it

Why is experimental repeatability important?

Confirms reliability of results

Why use pondweed in photosynthesis experiments?

Easy to see oxygen bubbles produced

Why is cut leaf used in starch test?

Ensures iodine can reach inside cells

What is Q10 value?

Change in rate of reaction for every 10°C temperature change

What is assay?

Procedure to measure activity (like photosynthesis rate)