Bioenergetics

Question 1

Recite the word equation for photosynthesis

Answer 1

Carbon Dioxide + Water —> Glucose + Oxygen

Question 2

Recite the Symbol Equation for Photosynthesis

Answer 2

6CO₂ + 6H₂O —> C₆H₁₂O₆ + 6O₂

Question 3

What are the 4 factors that affect the rate of photosynthesis?

Answer 3

• temperature (above 45 degrees the enzymes involved in catalysing the reaction denature)
• concentration of chlorophyll
• intensity of sunlight
• concentration of carbon dioxide

Question 4

What do plants use glucose for?

Answer 4

• respiration
• production of starch
• productions of fats and oils
• production of cellulose
• production of protiens (nitrogen is needed for this so they absorb nitrate ions from the soil)

Question 5

Recite the inverse square law

Answer 5

light intensity = intensity at source / distance²

rearranged

distance = 1 / √ light intensity

Question 6

Describe an experiment for testing the rate of photosynthesis where there is a change in light intensity.

Answer 6

• use an aquatic plant (e.g, pondweed)
• change the distance between the pondweed and the light source
• measure the bubbles produced per unit of time

Question 7

What type of a reaction is respiration?
What type of a reaction is photosynthesis?

Answer 7

Respiration - Exothermic (releases energy)
Photosynthesis - Endothermic (absorbs heat energy from surroundings)

Question 8

Recite the 3 different respiration reactions.

Answer 8

Aerobic (in the mitochondria): Glucose + Oxygen —> Carbon Dioxide + Water (+energy)
C₆H₁₂O₆ + 6O₂ —> 6CO₂ + 6H₂O (+energy)

Anerobic (in animals): glucose —> lactic acid

Anerobic (in plants): glucose —> ethanol + carbon dioxide
(in yeast cells, this is fermentation)

Question 9

What is metabolism?
Recite 4 different metabolic reactions.

Answer 9

Metabolism referrs to all the chemical reactions that occur in an organism.

• Making amino acids (nitrate ions + glucose)
• Making lipid mollecules (glycerol + fatty acid)
• Breaking down excess protiens (produces urea, which is then excreted)
• Converting glucose into something else (for plants, starch, for animals, glycogen, for plants, cellulose)

Question 10

What happens during anerobic respiration?

(3 marks)

Answer 10

• lactic acid builds up in muscles and causes pain and fatigue
• extra oxygen is needed to clear the lactic acid from the cells (oxygen debt)
• blood transports the lactic acid to the liver, of which it reacts with oxygen to produce carbon dioxide and water

(3 marks)