Bioenergetics

Question 1

Photosynthesis

Answer 1

Carbon dioxide + water → oxygen + glucose

6CO₂ + 6H₂O → 6O₂ + C₆H₁₂O₆

→ = sunlight and chlorophyll

Question 2

Factors affecting the rate of photosynthesis

Answer 2

Light

Temperature

Carbon dioxide concentration

Amount of chlorophyll

Question 3

Effect of light intensity on photosynthesis practical

Answer 3

Set up a boiling tube containing 45 cm3 of sodium hydrogen carbonate solution

Cut an 8cm piece of pondweed and use forceps to place into the boiling tube

Position the boiling tube so that the pondweed is 10 cm away from the light source

Count the number of bubbles emerging from the cut end of the stems in one minute

Question 4

Glucose in a plant

Answer 4

Can be stored as starch (in leaves, seeds, roots)

Cellulose strengthens cell walls

Growth and repair for damaged cells or tissues

Used in respiration

Energy stored as sucrose

Question 5

Aerobic respiration

Answer 5

Occurs in the presence of oxygen and in most cells most of the time

Takes place in the mitochondria

O₂ is present

Question 6

Aerobic respiration formula

Answer 6

Glucose + oxygen → carbon dioxide + water + ATP (energy)

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

Opposite to photosynthesis

Question 7

Anaerobic respiration

Answer 7

Occurs without oxygen and much less frequently than aerobic respiration

Takes place in the cytoplasm

O₂ is not present

Question 8

Anaerobic respiration formula in muscles

Answer 8

Glucose → lactic acid + ATP (energy)

C₆H₁₂O₆ → 2C₃H₆O₃ + ATP (energy)

Question 9

Anaerobic respiration formula in yeast (fermentation)

Answer 9

Glucose → ethanol + carbon dioxide + ATP (energy)

C₆H₁₂O₆ → 2C₂H₅OH + 2CO₂ + ATP (energy)

Question 10

Lactic acid

Answer 10

Taken to the liver via the bloodstream and;

oxidised to CO₂ or H₂O
or
converted into glucose, then glycogen

Question 11

Oxygen debt

Answer 11

The amount of extra oxygen the body needs after exercise to react with the accumulated lactic acid and remove it from the cells

Question 12

Metabolism

Answer 12

The sum off all chemical reactions in a cell / body

E.g. respiration, breakdown of protein, forming lipids from glycerol and fatty acids

Question 13

Function of the liver

Answer 13

Detoxifying poisonous substances (ethanol from alcohol)

Breaking down worn blood cells

Remove lactic acid

Question 14

Hepatic portal vein

Answer 14

Carries blood containing digested food from the intestines to the liver

Question 15

Hepatic artery

Answer 15

Brings oxygenated blood to the liver

Question 16

Hepatic vein

Answer 16

Carries blood from the liver to the heart with level of food adjusted