B4 core questions
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Topic 4 Bioenergetics – Concept Questions for Assessment 1 of 2
1
State the word equation for photosynthesis.
Carbon dioxide + water -> glucose + oxygen (light above the arrow)
2
State the balanced chemical symbol equation for photosynthesis.
6CO₂ + 6H₂O -> C₆H₁₂O₆ + 6O₂
3
Is photosynthesis an endo- or exothermic reaction?
Endothermic
4
What energy transfer occurs in photosynthesis?
Light energy to chemical energy
5
Where does photosynthesis occur in a plant or algal cell?
Chloroplasts
6
What are chloroplasts filled with?
Chlorophyll
7
What is the function of chlorophyll?
Captures light energy
8
Name the three factors which affect the rate of photosynthesis.
Temperature, light intensity, carbon dioxide concentration
9
(HT only)
What is the formula for the inverse square law (for light intensity)?
The symbol ∝ means 'is proportional to'
10
(HT only) Describe how the inverse square law applies to light intensity and distance.
The intensity of light is inversely proportional to the square of the distance from the light source. E.g. if you halve the distance, the light intensity will be 4 times greater
11
(HT only) What does the inverse square law mean in practice when considering how plants grow?
When the light is moved twice as far from the plant it will receive a quarter of the energy
12
(HT only) Why can't a commercial grower of plants just increase all three limiting factors of PHS to maximum levels to obtain optimum growth?
Light, temperature and CO2 all cost money to supply – a balance between expenditure and income must be struck for a profit to be made
13
Name three ways glucose produced in photosynthesis is used in plants.
Used for respiration, converted into insoluble starch for storage, used to produce fat or oil for storage, used to produce cellulose which strengthens the cell wall and/or used to produce amino acids for protein synthesis.
14
What else, other than glucose, do plants need to produce proteins?
Nitrate ions
15
Where are mineral ions absorbed from and through which plant organ?
From the soil, through the roots
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Topic 4 Bioenergetics – Concept Questions for Assessment 2 of 2
16
What is aerobic respiration and where does it occur in cells?
Respiration WITH oxygen, in the mitochondria
17
What is anaerobic respiration and where does it occur in cells?
Respiration WITHOUT oxygen, in the cytoplasm
18
Is respiration an endo- or exothermic reaction?
Exothermic
19
State the balanced symbol equation for aerobic respiration.
C₆H₁₂O₆ + 6O₂ -> 6CO₂ + 6H₂O
20
State the word equation for anaerobic respiration in animal cells.
Glucose -> lactic acid
21
State the word equation for anaerobic respiration in plant and yeast cells.
Glucose -> ethanol + carbon dioxide
22
Which transfers more energy, aerobic or anaerobic respiration?
aerobic respiration
23
How have humans used our understanding of anaerobic respiration in plant and yeast cells in manufacturing?
Production of bread and alcoholic drinks
24
Name three physical ways in which the human body reacts to an increased demand for energy.
Heart rate, breathing rate and breathe volume all increase
25
Why do heart rate, breathing rate and breathe volume increase when the body needs more energy?
To increase the oxygenation of the blood and to supply the muscles with more oxygenated blood
26
What does a build-up of lactic acid cause in muscles?
Muscle fatigue
27
What is an oxygen debt?
The amount of extra oxygen the body needs after exercise to react with the accumulated lactic acid and remove it from the cells
28
(HT only) Where is lactic acid converted back into glucose?
The liver
29
(HT only) How is lactic acid transported to the liver?
Via the blood
30
What is produced when enzymes chemically break down carbohydrates?
Simple sugar monomers
31
What is produced when enzymes chemically break down a lipid?
1 glycerol, 3 fatty acids
32
What is produced when enzymes chemically break down proteins?
Amino acids
33
What is "metabolism"?
The sum of all the reactions in a cell or the body
34
Name three cellular reactions which could be included under the term "metabolism".
· Conversion of glucose to starch, glycogen and cellulose;
· The formation of lipid molecules from a molecule of glycerol and three molecules of fatty acids;
· The use of glucose and nitrate ions to form amino acids which in turn are used to synthesise proteins;
· Respiration;
· Breakdown of excess proteins to form urea for excretion