Grade 12 Biology (SBI 4U1) Unit Test
Unit: Metabolism 70 Marks
**DO NOT WRITE ON THE QUESTION PACKAGE**
Part A: Multiple Choice (27 marks)
1. What happens to a molecule that is reduced?
a) it gains hydrogen ions (H+)
b) it loses hydrogen ions (H+)
c) it gains electrons
d) it loses electrons
2. What type of reaction is ADP + Pi --> ATP + H2O?
a) endergonic
b) exergonic
c) catabolic
d) a) and c)
e) b) and c)
3. Which group of organic compounds includes the enzymes?
a) nucleic acids
b) lipids
c) carbohydrates
d) proteins
e) amino acids
4. Of the following characteristics, which one is not true about enzymes?
a) They are essential to the metabolism of cells for the conversion of energy.
b) They function best at specific temperatures but break down at high temperatures.
c) Some enzymes need activators or cofactors.
d) They function best at a particular pH.
e) They undergo major chemical change after reacting with their specific substrate.
5. The activity of an enzyme can be altered by changing the pH of its surroundings slightly. This change in pH works by:
a) causing the enzyme to precipitate
b) masking its active site
c) increasing the activation energy of the reaction
d) breaking its peptide bonds
e) altering its three dimensional shape
6. Enzymes work as catalysts by doing which of the following?
a) increasing the free energy of the reactants
b) decreasing the free energy of the reactants
c) increasing the activation energy
d) decreasing the activation energy
e) bypassing the need for a transition state to occur
7. Which of the following statements regarding enzyme inhibition is incorrect?
a) Competitive inhibitors have a similar structure to the normal substrate.
b) Competitive inhibitors bind to the active site of an enzyme.
c) Noncompetitive inhibition can be overcome by adding more substrate.
d) Noncompetitive inhibitors do not have a similar structure to the normal substrate.
e) Noncompetitive inhibitors do not bind to the active site of an enzyme.
8. At 30°C the optimum pH of a certain human digestive enzyme is 8. A greater reaction rate could be achieved by:
a) decreasing the temperature by 5°C and keeping the pH at 8.
b) increasing the temperature by 5°C and keeping the pH at 8.
c) maintaining the temperature at 30°C and increasing the pH to 9.
d) maintaining the temperature at 30°C and decreasing the pH to 7.
9. What is the function of the allosteric site in an enzyme?
a) it is the place where the substrate fits into the enzyme
b) it is the place where the enzyme fits into the substrate
c) it is the place where the activator fits into the enzyme
d) it is the place where the inhibitor fits into the enzyme
e) both c) and d) are correct
10. In which of the following situations would you least expect to find anaerobic respiration occurring?
a) a vat in which beer is being manufactured
b) a human brain engaged in writing this test
c) the inside of a bacterium living inside a human intestine
d) a runner's leg muscle during a 400-m dash
e) the sediments at the bottom of a pond
11. Which of the following statements about adenosine triphosphate (ATP) is NOT true?
a) it is used as an energy currency by all cells
b) it is formed only under aerobic conditions
c) it provides energy for many different biochemical reactions
d) it is a nucleic acid molecule
12. Glycolysis can best be described as which of the following kinds of pathways?
a) catabolic and synthetic
b) anaerobic and catabolic
c) anaerobic and anabolic
d) aerobic and catabolic
13. At the end of glycolysis, most of the energy originally found in glucose is located in moleculesof
a) phosphoglyceraldehyde (PGAL)
b) ATP
c) reduced NAD+
d) lactate
e) pyruvate
14. In the electron transport chain of the mitochondria, electrons are commonly transferred from one molecule to another. In one such reaction a Fe3+ ion in a cytochrome is converted to a Fe2+ ion. This is known as
a) isomer formation
b) hydrolysis
c) reduction
d) oxidation
15. Where in the electron transport chain does the energy come from for the synthesis of ATP?
a) the combination of hydrogen ions, electrons, and oxygen to form water
b) the breakdown of water
c) the cytochromes
d) an electrochemical gradient across the inner mitochondrial membrane
e) oxygen
16. How many H+ ions from FADH2 have to pass through ATP synthase to make one ATP?
a) one
b) one pair
c) two pairs
d) three pairs
17. Fatty acids can enter Krebs cycle as which of the following?
a) acetyl-Coenzyme A
b) phosphoglyceraldehyde (PGAL)
c) pyruvate
d) oxaloacetate
e) a-ketoglutarate
18. The following molecules can be found at various stages during cellular respiration:
I. acetyl-CoA
II. carbon dioxide
III. glucose
IV. glyceraldehyde phosphate
V. pyruvate
Which of the following sequences represents the above molecules in order from the largest to the smallest amount of chemical energy?
a) II, I, V, IV, III
b) III, I, V, IV, II
c) III, IV, V, I, II
d) IV, III, II, I, V
e) III, IV, I, V, II
19. In terms of the spectrum of white light, which of the following is the least effective for photosynthesis?
a) red light
b) yellow light
c) green light
d) violet light
e) blue light
20. What colour of light has the most energy?
a) green
b) blue
c) red
d) violet
e) orange
21. What is the function of water in photosynthesis?
a) accept electrons during the Calvin cycle
b) accept electrons from oxygen
c) supply H+ ions for ATP synthesis
d) supply electrons for the reduction of NADP+
e) both (c) and (d)
22. A kind of herbicide works by disrupting the structure of the internal membranes of a chloroplast. Which segment of photosynthesis would be the most affected?
a) activation of the photosystems
b) manufacture of ATP
c) reduction of chlorophyll
d) evolution of oxygen
e) absorption of light
23. Electrons released as a result of photolysis
a) combine with H+ ions and oxygen to form water
b) are used directly in the fixation of carbon during the Calvin cycle
c) reduce photosystem I chlorophyll molecules
d) reduce photosystem II chlorophyll molecules
e) oxidize NADP+
24. When photosynthesis occurs, the oxygen that is released comes from
a) chlorophyll
b) water
c) an intermediate of the Calvin cycle
d) carbon dioxide
e) a carbohydrate
Use the following information to answer questions 25 to 27.
Imagine you have five small glass jars that are sealed to the atmosphere. All the jars are filled with a bicarbonate solution (as a source of carbon dioxide) and an indicator. The differences between each jar are described below:
Jar #1: Has a small fish.
Jar #2: Has one small fish in addition to some aquatic plants.
Jar #3: Has three small fish in addition to some aquatic plants.
Jar #4: Has some aquatic plants.
Jar #5: Has some aquatic plants, but the jar is completely surrounded by aluminum foil.
The indicator shows you how much carbon dioxide is in each jar. The following table shows the relative amounts:
Colour of pH indicator solution / Relative amount of carbon dioxidered / high
green / medium (equivalent to atmosphere)
blue / low
The following table shows the results of an experiment where the tubes were allowed to stand under natural light for several hours.
Observation / Jar #1 / Jar #2 / Jar #3 / Jar #4 / Jar #5Starting colour of indicator / green / green / green / green / green
Final colour of indicator / red / green / red / blue / green
25. The following are statements regarding the above results:
I. respiration is taking place in all five jars
II. respiration is exceeding photosynthesis in Jar#3
III. photosynthesis is occurring in Jar#5
IV. the lowest concentration of carbon dioxide is found in Jar#2
Which of the above statements are correct?
a) II and III
b) II and IV
c) I and II
d) III and IV
e) I and IV
26. Under what circumstance would the indicator change from green to blue in Jar#5?
a) taking away some of the aquatic plants
b) illuminating the jar with green light
c) adding more fish to the jar
d) adding more aquatic plants to the jar
e) taking the aluminum foil off of the jar
27. Under what circumstance would the indicator change from red to green in Jar#3?
a) removing some of the aquatic plants
b) illuminating the jar with green light
c) adding some aquatic plants to the jar
d) adding some fish to the jar
e) covering the jar with tin foil
Grade 12 Biology (SBI 4U1) Name: ______
Unit: Metabolism Unit Test - 70 Marks
Part A: Multiple Choice (27 marks)
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Part B: Short Answers (43 marks)
1. Explain the effect of low pH levels on enzymes. (2 marks)
2. Listed below is a sequence of substances in the cell (A, B ,C , D, E, F and G), and the enzymes (1,2, 3, 4 and 5) needed to convert them to the next substance in the sequence. Since each substance has a use in the cell, it is not immediately converted to the next substance and so each compound can be detected in this system.
A ----1-----> B ----2----> C ----3----> D ----4----> E ----5-----> F ---6 --->G
In order to study this multi-enzyme system, radioactively labelled substance A was added to the cell. The cell was studied in an attempt to locate the radioactive label in any of the other substances. In an untreated cell, adding labelled-A will result in high levels of labelled-G with low levels of labelled-B, C, D, E and F.
If chemical ‘R’ is added: low levels of labeled-B; very low levels of labeled-C; high levels of labeled-D only are found. If labelled-E is then added, high levels of labelled-F and low levels of labelled-G are detected.
Explain the effect of chemical ‘R’ on EACH of enzymes 1, 2, 3, 4, 5 and 6. (5 marks)
3. A cell without access to oxygen must perform anaerobic respiration. The following questions deal with this process.
a) In what type of cell does lactic acid fermentation occur? (1 mark) ______
b) Write the full equation for either lactic acid fermentation OR alcohol fermentation. (2 marks)
c) What is the advantage, in energy terms, of lactic acid fermentation over alcohol fermentation? (2 marks)
4. Complete the following table for the breakdown of a 28-carbon fatty acid into 14 acetyl-CoA molecules by beta-oxidation, followed by Krebs’ cycle and ETC. Some numbers have been supplied. You must fill in the missing numbers. READ column headings carefully. (5 marks)
14 xacetyl-CoA / Beta OXIDATION / NET / equivalent
ATP / 28 carbons of
GLUCOSE
ATP / ATP / 1 ATP / 1 ATP / ATP
NADH / 13 NADH / NADH / ATP
14 FADH2 / FADH2 / FADH2 / ATP
TOTAL / ATP
5. CHOOSE THREE of the following enzymes or types of enzymes.
i. rubisco ii. dehydrogenase iii. decarboxylase iv. phosphorylase
Answer the following two questions about the THREE enzymes you have chosen.
(3 x 2 marks = 6 marks)
a) EXPLAIN the function of the enzyme.
b) State whether the product has more or less energy than the substrate the enzyme acted on.
6. The diagram below shows the light reactions and electron transport system in photosynthesis.
a) Label the stroma and thylakoid space on the diagram below. (1 mark)
b) Label the pathway of electrons (1 mark)
c) Label the splitting of water and the final electron acceptor. (2 marks)
d) Show the movement of H+ ions across the membrane. (1 mark)
e) Show where and how ATP is made. (1 mark)
Legend
Z: protein II: photosystem II Q: plastoquinone
b6-f: b6-f complex Pc: plastocyanin I: photosystem I
Fd: ferredoxin N: NADP reductase A: ATP synthase
7. Fill in the blanks to show what has occurred between the two molecules shown below. (3 marks)
The following reaction is from cell respiration.