Carbon cycle

9.Which of the following is a use of burning fossil fuels?

10.Large amounts of greenhouse gases in the atmosphere lead to:

11.Planting more trees would most likely:

12.If humans reduce the amount of fossil fuels burned, what would be the expected effect on carbon dioxide levels and global warming?

13.A student measured the carbon dioxide concentration in a sealed greenhouse over 24 hours. The graph showed a decrease during the day and an increase at night. Which process explains the decrease during the day?

14.In an experiment, 10 g of wood was burned completely. The mass of carbon dioxide released was measured as 14.7 g. Assuming all carbon in the wood was converted to CO₂, what is the approximate percentage by mass of carbon in the wood? (Ar: C=12, O=16)

15.The table shows the relative amounts of carbon stored in different reservoirs. Which reservoir contains the most carbon?

16.Which of the following is a process that returns carbon to the atmosphere?

17.A forest fire burns 1000 tonnes of biomass containing 40% carbon by mass. How many tonnes of carbon dioxide are released into the atmosphere? (Ar: C=12, O=16)

18.Scientists measured the rate of photosynthesis in a plant at different carbon dioxide concentrations. Which graph shape best represents the expected relationship?

19.Which of the following is NOT a fossil fuel?

20.A student set up two sealed jars with a plant and a sensor. Jar A was kept in light, Jar B in darkness. After 24 hours, which jar had a lower carbon dioxide concentration?

21.The graph shows atmospheric CO₂ levels measured at Mauna Loa since 1958. The upward trend is mainly due to:

22.In the carbon cycle, which process converts carbon in fossil fuels into atmospheric carbon dioxide?

23.What is the main form of carbon in the atmosphere?

24.A sample of limestone (calcium carbonate) was heated strongly, producing 11.2 g of calcium oxide and 8.8 g of carbon dioxide. What mass of limestone was used?

25.A student set up an experiment to measure the rate of photosynthesis in pondweed. They placed a lamp at different distances from the pondweed and counted the number of bubbles produced per minute. Which variable should be kept constant in this experiment?

26.In an experiment, a student placed a live snail and a plant in a sealed container in the light. After 24 hours, the concentration of carbon dioxide in the container was measured. Which of the following is the most likely outcome?

27.A student investigated the effect of temperature on the rate of decomposition of dead leaves by microorganisms. They measured the mass loss over 10 days. Which of the following graphs best represents the expected results?

28.A student wants to investigate the effect of light intensity on the rate of photosynthesis in aquatic plants. Which piece of equipment is most suitable for measuring the rate of photosynthesis?

29.In an experiment to measure the carbon dioxide concentration in a sealed greenhouse over 24 hours, a student obtained a graph that decreased during the day and increased at night. Which of the following conclusions is correct?

30.Which of the following is a process that releases carbon dioxide into the atmosphere?

31.A student measured the mass of carbon dioxide released when burning 10 g of wood. The wood contained 40% carbon by mass. Assuming all carbon is converted to CO₂, what mass of CO₂ is released? (Ar: C=12, O=16)

32.In the carbon cycle, which of the following processes returns carbon to the atmosphere over a very short timescale (days to years)?

33.A student set up two sealed jars: Jar A contained a plant and a CO₂ sensor, Jar B contained a plant, a snail, and a CO₂ sensor. Both jars were placed in light for 6 hours. Which jar is likely to have a lower CO₂ concentration after 6 hours?

34.Carbon dioxide is a greenhouse gas. Which of the following is a consequence of increased greenhouse gases in the atmosphere?

35.A student wants to compare the amount of carbon stored in a tree versus in the atmosphere directly above it. Which method would best estimate the carbon stored in the tree?

36.Decomposers play a key role in the carbon cycle. Which of the following best describes what decomposers do?

37.In an experiment, a sealed container with a plant and a CO₂ sensor is placed in bright light for 6 hours, then in darkness for 6 hours. Which graph best shows the expected change in CO₂ concentration over the 12-hour period?

38.A student measured the carbon content of three soil samples: Sample A from a forest, Sample B from a grassland, and Sample C from a desert. Which sample is most likely to have the highest carbon content?

39.A power station burns 1000 tonnes of coal per day. The coal contains 80% carbon by mass. Assuming all carbon is converted to carbon dioxide, what mass of carbon dioxide is released per day? (Ar: C=12, O=16)

40.The table shows the mean residence time of carbon in different reservoirs. Which reservoir has the longest residence time?

41.Photosynthesis removes carbon dioxide from the atmosphere.

42.Which of the following are decomposers? (Select all that apply)

43.Arrange the following events in the order they occur in the carbon cycle, starting with carbon in the atmosphere.

44.Burning fossil fuels releases carbon dioxide that was stored for millions of years.

45.Which of the following processes returns carbon to the atmosphere over a very short timescale (days to years)?

46.Match each process to its role in the carbon cycle.

47.Which of the following are processes that release carbon dioxide into the atmosphere? (Select all that apply)

48.Plants remove more carbon dioxide from the atmosphere through photosynthesis than they put back into it through respiration.

49.In an experiment, a sealed container with a plant and a CO₂ sensor is placed in bright light for 6 hours, then in darkness for 6 hours. Which graph best shows the expected CO₂ concentration over the 12 hours?

50.A student investigates the effect of temperature on the rate of decomposition of dead leaves by microorganisms. Which piece of equipment is most suitable for measuring the mass loss of the leaves over time?

51.Fill in the blanks to complete the sentence.

52.A sample of wood contains 40% carbon by mass. If 10 g of wood is burned completely, what mass of carbon dioxide is released? (Ar: C=12, O=16)

53.What is the name of the process by which plants make glucose from carbon dioxide and water?

54.Complete the sentence about the carbon cycle.

55.Explain why burning fossil fuels increases the amount of carbon dioxide in the atmosphere.

56.A power station burns 500 tonnes of coal per day. The coal contains 75% carbon by mass. Assuming all carbon is converted to carbon dioxide, what mass of carbon dioxide (in tonnes) is released per day? (Ar: C=12, O=16)

57.Complete the following sentence about the carbon cycle.

58.A power station burns 500 tonnes of coal per day. The coal contains 75% carbon by mass. Assuming all carbon is converted to carbon dioxide, what mass of carbon dioxide is released per day in tonnes? (Ar: C=12, O=16)

59.State the name of the process that removes carbon dioxide from the atmosphere.

60.Complete the sentence about fossil fuels.

61.A student burns 5.0 g of a sample of wood that contains 45% carbon by mass. Assuming all carbon is converted to carbon dioxide, what mass of carbon dioxide is produced? (Ar: C=12, O=16)

62.Explain how the burning of fossil fuels contributes to global warming.

63.Describe how fossil fuels are formed and explain why their formation is a slow process.

64.Describe what the carbon cycle is.

65.Explain why planting more trees would reduce the amount of carbon dioxide in the atmosphere, and describe how this could affect global warming.

66.A sample of wood contains 40% carbon by mass. If 10 g of wood is burned completely, what mass of carbon dioxide is released? (Ar: C=12, O=16)

67.A power station burns 500 tonnes of coal per day. The coal contains 75% carbon by mass. Assuming all carbon is converted to carbon dioxide, what mass of carbon dioxide (in tonnes) is released per day? (Ar: C=12, O=16)

68.A power station burns 500 tonnes of coal per day. The coal contains 75% carbon by mass. Assuming all carbon is converted to carbon dioxide, what mass of carbon dioxide is released per day in tonnes? (Ar: C=12, O=16)

69.A student burns 5.0 g of a sample of wood that contains 45% carbon by mass. Assuming all carbon is converted to carbon dioxide, what mass of carbon dioxide is produced? (Ar: C=12, O=16)