EOC LS1.8 and LS1.9 Review

A scientist places a plant in an enclosed system. After five days, she determines that the amount of carbon dioxide has increased and the amount of oxygen has decreased. How can her findings be explained?

• Only photosynthesis occurred because the plant was in direct sunlight.

• Only respiration occurred because the plant was in the dark.

• Only anaerobic respiration occurred because the plant was in the dark.

• Only glycolysis occurred because the plant was in direct sunlight.

A team of biologists built a device designed to measure the rate of photosynthesis by measuring the change in the carbon dioxide concentration of a plant. The device encloses a tomato plant growing in a clay pot. Once sealed, the plant can be watered automatically and the temperature held constant without allowing any outside air into the device. The biologists hypothesize that their device will track the photosynthetic rate accurately because all the carbon dioxide will be used up steadily in the device until no more is left since no outside air can enter the device.

What problem is being overlooked based upon the biologists’ design and hypothesis?

• Plants also produce some carbon dioxide during aerobic cellular respiration, which will limit the device’s ability to measure the rate of photosynthesis accurately.

• Plants produce excess carbon dioxide during the process of photosynthesis, so the concentration of this gas will hold relatively steady, preventing an accurate measurement of photosynthetic rate.

• Plants release relatively large amounts of carbon dioxide gas through the process of transpiration, which will keep the carbon dioxide concentration artificially high in the device. 

• Plants will decompose glucose sugar into carbon dioxide and water when CO₂ concentrations are low in the atmosphere, leading to inaccurate estimates of the rate of photosynthesis.

Where do photosynthetic organisms get the energy needed to make glucose molecules?

• Mitochondria utilize the solar energy manufactured in the chloroplasts to make glucose molecules.

• Chloroplasts utilize the solar energy manufactured in the mitochondria to make glucose molecules.

• Mitochondria capture solar energy and convert it to the ATP and NADPH that are used to make glucose molecules.

• Chloroplasts capture solar energy and convert it to the ATP and NADPH that are used to make glucose molecules.

• photosynthesis, a process that requires energy

• photosynthesis, a process that releases energy

• cellular respiration, a process that requires energy

• cellular respiration, a process that releases energy

The graph shows the rates of photosynthesis and cellular respiration of a plant during daylight hours.

What can be concluded from the graph?

• The rate of photosynthesis is higher at dawn than at dusk.

• The rate of cellular respiration is higher at dusk than at dawn.

• The rate of photosynthesis is dependent on the amount of direct sunlight available.

• The rate of cellular respiration is dependent on the amount of direct sunlight available.

The diagram shows the breakdown of glucose through three different reactions.

What can be concluded from the diagram?

• Aerobic respiration occurs in yeast and in muscle cells.

• Aerobic respiration produces carbon dioxide and water.

• Anaerobic respiration produces carbon dioxide and water.

• Anaerobic respiration occurs in mitochondria and in muscle cells.

A scientist wanted to find out if more CO₂ is produced when humans hold their breaths before exhaling. He measured the amount of CO₂ exhaled by a group of volunteers using a CO₂ gas sensor. He prepared the graph based on the average readings received from the group. The first set of readings were taken when the volunteers breathed normally into the gas sensor device over a period of 600 seconds (10 minutes). Another set of readings were taken when the volunteers held their breath for 30 seconds before breathing normally, and the final set of readings were taken when the volunteers held their breath for 60 seconds prior to breathing normally.

What can the scientist conclude from the experiment?

• The amount of carbon dioxide exhaled varies from person to person.

• The amount of carbon dioxide exhaled is independent of the time the breath is held.

• The amount of carbon dioxide exhaled increases as the amount of time a person holds their breath increases.

• The amount of carbon dioxide exhaled decreases as the amount of time a person holds their breath increases.

A researcher conducts an experiment to see if mitochondria produce carbon dioxide at different rates in different types of tissues. Examine the data obtained during the experiment.

Which variable is the independent variable?

• time that carbon dioxide production was measured

• rate of carbon dioxide production

• number of carbon dioxide bubbles per second

• type of tissue in which mitochondria are located

The diagram shows the processes of photosynthesis and cellular respiration in relation to each other.

Which statement correctly describes the relationship between photosynthesis and cellular respiration?

• The reactants and products of both processes are the same.

• Photosynthesis and cellular respiration occur in all organisms.

• Products of photosynthesis form the reactants for cellular respiration.

• All ATP produced during photosynthesis is utilized during cellular respiration.

The diagram shows two ways in which an organism obtains energy in the form of ATP.

Which component is represented by the letter X in the diagram?

• Heat

• Hydrogen

• Oxygen

• Water