How photosynthesis and respiration feed each other
Grade 9 Science Worksheet - Challenge Me
Circle the best answer.
Ari reads a graph for one leaf at five light levels. At which light level does the CO₂ taken in by photosynthesis equal the CO₂ released by respiration?
- Light 40, where photosynthesis is highest
- Light 30, where photosynthesis is just above respiration
- Light 0, where the leaf sits in the dark
- Light 20
Bo uses the same graph. What is the leaf's net CO₂ change at light 40?
Use the picture in question 1.
- 3 mL taken in per hour
- 5 mL released per hour
- 13 mL taken in per hour
- 8 mL taken in per hour
Esme reads the same graph. Which statement does it support?
Use the picture in question 1.
- The two lines are unrelated, so where they cross means nothing
- At light 0 the leaf takes in CO₂ because photosynthesis runs in the dark
- Below light 20 the leaf gives off more CO₂ than it takes in
- Above light 20 respiration stops, so photosynthesis takes over
Read this first
Use the table
Card (real data, from OpenStax Biology 2e). Energy for the producers in a spring ecosystem, in kcal per square meter per year.
energy measure kcal per square meter per year captured by the producers 20,810 used in the producers' own respiration or lost as heat 13,187 Jun reads real data from a spring ecosystem. About what share of the energy the producers captured went to their own respiration or heat?
- About 0 percent, since producers make sugar and do not use it
- About 37 percent
- About 63 percent
- About 13 percent
Luz reads the card. How many O₂ molecules escaped from the model leaf to the air?
- 360 molecules
- 36 molecules
- 324 molecules
- 396 molecules
Use this
Flow diagram drawn as a loop (model, not to scale), inside a leaf cell. Two process boxes: photosynthesis, in the chloroplast, on the left; cellular respiration, in the mitochondrion, on the right. An arrow from photosynthesis to cellular respiration carries: glucose; oxygen. An arrow from cellular respiration back to photosynthesis carries: carbon dioxide; water. A wavy arrow points into photosynthesis: light energy. A wavy arrow points out of cellular respiration: energy moved to ATP and heat. Notebook, 3 lines. Line 1: Photosynthesis makes glucose and oxygen. Line 2: Cellular respiration uses glucose and oxygen and releases carbon dioxide and water. Line 3: So the energy that respiration releases returns to the leaf as light and powers photosynthesis again.
Milo reads a notebook entry about the loop. Which line has a flaw?
- No line: the energy goes round like the matter does
- Line 3: energy leaves as heat, so new light must keep coming in
- Line 2: plants do not carry out cellular respiration in their cells
- Line 1: photosynthesis uses glucose and oxygen
Use this
Flow diagram drawn as a loop (model, not to scale), inside a leaf cell. Two process boxes: photosynthesis, in the chloroplast, on the left; cellular respiration, in the mitochondrion, on the right. An arrow from photosynthesis to cellular respiration carries: glucose; oxygen. An arrow from cellular respiration back to photosynthesis carries: carbon dioxide; water. A wavy arrow points into photosynthesis: light energy. A wavy arrow points out of cellular respiration: energy moved to ATP and heat. Notebook, 3 lines. Line 1: The carbon atoms in glucose came from CO₂ taken in by the leaf. Line 2: The oxygen gas the leaf releases is the oxygen of that CO₂, set free when the carbon joins glucose. Line 3: In respiration, the carbon atoms of glucose leave the leaf as CO₂.
Pia reads a notebook entry that traces carbon and oxygen. Which line has a flaw?
- No line: the three lines match the loop
- Line 2: the released oxygen comes from splitting water, not from CO₂
- Line 1: the carbon in glucose comes from soil minerals
- Line 3: respiration keeps the carbon of glucose inside the leaf
Use this
Flow diagram drawn as a loop (model, not to scale), inside a leaf cell. Two process boxes: photosynthesis, in the chloroplast, on the left; cellular respiration, in the mitochondrion, on the right. An arrow from photosynthesis to cellular respiration carries: glucose; oxygen. An arrow from cellular respiration back to photosynthesis carries: carbon dioxide; water. A wavy arrow points into photosynthesis: light energy. A wavy arrow points out of cellular respiration: energy moved to ATP and heat.
Ren's friend says the loop is perfect: energy goes around it forever, just like the carbon. Which reply is best?
- Disagree: neither matter nor energy passes between the two processes
- Agree: the energy released in respiration powers the next round of photosynthesis
- Agree: heat from respiration is turned back into light and reused
- Disagree: matter cycles, but energy enters as light and some leaves as heat
Tala's friend says plants do only photosynthesis, because breaking glucose down is what animals do. Which reply is best?
- Disagree: plant mitochondria also break glucose down, using some of the leaf's oxygen
- Agree: plant cells have no mitochondria, so they cannot break glucose down
- Disagree: plants respire in their chloroplasts, which do both jobs
- Disagree: plants respire, but after dark once photosynthesis stops
Zee's friend says the oxygen a leaf releases is the oxygen of the CO₂ it took in. Which reply is best?
- Agree: the leaf removes the carbon from CO₂ and releases the oxygen as O₂
- Disagree: the light energy turns directly into O₂ gas
- Disagree: the O₂ comes from glucose that the mitochondria break down
- Disagree: the O₂ comes from splitting water, and the CO₂ carbon goes into glucose