How photosynthesis and respiration feed each other
Grade 9 Science Worksheet
Circle the best answer.
Read this first
Use the table
Card (model data). One leaf sits in a sealed jar; the jar is measured in bright light and again in darkness.
condition net CO₂ change in the jar (mL per hour) bright light 12 taken in darkness 4 released Ari reads a card for one leaf in a sealed jar. What is the leaf doing in the darkness row?
- Photosynthesizing, which takes in CO₂
- Resting, with no gas exchange without light
- Respiring, which releases CO₂
- Starting to respire now that the light is off
Bo sees that the jar lost 12 mL of CO₂ each hour in the bright light row. Which statement fits?
- Photosynthesis released 12 mL of CO₂
- The two processes cancelled, leaving no change
- Photosynthesis took in more CO₂ than respiration released
- Respiration stopped, so no CO₂ was released
Assume respiration releases CO₂ at the same rate in bright light as in darkness. Esme uses the card and the stated assumption. How much CO₂ did photosynthesis take in during the bright-light hour?
- 12 mL
- 8 mL
- 4 mL
- 16 mL
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.
Jun follows one carbon atom. It enters a leaf in CO₂, joins glucose, and later leaves as CO₂. Which process sends it out?
- Photosynthesis, in a chloroplast
- The splitting of water in the light
- Cellular respiration, in a mitochondrion
- No process, since plants keep glucose and do not release its carbon
Milo compares matter and energy in the loop. Which statement is right?
- Matter and energy both go round the loop again and again
- Matter goes round the loop; energy enters as light and some leaves as heat
- Energy goes round the loop, but matter is used up
- Neither passes between the boxes; each process works alone
Noah says the heat from respiration could be collected to power photosynthesis. What energy does photosynthesis use?
- Glucose the leaf made the day before
- Light absorbed by chlorophyll
- Heat collected from respiration
- Oxygen gas carried in from the air
Card for one model leaf (model data)
step energy (units) light energy absorbed 100 stored in glucose 40 released as heat 60 Pia reads an energy card for one model leaf. Which statement does the card support?
- The leaf made 60 new units of heat energy
- The 60 units of heat can be gathered to rebuild the 100
- The glucose holds the full 100 units, since light becomes sugar
- The 40 units stored and the 60 units of heat add up to the 100 that came in
Ren reads that it is noon with bright light. Which processes are running in a leaf cell?
- Neither, since the cell rests at midday
- Photosynthesis, since respiration waits for dark
- Both photosynthesis and cellular respiration
- Cellular respiration, since photosynthesis needs darkness
Tala reads that it is midnight and a leaf in a greenhouse gets no light. Which gas exchange fits the leaf?
- Takes in O₂ and gives off CO₂
- Gives off O₂ as it uses up the glucose
- Takes in CO₂ and gives off O₂
- Takes in and gives off nothing without light
Use the table
Card (real data, from OpenStax Biology 2e). Where the oxygen made in a leaf goes.
where it goes share of the oxygen used by mitochondria in the leaf about 10 percent escapes to the air the remainder Zee reads the oxygen card. Which statement follows from it?
- About 90 percent of the oxygen leaves the leaf
- About 10 percent leaves, since mitochondria claim most of it
- The leaf's mitochondria take no oxygen from it
- The whole amount escapes, since plant cells use no oxygen