Plant organs, xylem and phloem

Grade 9 Science Worksheet - Challenge Me

Circle the best answer.

1. Read this first

   Model of a leaf (model, not to scale)

   Two boxes, the air and the leaf. An arrow marked carbon dioxide runs from the air into the leaf through the stomata. An arrow marked water vapor runs from the leaf to the air through the stomata. In the model, the guard cells close the stomata, so both arrows are cut.

2. 1.

   Ren reads a model of a leaf. In the model, the guard cells keep the stomata closed all day in bright light. What happens, and why?

   • Water loss falls and sugar-making stays the same, because stomata are for water, not gases
   • Water loss falls and sugar-making slows, because less carbon dioxide enters
   • Water loss rises and sugar-making slows, because the guard cells swell
   • Water loss falls and sugar-making rises, because the leaf keeps its water

3. Model of a root (model, not to scale)

   Two boxes, the soil and the root. An arrow marked water and minerals runs from the soil into the root, across its surface. Root hairs reach out from the surface of the root. In the model, the root hairs are removed and the root length stays the same.

4. 2.

   Bo reads a model of a root. In the model, a root loses all of its root hairs. What happens to water uptake, and why?

   • Uptake falls, because the root has less surface area for absorbing
   • Uptake rises, because water no longer collects in the hairs
   • Uptake stays the same, because the root length sets the uptake
   • Uptake falls, because root hairs take up sugar from the soil around the root
5. 3.

   Model of a plant (model, not to scale). Kira reads a model of a plant. In the model, the phloem is blocked just below the leaves. What happens to the roots, and why?

   • They receive the same sugar, because roots make their own
   • They receive less water, because the phloem brings them water
   • They receive less sugar, because phloem brings them sugar from the leaves
   • They receive the same sugar, because the xylem brings them sugar from the leaves

6. Two cards side by side as one table (model data)

   hour	stomata	water lost in that hour (mL)
   0	closed	0
   6	partly open	4
   12	wide open	10
   18	partly open	4

7. 4.

   Esme reads two cards for one model plant on a sunny day, shown side by side. What happened from hour 6 to hour 12, and why?

   • The water lost rose by 10 mL per hour as the stomata opened wider
   • The water lost rose by 6 mL per hour as the stomata closed
   • The water lost rose by 6 mL per hour as the stomata opened wider
   • The water lost rose by 6 mL per hour as the roots pumped harder
8. 5.

   The textbook says up to 90 percent of the water the roots take up may be lost through the leaves. Luz reads a model data card of one plant. On which day did the leaves lose the largest share of the water the roots took up?

   • Day 3, where the leaves lost 90 of the 100 mL taken up
   • Day 2, where the leaves lost the most water, 192 mL
   • No day stands out, since the share is the same each day
   • Day 1, where the leaves lost 150 of the 200 mL taken up

9. Use the table

   Map of a plant (model, not to scale): the leaves send arrows marked sugar to three sinks, the roots, the shoot tip and a developing fruit. Table (model data), sugar delivered by the phloem, in units.

   part	stage 1	stage 2
   Roots	9	2
   Shoot tip	3	3
   Developing fruit	0	7
   Made by the leaves	12	12

10. 6.

    Noah reads a map and a table for one plant at two stages. Which statement do they support?

    • The shoot tip received more sugar at stage 2 than at stage 1
    • The roots received the same sugar at both stages, since phloem sends sugar down to them
    • The leaves made 7 more units at stage 2, since the fruit needed them
    • The sinks changed: the fruit gained 7 units while the roots lost 7 units

11. Use this

    Notebook (textbook facts), 4 rows. Columns: line, what it says. 1, Xylem carries water and minerals up from the roots. 2, Phloem carries sugar from sources to sinks. 3, A leaf can be a source, and a root can be a sink. 4, Phloem carries sugar down from the leaves to the roots and nowhere else.

12. 7.

    Jun reads a notebook on transport in plants. Exactly one line is wrong. Which line, and why?

    • Line 4, because phloem also carries sugar up to shoot tips and seeds
    • Line 1, because the phloem carries water and minerals up
    • Line 3, because a root makes sugar and so is a source
    • Line 2, because the xylem carries sugar from sources to sinks

13. Use this

    Notebook (textbook facts), 4 rows. Columns: line, what it says. 1, Two guard cells surround each stoma and open and close it. 2, Open stomata let carbon dioxide in and let oxygen and water vapor out. 3, Water vapor leaving the leaf is the main driver pulling water up the xylem. 4, When the stomata close, the leaf takes in the same amount of carbon dioxide.

14. 8.

    Tala reads a notebook on stomata. Exactly one line is wrong. Which line, and why?

    • Line 3, because the roots pump the water up the xylem
    • Line 4, because closed stomata let less carbon dioxide into the leaf
    • Line 2, because stomata let water vapor out but no gas in or out
    • Line 1, because the guard cells sit inside the xylem

15. Card (a model example of a textbook fact: a tuber can be a source or a sink, depending on stage and season)

    season	which way the phloem sugar moves at the tuber
    Summer	from the leaves into the tuber
    Spring	from the tuber to the new shoots

16. 9.

    Ari reads a card about an underground tuber. Why does the tuber receive sugar in summer but send sugar out in spring?

    • The tuber makes its own sugar underground, so it is a source in both seasons
    • A tuber is a sink while it fills with sugar and a source when it feeds new shoots
    • Sugar moves down in the phloem, so the spring movement must be the xylem
    • The leaves stop in spring, so the tuber takes sugar from the soil

17. Use this

    Card (textbook facts), 2 rows. Columns: part of a prickly pear cactus, what it does. Leaves, are spines, which have little surface for their size and so cut water loss. Stem, carries out photosynthesis and stores water.

18. 10.

    Milo reads a card about a cactus. Its leaves are spines, so it has no flat leaves, yet it makes sugar. How, and why does this help in a dry place?

    • The stem makes the sugar, and the spine leaves lose less water
    • The roots make the sugar, and the spine leaves hold more water
    • The cactus takes sugar from the soil, so it needs no leaves
    • The spines make the sugar, and the stem loses less water