Plant organs, xylem and phloem

Grade 9 Science Worksheet - Challenge Me

Circle the best answer.

1. Read this first

   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.

2. 1.

   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 root hairs take up sugar from the soil around the root
   • 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
3. 2.

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

4. 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

5. 3.

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

6. 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

7. 4.

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

   • The sinks changed: the fruit gained 7 units while the roots lost 7 units
   • The leaves made 7 more units at stage 2, since the fruit needed them
   • 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

8. Notebook (textbook facts)

   line	what it says
   1	The shoot system includes the leaves and stems
   2	Roots anchor the plant and absorb water and minerals
   3	Dermal tissue covers and protects the plant
   4	Ground tissue carries water and minerals up to the leaves

9. 5.

   Pia reads a notebook on plant structure. Exactly one line is wrong. Which line, and why?

   • Line 2, because roots make the sugar the plant needs
   • Line 1, because the leaves belong to the root system
   • Line 4, because vascular tissue, not ground tissue, carries water and minerals
   • Line 3, because dermal tissue, not vascular tissue, carries the water to the leaves

10. 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.

11. 6.

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

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

12. 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.

13. 7.

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

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

14. 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

15. 8.

    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
    • The leaves stop in spring, so the tuber takes sugar from the soil
    • Sugar moves down in the phloem, so the spring movement must be the xylem

16. Card (textbook facts)

    time	stomata	water vapor leaving the leaves	water in the xylem
    Noon	open	leaving	pulled up
    Night	closed	stopped	held in place

17. 9.

    Zee reads a card about a tall plant at night. The stomata are closed and no water vapor leaves, yet the water stays in the xylem. Why?

    • The root cells pump the water up at night, which stops it from sinking
    • Water molecules cling to each other and to the xylem walls, which holds the water in place
    • The cuticle seals the xylem at night, so the water cannot move
    • The phloem holds the water in place until the stomata open again

18. 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.

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