Biology: Plant Transport: Xylem, Phloem, and Transpiration Data
How plants move water, minerals, and sugars
Biology: Plant Transport: Xylem, Phloem, and Transpiration Data
How plants move water, minerals, and sugars
Biology - Grade 6-8
- 1
A plant needs to move water from its roots to its leaves. Which plant tissue does this job, and what else does it usually carry?
Think of the tissue that acts like upward water pipes in a plant.
Xylem moves water from the roots to the leaves. It also carries dissolved minerals from the soil. - 2
A plant makes sugar in its leaves during photosynthesis. Which plant tissue moves the sugar to other parts of the plant, such as roots and fruits?
Phloem moves sugar made in the leaves to other parts of the plant. It can move sugars to growing tissues, roots, fruits, and storage areas. - 3
Label the two transport tissues in a stem cross section. Tissue A is closer to the inside of the stem and tissue B is closer to the outside. In many stems, xylem is inside and phloem is outside. Identify A and B.
Remember the common order in many stems: xylem on the inner side and phloem on the outer side.
Tissue A is xylem because xylem is usually located closer to the inside of the stem. Tissue B is phloem because phloem is usually located closer to the outside. - 4
Explain how transpiration helps pull water upward through a plant.
Transpiration is the loss of water vapor from leaves. As water evaporates from the leaves, it creates a pulling force that helps draw more water upward through the xylem from the roots. - 5
A student places a leafy celery stalk in red-colored water overnight. The next day, red lines appear in the celery stalk and leaves. Which tissue became colored, and what does this show?
The colored water travels through the same tissue that normally carries water.
The xylem became colored. This shows that xylem carries water upward through the plant from the stem toward the leaves. - 6
Study the data: Plant A lost 6 mL of water in 1 hour, Plant B lost 3 mL of water in 1 hour, and Plant C lost 9 mL of water in 1 hour. Which plant had the greatest transpiration rate?
Plant C had the greatest transpiration rate because it lost 9 mL of water in 1 hour, which is more than Plant A or Plant B. - 7
A plant loses 12 mL of water over 4 hours. Calculate its transpiration rate in mL per hour.
Rate equals amount of water lost divided by time.
The transpiration rate is 3 mL per hour. This is found by dividing 12 mL by 4 hours. - 8
A class compares transpiration under two conditions. Plant 1 is kept in still air and loses 4 mL of water in 2 hours. Plant 2 is placed near a fan and loses 10 mL of water in 2 hours. What does the data suggest about wind and transpiration?
The data suggests that wind increases transpiration. The plant near the fan lost more water in the same amount of time than the plant in still air. - 9
Use the table: Low light, 2 mL lost per hour; medium light, 5 mL lost per hour; bright light, 8 mL lost per hour. Describe the pattern in the data.
Look for whether the numbers rise, fall, or stay the same as light changes.
The data show that transpiration increases as light intensity increases. The plant lost the least water in low light and the most water in bright light. - 10
A plant's stomata close during very dry conditions. Explain how this helps the plant survive.
Closing the stomata helps the plant survive by reducing water loss through transpiration. This helps the plant conserve water when the environment is dry. - 11
Why can a hot, sunny day cause a plant to lose water faster than a cool, cloudy day?
Think about how heat and sunlight affect evaporation and photosynthesis.
A hot, sunny day can increase evaporation from the leaves and may cause stomata to open for photosynthesis. Both factors can increase transpiration compared with a cool, cloudy day. - 12
A student says, "Xylem and phloem both move materials, so they do the same job." Explain why this statement is not correct.
The statement is not correct because xylem and phloem move different materials. Xylem mainly moves water and minerals, while phloem moves sugars made by photosynthesis. - 13
The graph shows water loss from a plant over time: 0 hours, 0 mL; 1 hour, 2 mL; 2 hours, 4 mL; 3 hours, 6 mL; 4 hours, 8 mL. What is the plant's transpiration rate?
Find how much the water loss changes during each hour.
The plant's transpiration rate is 2 mL per hour. The water loss increases by 2 mL each hour. - 14
A plant with many large leaves usually loses more water than a plant with a few small leaves. Explain why leaf size and number can affect transpiration.
A plant with many large leaves has more leaf surface area. More surface area usually means more stomata and more places where water vapor can leave the plant. - 15
Design a simple investigation to test how humidity affects transpiration. Include the variable you would change, what you would measure, and one thing you would keep the same.
A fair test changes only one main factor at a time.
The variable to change is humidity, such as comparing a plant in dry air with a plant in humid air. The measurement is the amount of water lost over a set time. One thing to keep the same is the plant type, light level, temperature, or length of the test.