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Transpiration

In this worksheet, students will explore the transportation of water in plants and the factors that affect this.

'Transpiration ' worksheet

Key stage:  KS 4

Curriculum topic:  Biology: Transport Systems

Curriculum subtopic:  The Need for Transport Systems in Multicellular Organisms

Difficulty level:  

down

Worksheet Overview

QUESTION 1 of 10

You should have just looked at the leaf – if you haven’t looked at the leaf yet, we recommend that you do before you look at this activity. It’ll make things a lot easier!

 

So, one of the amazing things about plants (apart from the fact that they make their own food) is that they can just sit there and drink using their home-made straws – or xylem. This makes plants one of the best living organisms for lazy people, you just chill out in one place and everything comes to you! Amazing right? But how do they control how much they are drinking? Well, we will look at transpiration in more detail now including the factors that affect it.

 

Water and food are in the xylem and phloem cells (see diagram below).

 

An image showing the xylem transporting water and the phloem with valves in transporting water and food.


Xylem cells carry water and minerals from the roots to the leaves. Water is needed for photosynthesis. As you already know, the xylem is like a big straw that allows the plant to suck up water from the roots. The leaves evaporate water from the stomata and that sucks up new fresh water to be used in photosynthesis. Some water is lost while carried to the leaves; it evaporates from the leaf's surface, so this is not a perfect system.

How much water is lost depends on your environment – a cactus will lose less water than a tree would as it needs to hold onto its water as much as it can because rain the desert is rare.

 

 

So what factors will affect the amount of transpiration that the plant will do?

 

  • temperature: increased temperature means water molecules have more energy and evaporate easily

 

  • amount of light: increasing light intensity causes stomata to open and more water escapes.

 

  • wind: wind causes more water molecules near stomata to be removed.

 

  • humidity: humidity is the amount of water in the air; if the concentration of water is low outside the leaf, more diffusion (movement of water molecules) takes place from the inside of the leaf to the outside.

 

We can measure the amount of transpiration by using an instrument called a potometer?. Very simply put, a potometer? is a bubble of air that is trapped in a tube. When you put a plant on one side of the potometer? it sucks up the water, and as it does this the bubble will move closer to the plant. This is a simple description – a better way of understanding this would be to watch this video.

 

 

Which cells carry water from the roots to the leaves of plants?

Xylem

Phloem

What do xylem cells form?

Food tubes

Phloem tubes

Vessels

What does a potometer measure? 

Rate of evaporation from the leaves?

Rate of movement of a bubble

Rate of transpiration

Tick two differences between phloem and xylem cells.

Xylem cells carry water, phloem cells carry glucose

Phloem cells die after carrying water, but xylem cells stay alive

Xylem cells die after forming vessels, but phloem cells stay alive

Xylem cells carry food and phloem cells carry water

What is the scientific name for water loss from plants?

Respiration

Photosynthesis

Transpiration

Evaporation

What are the small openings through which water is lost from the leaves?

Stomata

Stomota

Chloroplasts

Select two factors that increase the rate of transpiration.

Increased temperature

Decreasing light intensity

Increased carbon dioxide concentration

Low humidity

Why does increased humidity cause the rate of transpiration to decrease?

Water diffusion rate would decrease from the outside to the inside of the cell.

Water diffusion rate would increase from the inside of the cell to the outside.

Water diffusion rate would increase from the outside to the inside of the cell.

Why does increased temperature increase the rate of transpiration?

Less water molecules evaporate

Water molecules have more energy and move faster

Water molecules have more energy and move less

How does an increase in light intensity result in a higher rate of transpiration?

Stomata close and more water is lost

Stomata open more, so more water is lost

Stomata are not affected by an increased light intensity

  • Question 1

Which cells carry water from the roots to the leaves of plants?

CORRECT ANSWER
Xylem
EDDIE SAYS
Xylem cells carry water from the roots to the leaves of plants.
  • Question 2

What do xylem cells form?

CORRECT ANSWER
Vessels
EDDIE SAYS
Xylem cells form vessels, which are long thin tubes. Just like the vessels in the human body - only in a plant.
  • Question 3

What does a potometer measure? 

CORRECT ANSWER
Rate of transpiration
EDDIE SAYS
Potometers measure the rate of transpiration of a plant. Transpiration is caused by evaporation for the leaves and is represented by the movement of a bubble in some water, but we are measuring the amount of transpiration, not the other things.
  • Question 4

Tick two differences between phloem and xylem cells.

CORRECT ANSWER
Xylem cells carry water, phloem cells carry glucose
Xylem cells die after forming vessels, but phloem cells stay alive
EDDIE SAYS
Xylem cells carry water and minerals from the roots to the leaves, but phloem cells carry glucose. Xylem cells die after forming wood and make vessels, but phloem cells stay alive to be able to pass glucose from cell to cell.
  • Question 5

What is the scientific name for water loss from plants?

CORRECT ANSWER
Transpiration
EDDIE SAYS
Water loss from plants is called transpiration - water evaporates from the leaf's surface through the stomata.
  • Question 6

What are the small openings through which water is lost from the leaves?

CORRECT ANSWER
Stomata
EDDIE SAYS
Water evaporates from leaves through small openings called stomata.
  • Question 7

Select two factors that increase the rate of transpiration.

CORRECT ANSWER
Increased temperature
Low humidity
EDDIE SAYS
The rate of transpiration increases when the temperature increases and humidity in the air is low.
Transpiration is slowed down by increased light intensity, as it causes the stomata to open causing more water to escape.
  • Question 8

Why does increased humidity cause the rate of transpiration to decrease?

CORRECT ANSWER
Water diffusion rate would increase from the outside to the inside of the cell.
EDDIE SAYS
Water diffusion rate would increase from the outside to the inside of the cell, because there would be more water outside.
  • Question 9

Why does increased temperature increase the rate of transpiration?

CORRECT ANSWER
Water molecules have more energy and move faster
EDDIE SAYS
Higher temperature means that water molecules have more energy and can evaporate more easily.
  • Question 10

How does an increase in light intensity result in a higher rate of transpiration?

CORRECT ANSWER
Stomata open more, so more water is lost
EDDIE SAYS
An increase in light intensity causes the stomata to open more. This means that more water is able to evaporate out of the leaf through the bigger holes.
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