Download Plants: Keeping plants healthy

Plants: Keeping plants healthy
Objectives:
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Identify and describe the functions of different parts of flowering plants
Investigate the way water is transported within plants
Explore the requirements of plants for life and growth
Plenary
Pupils should go outside and try to pull up dandelions or other flowering weeds. By tugging
gently at the base, the roots can be extracted from the soil. Bring them into the classroom and
ask the pupils to identify the flower, the leaves, the roots and the stem.
Root, stem and leaves
Explain that every part of a plant has a job to do.
If a tree or flowering plant did not have roots, what would happen to it in the wind? Pupils
may suggest that the plant would not stay in the ground; roots help ‘anchor’ a plant.
As humans need to drink and eat, plants need water and food to stay alive. Water and
nutrients are extracted from the soil and taken into the plant by the roots.
Pupils must note:
The roots anchor the plant and take up water and nutrients from the soil.
Ask the pupils what the stem might be useful for. Compare the sturdy stem to the human
skeleton: it supports the plant. Explain that the stem also transports water and nutrients from
the roots to the rest of the plant.
Pupils must note:
The stem supports the plant and carries water and nutrients to different parts of the plant.
Explain that the leaves help the plant to breathe. There are lots of tiny holes on the leaf which
open to take in air. Importantly, the leaves also take in light from the sun.
Pupils must note:
The leaves take in air and sunlight.
Keeping plants healthy
Using what they have learnt, pupils should list the things plants need to survive: air, water,
nutrients and sunlight. Pupils should draw a simple diagram of a plant including leaves, stem
and roots. Add blue arrows to show how water and nutrients move into the roots and to the
rest of the plant through the stem. Add yellow arrows to show how sunlight falls on the
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leaves and add red arrows to show how air is taken in by the leaves. Air, water and sunlight
are vital, as plants use these ingredients to make its special type of food.
EXPERIMENT: Pupils may observe for themselves how water travels up the stem by placing
white flowers in a food dye solution. After 24 hours, the stem of the flower can be sliced
open and the coloured dye will be visible inside.
Pupils may complete the worksheet, circling the things that plants need to survive (air, water,
sunlight, nutrients).
OR
Pupils may look at the following short letters and write replies offering advice on how to look
after the plants more effectively:
I planted some sunflower seeds in soil and left them in the dark old cupboard under the stairs. I water
them every day so why do the plants look unhealthy? Please explain what I’m doing wrong.
I bought some tomato plants at the market last week and potted them in new, nutritious soil. I
haven’t watered them yet but they get lots of sunlight. Why are they wilting?
I put a new rose plant on my desk in front of a bright window. I didn’t have any soil or compost so I
used newspaper instead. Now the petals are dropping off and it’s going brown! What am I doing
wrong?
Discuss in a class how some plants may need more air, water, light or nutrients than others.
Would a cactus or a lotus plant need more water? Would a tillandsia (air plant) or a pear tree
need more nutrients? Which plants may need more or less sunlight than normal?
Possible extra-curricular questions
What kind of nutrients do plants take up?
Plants require 14 different nutrients to thrive. Plants can usually extract these nutrients from
normal soil, although when fertiliser or compost is used, more nutrients are available. The
main nutrients required are nitrogen, phosphorous and potassium.
How do nutrients get taken in by the roots?
The roots leak positively charged particles into the soil. These positively charged particles
cause positively charged nutrients to be repelled and separated from the barren soil. The
nutrients can then be taken up the roots.
How are water and nutrients carried through the plant?
Water and some nutrients are carried by a plant tissue called xylem. When water is
evaporates from the leaves of the plants (transpiration) water from the soil is transported
through the xylem and upwards through the plant to replace it (water potential). A tissue
called phloem transports the food that the plant makes through photosynthesis.
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How do plants make their own food?
This is a complicated process called photosynthesis. The plant takes in water from its roots
and air (specifically carbon dioxide) and sunlight from its leaves. Using these ingredients,
the plant produces oxygen and glucose, which is a type of sugar. The glucose is then stored in
the plant and used for growth.
© Education Umbrella 2015