KS3 Science BIOLOGY Unit
9D on "Plants for food"
What the Quiz is based on - original work schemes -
programmes of study
All of KS3 Science is now under review
and the quizzes will
be adapted to suit the NEW National Curriculum for KS3 Science
Chemistry Q's *
Integrated Science Q's
In this unit pupils:
about humans as part of a complex food web
about factors affecting plant growth
how management of food production has many implications for other animal and
plant populations in the environment
some of the issues involved in sustainable development of the countryside
In scientific enquiry pupils:
information in tables and graphs
the effects of fertiliser on plant growth
weeds growing in a habitat, using an appropriate sampling technique
This unit is expected to take approximately 7.5
The unit builds on unit 8D ‘Ecological
relationships’ and unit 9C ‘Plants and photosynthesis’.
It relates to unit 9A ‘Inheritance and
selection’, which considers genetic approaches to improving productivity on
farms, and to unit 9G ‘Environmental chemistry’, in which the importance of air
and water quality is considered.
This unit provides opportunities to revisit and
revise topics met in other units in years 7 and 8. With some pupils, teachers
may wish to consolidate the earlier work, to concentrate on some of the new
topics, extending activities, and with others, to spend more time on revision
of previous work.
There are opportunities for links with
citizenship in the teaching of food production issues. This unit relates to
unit 8E(i) ‘Producing batches (food)’ and unit 9A(i) ‘Selecting materials
(food)’ in the design and technology scheme of work, and to unit 14 ‘Can the
earth cope? Ecosystems, population and resources’ in the geography scheme of
This unit provides the foundation for work in
key stage 4 on the impact of humans on the environment, the management of
food-production systems and the importance of sustainable development.
At the end of this unit
in terms of scientific enquiry
most pupils will:
decide on an appropriate approach to investigating a question about the effects
of fertiliser, identifying relevant variables and choosing an appropriate
sample size; present results in tables and graphs which show features
effectively; draw conclusions that are consistent with the evidence,
identifying shortcomings, where appropriate, and relate them to scientific
knowledge and understanding
some pupils will not have made so much progress and will: suggest how to control variables identified
for them; present results in tables and graphs and point out patterns in these;
draw conclusions, relating these to scientific knowledge and understanding, and
suggest some improvements to their work
some pupils will have progressed further and will: consider critically tables of results and
graphs and explain how additional data would enable them to have more
confidence in their conclusions
in terms of life processes and living things
most pupils will: name
the products of photosynthesis and some of the nutrients supplied by
fertilisers; identify conditions in which crops will grow well; describe how
the abundance and distribution of organisms may be affected by pesticides or
weedkillers, relating this to knowledge of food webs; describe how other plants
compete with food crops, and other animals compete with humans for the food
crops, and that there are ways of achieving a balance between communities
some pupils will not have made so much progress and will: name the products of photosynthesis and some
of the nutrients provided by fertilisers; identify factors which affect the
growth of crops and identify some organisms which compete for resources where
crops are grown
some pupils will have progressed further and will: relate crop production to pyramids of numbers
and explain some ways of achieving a balance between the demands of different
communities within an environment; explain how toxic materials can accumulate
in a food chain
It is helpful if pupils:
about some of the life processes common to living things, eg movement, growth, reproduction, nutrition
Risk assessments are required for any hazardous
activity. In this unit pupils:
fertilisers which may contain hazardous substances
and carry out their own investigation
out work outside the school
Many employers have specific guidance on
fieldwork. Model risk assessments used by most employers for normal science
activities can be found in the publications listed in the Teacher’s guide. Teachers need to follow these as indicated in the
guidance notes for the activities, and consider what modifications are needed
for individual classroom situations.
Through the activities in this unit pupils will
be able to understand, use and spell correctly:
relating to managing plant production,
herbivore, pesticide, weedkillers, nutrient, fertiliser, toxin
with similar but distinct meanings,
insecticide, pesticide, fungicide, herbicide
with different meanings in scientific and everyday contexts, eg competition, balance, compete, yield
relating to scientific enquiry,
Through the activities pupils could:
the standpoint of the author of a text and how it affects the meaning
how effectively information is presented in whole texts, web pages,
sources to explore food production, farming and pests, eg CD-ROMs, photographs, video clips, gardening reference books and
other literature such as information leaflets produced by environmental,
farming and government organisations
of a wide range of crops or plants
slides showing starch grains in plants,
webs showing animals and plants associated with a crop, eg cereals
and/or wheat for growing
of packaging or advertisements for fertilisers, weedkillers, pesticides
about crop yields with, and in the absence of, weeds
studies about the use of pesticides,
effect on bird populations, effect on locusts, malarial areas
about use of pesticides and insecticides from different perspectives, eg ‘Silent Spring’ by Rachel Carson
about issues relating to plant breeding in newspapers and periodicals
television programmes which deal with issues relating to intensive crop
• visit a
rural or city farm to gain first-hand experience of farm practice
fruit picking to gain first-hand experience of harvesting crops
and harvest fruit and vegetables, eg
tomatoes, capsicums, to gain
practical experience of food production
Where does our
food come from?
use ideas about feeding relationships in a new context
• to combine ideas from different sources
pupils’ knowledge and understanding of feeding relationships by asking them
to draw food chains representing a typical meal that they may have eaten.
Help them to combine their responses to show the wide variety of foods that
humans eat, and the complexity of the human food web.
• Ask pupils questions about why plants can
be food sources and the importance of the Sun as an energy source for food
chains. Check pupils’ understanding and relate their ideas to the food web
• construct a food web showing feeding
relationships of humans
• explain the meaning of terms, eg producer, consumer, energy source,
herbivore, in relation to food chains
activity is designed to elicit pupils’ knowledge of feeding relationships.
Teachers will need to bear this in mind in later work.
this activity, teachers may need to provide information about the foods that
different animals are fed on farms.
• There is an opportunity here to revise the
concept of a balanced diet, covered in unit 8A ‘Food and digestion’, and to
consider cultural issues relating to food and diet, and the various diets
that are typical of different parts of the world.
Where does our
food come from? (Cont.)
different parts of plants are food sources of different kinds
some parts of plants are starch stores
the products of photosynthesis
• how plants respire
examples of food from plants, eg
carrot, pea, potato, wheat, maize, lettuce, apple, rice, mango, soya bean,
grape, radish, coconut, onion. Ask pupils for further examples and to
identify which parts of a plant each represents. Explain that each of these
foods contains materials produced by the parent plant. Ask them how plants
produce this material, and why plants keep large stores of starch in certain
parts (roots, stems, seeds), emphasising that it was not produced for humans
or animals to eat. Remind pupils about plant respiration.
pupils to test the samples for the presence of starch, and invite them to
suggest why some parts do not give positive results. Explain how the products
of photosynthesis may be converted into other substances by the plant.
• Provide microscope slides showing starch
grains inside cells, eg of a potato,
and help pupils to interpret what they see.
• identify which part of a plant is food for
• identify, from experimental results, starch
stores in some plants
• name some materials produced as a result of
• describe how plants respire
• relate knowledge of the products of
photosynthesis to ideas about plants as sources of food for humans and other
contain sugars and are for animals to eat as an aid to seed dispersal.
is an opportunity here to revise the process of photosynthesis, covered in
unit 9C ‘Plants and photosynthesis’, and adaptations for seasonal change,
covered in unit 7C ‘Environment and feeding relationships’.
will have tested for starch in unit 8A ‘Food and digestion’ and unit 9C
‘Plants and photosynthesis’.
pupils could be asked to find out about the reasons why humans do not eat
some parts of plants,
pupils should not eat the foods. Avoid the
use of peanuts if any pupils are allergic to them
• to relate together ideas about feeding
relationships and photosynthesis
• Ask pupils to make a concept map using
appropriate terms, eg producer,
consumer, food web, photosynthesis, energy, Sun, glucose, starch, root, leaf,
stem. Ask pupils to exchange maps and to suggest additional connections,
• make and explain connections between the use
of plants for food and photosynthesis and its products
How do fertilisers
affect plant growth?
identify relevant information and summarise it in a table
plants require a range of minerals for healthy growth
• that fertilisers supply these minerals to
pupils to use samples of fertiliser packs of different types and other
sources to find out about nutrients, eg
the range of nutrients that plants need, what role these nutrients play in
the life of the plant, which nutrients each fertiliser provides, how much a
plant requires, and to summarise the information in a table. Tell pupils
the cost of a pack of fertiliser, and the recommended application rate, and
ask them to calculate the cost per 100 square metres of crop.
• Show images, eg video clips, photographs, of large-scale fertiliser
application to farmland. Ask pupils to consider the great costs involved, and
any other implications of this practice.
• find information about fertilisers and plant
nutrients and summarise it in a table
• identify a range of minerals that plants
need for healthy growth
• describe how fertilisers supply these
minerals to crop plants
gardening reference CD-ROM, information from fertiliser packs and leaflets
from garden centres could be used to find out about the roles of different
chemical compounds in fertilisers.
are not expected to learn details of plants’ mineral needs, but to develop an
understanding of the range of minerals required, and that plants require only
small amounts of these minerals.
• Environmental effects of fertilisers are
decide which factors are relevant to a question
to deal with factors that cannot be controlled
decide which measurements/observations to make
draw conclusions from results and explain the significance of these
• to evaluate the method in terms of the data
• Extend this work by asking pupils to plan
and carry out an investigation into the effects of fertiliser, eg of nitrate fertiliser concentration on
duckweed growth, providing information about culturing the plant and a
maximum concentration; the effect of different fertilisers on wheat growth.
Ask pupils to produce a report of their investigation and to contribute
conclusions to a class summary, indicating whether they think they should
have confidence in what they found out.
• identify relevant factors, eg concentration of nitrate, mass of
• choose an adequate sample size to deal with
variation between individual plants
• choose an appropriate timescale for
• identify differences in growth and relate
these to variables,
eg composition, mass, of fertiliser
• give reasons why they have or do not have
confidence in their conclusions
investigation will need to run over 2–3 weeks.
is an excellent organism for this investigation, providing good results in
the space of 2–3 weeks. Growth is measured by counting the number of leaves
in the culture. Samples can be obtained from local ponds.
fertilisers will be oxidising and others may be harmful on contact. Eye
protection should be worn. Pupils’ plans must be checked for health and
safety before practical work begins
competition with other plants affect plant growth?
the organisms living in a habitat compete with each other for resources from
• how treating fields with selective
weedkillers affects food webs
pupils to suggest what the term ‘weed’ means, why weeds might affect yields
from food crops, and ways in which weeds compete with crop plants for
resources. If possible, provide pupils with data about the yields of crops
with, and in the absence of, weeds, and ask them to explain whether the data
supports their ideas. Ask pupils to suggest what the effects of killing the
weeds might be on other living things on the farm.
• Provide pupils with examples, eg specimens, photographs, of weeds
that often grow alongside food crops and show photographs or video clips of
workers in protective gear spraying food crops with weedkiller. Ask pupils to
find out about the chemicals used and their effects, eg using information from packaging, and to present this
information as a table.
• describe ways in which weeds compete with
crop plants for resources from the environment
• describe how treating fields with selective
weedkillers affects specific food webs
• explain how animals are affected by the
removal of a particular food plant
• suggest how a high crop yield might be
attained alongside preservation of animals’ food supply
information from packs of weedkiller could be photocopied for individuals or
groups to use. This could be supplemented by further reference literature,
such as leaflets and gardening books.
pupils could read about the possible effects of weedkillers on an ecosystem
and find out about specific examples and possible solutions, eg through the internet.
• Extension: pupils could be provided with a
detailed food web found in the countryside, including many wild plants and a
few crop plants. Ask them to erase some of the wild plants to show the effect
of weedkiller, and to note how many animals have a reduced food supply
because of this. Ask pupils to relate this to the work on yields from crops,
and to suggest approaches that might combine efficient crop production with
preservation of animals’ food supply.
plan and carry out an investigation involving sampling
present a report of their findings using tables and graphs
• to recognise and use scientific terminology
effectively and accurately
this work by asking pupils to carry out a survey of weeds growing,
eg in a lawn, allotment or crop field.
Provide a key for identifying weed plants and remind them how to use quadrats
to sample a population.
• This could be set in the context of having
to produce a report for the landowner about the types and numbers of weeds on
the land. In the report, pupils could be asked to explain the problems that
weeds present and to make suggestions about how to treat the land to remove
them, and to identify possible consequences of the treatment.
• follow their plan to collect data about the
population and distribution of weeds
• produce appropriate tables and graphs to
• write a report for a third party in a
suitable format, using scientific terminology effectively and accurately
pupils could compare the numbers of weed plants on a lawn with a similar area
of wasteland or recently dug-over ground, simulating the invasion of weeds
into arable land after ploughing.
all off-site visits should be carried out in accordance with LEA/school
guidelines. Pupils’ plans must be checked for health and safety before
practical work begins
How do pests affect plant growth?
the organisms living in a habitat compete with each other, eg for food resources from the
represent feeding relationships using pyramids of numbers
• that the numbers of a population of
predators influence the numbers of prey organisms
pupils about the types of animals that might feed on the crops grown and
establish that these are competing with humans for the crops. Ask pupils to
find out what these animals, eg
fieldmouse, cabbage white butterfly, aphid, snail, slug, feed on, and
emphasise that, for these animals, the food crops are part of the food web.
Help pupils construct pyramids of numbers for some of the feeding
pupils how farmers respond to pests, and consider methods of management,
including the use of pesticides. Show packaging or advertisements, eg for insecticides, snail and slug treatment,
and ask pupils to find out about what chemicals are used, how dangerous they
are, and whether they are specific to one type of animal.
• Show a food web and identify a pest species
that could be eliminated by a pesticide. Ask pupils to predict some effects
of this on the pest species and on other populations, eg fewer insect pests leads to a decrease in the bird population,
and to relate this to pyramids of numbers.
• identify some common animals, including
pests, which feed on crops and explain that they compete with humans for
• explain how the elimination of pests will
affect the populations of predator animals such as birds, relating
explanations to pyramids of numbers
is an opportunity here to revise animal classification, covered in unit 7C
‘Environment and feeding relationships’ and unit 8D ‘Ecological
relationships’. Pyramids of numbers are introduced in unit 8D ‘Ecological
an alternative, pupils could look for animals feeding on plants in the locality
of the school or their home.
• Gardening reference books and CD-ROMs
provide information on pests.
toxins enter a food chain when plants take them in or are in contact with
as animals feed on plants they may accumulate toxins taken in by the plant
at each step of the food chain persistent toxins are accumulated in the
carnivores and that this process is
• about advantages and disadvantages of using
pupils how to select information from a text and ask them to suggest ways in
which information about toxins in food chains might depend on the author of
the text. Provide pupils with secondary sources of information, eg textbooks, videos, environmental
leaflets, about the effects on the wild bird population of
bio-accumulation of toxins in the food chain, eg the effect of DDT used as a pesticide on the heron population, the
osprey and other birds of prey such as sparrowhawks, and the decline in
populations of some UK native birds as a result of pesticide use on farms.
pupils to consider and evaluate the information provided, and to extract from
it the key points to explain why the bird populations have declined.
• Provide pupils with secondary sources of
information about the use of pesticides, eg
in controlling populations of locusts, malarial mosquitoes. Ask pupils to
consider and evaluate the information provided and to extract from it the key
points about which pesticides were used and why they were used.
• describe how a persistent toxic material
passes up a food chain
• explain why pesticides and weedkillers are
used, identifying the dangers
• evaluate the information provided, relating
it to the standpoint of the author of the text
all toxins used as herbicides or pesticides will be passed on to animals that
feed on them. Many biodegrade over very short periods; it is only those
containing persistent substances that bio-accumulate.
• As an alternative, pupils working in groups
could be given information, presented as single sentences on cards, about the
effect of pesticides on the wild bird population. Ask pupils to put together
the evidence to describe and explain what happened to the birds. A similar
set of cards could be produced about the effect of a plague of locusts.
How do pests affect plant growth? (Cont.)
recognise the standpoint of the author of a text
evaluate how effectively information is presented in whole texts
• to evaluate conflicting evidence to arrive
at a considered viewpoint
the examples above to draw out issues and ask pupils to reflect on questions,
– Why are pesticides used?
– Are there alternatives?
– Who develops alternative, less
– What could be done to protect
vulnerable populations such as birds?
– Should pesticides be used to
produce more food for humans at the expense of other animals?
How are pests managed on
• describe the views of different people who
write about pesticides
• identify advantages and disadvantages of
pesticides, and people to whom each will be important
may wish to develop their own secondary sources or case studies based on
local or current events.
• Development of pesticides links with making
new materials in unit 9H ‘Using chemistry’.
What is the
perfect environment for growing plants?
environmental factors that influence plant growth
• to consider the advantages and
disadvantages of a controlled environment for growing crops
pupils about the conditions that plants need for healthy growth, eg light, water, minerals, warmth, carbon
dioxide. Reinforce by showing examples of plants that have been deprived
of one of these, eg grass seedlings
grown in the dark, in the cold, in dry conditions, or with a mineral
deficiency, and ask pupils to suggest reasons for the plants’ conditions.
• Show images of commercial greenhouses in
operation. Supplement with information about smaller-scale greenhouses, eg from a catalogue. Discuss the
advantages of growing crops this way, eg
control of climate, longer growing season, no weeds, and consider and
evaluate any problems associated with this type of production, eg appearance in the environment,
possible variation in taste.
• identify environmental factors which have
influenced the growth of plants
• suggest some advantages and disadvantages of
growing crops in a greenhouse
activity could be enhanced by a visit to a commercial greenhouse.
Alternatively, someone working in commercial food production could be invited
to talk about what they do and help evaluate the pupils’ designs in the next
• Extension: pupils could be asked to find
out about the seasonal nature of fruit crops and how some crops are now
available most of the year.
apply knowledge and understanding about plant growth to solve a problem
different approaches to crop production contribute to sustainable development
• to present ideas as drawings and diagrams
pupils to use their knowledge of the needs of plants and of growers to design
an ideal greenhouse environment for crop production on farms. They may
include control-technology devices to monitor and control the internal
environment. Their plans should be presented as annotated drawings that
include the reasons for each design feature.
• Ask pupils why most food crops are not
grown under protective cover.
• present an annotated drawing of a design for
a commercial greenhouse, relating this to knowledge and understanding of
• describe the benefits and drawbacks of
greenhouse crop development
• Genetically modified plants are considered
briefly in unit 9A ‘Inheritance and selection’.
identify key points about a scientific issue
• that there is often a balance of advantage
and disadvantage in development
together the concepts and issues from the previous activities, eg
– the need to provide food for humans and
the reasons for, and effect of, the
removal of hedges and woodland
– why pesticides and weedkillers are used
provide comparative information about alternatives, eg organic farming.
pupils to produce a piece of work that summarises the issues of plant
production for food, based on their scientific knowledge of the problems,
a magazine article highlighting
the main issues for the general public
a script for a radio or TV
a classroom debate in which
individuals or groups argue the case for and against intensive agriculture
a carefully scripted role play
where individuals act the parts of participants in a meeting to discuss the
• summarise understanding of an issue,
incorporating appropriate scientific knowledge and understanding, and explain
how a stable ecosystem is one in which
there is a balance of organisms
how human development can have a harmful
effect on the living things in an area
how sustainable development involves an
approach which aims to have minimal impact on the environment and living
• Further information on these issues can be
obtained from environmental groups and agencies, farming and government
organisations, large-scale food producers and the media.
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