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SUMMARY SHEET
THE WORLD OF PLANTS
SUBTOPIC (a) INTRODUCING PLANTS
GENERAL
Give
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examples of advantages of there being a wide variety of plants.
More characteristics available for breeding a wide variety of plants
Larger choice of plants for use as raw materials, foods and medicines
Provide different sources of food for animals,
As a habitat for other organisms.
Maintains a gas balance (takes in carbon dioxide that we breath out and provides us with
oxygen that we breath in),
 Improves our surroundings.
Foods
Plant
Wheat
Grapes
Sugar cane
Palms
Food Produced
Bread
Wine
Sugar
Oil
Raw Materials
Plant
Jute
Flax
Rose Petals
Heather
Raw Material
String
Linen
Perfume
Dyes
Medicines
Plant
Poppy
Foxglove
Rosy Periwinkle
Mandrake
Medicine
Morphine (pain relief)
Digitoxin (heart disease)
Vincristine (leukaemia)
Hyoscyamine (Sedation)
Describe 3 specialised uses of plants.
 Raw materials (plants are processed or treated before being used e.g.
paper/cotton/linen)
 Foods (jelly made from alginates from seaweed)
 Medicines
CREDIT
Explain the possible consequence to man and other animals of a reduction in the variety
of species.
 Loss of potential resources (food, raw materials and medicines),
 loss of habitats for animals,
 loss of food for animals,
 loss of potential breeding characteristics (loss of a genetic storehouse),
 loss of food supplies
Describe a production or refining process e.g. malting barley, rape seed, timber
production.
Timber production
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Tree seedlings raised in nursery
Trenches prepared by digging drainage ditches to remove excess water
Young trees from nursery planted out at 2-4 years and protected
Thinning of poorer trees to allow stronger trees to grow
Felled at 40-50 years for paper production, chip-board or furniture.
Malting process
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Barley soaked for 2-3 days (steeping)
Soaked barley spread on stone floors (enzymes in barley convert starch to maltose)
Grains dried in kilns to stop germination
Dried grains (malt) ground and taken to brewery or distillery to make beer/whiskey
Describe 2 potential uses of plants or plant products
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New medicines – antibiotics, morphine (from poppy), digitoxin (from foxglove) etc.
The extraction of protein (mycoprotein) from a fungus which can then be used as a new
food source.
SUMMARY SHEET
THE WORLD OF PLANTS
SUBTOPIC (b) GROWING PLANTS
GENERAL
Describe the function of 3 main parts of the seed of a dicotyledon: - seed coat, embryo
and food store.
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Flowering plants make seeds to reproduce.
The seed coat protects the embryo plant.
The food store provides food for growth.
The embryo is the young plant, made up of a young
root and shoot.
Describe the conditions necessary for germination.
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Germination is the process where the embryo inside the seed starts to grow into a new
plant. Before germination can take place the seed must have water, oxygen and a
suitable temperature (warmth). Memory Aid: WOW.
Water is needed for the seed to swell up allowing the embryo to grow.
Oxygen is needed to produce energy for germination.
A suitable temperature is needed for good germination.
Describe the functions of the parts of flowers – sepals, petals, stamen, anther, stigma,
ovary and nectary
PART OF FLOWER
Sepal
Petal
Stamen
Anther
Stigma
Ovary
Nectary
FUNCTION
Protects the flower when its in bud
Attracts insects to flowers by their
bright colours or scent
Male part of flower
Part of the stamen which makes the
pollen grains (male sex cells)
Female part of the flower which is
sticky to catch pollen grains
Female part of the flower which
contains ovules (female sex cells)
Contains sugary liquid called nectar
which attracts insects
Describe the methods of pollination
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Before we can produce a seed, pollen and ovule must come together – pollination.
Pollination is the transfer of pollen from the anther to the stigma. Self-pollination is
the transfer of pollen to the stigma of the same plant. Cross pollination is the transfer
of pollen to the stigma of another plant of the same species.
Most flowers rely on either the wind or insects to transfer their pollen.
It is often easy to tell the method of pollination used by a flower by its appearance.
Insect pollinated flowers use animals such as bees, butterflies and birds.
Wind pollinated flowers have structures which make use of the wind.
Describe the Growth of the Pollen Tube and Fusion of Gametes.
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Once the pollen has landed on the stigma the male
sex cell inside has to get to the female sex cell
(ovule).
To do this it has to grow a pollen tube down through
the style.
The stigma produces a sugary fluid to feed the
growing pollen tube.
Once the pollen grain has travelled to the ovule in
the ovary, it fuses (joins) with the ovule.
Describe Fertilisation and Fruit Formation
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Fertilisation is the fusion of the pollen nucleus with the ovule nucleus.
Fruits are formed from the ovary of the flower which surrounds the seed.
After fertilisation the ovary swells to form the fruit and the ovules become the
seeds.
In a fleshy fruit the main part of the fruit is soft and juicy e.g. plum or tomato.
In a dry fruit the main part is hard and dry e.g. dandelion or sycamore.
Describe One Example of Each of the Following Different Seed Dispersal Mechanisms
(Wind, Animal-internal, Animal-external)
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Once fertilisation has taken place, the flower withers and a seed and fruit are formed
from the ovary.
The seeds must be scattered as far away from the parent plant as possible.
This avoids the new plants competing with the parent for vital resources.
This “seed dispersal” is achieved in a variety of ways.
Wind
 Plants use the wind to scatter their seeds and they use different mechanisms to
achieve this.
Animal Internal
 These seeds are contained in a succulent fruit (soft and juicy).
 Seeds are eaten by animals along with the fruit.
Animal External
 The seed has hooks which catch onto animals’ fur and are transported by the animal
until they fall off and hopefully germinate elsewhere.
State the Stages of the Plant Life Cycle
FERTILISATI
ON
POLLINATION
SEED DISPERSAL
FLOWER
FORMATION
GERMINATION
Describe asexual reproduction by runners and tubers
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Asexual Reproduction is the production of new plants from a single parent plant without
fertilisation. No pollen or ovules (gametes) are involved in this process.
Asexual reproduction in flowering plants is called vegetative propagation. Vegetative
propagation can either be natural or artificial.
Natural vegetative propagation -:
Runners
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Runners – are side shoots which grow out from the parent plant and develop a bud at the
end. These buds eventually form roots and grow into new plants e.g. strawberry or
spider plants. The parent provides food through the runner until the new plant can
make its own, then the runner shrivels away.
Tubers
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Tubers – are underground food stores which
provide the plant with food over the winter until
it can make its own. New food made by the plant
is sent to make new tubers e.g. potato.
Describe ways of propagating flowering plants artificially by cuttings and grafting.
Artificial propagation-:
Cuttings – removing a small piece of stem with some leaves still attached and placing it in a
rooting powder to promote the growth of roots. Cutting is placed in soil and allowed to
grow.
Layering – bending the stem to touch the ground so that it will produce roots while still
attached to the parent plant.
Grafting – taking a portion of a plant and joining it to another plant with an established
root system.
CREDIT
Describe the changes in percentage germination that occur over a range of
temperatures.
Optimum
Temperature
% Germination
100
80
60
40
20
0
0
5
10
15
20
25
30
35
40
45
50
55
o
Temperature ( C)
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At temperatures between 0 – 5°C very few seeds will germinate because it is too
cold for the enzymes to operate.
Above 45°C very few seeds will germinate because the enzymes will be destroyed.
As the temperature rises from 5°C - 45°C the number of seeds which germinate
increases – the higher the temperature ( below 45°C) the greater the number of
seeds germinating as the enzymes will be able to operate.
The temperature at which seeds germinate best is called the optimum temperature.
Explain the structure of wind and insect pollinated flowers in relation to sexual
reproduction.
Insect Pollinated Flowers
Structure Description
Reason
Petals
Attracts insects
Pollen
Brightly coloured
and scented
Makes nectar
(sugar)
Sticky and spiky
Stigma
Sticky
Stamen
Inside the flower
Traps pollen when
insects brush past
Insects can brush
past to pick up
pollen
Nectary
Attracts insects
Sticks to insects
Wind Pollinated Flowers
Structure Description
Reason
Flower
No need to attract
insects
No need to attract
insects
Easily carried in the wind
Nectary
Pollen
Stigma
Stamen
Green and dull, no
scent
No nectary so no
nectar
Light and
produced in large
amounts
Feathery and
hangs outside the
flower
Large and hangs
outside the
flower
Large surface area to
catch pollen as it passes
by in the wind
Produce large amounts of
pollen and wind can carry
the pollen
Describe 1 example of each of the following different dispersal mechanisms – wind,
animal internal, animal external.
 Seeds must be dispersed or scattered in order to grow into new plants. There are 3
methods of dispersal – wind, animal internal and animal external
1.Wind seeds dispersed have extensions which act as parachutes or wings for carrying the
seed/fruit away by the wind e.g. dandelion, sycamore. Wind dispersed can also have fruits
when shaken by the wind act like a pepper pot (poppy).
Sycamore
Dandelion
Poppy
2. Animal internal – These seeds are contained in a succulent fruit (soft and juicy). Seeds are
eaten by animals along with the fruit. The seeds pass through the animal and are deposited
in the droppings (faeces) elsewhere, e.g. bramble, strawberry, raspberry, cherry, apple and
tomato.
Bramble
Strawberry
3. Animal external – The seed has hooks which catch onto animals’ fur and are transported by
the animal until they fall off and hopefully germinate elsewhere, e.g. Burdock.
Burdock
4. Some seeds are dispersed by a self explosive mechanism. This is a build up of pressure
inside the fruit which enables the seeds to shoot out of the fruit at high pressure e.g. pea
pods.
Pea Pods
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Pea Pods
Seed dispersal takes place in order that there is less competition for light, water and
nutrients from the soil.
Explain the advantages to man of artificial propagation in flowering plants
Advantage
Reason
Identical
Offspring
All the desirable features of the parent plant are retained in the
offspring (a clone).
Speed is fast
Many plants can quickly be produced from one parent (e.g. cuttings).
Grafting
The best features of two plants can be combined in one. Produces fruit of
known variety and quality. Bud grafting can be used to produce large
numbers of plants in a single stock.
Describe what is meant by the term clone.
 Asexual Reproduction can produce many new plants all from the same parent.
 As the new plants have grown from pieces of the parent plant, they will be identical to
the parent plant and to each other.
 The genetically identical offspring of a single parent produced in this way are
known as a CLONE.
Describe the advantages of both sexual and asexual reproduction in plants.
Advantages of Asexual Reproduction
Advantage
Reason
Spreads over new area quickly
Rapid Growth
Offspring suited to environment Are identical to the parent plant
Young plants receive food from
the parent plant
Rapid growth and reduces competition from other plants
Avoids vulnerable stages of
pollination, fertilisation and
germination
Allows rapid growth of plants
Advantages of Sexual Reproduction
Advantage
Reason
Variety of Offspring
Species has a better chance of surviving a change in
conditions.
Wide distribution
Less competition for light, space and nutrients when the
seeds spread to a new habitat which is over a wide area.
Sexual and Asexual Reproduction
Asexual
Sexual
Advantages
1. Early quick growth
2. Reduced competition
3. Identical Offspring
4. No pollination, fertilisation and
germination
1. Variety of Offspring
2. Seeds dispersed over wide area
Disadvantages
1. Overcrowding if plants grow in
same area
2. Quality doesn’t improve &
weaknesses passed on in genes
1. Gametes (sex cells) required
(pollination, fertilisation and
germination required)
2. Limited food store in seeds
SUMMARY SHEET
THE WORLD OF PLANTS
SUBTOPIC (c) MAKING FOOD
GENERAL
Explain the need for transport systems in a plant.
All parts of plants need both water and dissolved food, but water only enters through the
roots, and the leaves are the only source of food, so they need transport systems to move
these substances around the plant.
 Water is required for photosynthesis. Food manufactured in the leaves is needed for
growth and energy by the plant.
 Xylem and phloem are the two main transport systems.
Describe the pathways of movement of water and food in xylem and phloem
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Xylem carries water and minerals upwards from the soil roots to all parts of the plant.
Phloem carries dissolved food (sugars) from the leaves in all directions to parts of the
plant which cannot make their own food (growing tips, roots, etc.)
State that plants take in carbon dioxide from the air through stomata which can open
and close
 Stomata are tiny pores on the surface of a leaf.
 During photosynthesis, carbon dioxide enters the leaf through stomata and oxygen leave
the stomata.
 During the day stomata are open, during the night the stomata are closed.
 A leaf has a large surface area to allow the maximum amount of light to enter the leaf
and to expose it to as much air as possible.
Stomata
 Stomata open during daylight allowing carbon dioxide to enter.
 Water enters the guard cells which is transported from the roots via the xylem to the
guard cells. The guard cells become turgid and open the stomata.
 Stomata close during darkness when water transport to the guard cells decreases. The
guard cells become flaccid which closes the stomata.
Light
Dark
State that water vapour is lost through stomata
 When the stomata are open to allow carbon dioxide to enter the leaf, water vapour
diffuses out of the leaf.
 Too much evaporation of water vapour from the leaves may cause the cells to become
flaccid and the plant wilts.
 When this happens the guard cells close together, shutting the stomata and reducing
water loss.
State that green plants make their own food which may be stored as starch
 Green plants are able to make their own food. They make the food in the form of sugar.
 The sugar may be used by the plant straight away or converted to starch and stored.
 Plants use the process of photosynthesis to make their own food.
State that green plants convert light energy to chemical energy using chlorophyll.
Describe the process of photosynthesis in terms of raw materials.
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Light energy
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Carbon
Dioxide
+ Water
Raw Materials
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Glucose + Oxygen
Products
Photosynthesis takes place in leaves of green
plants.
Photosynthesis combines carbon dioxide and
water to produce glucose (sugar) and oxygen.
This process requires the green pigment
chlorophyll and light to take place.
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The process by which green plants make
their own food is known as
photosynthesis.
Photosynthesis is a process which
converts light energy into chemical energy
using chlorophyll. Chlorophyll traps the
light energy from the sun and this is used
to combine carbon dioxide and water.
Chlorophyll is found in the chloroplasts of
plant cells and is essential for
photosynthesis.
CREDIT
Describe the structure of xylem and phloem and identify other functions of the transport
system
Vascular Bundles
Root Vascular Bundle
Stem Vascular Bundle
Cortex
Xylem
Phloem
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Xylem and phloem are usually found close together in groups called vascular bundles.
In a stem the vascular bundles are found around the outside.
In a root the vascular bundles are found in the centre.
Vascular bundles help to support the stem.
Xylem
 Xylem vessels are dead.
 The end walls have disintegrated to leave hollow tubes.
 The side walls have become strengthened with rings or spirals
of lignin.
 Xylem functions are to carry water and minerals up the stem
and to support the plant.
Phloem
 Phloem cells are alive.
 Companion cells provide the energy for the tube cells.
 The end walls of the tube cells have pores through which food
is transported from cell to cell in the form of dissolved
sugars.
 These are known as sieve plates.
Describe the external features and internal structure (epidermis,mesophyll and veins) of
a leaf in relation to its function in gas exchange
Leaf Surfaces
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A leaf is thin to allow the carbon dioxide to pass quickly to the cells which carry out
photosynthesis.
A leaf is thin to allow oxygen to leave the leaf as quickly as possible.
A leaf is thin to allow sunlight to penetrate to all the cells.
Leaf Structure
Structure
Feature
Function
Waxy Cuticle
Waxy top surface
Reduces evaporation of water through
the epidermis and is waterproof
Upper and lower Transparent
epidermis
Palisade
Mesophyll
Lets maximum light enter and protects
the leaf
Tall and tightly packed together. To absorb maximum light and to carry
Contain chloroplasts
out Photosynthesis
Spongy Mesophyll Loosely packed together with air Allows carbon dioxide to diffuse to the
spaces
palisade mesophyll cells and oxygen to
diffuse out of the leaf
Veins
Contains xylem and phloem
Delivers water and minerals. Takes away
sugars produced in the mesophyll cells
Stoma (Stomata) Close in darkness and open in
light. Present on the lower
surface of the leaf
Allow Carbon dioxide to enter, oxygen
and water vapour to leave
Guard Cells
Control opening and closing of stomata
Water enters to open the
stomata
Describe the fate of carbon dioxide as structural and storage carbohydrates in plants
and as energy sources
Used as
building
Material
(e.g. cellulose
in cell walls
Stored as starch
And Converted
back when Sugar
is needed by
Plant.
Sugar
Used
immediately
For energy
Sugar made by plants from carbon
dioxide and water can be:1. stored as starch until needed
2. used to supply energy
3. used as building material –
cellulose in plant cell walls
Explain what is meant by a limiting factor and describe the main limiting factors in the
process of photosynthesis
 A limiting factor is a factor that if in short supply can cut down or limit the rate of
photosynthesis
 The main limiting factors in photosynthesis are carbon dioxide , light, temperature and
water
Limiting Factor Graphs
Point X Optimum
Increasing
rate of
photosynthesi
s
Increasing light
intensity
Part A
Part B
As light intensity
increases the rate
of photosynthesis
increases.
Further increases in light causes
no further increase in the rate of
photosynthesis since the rate is
limited by a shortage of some
other factor e.g. carbon dioxide or
temperature
Point X Optimum
Increasing rate
of
photosynthesis
Carbon Dioxide Concentration
Part A
As CO2 conc.
increases the rate of
photosynthesis
increases.
Part B
Further increases in CO2 conc. causes
no further increase in the rate of
photosynthesis since the rate is limited
by a shortage of some other factor e.g.
light or temperature
Limiting Factors
 If any factor is lacking, photosynthesis will not take place as fast as it could.
 Frosty but sunny winter day: Temperature is too low for enzymes to work well, so
temperature is the limiting factor.
 Cloudy but warm summer day: light intensity is below the optimum, so light is the limiting
factor.
 Warm sunny summer day: carbon dioxide is now likely to be the limiting factor.