Download 1a. General: Give examples of advantages of there being a wide

1a. General: Give examples of advantages of there being a
wide variety of plants.
 Greater number of characteristics for breeding.
 Bigger choice for use as raw materials, foods and medicines.
 Provide different sources of food for animals.
 Maintains gas balance.
 Improves our environment.
1b. Credit: Explain possible consequences to man and other animals
of a reduction in the variety of species.
 Loss of potential resources.
 Loss of habitats.
 Loss of potential breeding characteristics.
 Loss of food supplies for animals.
2a. General: Describe 3 specialised uses for plants.
 Plants can be used as:
i. raw materials
ii. foods
iii. medicines
2b. Credit: Describe a production or refining
process e.g. malting barley, rapeseed,
raspberries, timber.
 Describe timber production as:
i. tree seedlings raised in nursery
ii. planted out at 2-4 years
iii. first trees harvested at 15 years
iv. felled at 40-50 years
v. timber used in a variety of ways as stated in 2a.
2c. Credit: Describe 2 potential uses of new plants or plant products
e.g. new medicines, new food sources.
 Sugar cane crops can be converted into sugar cane alcohol and used in
warmer countries, such as Brazil, as a fuel source for cars.
 Development of new medicines, particularly new antibiotics and anticancer drugs.
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3. General: Describe the functions of three main parts of
the seed of a dicotyledon, i.e. seed coat, embryo, food
store.
 The seed coat is a protective layer.
 The embryo plant is made up of a young root and young
shoot.
 The food store provides the embryo plant with food.
4a. General: Describe the effect of temperature and the
availability of water and oxygen on germination.
 Germination is the stages involved in the development of a
new plant from the embryo plant in a seed.
 Before germination can take place a seed must have water,
oxygen and a warm temperature.
 Water is needed for the seed to swell up and allow the
embryo to grow.
 Oxygen is needed to produce energy for germination.
 A warm temperature is needed for good germination.
4b. Credit: Describe the changes in percentage germination that
occur over a range of temperatures.
 The percentage of seeds germinating at very low temperatures (0-5°C)
or at very high temperatures (above 45°C) is very low or zero.
 Seeds normally have a high percentage germination over a range of
temperatures with highest germination taking place at a temperature
known as the optimum.
5a. General: Describe the functions of the parts of
flowers, i.e. sepal, petal, stamen, anther, stigma, ovary,
nectary.
 The function of the parts of the flower are:
i.
Sepal = protects the flower when it is a bud.
ii.
Petal = attracts insects to the flower.
iii. Stamen = male part of the flower.
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petals
iv.
Anther = Produces pollen
grains.
v.
Stigma = Catches pollen
grains.
vi.
Ovary = Contains the
ovary
ovules (egg cells).
vii.
Nectary = Makes a
sepals
sugary liquid called nectar.
anther
stigma
nectary
5b. General: Describe methods of pollination.
 Pollination is the transfer of pollen grains from the anther
to the stigma.
 Self-pollination is the transfer of pollen to the stigma in the
same flower or another flower on the same plant.
 Cross-pollination is the transfer of pollen to the stigma of
another plant of the same species.
5c. General: Describe fertilisation and fruit formation.
 Fertilisation occurs after pollination, and is when the male
gamete in the pollen tube joins with the female gamete in
the ovule.
 Following fertilisation, fruits are formed from the ovary of
the flower, which surrounds the seeds.
 After fertilisation the ovary swells to form the fruit and
the ovules inside become the seeds.
 In a fleshy fruit the main part of the fruit is soft and juicy
e.g. tomato, plum.
 In a dry fruit the main part of the fruit is hard and dry e.g.
dandelion, sycamore.
5d. Credit: Explain the structure of wind- and insect-pollinated
flowers in relation to sexual reproduction.
 The structure of insect pollinated flowers in relation to sexual
reproduction is:
i.
have brightly coloured petals to attract insects.
ii.
have a smell to attract insects.
iii. usually produce nectar to attract insects.
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iv.
have sticky/spiky pollen grains to stick to
insects.
v.
have sticky stigmas inside the flowers so
that insects have to brush past it and transfer pollen.
vi.
stamens are inside the flowers surrounded
by petals so that insects will brush past them and pick
up pollen.
 The structure of wind pollinated flowers in relation to sexual
reproduction is:
i.
have small flowers with green or dull coloured petals as they
do not need to attract insects.
ii.
have no smell as they do not need to attract insects.
iii. does not produce nectar as they do not need to attract insects.
iv.
produces large amounts of very light pollen grains so that it
can be blown by the wind.
v.
have feathery stigmas, which hang outside the flower so that
pollen in the air can be trapped on them.
vi.
Have large stamens, which hang outside the flower to catch
the wind, which will blow the pollen away.
5e. Credit: Describe the growth of the pollen tube and fusion of
gametes.
 During fertilisation a pollen tube carrying the male gamete (sex cell)
grows out of the pollen grain and down the style to the ovary.
 Fertilisation is the fusion of the male gamete in the pollen tube with
the female gamete in the ovule.
6. Credit: Describe one example of each of the following different
dispersal mechanisms: wind, animal-internal, animal-external.
 The three methods by which seeds can be dispersed are:
i.
wind
ii.
animal-internal
iii. animal-external
 Wind 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 which when shaken by the wind,
act like a pepper pot.
 Animal-internal = cherry, tomato – juicy fruit to appeal to animals,
with seeds that have indigestible coatings to survive digestive juices of
the animal.
 Animal-external = Burdock – has hooks to attach to the coats of
passing animals.
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 Some plants may have self or explosive dispersed seeds. These build
up pressure inside the fruit, which will disperse seeds when they shoot
out of the fruit at high pressure.
7a. General: Describe ways of propagating flowering plants
artificially by cuttings and grafting.
 Flowering plants can be propagated by:
i.
taking a stem cutting by removing a small piece of
stem with some leaves still attached and placing it in
a rooting medium.
ii.
grafting by taking a portion of a plant and joining it
to a plant with an established root system.
iii. layering by bending the stem to touch the ground so
that it will produce roots while still attached to the
parent plant.
7b. Credit: Explain the advantages to man of artificial propagation in
flowering plants.
 Quick method of reproduction.
 Can produce required varieties easily.
 Grafting produces fruit of known variety and quality.
 Bud grafting can be used to produce large numbers of plants on a
single stock.
7c. Credit: Describe what is meant by the term “clone”.
 A clone is a group of cells all originating from the same single parent
cell and are therefore identical to each other and the parent.
8a. General: Describe asexual reproduction by runners and
tubers.
 A runner is a side shoot, which grows out from the parent
plant. Buds form at points along this runner and eventually
root and grow into new plants e.g. spider plants,
strawberries.
 A tuber is an underground food
store, which stores food over the
winter and provides the new plant with
food until it can make its own. New
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food made by the plant is sent to make
new tubers e.g. potatoes, carrots.
8b. Credit: Describe the advantages of both sexual and asexual
reproduction in plants.
 Sexual reproduction
i.
gives rise to variation, which may be an advantage if
conditions change.
ii.
allows dispersal of seeds to new areas.
 Asexual reproduction
i.
early, quick growth possible because there is no fusion of
gametes involved.
ii.
offspring share parental characteristics allowing beneficial
characteristics to be passed on.
iii. offspring dispersed in a clump so reducing competition from
other species.
iv.
vulnerable stages of germination and pollination are not
present.
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9a. General: Explain the need for transport systems in a
plant.
 Water is required for photosynthesis.
 Food manufactured in the leaves is needed for growth and
energy by the plant.
9b. General: Describe the pathways of movement of water
and food in xylem and phloem.
 Water and minerals are carried from the roots to the leaves
in tubes called xylem vessels.
 Food is carried from the leaves to those parts of the plant
that need it for growth or energy or to areas where it is
stored, in tubes called phloem.
9c. Credit: Describe the structure of phloem and xylem and identify
other functions of the transport system.
 Xylem and phloem are usually found close together in groups called
vascular bundles.
 In the stem the vascular bundles are round the outside.
 In a root the vascular bundles are in the centre.
 Vascular bundles also help to give the stem support.
 Xylem cells are dead.
 The walls of xylem have rings or spirals of a tough substance called
lignin.
 Phloem cells are alive.
 Phloem contains two types of cell: 1) sieve tubes and 2) companion
cells.
 The end walls of sieve tubes have pores.
10a. General: 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.
 Carbon dioxide enters the leaf through the stomata.
 During the day stomata are open.
 During the night stomata are closed.
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10b. Credit: Describe the external features and internal structure
(epidermis, mesophylls, veins) of a leaf in relation to its function in
gas exchange.
 A leaf has a large surface area to allow the maximum amount of light
to enter the leaf.
 A leaf has a large surface area to expose it to as much air as possible.
 A leaf is thin to allow the carbon dioxide to pass quickly to the cells,
which carry out photosynthesis, and allow oxygen to leave the cells as
quickly as possible.
 A leaf is thin to allow sunlight to penetrate to all cells.
 The outer layer of cells on a leaf is called the epidermis.
 The epidermis is transparent to allow light through.
 The epidermis contains stomata, which allow gases in and out.
 The top layer of cells in a leaf is called the palisade mesophyll layer.
 The layer of cells below the palisade layer is called the spongy
mesophyll.
 The spongy mesophyll cells are loosely packed with large air spaces to
allow carbon dioxide and oxygen to get to and from cells quickly.
 Leaf veins are made up of xylem and phloem within a short distance
of every mesophyll cell to carry food away from and water to leaf
cells.
11a. General: State that water vapour is lost through
stomata.
 The tiny pores (stomata) on the surface of a leaf allow
water to be lost from the leaf.
12a. General: State that green plants
make their own food which may be
stored as starch.
 Green plants are able to make their
own food.
 Green plants make food in the form
of sugar.
 The sugar made by the plant is
either used straight away or
converted to starch and stored.
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12b. Credit: Describe the fate of carbon dioxide as structural and
storage carbohydrates in plants and as energy stores.
 Sugar made by plants from carbon dioxide and water can be:
i.
stored as starch until needed
ii.
used as supply energy
iii. used as building material e.g. cellulose in plant cell walls
13a. General: State that green plants convert light energy
to chemical energy using chlorophyll.
 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.
 Photosynthesis takes place in the leaves of green plants.
13b. General: Describe the process of photosynthesis in
terms of raw materials and products.
 Photosynthesis combines carbon dioxide and water to
produce glucose (sugar) and oxygen.
 Chlorophyll found in the chloroplasts of plant cells is
essential for photosynthesis.
 Chlorophyll traps the light energy from the sun.
 The light energy from the sun is used to combine carbon
dioxide and water.
13c. Credit: 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.
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