Standard Grade Biology
Learning Objectives
WORLD OF PLANTS
Summary Notes
Learning Objectives
GENERAL and CREDIT
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Introducing plants
Give examples of advantages of there being a wide
variety of plants.
Explain possible consequences to man and other
animals of a reduction in the variety of species.
Describe 3 specialised uses for plants.
Describe a production or refining process, eg malting
barley, rape seed, raspberries, timber.
Describe 2 potential uses of new plants or plant
products e.g. new medicines, new food sources.
 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.
 Loss of potential resources.
 Loss of habitats.
 Loss of potential breeding characteristics.
 Loss of food supplies for animals.
Plants can be used as:
 raw materials
 foods
 medicines
Describe timber production as:
 tree seedlings raised in nursery
 planted out at 2-4 years
 first trees harvested at 15 years
 felled at 40-50 years
 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.
Growing Plants
Describe the functions of three main parts of the seed of
a dicotyledon, i.e. seed coat, embryo, food store.
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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.
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Standard Grade Biology
Learning Objectives
WORLD OF PLANTS
Learning Objectives
GENERAL and CREDIT
Summary Notes
 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
Describe the effect of temperature and the availability
temperature.
of water and oxygen on germination.
 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.
 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.
Describe the changes in percentage germination that
 Seeds normally have a high percentage germination over a range of
occur over a range of temperatures.
temperatures with highest germination taking place at a temperature known as
the optimum.
The function of the parts of the flower are:
 Sepal = protects the flower when it is a bud.
 Petal = attracts insects to the flower.
 Stamen = male part of the flower.
Describe the functions of the parts of flowers, i.e. sepal,
 Anther = Produces pollen grains.
petal, stamen, anther, stigma, ovary, nectary.
 Stigma = Catches pollen grains.
 Ovary = Contains the ovules (egg cells).
 Nectary = Makes a sugary liquid called nectar.
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Describe methods of pollination.
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Describe fertilisation and fruit formation.
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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.
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.
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Standard Grade Biology
Learning Objectives
WORLD OF PLANTS
Learning Objectives
GENERAL and CREDIT
Summary Notes
The structure of insect pollinated flowers in relation to sexual reproduction is:
 have brightly coloured petals to attract insects.
 have a smell to attract insects.
 usually produce nectar to attract insects.
o petals
o ovary
o anther
o sepals
o stigma
o nectar
 have sticky/spiky pollen grains to stick to insects.
 have sticky stigmas inside the flowers so that insects have to brush past it and
transfer pollen.
Explain the structure of wind- and insect-pollinated
 stamens are inside the flowers surrounded by petals so that insects will brush past
flowers in relation to sexual reproduction.
them and pick up pollen.
Describe the growth of the pollen tube and fusion of
gametes.
The structure of wind pollinated flowers in relation to sexual reproduction is:
 have small flowers with green or dull coloured petals as they do not need to
attract insects.
 have no smell as they do not need to attract insects.
 does not produce nectar as they do not need to attract insects.
 produces large amounts of very light pollen grains so that it can be blown by the
wind.
 have feathery stigmas, which hang outside the flower so that pollen in the air can
be trapped on them.
 Have large stamens, which hang outside the flower to catch the wind, which will
blow the pollen away.
 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.
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Standard Grade Biology
Learning Objectives
WORLD OF PLANTS
Learning Objectives
GENERAL and CREDIT
Summary Notes
The three methods by which seeds can be dispersed are:
 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.
Describe one example of each of the following different
 Animal-internal = cherry, tomato – juicy fruit to appeal to animals, with seeds that
dispersal mechanisms: wind, animal-internal, animalhave indigestible coatings to survive digestive juices of the animal.
external.
 Animal-external = Burdock – has hooks to attach to the coats of passing animals.
Describe ways of propagating flowering plants
artificially by cuttings and grafting.
Explain the advantages to man of artificial propagation
in flowering plants.
Describe what is meant by the term “clone”.
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.
Flowering plants can be propagated by:
 taking a stem cutting by removing a small piece of stem with some leaves still
attached and placing it in a rooting medium.
 grafting by taking a portion of a plant and joining it to a plant with an established
root system.
 layering by bending the stem to touch the ground so that it will produce roots
while still attached to the parent plant.
 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.
A clone is a organism that is genetically identical to the parent plant
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Describe asexual reproduction by runners and tubers.
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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 food made by
the plant is sent to make new tubers e.g. potatoes, carrots.
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Standard Grade Biology
Learning Objectives
WORLD OF PLANTS
Learning Objectives
GENERAL and CREDIT
Summary Notes
Sexual reproduction
 gives rise to variation, which may be an advantage if conditions change.
 allows dispersal of seeds to new areas.
Asexual reproduction
Describe the advantages of both sexual and asexual
 early, quick growth possible because there is no fusion of gametes involved.
reproduction in plants.
 offspring share parental characteristics allowing beneficial characteristics to be
passed on.
 offspring dispersed in a clump so reducing competition from other species.
 vulnerable stages of germination and pollination are not present.
Making Food
Explain the need for transport systems in a plant.
Describe the pathways of movement of water and food
in xylem and phloem.
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Describe the structure of phloem and xylem and identify
other functions of the transport system.
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State that plants take in carbon dioxide from the air
through stomata, which can open and close.
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Water is required for photosynthesis.
Food manufactured in the leaves is needed for growth and energy by the plant.
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.
Xylem and phloem are usually found close together in groups called vascular
bundles.
o In the stem the vascular bundles are round the outside.
o In a root the vascular bundles are in the centre.
o Vascular bundles also help to give the stem support.
Xylem cells are dead.
o The walls of xylem have rings or spirals of a tough substance called lignin.
Phloem cells are alive.
o Phloem contains two types of cell: 1) sieve tubes and 2) companion cells.
o The end walls of sieve tubes have pores.
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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