Download 2- (G) Explain what true breeding is

World of Plants
1- Give examples of advantages of
having a wide variety of plants
2- Describe three specialist uses
of plants (i.e. raw plant material
needs to be processed before use)
and give two examples for each.
3- (C) Explain possible
consequences to humans and other
animals of a reduction in the
variety of plant species
4- (C) Describe a production or
refining process e.g. malting barley,
paper making, biofuel.
(answer provided for malting
barley)
5- (C) Describe two potential uses
of plants or plant products ( e.g.
new medicines, new food sources)
World of Plants
1- Describe the functions of the
three main parts of a seed.
1- Introducing plants
- provides a wide range of edible products
- provides a wide range of medicinal substances
- medicine: e.g. morphine from poppies, digitalin from
fox gloves.
- clothing: e.g. cotton and linen
- paper from wood
- Loss of potential new medicines
- Loss of potential crop species
- Loss of genetic storehouse to improve crops by
genetic engineering
The barley is left to germinate for a few days. During
this process called malting, the sugar maltose is
produced from grain’s starch. Yeast uses maltose to
produce alcohol in a process called alcoholic
fermentation (= anaerobic respiration)
New medicines: new antibiotics
New food sources: new species resistant to pests/
drought
2- Growing plants
1- seed coat: protects embryo
2- embryo: develops into a new plant
3- food store: food (starch) available to provide
energy for embryo growth until food can be obtain by
photosynthesis.
2- Describe the effect the
following factors on germination:
- temperature
- water
- oxygen
- temperature: too low → germination prevented
because enzymes cannot work efficiently enough.
Too high  enzymes will be denatured
- water: needed for cell processes and for making
new cells
- oxygen: needed to release energy from food store
Low temperature → enzymes work inefficiently or
not at all
Optimum temperature  enzymes work most
efficiently
High temperature → enzyme work inneficiently or
may be denatured (i.e. irreversibly damaged)
3- (C) Describe the changes in
percentage germination that occur
over a range of temperatures.
4- Identify and describe the
function of the parts of a flower
1- Flower stalk: supports flower so they stand out.
2- Sepal: protects flower bud from insects and cold.
3- Petal: attract pollinators + protection of sexual organs
4- Stamen: male sex organ of plant
4a: filament: supports anther
4b: anther: produce male gamete (sex cell) called pollen
5- Carpel: female sex organ of plant
5a: ovary: produces ovule containing female gamete
5b: stigma: sticky platform on which pollen is
deposited.
6- Nectary: produce nectar (sugary liquid to attract pollinator)
What is meant by pollination?
What is self-pollination?
What is cross-pollination?
5- Describe methods of pollination
1/Insect
2/Wind
6- (C) Explain the structure of
insect and wind-pollinated flowers
in relation to sexual reproduction.
1- Petals
2- Stigma
3- Anthers
4- Pollen
5- Nectaries
7- Describe fertilisation.
8- (C) Describe the growth of the
pollen tube and the fusion of
gametes.
When a pollen grain is transferred from an anther to
a stigma
Pollen of a flower is transferred to the stigma of the
same flower
Pollen of a flower is transferred to the stigma of a
different flower
1/Insect enters flower to find nectar, brushes
against anthers and pollen stick to its body. Insect
flies into other flower and brushes its body covered
in pollen against stigma → pollination.
2/ Pollen grain are carried away by wind to the stigma
Insect Pollinated
Wind Pollinated
Large, brightly coloured,
Small, green, not
scented
scented → no need to
→ attract pollinator
attract insect
Small and sticky
Large, feathery, hanging
2 → insect brushes onto them → large surface area
exposed to wind
3 Small and firmly held
Large, loosely attached
→ insect brushes onto them → pollen can be shaken
off easily
4 Small quantities produced Large quantities produced
Spiky → attaches to insect smooth and light → easily
carried by the wind
5 Present
Absent
1
The fusion of the two nuclei, the male gamete from
the pollen grain and the female gamete contained in
the ovule.
After landing on the stigma, the pollen grain
germinates, i.e. it grows a pollen tube which
eventually reaches the ovule. The male gamete
travels down the pollen tube to fuse with the female
gamete.
9- Describe fruit formation.
10- (C) Describe an example of
each of the following different
seed dispersal mechanisms.
1/ Wind
2/ Animal internal
3/ Animal external
4/ Self-explosive
11a- Describe ways of propagating
flowering plants artificially by
cutting
11b- Describe ways of propagating
flowering plants artificially by
grafting
12 (C)-Explain the advantages to
humans of artificial propagation
13- State what is meant by asexual
reproduction
14- Describe asexual reproduction
by runners; Give an example.
15- Describe asexual reproduction
by tubers; Give an example.
After fertilisation, the ovule develops into a seed
which contains the embryo plant. The outer part of
the ovule becomes the seed coat. The ovary wall may
become fleshy (e.g. apple) or hard (e.g. hazelnut), i.e.
a fruit.
1/ Wind: e.g. dandelion, sycamore → light seeds with
wing-like extensions or parachutes → blown by wind
away from mother plant
2/ Animal internal: e.g. tomato, apple → seed carried
away from parent plant in digestive system of animal
→ excreted with faeces (fertiliser).
3/ Animal external: e.g. sticky willy → dry hooked
fruits stick to animal fur → carried away from parent
plant
4/ Self-explosive: e.g. gorse  when fruits dry they
explode sending the seeds away from the mother
plant
- stem cut just below leaf/leaf bud
- Hormone powder dusted onto basis of stem
- stem placed in damp compost
- new roots and shoots develop after a few weeks
- notch cut made into receiving branch called stock
- part of branch of donor plant is cut to fit notch.
- desirable characteristics conserved
- fast
- grafts: best features of two plants can be combined
The generation of offspring from only one parent
which does not involve gametes (i.e. sex cells).
- horizontal shoot grows over ground
- young plant develops at the end of shoot
- young plant obtains nutrients and water from
mother plant until able to grow independently.
e.g. Strawberry
- underground stems swell up during growing season
and stores food (e.g. starch in potatoes).
- plant dies in autumn, underground swollen stem
remains.
- following spring, shoots and roots are growing from
underground stem → new plants are produced
e.g. potatoes
16a-(C) Advantages and
disadvantages of sexual
reproduction
16b-(C) Advantages and
disadvantages of asexual
reproduction
World of Plants
1- Explain the need for a transport
system in plants.
2- Describe the role of the xylem
3- Describe the role of the phloem
4- Identify xylem and phloem from
the diagrams:
Advantages
- variety of offspring:
more likely to adapt to
environmental change
and resist disease.
- seeds dipersed away
Less competition for
resources (e.g. light,
water)
Disadvantages
- variety of offspring:
some characteristics
may be lost in offspring
- seeds dipersed away
May land in unsuitable
environment
- requires pollination:
chancy process
Advantages
Disadvantages
- no variety of offspring:
-no variety of offspring:
Good characteristics are
May not be able to adapt
kept through generations
to changes in environment
- grows next to parent :
and resist disease.
Environment suitable
- grows next to parent :
for growth
May compete with.
- no need for pollination
parent
3- Making food
- to transport water and minerals from roots to
leaves
- to transport food (i.e. sugar) from leaves to parts
of the plant which do not make food
Transport water and soluble minerals after they
enter root hairs to all parts of the plant up to leaves.
Transports food from food-producing cells to other
parts of the plants where it is needed (root, shoots
and fruits)
- 1: xylem (at the centre of the root and stem’s
vascular bundle; on the upper side of the leaf’s vein)
- 2: phloem (to the outside of the vascular bundle in
the root and stem; on the lower side of the leaf’s
vein)
5- (C) Describe the structure of
the xylem and identify other
functions of the transport system.
- Xylem cells are dead cells forming tubes.
- Ligning bands are strengthening the tubes, give
structural support to the plant. Eventually, old and
unused xylem tubes become wood.
1- cell wall
2- ring of lignin
3- pit ( allow water and minerals to reach
neighbouring cells
4- direction of the flow (from roots to leaves)
5- xylem tube
6- (C) Describe the structure and
function of cells in the phloem.
Identify the different parts from
a diagram.
- Phloem is made of two types of living cells:
- sieve tubes: cells arranged as a tube with
perforated cell wall in between (sieve plate). Strands
of cytoplasm transport sugar from cells to cells.
- companion cells: have nucleus and cytoplasm,
they control neighbouring sieve tubes.
12345-
6- Explain how carbon dioxide is
transported from the air to
photosynthesising cells inside
leaves.
8- State where these ‘holes ‘are
located.
Explain what the meaning of “clone”
sieve tube
sieve plate
strands of cytoplasm
companion cell
direction of flow, from photosynthesising cells in
leaves to cells that cannot produce their own food.
Through holes called stomata (Sing. Stoma).
When the stoma opens: carbon dioxide goes in and
oxygen and water vapour go out by diffusion.
Stomata are found mostly on the lower surface of
leaves.
An organism which is genetically identical to the
organism from which it has been produced.
9- State what is lost through these Water vapour is lost when the stomata are open. At
‘holes’
night, when there is no light for photosynthesis,
stomata close to prevent water loss.
10- (C) Describe the external
features and internal structures of
a leaf in relation to its function in
gas exchange.
11- State where plants get their
food from and how they store it.
12- State what energy change
takes place during photosynthesis
13- State which (green) chemical
substance is needed for
photosynthesis.
14- Describe the process of
photosynthesis in terms of raw
materials and products.
15- (C) Describe the fate of
carbohydrates made during
photosynthesis.
16- (C) Explain what is meant by a
limiting factor and describe the
main limiting factors in the process
of photosynthesis.
1- Waxy cuticle: prevents water loss
2- Upper epidermis: protection
3- Palisade mesophyll: where most photosynthesis
takes place.
4- Spongy mesophyll: where some photosynthesis
takes place. Cells are not compactly packed and have
a large surface area exposed to air. This allows the
diffusion of carbon dioxide into cells.
5- Air spaces: allow free movement of gases inside
the leaf.
6- Lower epidermis: protection
7- Guard cells: specialist cells which open or close the
stoma
8- Stoma: allows gas exchange with the atmosphere
(carbon dioxide goes in; oxygen and water vapour go
out)
9- Phloem
10- Xylem
11- Veins: carries water and minerals to
photosynthesising cells, takes away sugar from
photosynthesising cells to other parts of the plants.
Plants make their own food from CO2 + H20 using
light energy. They store it as starch.
Light energy is converted into chemical energy.
Chlorophyll in chloroplasts.
Raw materials: carbon dioxide and water
Products: oxygen and sugar (glucose)
- used directly for energy (i.e. during respiration)
- stored as starch= storage carbohydrate (i.e. food
reserve)
- made in cellulose= structural carbohydrate to build
new cell wall.
An environmental factor, that, when in short supply,
prevents photosynthesis happening at its optimum
rate.
Main limiting factors are: carbon dioxide,
temperature and light intensity.