Transcript World of plants - World of Teaching

Standard Grade
Biology
Topic 2
The World of Plants
World of Plants is divided into:
A- Introducing plants
B- Growing plants
(Pollination, Fertilisation,
Asexual reproduction)
C- Making food
The life cycle of a plant
• There are 7 stages in the life cycle of a
plant.
seed / fruit
Formation
fertilisation
seed
dispersal
pollination
germination
flower
formation
development
Seed Structure
• Parts are:
Seed coat
Forms a tough
protective
layer
Food store
Provides the
embryo plant
with food.
Embryo
shoot
Embryo
root
Embryo
– grows
into
plant
Seed Dissection
• Using a scalpel, carefully dissect your
seed in half lengthways.
• Draw a diagram of what you can see.
• Identify the parts,
and label your drawing
(workbook p13).
Seeds
Investigation: Germination
• This is an Exam Board Investigation that
makes up part of your Practical
Abilities grade (20% of finals)
• Planning may be done in small groups
but after this you must work on your
own
• Write in your Investigation booklet.
What affects germination?
3Bio2 Brainstorm 16/03/07
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Spacing / number of seeds
Humidity / water volume
Type of seeds
Size of seeds
Type of soil / mass
Temperature
Depth of planting
Gases / oxygen levels
Measure by % germination after set time
Germination and Temperature
• Example of results table. Also draw a graph.
Temperature
oC
4
20
50
No. of
seeds
No. of
Percentage
seeds
germination
germinated
25
25
25
• What conclusions can you draw from your
experiment?
• How could you have improved it?
Germination conditions
• Germination is the development of a new
plant from the embryo in a seed.
• Seeds need certain conditions to
germinate:
– Water
• to activate enzymes which digest stored food
– Oxygen
• Needed for the production of energy for
germination
– Warmth
• Needed for the enzymes to work effectively.
Germination and Temperature
• The best temperature for germination
of a species of plant is known as the
optimum temperature.
• The optimum temperature is normally
between 15oC and 30oC.
Structure of a Flower
Petal
Stigma
Anther
Carpel
female
parts
Stigma
Petals
Stamen
male
parts
Style
Ovary
Ovules
Sepals
Anther
Filament
Nectaries
Collect a cut-out flower, colour it in and put it together.
What do the parts do?
Sepalsprotect the
flower when
it is a bud
Petalscolourful to
attract the
insects
Nectariesgive out
sugary liquid
to attract
insects
Stamen- anther
produces male sex
cells (pollen)
Carpel- stigma
traps pollen
Style is where
pollen tube grows
down to female sex
cells.
Carpel- ovary
produces female
sex cells (ovules)
Quick Test
1.
2.
3.
4.
Why is the seed coat important?
Name the parts of the embryo plant.
Why is the food store in a seed important?
Name the three factors required for
germination.
5. Where are a plant’s sex organs found?
6. Name two parts of a flower that attract insects.
7. Name the male part of a flower.
8. Which part of the flower contains ovules?
9. Which part of the flower produces pollen?
10. Which part of a flower catches pollen grains?
Pollination
• Pollination involves the transfer of pollen
(male gamete) from the anther to the stigma
(outermost female part)
• If it is in the same flower it is called
self-pollination.
• If between different flowers it is called
cross-pollination
• Plants are pollinated by insects or the wind.
Insect Pollinated Plants
Wind Pollinated Plants
Pollination Activity
• Look at the Botanics Posters
• Which features are from wind
pollinated or insect pollinated plants?
• Workbook p28
– Construct a table to show
the differences between
insect and wind pollinated
plants.
Pollination Summary
Structure
Petals
Pollen
Stamen
Stigma
nectar
Wind
Pollinated
Insect
Pollinated
dull
bright colour
light
sticky
dangling
inside flower
feathery
sticky
none
makes sugar
Hayfever
World of plants workbook
G – pages 34 &35
C- pages 36 & 37
• Answer Q 1 – 5 on hayfever
and
• Answer Q 1 – 5 on pollen
in the air from Feb - Sept
Fertilisation
• Fertilisation involves the fusion of the
nucleus of the male gamete (in the
pollen) with the nucleus of the female
gamete (in the ovules).
Fertilisation
Pollen tubes
• The pollen grain grows a tube.
• The tube reaches an ovule.
• The gamete nuclei fuse (fertilisation) and a
zygote (seed) forms.
Pollen tube growth
Fertilisation
Once fertilisation has taken place the
zygote (fertilised ovule)becomes a seed,
and the ovary becomes a fruit.
The petals die and fall off.
The plant seeds are in the fruit.
What are fruits like?
The fruits can be:
- soft & fleshy
- hard & dry
• What fruits can you think of?
• What are their seeds like?
• Draw a table with headings for each
type and write some examples for them.
Types of Fruits
Soft & fleshy
Apple
Tomato
Hard & dry
Hazelnut
Seed Dispersal- why?
Seeds must be carried away (dispersed /
scattered) from the parent plant to:
• Reduce overcrowding
• Reduce competition for:
- Water
- Light
- Nutrients
Seed Dispersal
Dispersal
method
Description
Wind
Seeds are designed to
travel as far as
possible.
May have extensions
which act as
parachutes or wings.
Fruits may be shaken
like a pepper pot.
Seeds/
Fruits
Seed Dispersal
Dispersal
method
Description
Animal
(internal)
Fruit is brightly
coloured to attract
animals.
When eaten the seed
travels with the
animal, survives acidic
digestive juices and is
passed out in the
faeces.
Seeds/
Fruits
Seed Dispersal
Dispersal
method
Description
Animal
Some have little hooks
(external) or sticky substances so
they stick onto the
animal’s fur, are
carried away and
rubbed off later.
Some carried away by
animals and dropped.
Seeds/
Fruits
Activity
• Cut out the seeds, match and stick them
into appropriate columns in a table, for:
Wind
Animal (external)
Animal (internal)
[There is also mechanical (eg broom, sea
cucumber) and water (eg coconut) but you don’t
need to know them for Standard grade]
Activity
• Listening exercise on seed dispersal
– Listen to the tape,
– Use the commentary to help you answer
questions on your handout.
World of Plants Workbook p41
Comparing Lime and Sycamore seeds.
Go through the problem solving activity
Quick Test-A
1. What term is used to describe male and
female gametes?
2. What is pollination?
3. Name the two types of pollination.
4. Describe the differences in the pollen
between insect and wind pollinated plants.
5. Explain why the stigmas of wind pollinated
flowers hang outside the flowers.
Quick test-B
1. Why do wind pollinated flowers not
produce nectar?
2. How does the male gamete reach the
female gamete?
3. What is a fruit?
4. Name three ways in which fruits and seeds
are dispersed.
5. Why is it important that fruits and seeds are
carried away from the parent plant?
Types of reproduction
Sexual reproduction
Involves 2 parents and sex cells ie. pollen and
ovule join to make a new individual.
Asexual reproduction
Involves 1 parent and no sex cells.
Ways they naturally reproduce include:
- Tubers
- ( Bulbs )
- Runners
Tubers
Tubers are underground
food stores which stores
food over the winter and
provides a new plant with
food until it can make its
own.
Examples: potato,
artichoke, yam, cassava,
water chestnut, arrowroot
TaroJapanese
potato
Food made by the new plant
is sent to make new tubers.
Thereby reproducing itself.
Arrowroot
arrowroot = arrow root =
Chinese potato (this name
also is used for jicama) = goo
= seegoo = arrowhead =
Chinese arrowhead = tse goo
= ci gu = tsu goo
Notes: The name arrowroot is more commonly associated
with a thickener that's made from the plant.
A fresh arrowroot tuber looks like a small onion, only without
the layers.
It should be peeled, and then it can be boiled or stir-fried.
Look for it in Chinese markets during the winter.
Cassava
cassava = casava = manioc =
mandioca = tapioca root =
yucca = yucca root = yuca
root = Brazilian
arrowroot Pronunciation:
kuh-SAH-vuh
Notes: People in Hispanic countries use cassavas much like
Americans use potatoes. There's both a sweet and a bitter variety
of cassava. The sweet one can be eaten raw, but the bitter one
requires cooking to destroy the harmful prussic acid it contains.
Topinambour
Topinambour
Water chestnut
Chinese water
chestnut
Notes: Water chestnuts are delightfully sweet and crisp- if you
buy them fresh. You need to peel off their brown jackets and
simmer them for five minutes before stir-frying.
Tinned Water chestnuts are easily available but not nearly as
good. If you use them, blanch them first in boiling water for
thirty seconds.
Bulbs
Bulbs are also underground food stores which work in
the same way as tubers.
The difference is that bulbs have thick fleshy
‘leaves’.
Keukenhof
gardens
near
Amsterdam
Holland.
Stargazer lily
Examples: snowdrop,
crocus, daffodil, iris, lily,
hyacinths, amaryllis, onion,
garlic.
1. Sept.- Oct. Planting Time
The tulip bulbs are going to be planted
twice as deep as the bulb is high. They
have no roots at this stage.
2. November Making Roots
The roots start growing out of the base,
establish themselves taking nutrients from
the soil. Mother bulbs get ready for
winter.
4. Feb. – March Growing Period
The bulbs begin to change as the starch,
or carbohydrates in them turns to sugar.
As this occurs, the leaves and flower
gradually push up-wards out of the bulb.
5. April – May Blooming Time
The tulips are in bloom-they receive their
nourishment from the roots-only the
brown skin of the bulb remains as all of
the energy has gone to the bloom.
6. May – June Regeneration
After flowering the blooms are cut and
the leaves are left on the plant. The new
daughter-bulbs use the food in the leaves
to grow.
3. Dec. - Jan.Cooling Period
Rest period. In order for bulbs to bloom in
the spring they need weeks of at least 5oC.
Frost at this time doesn’t harm them.
7. July - Sept. Multiplying
Up to five small bulbs can be expected to
grow out of the mother bulb. They form
their roots slowly, and develop their
blooms and leaves within the bulb, for next
year's plant.
Runners
Runners are side shoots
which grow out from the
parent plant.
Buds form at points along
the runner and eventually
these buds form roots and
grow into new plants.
Examples: spider plant
(Anthericum), strawberry
(Fragaria x ananassa)
Flame violet
(Episcia reptans)
Collect Information Card
“Asexual Reproduction”
Take short notes from it.
Activity
World of plants workbook
Read p20
“Advantages of asexual reproduction”
Read p32 & 33.
– Copy and complete the table.
Summarising advantages & disadvantages
of sexual versus asexual reproduction
Reproduction- advantages
Asexual
Sexual
Genetically identical
offspring (clones) which
have parent’s strong
characteristics (but weak
ones also passed on) and
are suited to their
environment.
Genetically different
offspring- variation.
More chance of survival if
conditions change.
Wide distribution
Reduces competition for
water/light/nutrients as no
dense growth around the
parent.
Using seeds allows the
offspring to travel to new
areas.
Narrow distribution
spreading over the area
quickly as no vulnerable
stages involved.
Clones
A clone is the name given to the
genetically identical plants produced
from a single parent plant.
They are formed during asexual
reproduction only.
Artificial Propagation
People can make use of plants’ ability to
reproduce asexually (instead of using
seeds) by using methods of artificial
propagation such as:
- Cuttings
- Graftings
Again this produces genetically identical
offspring (clones).
Cuttings
Cuttings are small pieces of stem with some
leaves attached, the new plant grows from this.
They can be placed in moist
soil or water (and sometimes
dipped in rooting
powder).
Grafting
A cut stem of one plant (with good flower or
fruit growth) (the graft) is taken and firmly
attached to the rootstock of another plant
(which has a strong, established root system)
(the stock).
Examples- roses, fruit trees
Grafting- advantages
Allows you to clone the commercial qualities
of a particular fruit variety on another tree.
Seed trees have highly variable fruit quality.
They come into production much earlier (2-3
years) than trees grown from seed (5-10
years).
Activity
World of Plants Workbook p42
The effect of rooting powder on cuttings
Collect some graph paper and work
through the problem solving activity
Activity
World of plants workbook p33
“Artificial propagation- commercial
advantages”
Read page. Collect Information sheet
Write short notes on it.
Commercial aspects
Artificial propagation has allowed us to
adapt and improve plants for our own
use.
Some of the benefits include:
•Quick production of large numbers of
genetically identical plants.
•Specific varieties, desired features or
consistent quality can be produced
especially in fruit, flowers.
Quick Test-C
1. How many parents are involved in asexual
reproduction? One
2. Name 3 ways in which plants reproduce
asexually.
Runners, tubers, bulbs
3. Give 2 examples of plants that reproduce
asexually by producing runners.
Spider plant, strawberry
4. What term is used to describe a population of
genetically identical plants? Clones
5. Name 2 common methods of artificial
propagation.
Cuttings, grafting
6. Give the commercial advantages of artificial
propagation. Quick method, producing large numbers of
plants, of known quality and specific variety
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