The World Of Plants Std Grade

INTRODUCING PLANTS

PLANTS - THE BASICS A huge variety of plants in the

world Live in almost every habitat Can survive the harshest

environments The link between the sun and all

other living things Maintain the balance of

atmospheric gases

MORE PLANT BASICS They regulate the water content

of the soil

They provide habitats for other organisms

And ……….

…. they give us some beautiful artistic moments!

VARIETY

MORE VARIETY

HABITATS

MORE HABITATS

PLANTS AND THE SUNPlants turn the sun’s energy ………

into food

This is called………. Photosynthesis

PLANTS ARE ALSO HABITATS

WHAT DO WE NEED PLANTS FOR ?

For food

For raw materials

For medicines

PLANTS AS FOODS Cereals such as rice,maize,and

wheat form the staple foods of most countries

Vegetables and fruits add variety to our diets

Herbs,spices,sugar,tea,coffee and nuts are all plantsand…… we get chocolate from plants !!!!!

…. IN SCOTLAND

Barley is used to make….

AND……

Plant-based dyes are used for…..

PLANTS AS MEDICINES Known about since 2000BC Used for pain relief, reducing fever,

sedation and upset stomach, and curing infections

Many are used for treating cancer

……And many more medicinal uses

PLANTS TREAT CANCERIt is thought that at least 2000 plants may contain chemicals which can help to treat cancer

This is the purple coneflower

PLANTS CLEAR YOUR HEAD

This is the titfruit. Its extract can clear blocked sinuses

MORE PLANT MEDICINES…Plants can be used for hormone replacement

This is squawberry juice being extracted

Plants can help with urinary infectionsThis is saw palmetto used for cystitis and Prostate problems in men

DO YOU KNOW THIS ONE ?

PLANTS AS MATERIALS Cotton for clothes and linens Jute and hemp for rope Trees for timber Rape seeds for oil Seaweeds for alginates

How many more can you think of ?

PLANTS ARE SO INTERESTING…..

These american native indians even worshiptheir cacti….

SO…… PLANTS ARE ?Much more complex and varied than you knew

“World of plants” will show you how

and why .

Ecological loss Tropical rainforests have the greatest

variety of plants on earth There loss is disastrous For every type of plant that becomes

extinct a wide variety of other dependent organisms are also endangered.

For every species of plant that becomes extinct,four species of animal also die out,upsetting the balance of life on earth

ENDANGERED SPECIES

FOOD PLANTS MOST OF THE WORLDS FOOD

COMES FROM A VERY FEW TYPES OF PLANTS

AS THE POPULATION INCREASES,THEN SOME OTHER TYPES OF PLANT WHICH ARE NOT WELL KNOWN MIGHT PROVIDE FOOD

EVEN FLOWERS !

MEDICINAL PLANTS Many important medicines come

from plants

In the future,possible medicines may never be discovered if the plants are made extinct by destroying the rainforests.

WILD PLANTS…… Wild plants also contain many different

characteristics ….and different genes which could be useful in the future.

….. So its important to protect the wild varieties for possible future use.

THIS IS CALLED A GENETIC STOREHOUSE

GENETIC STOREHOUSE Cultivated plants have been bred to be

very alike They contain almost exactly the same

genes If a new disease infected one,it could

easily damage all of them Wild varieties are often resistant to many

different diseases It is possible to cross-breed them with

cultivated plants to increase the resistance to disease

Seed Germination When spring arrives,the seed

bursts open and a new plant starts to grow

This is called GERMINATION

What’s in a seed ? Seeds usually have a hard coat. This is also called the TESTA It’s a tough,fibrous layer which

protects the internal structures of the seed

Lets have a look at the inside of a seed

Inside the seed This Broad bean

seed has been left to soak in water overnight.

This softens the seed coat and allows us to pull it away from the seed

You can now examine the internal structures of the seed

Structure of the mature seed

In dicot seeds:– Hypocotyl terminates in the

radicle (embryonic root)– Epicotyl terminates in the

plumule (shoot tip) Monocot seeds have a

special cotyledon called a scutellum:– Large surface area - absorbs

nutrients from endosperm during germination

– Embryo enclosed in sheath: Coleoptile protects the shoot Coleorhiza protects the root

Inside the Bean seed The inside of a seed is

called ….. The EMBRYO It’s made up of two

parts… The young shoot(called

the PLUMULE ) And the young root ( called the RADICLE)There is also a pair of seed

leaves (called COTYLEDONS) they act as a food store

The seed germinates First the seed takes up water.This

makes it swell The seed coat splits and the new plant

starts to grow out,root first Next,the shoot starts to grow. The root grows downwards ….. And the shoot grows upwards The shoot is bent back to protect its

delicate tip as it pushes up through the soil

…. The embryo starts to grow

You can see the root starting To grow downwards

Germination continues…. The root tip is protected from damage

as it grows down through the soil by a mass of cells called the Root Cap

The root grows tiny side branches to help anchor the young plant into the ground

These hairs also increase the surface area for absorbtion

…. The root grows hairs

We can see the root hairs starting to grow

Roots – function and structure

Hold plant in positionAbsorb water and minerals

from the soilSpecialised cells to increase

surface area for water intake

Wheat seed

Root hairs

Fragile parts of cells that grow from the main root

They massively increase the surface area for absorption

Root hair cells (x150)

Root ‘B’ has had the hairs damaged -

….and finally The young shoot

breaks through the soil surface

It straightens out The first leaves open

out and turn green Germination is

complete and the new plant is called a seedling

Factors affecting germination

Temperature. Warmth is needed by most seeds.This is why they don’t germinate until the spring

Water is needed for the seed to swell and burst open. It is also necessary for the stored food to be made soluble and moved to the growing embryo

Oxygen is needed for the embryo to respire.It supplies the embryo with the energy to grow and develop

What about light ? Most seeds will germinate in light or dark

conditions However some will only germinate in one

or the other. The amount of light needed may be very

small.One quick flash is enough in some cases

All plants need light once the shoot breaks through the surface of the soil. This is to make the leaves open out and form CHLOROPHYLL FOR PHOTOSYNTHESIS

CRESS SEEDS GERMINATING

REPRODUCTIONIN

FLOWERING PLANTS

Floral diversity

THEY ALL LOOK DIFFERENT…BUT ALL HAVE THESAME PARTS FOR REPRODUCTION…

The Parts of a Flower Most flowers

have four parts: sepals, petals, stamens, carpels.

The parts of a flower Sepals protect the

bud until it opens. Petals attract

insects. Stamens make

pollen. Carpels grow into

fruits which contain the seeds.

Stamen (male) Anther: pollen

grains grow in the anther.

When the grains are fully grown, the anther splits open.

Carpel(female) Stigma Style ovary Ovules (eggs)

Pollination Flowering plants

use the wind, insects, bats, birds and mammals to transfer pollen from the male (stamen) part of the flower to the female (stigma) part of the flower.

Pollination A flower is

pollinated when a pollen grain lands on its stigma.

Each carpel grows into a fruit which contains the seeds.

Fertilisation Pollen grains

germinate on the stigma, growing down the style to reach an ovule.

Fertilised ovules develop into seeds.

The carpel enlarges to form the flesh of the fruit and to protect the ovary.

The ovary develops into a fruit adapted for seed

dispersal A true fruit is a ripened

ovary Fruits can be classified

by their origin:– Simple fruits:

derived from a single ovary e.g. cherry

– Aggregate fruits: derived from a single flower with several carpels e.g. blackberry

BUT …WHAT ABOUT ‘FALSE FRUITS’ ?

Wind pollination Some flowers, such

as grasses, do not have brightly coloured petals and nectar to attract insects.

They do have stamens and carpels.

These flowers are pollinated by the wind.

Seed dispersalSeeds are dispersed

in many different ways:

Wind Explosion Water Animals Birds Scatter

How birds and animals help seed dispersal

Some seeds are hidden in the ground as a winter store.

Some fruits have hooks on them and cling to fur or clothes.

How birds and animals help seed dispersal

Birds and animals eat the fruits and excrete the seeds away from the parent plant.

ASEXUAL REPRODUCTION Plants can be produced by a single

parent No need for sex cells and fertilisation Because of this, there will be NO

variation and new plants formed will be….

GENETICALLY IDENTICAL to one another AND to their parent

Asexual reproduction in plants is known as VEGETATIVE PROPAGATION.

Methods of Artificial propagation…

Offspring can be formed from a plant’s stem or buds

These are known as RUNNERS

The runner carries food from the parent to the new plant whilst it grows leaves and roots

Strawberry and Spider plants are good examples ofSpecies which use RUNNERS for asexual reproduction

Some plants produce large swollen roots called TUBERS

These are food storage organs full of STARCH

A plant may produce several of these.

Each will produce a new plant which may make many more TUBERS

Examples of plants which use this method ofVEGETATIVE PROPAGATION include ….

Artificial Propagation Some plants lack their own natural methods

of artificial propagation These plants can be reproduced by

artificial processes. This can be done for several reasons… (1) uniformity is guaranteed (2) Sterile varieties can be reproduced in

vast quantities, such as seedless grapes and citrus fruits

(3) Rare species can be conserved to protect against extinction

TWO METHODS ARE COMMONLY USED……CUTTINGS AND GRAFTING.

…CUTTINGS

Stems and leaves are used to grow new plants

Roots form from the cutting when it is placed in good soil

REMEMBER….ALL CUTTINGS GROW INTO PLANTSWITH FEATURES IDENTICAL TO THEIR PARENT

GRAFTING A cutting (SCION)is

grafted onto the STOCK of a hardy variety as shown

The scion may come from a high yield fruiting plant

This method can combine the good qualities of TWO or more plants

The cut surfaces bond together, healing the wound whichIs protected from infection by being sealed with wax. TwineHolds the cut surfaces tightly together to promote healing

Are these plants clones YES…THEY ARE A CLONE is a

group of organisms which have exactly the same genetic info and have been produced from a common ancestor by ASEXUAL REPRODUCTION

So the term CLONE can be used to refer to a group of Plants produced from cuttings or graftings from the SAME PARENT PLANT

There are two film clips coming next They show cutting and grafting

taking place in the south of the USA Please be patient…they take a few

seconds to load You can only see them if you are

watching this presentation on a computer logged on to the internet

pinks_16x9_bb.ram

pecangrafting1.ram

Plant growthPlant growthPlants grow using food they make through

photosynthesis. So what else do they need?

Plants also need three important minerals to keep healthy. They absorb these through their roots.

Root hair cells

Plant roots are made of “root hair cells” which have a large surface area and a thin cell membrane to help absorb the minerals:

Thin cell membrane

Large surface area

Plant A Plant BBoth plants were planted at the same time and left to grow on the same window sill for the same length of time.

Why do you think that plant A is so much bigger than plant B?

How do plants get the minerals they need?

The plant takes in minerals from the soil. It absorbs these minerals through their

roots. Remember a plant does not get food from

the soil it is capable of making its own food

Some plants which grow on poor soil have evolved a clever way to get the nutrients they need.

Where do you think they get them from?

The three main types of nutrient are:The three main types of nutrient are:

1. Nitrates – used to make proteins

2. Phosphates – used to provide phosphorus to help photosynthesis and respiration

3. Potassium – helps the enzymes that are needed for photosynthesis and respiration

Lack of the three minerals would lead to a “Deficiency Symptom”:

Lack of nitrates:Small plant, yellow leaves

Lack of phosphates:Small roots and purple leaves

Lack of potassium:Yellow leaves with dead bits

The Three Main Minerals Needed by Plants.

Mineral Why its needed

Symptom if deficient

Nitrate To make proteins

A small plant with yellow older leaves.

Phosphate Needed for photosynthesis and respiration

Poor root growth and purple younger leaves

Potassium Helps chemicals in the plant work properly.

Yellow leaves with dead bits

Plant Doctor.1. Mr Smith’s plants were small and

had yellow leaves, which mineral were they missing?

2. Mr Lewis’s plants were a normal size but had yellow leaves, which mineral were they missing?

3. Mr Brooke had a plant which had some purple and some yellow leaves, which minerals were they missing?

The Transport System

There are a set of tube-like tissues that go up and down the leaf stem and shoots that transport the other essential ingredients for photosynthesis : water and minerals

There are two tubes called xylem and phloem tissues.

The Transport System

The xylem brings up the water from the roots

The phloem takes away the sugars made by the chloroplasts to places where the energy is needed

The tubes are in the middle of the leaf so that there are near all the cells to bring up water and to take away sugars.

The transport system The transport system is far less

elaborate than in mammals due to:– plants are less active and therefore

‘supplies’ don’t run out so quickly– because of the branching system,

gases for respiration and photosynthesis. Can be obtained from diffusion in the air

– two separate systems; xylem and phloem

Xylem Xylem carries the water and minerals It is made of many hollow dead cells joined

end to end of which the end cell wall has disappeared to form a long tube

Xylem vessels run from root to every leaf Xylem vessels contain no cytoplasm or nuclei Their walls are made of cellulose and lignin Lignin is very strong and so xylem help keep

the plant upright

Close up of Hibiscus rosa xylem

Phloem Transport the ‘food’ They are also made of many cells joined end

to end, however their end wall is not completely broken down; instead they form sieve plates

The cells contain cytoplasm but no nucleus and they do have lignin in their walls

Each sieve cell has a companion cell next to it which does contain a nucleus and many other organelles

Phloem tubes

Vascular bundles Xylem and phloem tubes are normally found

close together, when they are this is called a vascular bundle

In a root vascular tissue is found at the centre

In a shoot they are found near the outside edge to help support the plant

Transverse section of a stem

The transport of water Plants take in water from the soil through the

root hairs and is carried in the xylem throughout the plant

Water gets into root hair by osmosis. The cytoplasm and cell sap inside it are quite

concentrated solutions and the water in soil is normally quite dilute

Water therefore diffuses down its concentration gradient through a partially permeable membrane

A root tip showing root hairs

Transpiration The evaporation of water from the plant Most of which takes place from the leaves

through the stomata Guard cells around the stomata control the

rate of transpiration by opening and closing

Transpiration When water is lost through transpiration

water from the xylem vessel in the leaf will travel to the cells to replace it

Water is constantly being taken from the top of the xylem vessel to supply the cells in the leaves

This reduces the pressure at the top of the xylem so water flows up

This process is known as the transpiration stream

Leaves

THE LEAF! A leaf is an example of a plant

organ It is composed of many tissues

that work together. The tissues are designed to

maximise the levels of photosynthesis.

Function of leaves Trap light energy for photosynthesis

Producing sugar from photosynthesis

Exchange of gases – oxygen and carbon dioxide

Structure

Wide

Helps to catch more light energy

Thin

Help get carbon dioxide from bottom to top of leaf for photosynthesis

Leaf structure

Greener on top

CO2 gets in here

Leaf diagram – palisade layer

CO2

Most chlorophyll

Leaf cell - palisade

Position?Upper surface

of leafFeatures?

Box shapeChloroplasts

Function?Photosynthesis

Plant cells have three “extra” things Plant cells have three “extra” things than animal cells:than animal cells:

Both types of cell have these: Only plant cells have these:

4) Cell wall – provides support

Large Vacuole – contains sap

Chloroplasts – contain chlorophyll

1)

5)

6)

2)

3) Cell Membrane – holds the cell together

Cytoplasm - this is where the reactions happen

Nucleus – The “brain” of the cell

Gas exchange Leaves are designed to allow

carbon dioxide to get to the main chlorophyll layer at the top of the leaf

They have small holes called stomata on the under surface

Each hole is open & closed by 2 guard cells

Leaf diagram – stoma and guard cells

Stoma position

Stoma is a small holeIts size is controlled by 2 guard cells

closed open

Stoma function is for gas exchange in the leaf

Carbon dioxide

oxygenGuard cell

Provided plant is photosynthesising

Stomata open and close at different times of the day

When it is light the plant needs CO2 for photosynthesis so the stoma open

At night (darkness) they close

Gas exchange

PhotosynthesisPhotosynthesisA Photosynthesis is the process a

plant uses to make food and grow. The food produced is

GLUCOSE. This is a carbohydrate.They are made up of…CARBON, HYDROGEN, andOXYGEN.Glucose is SOLUBLE so thePlant has to convert it intoSTARCH which is INSOLUBLEOr CELLULOSE for buildingCell walls.

STARCH is a STORAGE carbohydrateCELLULOSE is a STRUCTURAL carbohydrate

Four things are needed for photosynthesis:

Travels up from the roots

WATER

CARBON DIOXIDE

Enters the leaf through small holes on the underneath

SUNLIGHT

Gives the plant energy CHLOROPHYL

L

The green stuff where the chemical reactions happen

The word and chemical equations for photosynthesis:

Carbon dioxide + water glucose + oxygen

6CO2 + 6H20 C6H12O6 + 6O2

Sunlight

Chlorophyll

Sunlight

Chlorophyll

Four factors affect Four factors affect photosynthesis:photosynthesis:

1. Light – if there is more light photosynthesis happens faster

2. Water – if there is not enough water photosynthesis slows down

3. Temperature – the best temperature is about 300C – anything above 400C will slow photosynthesis right down

4. CO2 – if there is more carbon dioxide photosynthesis will happen quicker

These are known as LIMITING FACTORS becauseLack of any one or more will slow down photosynthesis