Transcript with food / energy. Plants are able to make their own food by

9D Plants for food
© Tony P. Thould
September 2000
PLANTS FOR FOOD - AN OVERVIEW
•Every animal, including Man, needs plants to
survive.
•Plants supply animals directly ( Herbivores ) or
indirectly ( Carnivores ) with food / energy.
•Plants are able to make their own food by
Photosynthesis from Carbon Dioxide and Water
using sunlight energy absorbed by Chlorophyll.
•The leaves are the main food producing organs of
a plant.
•Man must know how to take care of plants so that
their food supply is maintained.
One of the eight characteristics of living things
is that every living thing needs to feed.
From the food they get the fuel to change into
the sort of energy they need.
The energy can be then used by the plant or
animal for movement, growth etc.
WHERE DOES THE ENERGY COME FROM?
PHOTOSYNTHESIS
This is the way by which green plants
make their own food.
They use Carbon Dioxide and Water as these
two raw materials contain the elements
Carbon, Hydrogen and Oxygen which are all
needed to make Glucose sugar - their food.
Energy from the sun is absorbed by Chlorophyll
and used to make the Glucose. This stores the
sun’s energy as chemical energy
PHOTOSYNTHESIS
This is how green plants make food:-
Sun’s
Energy
Carbon
Dioxide
Water
Chlorophyll absorbs the
light energy from the sun
and uses it to make
Glucose sugar from
carbon dioxide and water
The Glucose make by Photosynthesis can be
added to in order to form other essential
substances for the plant to grow well.
For example by taking in Nitrogen, the plant
has the right materials ( along with the
Carbon, Hydrogen and Oxygen in Glucose ),
to form proteins. Proteins are essential to
grow new cells and repair damaged ones.
A SPECIALISED PLANT CELL
A Palisade Leaf Cell specialised to be the main food
making centre in a plant. Each cell has a great many
Chloroplasts containing Chlorophyll. This absorbs the
sun’s energy, essential for Photosynthesis.
NUCLEUS
CELLULOSE
CELL WALL
VACUOLE
CYTOPLASM
CELL
MEMBRANE
CHLOROPLASTS
PHOTOSYNTHESIS
Using Sunlight
Energy
Carbon
Dioxide
+
Water
Glucose
+
Oxygen
Absorbed by
Chlorophyll
!!!YOU MUST LEARN THIS EQUATION!!!!
Energy from the sun
reaches the plant in the
form of light and heat.
PRODUCER
The plant uses
the suns’ energy
to make food by
Photosynthesis
The Palisade cells in the leaves make
the food by Photosynthesis
FOOD CHAINS AND FOOD WEBS
At the start of every food chain is a green plant. This is
because plants produce their own food and in turn
become food for animals.
The animals that eat the plants are called Primary
Consumers. They are Herbivores - plant eaters.
Secondary Consumers are Carnivores as they eat the
Primary Consumers.
This is the basis of of Food Chain I.e.
PRODUCER
PRIMARY
CONSUMER
SECONDARY
CONSUMER
The arrows shows the energy passing from one link to the next.
How may
Food Chains
make up this
Food Web?
Why is it
important for
Man to look
after his crops
and wild plants?
From the AIR
SUN’S
ENERGY
Carbon
Dioxide
WATER
(
Hydrogen and
Oxygen )
6CO2 + 6H2O
CHLOROPHYLL
in the Leaves
C6H12O6
+
6O2
Plants make their own food - Glucose - which is a
Carbohydrate ( made up from Carbon, hydrogen and
Oxygen ) and stores it as Starch.
From the AIR
___________
SUN’S
________
___________
WATER
(
____________ and
__________ )
6CO2 + 6H2O
_______________
in the Leaves
C6H12O6
+
6O2
Plants make their own food - ___________- which is a
Carbohydrate ( made up from ________, __________
and ___________) and stores it as Starch.
Plants need a Balanced Diet too!
We must eat a good variety of foods
to keep us healthy - all the right
nutrients - we cannot just eat chips.
Plants cannot just live on the Glucose
made by Photosynthesis but need a
variety of nutrients to keep them
healthy.
FERTILIZERS
The soil has many more nutrients which the
plant needs to grow healthily. These include
Nitrogen ( N ), Phosphorus ( P ) ,
Potassium ( K ) and Magnesium (Mg ).
N, P, K and Mg may be added to the soil by
using Fertilizers in the form of granules,
manure or compost.
FERTILIZERS
Bags of fertilizers have labels on them to show what
the fertilizer contains. This is usually in the form of
numbers e. g. 20 :10 :10, 5 : 15 : 25
These numbers stand for the amounts of N, P and K
contained in the bag of fertilizer.
Nitrogen gives the plant good leaves and stems
Phosphorus makes good roots
Potassium makes good flowers, seeds and fruits
FERTILIZERS
Bags of fertilizers have labels on them to show what
the fertilizer contains. This is usually in the form of
numbers e. g. 20 :10 :10, 5 : 15 : 25
These numbers stand for the amounts of __ __ _____
___ contained in the bag of fertilizer.
Nitrogen gives the plant good ___________________
Phosphorus makes good _________
Potassium makes good _________________________
P
K
N
20 : 5 : 15
SUPER
GROW
FEEDING THE PARTS OF THE PLANT
K
N
Nitrogen for
good stem
and leaves
Potassium for
good flowers,
fruits and seeds
Phosphorus
for good roots
P
The parts get
bigger and better
20 : 15 : 15
SUPER
GROW
K
N
P
MAGNESIUM ( Mg )
Plants need this to make Chlorophyll
No Chlorophyll
No Mg
Has Mg
Plenty of Chlorophyll
Which leaf would not make food by Photosynthesis - why?
Pesticides Pests and diseases
Commercial crop growing
Need to feed population
Weeds
Plants in our diet directly and
indirectly.
Plants in our diet directly and indirectly.
A pupil once said that he did not care
about plants as all he ever ate for any meal
was meat and all he ever drank was milk.
What would you say to him about the
importance of plants in his diet?
PLANTS IN OUR DIET
Which of the following foods came from
plants either directly or indirectly?
Chips
Bacon
Cake
Toast
Cheese
Butter
Cornflakes
Spaghetti
Yoghurt
Chocolate
Eggs
Lamb
Baked Beans
Beefburgers
Biscuits
Rice
Pests, Diseases and Weeds
•Name some pests, diseases and weeds found
in crops grown in this country.
•How do the above have an affect upon the
food supply of our country?
•What can Man do to try and stop these three
from affecting our crops?
•Are there any side effects upon the
environment e.g. on food chains, in using
these methods?
Pests, Diseases and Weeds
•Pests such as greenflly feed on the sap in the
plants and drain them of vital nutrients. The
plants become weak and produce fewer fruits.
•Diseases such as mildew makes the plant leaves
and fruit bad so that the crop is unfit to pick and
eat.
•Weed compete with the crop for food, light, water
and space. Weeds are often hardier and more
successful at surviving than the crop and therefore
the crop becomes weak and less productive.
Pesticides and Herbicides - the
knock on effect.
By spraying crops with chemical pesticides and
herbicides, a grower may kill not only the pests
but also other beneficial creatures.
By killing various animal and plant pests, the
grower is saving the crop but affecting the food
supply of a number of links in the food chain and
food web.
Some of the chemicals sprayed onto crops stay in
the soil for years and so affect the environment
for a long time.
Need to feed population and
Commercial crop growing
Growers have developed several methods of
growing crops in conditions that will produce
larger, better quality and a higher yield than
would normally be found.
What are some of these Methods?
Need to feed population and
Commercial crop growing
Many growers grow their plants in green
houses.
Growers can and fertilisers to the crops.
New breeds of plants can improve the yields
of the crops and also help them to tolerate
extreme weather conditions.