Plants
nutrition
Chapter 6
6.1 Making carbohydrates
using light energy
Objectives:
By the end of this lesson we will be able to:
State the word equation for photosynthesis.
Write the balanced equation for photosynthesis.
Describe the role of chlorophyll in transferring energy
from light to carbohydrates, in photosynthesis.
Outline the uses of starch, cellulose, sucrose and
nectar, made from the carbohydrates made in
photosynthesis.
State the function of nitrate ions and magnesium ions
in a plant.
Plant nutrition:
Plantscan make the organic nutrients
(carbohydrate, proteins and fats) from inorganic
substances. They use carbon dioxide, water and
mineral ions, which they take from the air and soil.
Photosynthesis:
The process by which plants synthesise
carbohydrates from raw materials using energy
from light.
Inthe chloroplasts of a plant's leaves, water and
carbon dioxide react together to make
carbohydrates and oxygen.
Chloroplasts also contain a green pigment called
chlorophyll, which able to capture energy from
sunlight and transfers it to water molecules and
carbon dioxide molecules.
Thisenergy makes these substances react,
producing a kind of carbohydrate called:
glucose which contain energy.
Chlorophyll has transferred some of the energy in
the sunlight into chemical energy in
carbohydrates.
The photosynthesis equation:
Inphotosynthesis, water react with carbon
dioxide to produce glucose and oxygen in the
presence of sunlight and chlorophyll. Like all
reactions in organisms, photosynthesis depends
on enzymes to help it take places.
We can write this equation as words:
b
We can also write a balanced chemical b
equation, which include the chemical formula
for each of the reactants and products. Also it
provides in formation about how many
molecules of each are involved in the reaction.
How a plant uses carbohydrates:
There are two products of photosynthesis,
glucose and oxygen. The oxygen is released
into the atmosphere or in water if the plant is
aquatic. The glucose is used for many different
purposes:
1. releasing useful energy:
Some of glucose is used by plant to provide
energy foe various activities that cell need to do
like the movement of mineral ions into root hairs
by active transport, growth, build proteins.
The energy released from glucose by respiration.
2. Storing to use later:
Plant usually make much glucose than they need
to use for energy immediately, they store it by
turning it into starch.
3. Making cellulose, to built cell wall:
As plants grow, they make new cells. Every cell
needs a cell wall, so a growing plant must make
cellulose molecules to form these walls.
4. Making sucrose, for transport:
Plants can only make glucose in leaves which
contain chlorophyll, all other parts of the plants
have glucose delivered to them.
Plantsdon’t transport glucose, they first change it
into a sugar with large molecules called: sucrose
it makes of glucose and fructose.
The
sucrose is carried from one part of plant to
another inside tubes called: phloem.
When sucrose reaches it destination, it can be
changed back to glucose again and used in
respiration to release energy.
5. Making nectar to attract pollinators:
Many plants reproduce sexually, producing male
and female gametes in flowers. But they cannot
move themselves.
Flowers produce nectar that animal and insects
can feed on so they carry pollen from place to
place.
Nectar contains different kinds of sugar, all made
from glucose.
6. making amino acids, to make proteins:
Plants use some glucose made in photosynthesis
to make amino acids which can be used to make
proteins for growth.
In order to make proteins from glucose, plants
need a sources of nitrogen, they get it from the soil
in form of nitrate ions.
Nitrate ions are taken by active transport through
the root hair cells and then transported to all parts
of the plant, where they can be combine with
glucose to make amino acid.
7. making other substances e.g: chlorophyll
Glucose can also be used to make chlorophyll.
Chlorophyll not a protein, but it contains nitrogen,
and magnesium ions.
Without these ions, the plant's leaves will look yellow.
Questions
Thank you my lovely student
