Photosynthesis:
2.
What is the chemical
process of photosynthesis? What does in need? What does it make?
Doc Brown's Biology exam study revision notes
There are various sections to work through,
after 1 they can be read and studied in any order.
INDEX
of PHOTOSYNTHESIS notes
(2) What is the
chemical process of photosynthesis?
You need four 'basic' things for photosynthesis:
(i) water - absorbed through the roots,
(ii) carbon dioxide - absorbed from air by
diffusion,
(iii) chlorophyll - green pigment in palisade
cells of stems and leaves,
(iv) visible sunlight energy - converted to chemical
potential energy in glucose molecules.
Obviously other nutrients are needed as
well, including the magnesium ion, Mg2+, which is
an essential part of the chlorophyll molecule.
A simplified version of the
biochemistry of photosynthesis
-
Plants absorb water through their
roots and carbon dioxide through their leaves and covert these into
carbohydrate molecules, initially in the form of glucose, the waste
product is oxygen! handy for us!
-
The carbon dioxide in air diffuses into
leaves through the stomata, water comes up from the roots via the xylem tubes, oxygen diffuses
out and sugars are transported around the plant by the phloem tubes.
-
Carbon dioxide into leaves and oxygen
out of the leaves is an example of gas exchange system on the
surface pores (stomata) of the leaves.
-
The biochemical process of photosynthesis
takes place in the chloroplasts of plant cells in the green leaves
and stems with the help of green
molecules called chlorophyll.
-
The chemistry of
photosynthesis
-
Photosynthesis is summarised
by the equation:
-
carbon dioxide + water == light +
chlorophyll ==> glucose + oxygen
-
6H2O(l)
+ 6CO2(g) == sunlight ==> C6H12O6(aq)
+ 6O2(g)
-
This
is overall an endothermic chemical reaction, energy is taken in,
i.e. sunlight energy
is absorbed in the process of photosynthesis.
-
Photosynthesis
is the process by which plants make food, initially in the form of
glucose, for themselves, and for most
animal life, including us too via food chains!
-
The plant will use some of the glucose
immediately to fuel all the necessary life maintaining processes.
-
The plant converts some of the glucose
to starch - a chemical potential energy food store for the plant and
animals like us too!
-
Photosynthesis utilises sunlight
energy to convert carbon dioxide and water into glucose (basis of food)
and oxygen.
-
The green pigment chlorophyll is in
the subcellular structures
called chloroplasts, where photosynthesis takes place in green
plant cells.
-
All of the
photosynthetic chemistry facilitated by enzymes (biological catalysts).
-
The chemistry of photosynthesis is very
complicated but it takes place in two main stages.
-
1. Chlorophyll absorbs a photon of
light energy. This sunlight energy (visible light
photons) splits water (H2O) into hydrogen ions (H+)
and oxygen (O2).
-
2. The hydrogen ions combine with carbon
dioxide (CO2) to form glucose molecules (C6H12O6).
-
The carbon dioxide diffuses in
through the stomata of the guard cells - effectively pores that can open and
close ie CO2 in, and oxygen O2 out in the day and O2
in at night.
-
In daylight the rate of photosynthesis
will exceed the rate of respiration.
-
At night the rate of respiration will
exceed that of photosynthesis.
-
Both processes are need to keep the plant
alive.
-
During photosynthesis light energy is absorbed by
the green chlorophyll, which is
found in chloroplasts in some plant cells and algae.
Keywords, phrases and learning objectives for this part on
photosynthesis
Be able to describe in words and equations the
chemical process of photosynthesis?
Know hat is needed for photosynthesis i.e. water
carbon dioxide sunlight chlorophyll and what is produced i.e.
glucose and the 'waste' product oxygen gas.
WHAT NEXT?
TOP OF PAGE
INDEX
of biology notes on PHOTOSYNTHESIS
INDEX of all my BIOLOGY NOTES
This is a BIG website, so try using the [SEARCH
BOX], it maybe quicker than the many indexes!
email doc
brown - comments - query?
Basic Science Quizzes for
UK KS3 science students aged ~12-14, ~US grades 6-8
Biology * Chemistry
* Physics for UK
GCSE level students aged ~14-16, ~US grades 9-10
Advanced Level Chemistry
for pre-university age ~16-18 ~US grades 11-12, K12 Honors
Find your GCSE/IGCSE
science course for more help links to all science revision notes
Use your
mobile phone or ipad etc. in 'landscape' mode?
SITEMAP Website content © Dr
Phil Brown 2000+. All copyrights reserved on Doc Brown's biology revision notes, images,
quizzes, worksheets etc. Copying of website material is NOT
permitted. Exam revision summaries and references to science course specifications
are unofficial.
Using SEARCH some initial results may be ad links you
can ignore - look for docbrown
|