Photosynthesis is the process by which plants, algae, and some bacteria use sunlight, water and carbon dioxide to produce oxygen and energy in the form of glucose. It takes place in chloroplasts, which contain the green pigment chlorophyll. There are two phases - the light reaction phase which uses energy from sunlight to split water and produce ATP and NADPH, and the Calvin cycle which uses this energy to fix carbon from carbon dioxide into organic molecules like glucose. The rate of photosynthesis is affected by factors like light intensity, temperature, and carbon dioxide levels. Lihops, a type of South African living stone, has adaptations like translucent leaf pockets and non-photochemical quenching to boost photosynthesis in

1. Photosynthesis
BY BN NTHITE
218023104

2. Learning outcomes
 What is photosynthesis?
 Overview of photosynthesis?
 Chloroplasts
 Why are plants green?
 South African Lihops?
 Factors affecting the rate of photosynthesis
 Photosynthetic processes : Light reaction phase
Calvin Cycle

3. What is Photosynthesis
• Plants are called autotrophs because they can use the suns energy to make their own
food
• This is a process by which green plants use energy from the sun to synthesize
nutrients from Carbon Dioxide and water
• It is performed by all plants,algae and even some micro-organisms
• For this process to take place use sunlight,water and gases in the air
• They make organic molecules (glucose)out of inorganic materials
(Co2 and H2O)
• It begins all food chains /webs making all life supported by this process
• Sometimes called Carbon assimilation

4. Photosynthesis in Overview
• In this process plants and other autotrophs store the energy of
sunlight into sugars.
• Requires sunlight, water, and carbon dioxide.
• Overall equation:6CO2 + 6H2O-----------C6H1206+6O2
• By taking in water through the roots ,carbon dioxide from the air and
light and energy from the sun , plants can photosynthesize
• to make glucose and sugar
• After the sugar is made by mitochondria into energy that can be used
for growth and repair
• Just as animals plants too respire. Animals,howver take in the gas
Oxygen through respiration .

5. Chloroplasts
•Photosynthesis occurs in chloroplasts, organelles in certain plants
All green plant parts have chloroplasts and carry out photosynthesis
•The leaves have the most chloroplasts
•Chloroplasts contain the pigment chlorophyll ,which reflects green light by absorbing
Red and blue light .Chloroplasts are surrounded by a double membrane and contain stacks of
Thylakoids
Chlorophyll is located within the thylakoid membrane and the space between the two is called the
stroma
•A chloroplast contains:
ostroma, a fluid
oGrana, stacks of thylakoids

6. Chloroplasts continued..
http://www.skinnerscience.com/Biology/gcse%20unit2%20revision%20notes.ht m

7. But why are plants green?
• Light which can be seen by the human eye-visible light spectrum,appears in several
colours from blue to red.We perceive the colour when the object reflects light back into
our eyes.
• Other colours are absorbed and we only see the reflected wavelengths
• Chlorophyll absorbs blue and red light and reflects green light ,that is why they appear
green in colour
Gamma
rays X-rays UV Infrared Micro-
waves
Radio
waves
Visible light
Wavelength (nm)
Why are plants
green? Transmitted
light

9. Lihops –a type of South African living
stone
 This unique plant that lives underground uses multiple mechanisms to boost
photosynthesis and has shown new ways in how to adapt to extreme conditions
 The underground life makes it difficult to gain light for photosynthesis and still
conserve water . Lihops have adaptations to do this
 They have a top surface of translucent pockets which allows light to penetrate
deep within the leaf .But too much light can be dangerous ,the plant has organ
called non-photochemical quenching (NPQ) that block out harmful uv rays of the
sun

10. South African living stone plant adapts to extreme conditions in new ways

11. Factors affecting the rate of
Photosynthesis
LIGHT INTENSITY TEMPRETURE CO2

12. Photosynthetic Reactions
 There are two phases in photosynthesis ;There are light dependant and light
independent reactions.
 Light dependant reactions use light and light independent reactions do not ,we say
they are independent of light or dark
 Remember not refer to light independent factors as dark reactions (darkness is
not required)

13. Light process
. Light Reaction (Electron Flow )
• Occurs in the Thylakoid membranes
• During the light reaction, there are two possible routes for
electron flow.
Here the energy of the sunlight is used to split h2o into hydrogen
ions and hydroxyl ions .Oxygen is then formed from reactions
,involving hydroxyl ions ,as a by product –and can be used in cellular
respiration

14. Processes
Calvin cycle
• In plants,CO2 enters the interior of a leave through the stomata
and diffuses into the stroma of the chloroplast ,The site of the
Calvin Cycle
• During this step also known as carbon fixation ,energy from
ATP AND NADPH generated from the light reaction drives
chemical pathways that uses the carbon in the carbon dioxide to
build free sugar called glyceraldehyde-3-phosphate
• Cells then use that sugar to build a wide variety of other sugars
• Much of this occurs outside the chloroplast
• The products of this are then transported to other parts of the
cells
• In plants some sugars are stored as Starch
Ligh
t
reaction
s
Calvi
n
cycl
e

15. References
 https://www.slideshare.net/eLearningJa/int-sc-m1u2l4-photosynthesisprocess-
final/15
 https://www.slideshare.net/earshadshinichi/photosynthesis-a-detailed-lesson
 https://www.slideshare.net/diverzippy/bioknowledgy-29-photosynthesis/3
 https://www.slideshare.net/BiologyIB/photosynthesis-powerpoint-3983595/2
 Vidallo , E.(2015).Photosynthesis : light and dark phase . Available at:
https://www.slideshare.net/conan_emanz/photosynthesis-51038295/15

16. Thank you!!!