This slides explains the life processes, types of nutrition, mechanism of photosynthesis in plants and the structure of leaf. Ignited Minds CBSE tuition classes Tutoring Service in farrukhabad https://www.facebook.com/ignitedmindscbse https://www.youtube.com/channel/UCsGu08EmuAY9H3L16bft1ig +91 81141 14995 ignitedmindscbse@gmail.com

1. Nutrition in Plants
CBSE Class 10 Biology Life Processes Pt. 1
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2. life processes
• The basic functions performed by organisms to maintain their life on
the Earth are called life processes.
Life
Processes
Nutrition Respiration Transportation Excretion

3. Autotrophic Nutrition
• It is the mode of nutrition in which
organisms synthesise their own food
from simple inorganic substances such
as water and carbon dioxide.
• Green plants are autotrophs. They
synthesise food by the process of
photosynthesis.
• Photosynthesis is a physiological
process by which plant cells containing
chlorophyll produce food in the form of
carbohydrates by using carbon dioxide,
water and light energy. Oxygen is
released as a by- product.

4. Chlorophyll – The Vital
Plant Pigment
Chlorophyll is the green
pigment found in green
plants. It is a complex
substance made of carbon,
hydrogen, oxygen, nitrogen
and magnesium.
Although there are nine
types of chlorophyll, two
types—chlorophyll a and
chlorophyll b—are best
known and abundant.

5. Chloroplast
• Chloroplast is a
membrane-bound oval
cell organelle.
• It is enclosed by a
double membrane. Its
interior contains closely
packed flattened sacs
called thylakoids.
Chlorophyll is present in
thylakoids.
• Thylakoids are arranged
in piles called grana
lying in a colourless
ground substance called
stroma.

6. Section of Leaf
• Cells present in the spongy
mesophyll layer and the
palisade layer contain
chloroplasts; therefore,
they are the site of
photosynthesis.

7. Stomata
• Stomata are minute openings present in the epidermal layers of
leaves. They are responsible for gas exchange during photosynthesis.

8. Process of Photosynthesis
• The palisade layer is the centre for photosynthesis. Light energy is
trapped in the chlorophyll of mesophyll cells of the palisade layer of
leaves.
• The chemical equation for photosynthesis is

9. Two main phases are involved in the
mechanism of photosynthesis:
Mechanism of
Photosynthesis
Light-dependent
Phase
Light-
independent
Phase

10. Light-Dependent Phase
• Light-dependent phase is also known as the Hill reaction or
photochemical reaction. This phase occurs in the thylakoids of the
chloroplast.
• Activation of chlorophyll - On exposure to light, chlorophyll becomes
excited and absorbs photons (a photon is the smallest unit of light
energy) to get activated.
• Photolysis of water - Energy absorbed is used in the splitting of water
molecules into hydrogen ion (H+) and hydroxide ion (OH−). During
this process, electrons are released.

11. Light-Dependent Phase
• Production of reducing agent - NADP (nicotinamide dinucleotide
phosphate) picks up the hydrogen ion and is reduced to NADPH.
• Formation of molecular oxygen - Hydroxide ion is oxidised to hydrogen
peroxide which decomposes to form molecular oxygen (O2). Molecular
oxygen is released during photosynthesis.
• Photophosphorylation - Electrons are used in converting ADP (adenosine
diphosphate) into energy-rich compound ATP (adenosine triphosphate) by
adding one phosphate group.
• The process of addition of phosphate is called phosphorylation. Because
the energy used comes from light, it is also called photophosphorylation.

12. Light-Independent Phase
• This phase is also known as the Calvin cycle or biosynthetic phase. It
occurs in the stroma of the chloroplast.
• This phase occurs simultaneously with the light-dependent reaction.
• The time gap between the two phases is less than one thousandth of
a second.
• Formation of glucose - Carbon dioxide is converted into glucose by
using ATP and NADPH produced during the light reaction.

13. Experiment 1: Chlorophyll is necessary for
photosynthesis

14. To test a leaf for starch

15. Experiment 2: To show that carbon dioxide is
necessary for photosynthesis

16. Heterotrophic Nutrition
• It is the mode of nutrition in which organisms
cannot synthesise their own food, but they are
dependent on other organisms for food.
• Organisms exhibiting heterotrophic nutrition are
called heterotrophs.
• Examples: Yeasts, fungi, bacteria, human beings,
tiger, monkey, birds, lion, cow etc.
This Photo by Unknown Author is licensed under CC BY-SA

17. Types of Heterotrophic Nutrition
1. Saprotrophic Nutrition
–
• Organisms obtain their
food from dead, decaying
plants and animals.
• Such organisms are
called saprophytes.
• Examples: Mucor,
mushroom
This Photo by Unknown Author is licensed under CC BY-SA

18. 2. Parasitic
Nutrition
• Organisms obtain their food from the
body of other living organisms.
• The organism which feeds on
another living organism is called a
parasite.
• The organism from whose body the
food is obtained is called a host.
• Parasites usually harm the host while
obtaining their food.
• Example: Cuscuta is a parasitic plant,
plasmodium is a malarial parasite and
roundworms live inside a human
being’s body to obtain food.
• Other examples include leeches, lice,
tapeworms and ticks.
This Photo by Unknown Author is licensed under CC BY-SAThis Photo by Unknown Author is licensed under CC BY-SA
This Photo by Unknown Author is licensed under CC BY-SA
This Photo by Unknown Author is licensed under CC BY-NC-ND

19. 3. Holozoic Nutrition
• It is a mode of nutrition in which
organisms feed on solid food. The food
is complex organic material which
when ingested is broken down into
simple inorganic substances by the
process of digestion.
• Examples: Human being, tiger, lion,
bear, frog, fish, amoeba etc.

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