Class VII

2. Nutrition
• Process by which organisms obtain and
use the nutrients required for maintaining
life

3. Modes of nutrition
• Ways of obtaining and using nutrients
Nutrition
Autotrophic Heterotrophic
nutrition nutrition
Holozoic Saprophytic Parasitic
nutrition nutrition nutrition

4. Autotrophic nutrition
• make their own food (complex
organic substances) using
simple inorganic substances
– the organism  autotrophs
• e.g. Green plants
– by photosynthesis

5. Heterotrophic nutrition
• depends on other organisms or dead
organic matters as their food sources
– the organism  Heterotrophs
• Cannot make their own food and obtain
their food in organic form

6. Autotrophic nutrition
• PHOTOAUTOTROPHS CHEMOAUTOTROPHS
Photosynthetic organisms Deriving energy
are photoautotroph which from chemical reactions,
means that they are synthesize all necessary
repositories of energy, they organic compounds
are able to synthesize food from carbon dioxide.
directly from carbon dioxide, eg- bacteria
water, and using energy from
light.

7. Other modes of nutrition in
plants
• Parasitic
• Insectivorous
• Saprophitic
• symbiotic

8. Parasitic plants
Cuscuta growing on other
plants

9. Insectivorous plants

10. Symbiotic plants
Lichens

11. Sybiosis- Leguminous plants

12. Saprophytic nutrition
(Saprophytism)
• Organisms feed on dead organisms or non-
living organic matter
– Saprophytes
(e.g. fungi, bacteria)

13. How A Saprophyte
Obtains Its Nutrients?
Example : Mucor & Rhizopus (bread mould)
• • Mass of hyphae = are
• Digestedrelease
Hyphae products
Enzymes digest
Sporangium enzyme into
: produces
digestiveby hyphae
mycelium organic
absorbed
complex
sporesbread
the for reproduction
molecules in bread
into simple, soluble
molecules
(extracellular
digestion )

14. Importance of saprophytes
• As decomposers
– Allow essential materials (e.g. C, N)
to be recycled in the ecosystem
Enzyme from
Complex organic saprophytes Simple soluble
substances compounds

15. To observe Mucor

16. Why is it necessary to leave the moist bread
uncovered for 30 minutes ?
Ans: Because the spore of Mucor are carried by
air current. They can drop onto the bread
and then germinate.

17. What are the thread-like structures growing on the
surface of the bread ?
Ans: The thread-like structures are used for feeding.
They are called hyphae which can produce
enzymes for digesting the organic food.

18. ~ END ~