- Nutrition is the process by which organisms obtain and use nutrients to maintain life. There are two main modes of nutrition: autotrophic and heterotrophic. - Autotrophic organisms like plants can produce their own food through photosynthesis. Heterotrophic organisms depend on other organisms or dead organic matter for food. - Heterotrophic nutrition includes holozoic, saprophytic, and parasitic nutrition. Holozoic organisms ingest living organisms. Saprophytic organisms feed on dead organic matter. Parasitic organisms obtain nutrients from living hosts, harming the host. - Saprophytes and parasites play important roles in ecosystems by recycling nutrients as they feed. Parasites can harm hosts by

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

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

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

5. Heterotrophic nutritionHeterotrophic 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. Holozoic nutritionHolozoic nutrition
• Organisms take in solid organic food from
ingesting other living organisms
• Food needs to be broken down into small
molecules (i.e. digested)
before they can be absorbed
and used by the organisms

7. Types of animalsTypes of animals
taking holozoictaking holozoic
nutritionnutrition
• Herbivores
– Feed on plants only
• Carnivores
– Feed on animals only
• Omnivores
– Feed on both plants and
animals

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

9. How a saprophyteHow a saprophyte
obtains its nutrients?obtains its nutrients?
Example : Mucor & Rhizopus (bread mould)
• Hyphae release
digestive enzyme into
the bread
• Enzymes digest
complex organic
molecules in bread
into simple, soluble
molecules
(extracellular
digestion )
• Digested products are
absorbed by hyphae
Mass of hyphae =
mycelium
Sporangium : produces
spores for reproduction

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

11. To observe Mucor

12. 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.

13. 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.

14. Parasitic nutritionParasitic nutrition
(Parasitism)(Parasitism)
• Organisms (parasite) obtain organic
compounds from another living
organism of a different species (host)
–Parasite is benefited
–Host is harmed

15. How a tapewormHow a tapeworm
obtains its nutrient?obtains its nutrient?
• Live inside the small intestine of human
• Food in small intestine is already digested
∴Can be absorbed
directly through
the body wall of
tapeworm by
diffusion

16. Structural adaptationsStructural adaptations
of tapewormof tapeworm
• Head bears hooks and
suckers
– To attach itself to the
intestinal wall of the host
∴Prevent being egested by
peristalsis of intestine

17. Structural adaptations ofStructural adaptations of
tapewormtapeworm
• Long, flattened body
– To increase the surface area for more
absorption of digested food by diffusion

18. •Body covered by cuticle & secretes anti-enzyme
–To protect itself from the attack of digestive
enzymes from the host
•Each host can only house one tapeworm
because it is too long.
-To reproduce by having both male and female
reproductive organs (testes and ovaries)

19. Parasitic nutritionParasitic nutrition
(Parasitism)(Parasitism)
• Lose weight & become weaker
• Parasite produces toxic compounds  harm the
host
• May block the ileum
• Difficult movement of food along the intestine
• Hooks & suckers damage host’s intestinal wall
Effect on Host:

20. To observe a Tapeworm

21. Does the tapeworm have a
mouth ?
Ans: The tapeworm does not
have a mouth.

22. Does the tapeworm have a
digestive tract ? Why ?
Ans: No. It is not necessary for a
tapeworm to digest food
because it obtains food
directly from its host’s
ileum by diffusion.

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