TUTTEE ACADEMY LOGO
broken image
  • Home
  • About Us
  • Subjects 
    • CHEMISTRY
    • BIOLOGY
    • PHYSICS
    • MATHEMATICS
    • PSYCHOLOGY
    • ECONOMICS
    • BUSINESS
    • COMPUTER SCIENCE
    • CHINESE
    • ENGLISH
    • SPANISH
    • IBDP IA / EE
    • IBDP TOK
    • ONLINE TUTORIAL
  • Exam Boards 
    • IBDP
    • IBMYP
    • IGCSE & GCSE
    • HKDSE
    • GCE A-LEVELS
  • Courses 
    • IBDP Tuition
    • GCE A-Level Tuition
    • IBMYP Tuition
    • I/GCSE Tuition
    • HKDSE Tuition
  • Admission Test Prep 
    • PREDICTED GRADE
    • SAT / SSAT
    • UKISET (UK)
    • BMAT
    • UKCAT / UCAT
    • LNAT
    • TMUA (Cambridge)
  • Student Results 
    • IBDP STUDENT RESULTS
    • IGCSE & GCSE MATHEMATICS
    • A-LEVEL STUDENT RESULTS
    • IGCSE STUDENT RESULTS
    • GCSE STUDENT RESULTS (UK)
    • HKDSE STUDENT RESULTS
    • OUR STORIES
  • Question Bank
  • Resources
SCHEDULE A LESSON NOW

AS/A-level Biology - Modes of Nutrition (1)

Modes of Nutrition

· Autotrophs,Heterotrophs,Holozoic nutrition,Fungi,A-level Biology

When it comes to AS/A-level Biology, do you remember what is autotrophic and heterotrophic nutrition?

Autotrophic Nutrition

  • Use external sources of energy (energy from sun or chemical reactions) in the synthesis of organic food materials.
  • Autotrophs are the producers in the ecosystem.

(a) Photosynthetic autotrophs - obtain energy from suns radiation which is used to build essential organic compounds from inorganic molecules by the process of photosynthesis.

  • They contain pigment, chlorophyll, to absorb light energy.
  • E.g. algae, green plants

6CO2 + 6H2O → C6H12O6 + 6O2

(b) Chemosynthetic autotrophs - use energy from certain chemical reactions to synthesise organic molecules from inorganic molecules.

  • E.g. nitrifying bacteria – Nitrosomonas and Nitrobacter

Heterotrophic Nutrition

  • Heterotrophs must be supplied with readymade organic compound from which to derive their energy.
  • Heterotrophs are the consumers.

Types of heterotrophic nutrition

  1. Holozoic nutrition
  2. Saprobiontic nutrition - feed on dead material
  3. Mutualistic nutrition - 2 or more organisms associated with each other. Both contribute and benefit from relationship.
  4. Parasitic nutrition - feed on living host

1. Holozoic Nutrition

  • Characteristic of higher animals including humans.
  • It involves feeding on organic matter from the bodies of other organisms.
  • There are 5 stages to holozoic nutrition:
  1. Ingestion - taking food into the mouth
  2. Digestion - mechanical and chemical breakdown of food (chewing and mixing with enzymes)
  3. Absorption - small, soluble molecules taken into the bloodstream
  4. Assimilation - use of absorbed products
  5. Egestion - getting rid of undigested parts of food

2. Saprobiontic Nutrition

  • Organisms feed on dead/ decayed matter.
  • Do this by secreting enzymes to digest the material (lipase, protease, and carbohydrase etc.) and then absorbs nutrients from the digested organic matter.
  • Digestion is classed as extracellular.
  • Saprobionts have no digestive system of their own.
  • E.g. Bacteria and fungi

For example,

Rhizopus Stolonifera

  • Also known as pin mould.
  • Found on bread.
  • Immature stage - cotton-like structures.
  • Mature stage - produces stalks with heads used to spread spores.
  • Rhizoids- ‘roots’ penetrate organic matter and secretes digestive enzymes and absorbs nutrients. (Also known as rhizoid hyphae)
  • Hyphae - ‘stalks’ of a mould or fungus. Joined by stolon.
  • Sporangia - mature hyphae topped by spores.
  • Aseptae - hyphae unjoined by cross walls
  • Septae - hyphae joined by cross walls.
  • Stolon - external hyphae connecting other hyphae.
broken image

In part 2, you will know more about mutualistic and parasitic nutrition.

broken image

CLICK HERE TO LEARN MORE ABOUT OUR AS/A-LEVEL BIOLOGY COURSES

SIGN UP FOR AS/A-LEVEL BIOLOGY TRIAL NOW!

Drafted by Bonnie (Biology)

Subscribe
Previous
AS/A-Level Mathematics - Natural Log
Next
AS/A-level Biology - Modes of Nutrition (2)
 Return to site
Profile picture
Cancel
Cookie Use
We use cookies to improve browsing experience, security, and data collection. By accepting, you agree to the use of cookies for advertising and analytics. You can change your cookie settings at any time. Learn More
Accept all
Settings
Decline All
Cookie Settings
Necessary Cookies
These cookies enable core functionality such as security, network management, and accessibility. These cookies can’t be switched off.
Analytics Cookies
These cookies help us better understand how visitors interact with our website and help us discover errors.
Preferences Cookies
These cookies allow the website to remember choices you've made to provide enhanced functionality and personalization.
Save