WEEK 8 & 9
PROPERTIES AND FUNCTIONS OF CELLS (NUTRITION)
MODES OF NUTRITION
- Macro and Micro Nutrients
- Macro nutrients are essential nutrients that the body requires in relatively large amounts, including carbohydrates, proteins, and fats. They provide the energy necessary for bodily functions.
- Micro nutrients are nutrients needed in smaller quantities, including vitamins and minerals. These play crucial roles in various physiological processes and overall health.
Mode of Nutrition
The mode of nutrition refers to how organisms obtain and consume nutrients for their growth and metabolism. There are two main modes of nutrition:
- Autotrophic Nutrition: Organisms capable of synthesizing their own food from inorganic substances use autotrophic nutrition. Plants, algae, and some bacteria perform photosynthesis or chemosynthesis to produce their own organic molecules.
- Photosynthesis is the biological process by which green plants, algae, and some bacteria convert light energy into chemical energy stored in the form of glucose or other organic compounds. It takes place in the chloroplasts of plant cells and involves the use of sunlight, carbon dioxide, and water.
- Processes:
- Light Absorption: Pigments in chloroplasts, such as chlorophyll, absorb light energy.
- Water Splitting: Water molecules are split, releasing oxygen and providing electrons and protons.
- Carbon Fixation: Carbon dioxide from the air is incorporated into organic molecules (initially into a three-carbon compound during the Calvin cycle).
- Glucose Synthesis: Through a series of chemical reactions, glucose and other organic compounds are synthesized.
- Conditions:
- Light: Photosynthesis requires light, usually provided by sunlight. Light is absorbed by chlorophyll to initiate the process.
- Carbon Dioxide: Plants take in carbon dioxide from the air during photosynthesis.
- Water: Water is crucial for the initial reactions, providing electrons and protons. It is absorbed by plant roots from the soil.
- Significance:
- Oxygen Production: Photosynthesis is a primary source of oxygen, crucial for the survival of many organisms.
- Energy Storage: The process stores solar energy in the form of chemical energy (glucose), which is later used by organisms for metabolic activities.
- Food Production: Photosynthesis forms the basis of the food chain by producing organic compounds that serve as a source of nutrition for heterotrophic organisms.
- Carbon Cycle: It plays a key role in the carbon cycle by fixing carbon dioxide from the atmosphere.
- Chemosynthesis: Is a process by which certain organisms produce carbohydrates from chemicals rather than using sunlight as an energy source, as in photosynthesis. This process is typically found in environments with limited or no sunlight, such as deep-sea hydrothermal vents, certain caves, and some extreme environments.
- Heterotrophic Nutrition: Organisms that cannot produce their own food and rely on external sources for nutrients practice heterotrophic nutrition. Animals, fungi, and some bacteria are examples. They obtain organic compounds by consuming other organisms or organic matter.
- I. Holozoic Nutrition: Holozoic nutrition is a type of nutrition in which organisms ingest complex organic substances, then digest and absorb the nutrients. It is characteristic of most animals, including humans.
- Process: In holozoic nutrition, organisms consume solid or liquid organic matter, digest it internally through processes like mechanical and chemical digestion, and absorb the resulting nutrients for energy and growth.
- II. Parasitic Nutrition: Parasitic nutrition is a type of heterotrophic nutrition where an organism (parasite) lives on or inside another organism (host) and derives nutrients at the expense of the host. This relationship is usually harmful to the host. Examples: Tapeworms in the human intestine or fleas on a dog are examples of parasites that obtain their nutrients from the host organism.
- III. Symbiotic Relationship: Symbiotic relationships involve a close and often long-term interaction between two different species, where at least one of the species benefits. It can be classified into mutualism, commensalism, and examples include:
- Mutualism: Bees and flowers – bees get nectar, while flowers get pollination.
- Commensalism: Barnacles on a whale – barnacles benefit by having a surface to attach to, while the whale is unaffected.
- 3. Saprophytic Nutrition: Saprophytic nutrition is a type of nutrition in which organisms feed on dead and decaying organic matter. These organisms, called saprophytes or decomposers, play a crucial role in breaking down organic material and recycling nutrients. Examples: Fungi like mushrooms and certain bacteria are saprophytes that obtain nutrients from decaying organic material.
Evaluation:
- Identify the two modes of nutrition
- What is photosynthesis, describe the process of photosynthesis
- What is heterotrophic mode of nutrition
- Differentiate between photosynthesis and chemosynthesis
Assignment:
Explain the process of feeding in amoeba and Paramecium
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