Microorganisms and Plant Biology: Essential Concepts
Understanding Viruses and Microorganisms
Viruses are not considered living things because they cannot perform nutrition or interaction. To reproduce, viruses invade an organism. The virus structure is very simple: a capsid (an external shell made of proteins that contains genetic material) and nucleic acid (genetic information).
Pathogens are microorganisms that cause infectious diseases.
A microorganism is a living thing so small that it requires a microscope to be seen. We use microorganisms to make food (such as bread and wine) or to produce medicines like antibiotics.
The 5 Groups of Microorganisms
The five groups are: bacteria, unicellular algae, protozoa, mould, and yeast.
The 3 Kingdoms
- Bacteria
- Protoctista (unicellular algae and protozoa)
- Fungi (mould and yeast)
Note: Viruses do not belong to any kingdom.
Examples:
- Protoctista kingdom: Plasmodium, green or brown algae, amoeba.
- Fungi kingdom: Mould, yeast.
The plasma membrane of bacteria controls the passage of substances.
Interaction in Microorganisms
Algae: Some use flagella, while others form colonies.
Protozoa: These move in different ways: Paramecium (use cilia), Trypanosoma (use flagella), Amoeba (use pseudopodia), and Plasmodium (do not move independently).
Bacteria: Respond to simple stimuli. Some have a flagellum to move.
Fungi: Unicellular organisms form colonies, and multicellular organisms form mycelia.
Classification and Structure
Algae classification: Brown (multicellular); red and green (unicellular or multicellular).
Bacteria shapes: Coccus, bacillus.
Fungi kingdom groups: Yeast and mushrooms (unicellular); moulds (multicellular). The mycelium is the main part of a fungus and is made of hyphae.
Plant Classification
Plants Without Seeds
- Mosses: Do not have real organs, flowers, seeds, roots, or leaves. Water is absorbed through all their surfaces. They are non-vascular.
- Ferns: Have large leaves known as fronds. They are vascular plants but have no flowers or seeds.
Plants With Seeds
These are vascular plants divided into Angiosperms (produce fruit) and Gymnosperms (no fruit).
Plant Organs and Functions
- Roots: Usually grow underground. Functions: Absorb water and minerals through root hairs, anchor the plant, and store nutrients.
- Stem: Functions: Transport water, minerals, and organic matter; support leaves, flowers, and fruit.
- Leaves: Contain chloroplasts with chlorophyll for photosynthesis. They have pores called stomata for gas exchange.
Plant Nutrition
Plant nutrition is autotrophic, transforming inorganic matter into organic matter.
- Roots absorb water and minerals (xylem sap).
- Conductive vessels carry xylem sap to the leaves.
- Photosynthesis: Leaves absorb CO2 and sunlight. Chloroplasts use chlorophyll to transform xylem sap into organic matter (phloem sap). Oxygen is released as a byproduct.
Equation: water + minerals + CO2 + sunlight → organic matter + O2
- Phloem sap is transported to the rest of the plant.
- Cell respiration: Takes place in the mitochondria to produce energy.
Equation: Organic matter + O2 → H2O + CO2 + energy
- Elimination of waste: Waste is released through stomata. CO2 results from cell respiration, O2 from photosynthesis, and water is released as vapour (transpiration).
Plant Reproduction
- Asexual: No gametes required. Occurs through spores or vegetative parts.
- Sexual: Requires male gametes (pollen) and female gametes (ovules). Fertilisation creates a zygote.
- Alternation: Plants that reproduce both asexually and sexually.
Asexual Reproduction Methods
- Sporogenesis: Reproduction through spores.
- Vegetative reproduction: New plants grow from parts of the parent. Examples: Bulbs (onion), Tubers (potato), Stolons (strawberry), Rhizomes (Iris).
Sexual Reproduction
Gymnosperms: Have exposed seeds and use cones. The same plant has both male and female cones.
Angiosperms: Have flowers and ovaries that enclose their seeds.
