11th Class Biology Chapter 7 Notes | Get Now
11th Class Biology Chapter 7 Notes cover Kingdom Protista, also known as Protoctista, one of the most diverse chapters in the Punjab Board FSc Part 1 syllabus. This chapter introduces students to protozoans, algae, slime moulds, and water moulds.
Credit to taleem360.
Many students find this chapter lengthy because it combines animal-like, plant-like, and fungus-like organisms in one kingdom. These 11th Class Biology Chapter 7 Notes simplify every concept with clear definitions and structured explanations.
For More Notes Visit Now.
What is Kingdom Protista?
Kingdom Protista includes a vast variety of aquatic eukaryotes with different structures, body forms, reproductive systems, and nutrition types. These organisms evolved from prokaryotes.
According to these 11th Class Biology Chapter 7 Notes, protists include:
- Protozoans
- Unicellular and multicellular algae
- Slime moulds
- Oomycetes
Features of Kingdom Protista
- Members are unicellular, colonial, or simple multicellular
- Eukaryotic cell organization is found
- No embryo or blastula stages occur
- Protists are ancestors of Fungi, Plantae, and Animalia kingdoms
Historical Perspective of Protists
This section is frequently asked in exams. Key proposals include:
- J. Hogg (1861) – Proposed protista for microscopic organisms
- E. Haeckel (1866) – Placed bacteria and Euglena in kingdom protista, later separated prokaryotes as Monera
- H. Copeland (1938) – Gave separate kingdom status to prokaryotes
- R. Whittaker (1969) – Introduced the five kingdom system
- Margulis & Schwartz (1982) – Modified the system by adding simple multicellular and colonial eukaryotes
These 11th Class Biology Chapter 7 Notes explain how classification evolved over time to accommodate diverse organisms.
Why Are Protists Polyphyletic?
Protists are considered polyphyletic because they do not share a single common ancestor. Margulis and Schwartz classified protists into 27 phyla due to their great diversity.
Diversity Among Protists
- Difference in size and structure
- Different means of locomotion
- Different types of nutrition
- Interactions with other organisms
- Different habitats
- Different kinds of reproduction
Animal-Like Protists (Protozoa)
Protozoans are unicellular organisms where “Proto” means first and “Zoa” means animals. This section of these 11th Class Biology Chapter 7 Notes covers six major groups:
| Group | Locomotion | Example |
|---|---|---|
| Zooflagellates | Flagella | Trypanosoma, Euglena |
| Amoebas | Pseudopods | Amoeba, Entamoeba |
| Actinopods | Pseudopods | Radiolarians |
| Foraminifera | Pseudopods | Forams |
| Apicomplexans | None | Plasmodium |
| Ciliates | Cilia | Paramecium, Stentor |
Amoebas
- Free living organisms with irregular body shape
- Reproduce by binary fission and multiple fission
- Move using pseudopodia
- Entamoeba histolytica causes human dysentery
Zooflagellates
- Mostly unicellular with whip-like flagella
- Obtain food from living or dead organisms
- Trypanosoma causes African Sleeping Sickness, transmitted by tsetse flies
Ciliates
Ciliates possess cilia for locomotion and feeding. They have a pellicle, plus micro and macronuclei:
- Macronucleus – polyploid, controls metabolic activities
- Micronucleus – diploid, controls reproduction
Sexual reproduction occurs through conjugation, while asexual reproduction happens by binary fission. Paramecium and Stentor are common examples.
Apicomplexans and Malaria
Apicomplexans are parasitic protozoans. Malaria is caused by Plasmodium, transmitted through female Anopheles mosquitoes. The life cycle involves:
- Sporozoites injected into humans
- Merozoites formed in the liver
- Gametocytes developed from merozoites
- Zygote formed inside the mosquito
Plant-Like Protists (Algae)
Algae are eukaryotic unicellular, colonial, and filamentous aquatic plants. The study of algae is called Phycology. These 11th Class Biology Chapter 7 Notes cover major algal phyla in detail.
Major Phyla of Algae
| Phylum | Common Name | Example |
|---|---|---|
| Euglenophyta | Euglenoids | Euglena |
| Pyrrophyta | Dinoflagellates | Gonyaulax, Ceratium |
| Chrysophyta | Diatoms | Diatoma, Pinnularia |
| Phaeophyta | Brown Algae | Fucus, Macrocystis |
| Rhodophyta | Red Algae | Chondrus, Polysiphonia |
| Chlorophyta | Green Algae | Chlorella, Ulva, Spirogyra |
Euglenoids
Euglenoids show a twin character, behaving like autotrophs when chlorophyll is present and like heterotrophs when it is lost in dark conditions.
Brown Algae (Phaeophyta)
- Found in cool marine water along rocky coastlines
- Multicellular with parenchymatous thallus
- Body divided into blades, stipes, and hold fasts
- Kelp is the largest brown algae
Red Algae (Rhodophyta)
- Non-flagellate, mostly thalloid
- Contain phycocyanin and phycoerythrin pigments
- Important in reef formation
- Examples: Chondrus, Polysiphonia
Green Algae (Chlorophyta)
Green algae are considered ancestors of land plants because of:
- Similar pigmentation
- Starch as reserve food material
- Cellulose cell walls
- Similar RNA sequences
Fungus-Like Protists
The final section of these 11th Class Biology Chapter 7 Notes covers slime moulds and water moulds, which resemble fungi but have important differences.
Slime Moulds (Myxomycota)
- Also called plasmodial slime
- Vegetative phase is called Plasmodium, a multinucleated mass of protoplasm
- Can grow up to 30cm in diameter
- Reproduce through sporangia and haploid spores
- Physarium polycephalum is a model organism for research
Water Moulds (Oomycetes)
- Hyphae are aseptate, meaning no cross walls
- Cell wall contains cellulose, not chitin
- Phytophthora infestans causes late blight of potatoes
This disease caused the Irish Potato Famine of 1840, leading to starvation and mass migration due to crop failure.
Economic Importance of Algae
Algae play a major role in daily life, as highlighted in these 11th Class Biology Chapter 7 Notes:
- Human Food – Laminaria is used as food, especially in Japan and China
- Cattle Food – Sea weeds are used for animal feed
- Oxygen Supply – Algae release oxygen during photosynthesis
- Antiseptic Role – Chlorella is used in antibiotic synthesis
- Source of Algin and Agar – Used in food and laboratory industries
FAQs
Q1: What is covered in 11th Class Biology Chapter 7 Notes?
These notes cover Kingdom Protista, including protozoans, algae, slime moulds, and water moulds, following the complete Punjab Board FSc Part 1 syllabus.
Q2: What are the main groups of Kingdom Protista?
Kingdom Protista includes animal-like protists (protozoa), plant-like protists (algae), and fungus-like protists (slime moulds and water moulds), based on their nutrition and structure.
Q3: Who introduced the five kingdom system?
R. Whittaker introduced the five kingdom system in 1969, which included Monera, Protista, Fungi, Plantae, and Animalia as separate kingdoms.
Q4: What causes malaria according to this chapter?
Malaria is caused by Plasmodium, an apicomplexan parasite transmitted through the bite of female Anopheles mosquitoes, as explained in detail in the chapter.
Q5: Why are 11th Class Biology Chapter 7 Notes important for exams?
This chapter frequently appears in board exams with long and short questions on classification, protozoan groups, and algae types, making these notes essential for preparation.
Q6: Why are green algae considered ancestors of plants?
Green algae share similar pigmentation, starch storage, cellulose cell walls, and RNA sequences with land plants, providing strong evolutionary evidence of their common ancestry.