Kingdom Plantae are also called Plant Kingdom. Earlier we use simple morphological characters to classify like color, habits, leave structure other visible characters. Artificial System of Classification are groups of organisms which based on visible characters, not evolutionary relationship. Also artificial system gave equal weightage to vegetative and sexual characters. This system was introduced by Carl Linnaeus in 1753. Natural Classification System is a group of organisms which based on evolutionary relationship and genetic similarities. Also this system consider Internal features such as anatomy, embryology etc. This system was developed by George Bentham and Joseph Dalton Hooker in 1862.

Currently we use Phylogenetic Classification System, it based on evolutionary relationship and ancestry. It was given by Ernst haeckel in 1866.

Numerical Taxonomy is method of classification by using computers which based on observable characters. In this method we can consider hundreds of character at a same time. Cytotaxonomy, it is based on cytologocal information like chromosome number, structure, behaviour etc. Chemotaxonomy is based on mainly chemical information and it also use these days for classification.

ALGAE-

  • General introduction– It contain chlorophyll, have simple and thalloid structure.
  • Habitat- found in aquatic environment(fresh and marine water), in moist stone, soil and on wood.
  • Structure- Form and size are different and form filamentous structure.
  • Reproduction- Algae reproduce by vegetative, sexual and asexual method. Vegetative reproduction by fragmentation where every fragment develop a thallus. Asexually reproduction is by production of different type of spores are commonly called Zoospores. The zoospore is flagellated(motile) and give new plant when it germinate. Sexually reproduce by fusion of 2 gametes. Isogamous are fusion of 2 gametes which are flagellated and similar in size or non-flagellated but similar in size, such reproduction is called isogamous. Anisogamous are fusion of 2 gametes which are dissimilar in size(eg. Eudorina). Oogamous are fusion between 1 large non- motile female gamete and 1 small motile male gamete.(eg. Volvox, Fucus).
  • Benefits of Algae- Algae carried about 1/2 of total CO2 fixation. About 70 species of marine algae used as food for marine animals. Agar are obtain from Gelidium and Gracilaria which used in grow microbes and making jellies and ice-cream. Chlorella are unicellular alga(single organisms) is protein rich substance which used as food for space travellers.
  • The algae are divided into 3 main classes-
  1. Chlorophyceae(also called green algae)–
  • Habitat- Found in aquatic habitat(fresh water + marine water), brackish water(salty water).
  • Main pigment- Chlorophyll a, b which responsible for green color. This is chloroplast.
  • Food- Food store in form of starch and some are in form of oil droplets. Many members of algae have more than 1 storage bodies called pyrenoids (present in starch) which contain protein.
  • Cell wall- Green algae have rigid cell wall which inner layer of cellulose and outer layer of pectose.
  • Reproduction- Vegetatively reproduce by fragmentation or by formation of different type of spores. Asexually reproduce by flagellated zoospores(form in zoosporangia). Sexually reproduced by formation sex cell which may be isogamous, anisogamous or oogamous.
  • Examples- Chlamydomonas, volvox, Ulothrix, Spirogyra, Chara etc.

2. Phaeophyceae(also called brown algae)–

  • Habitat- Fresh water, brackish water, salty water.
  • Main pigment- It contain chlorophyll a, c, fucoxanthin, carotenoids, xanthophyll(color and shades depent on it).
  • Food- Store as carbohydrates which may be in form of laminarin or mannitol.
  • Cell wall- Composed of cellulose and algin.
  • Reproduction- Vegetatively reproduced by fragmentation. Asexually reproduce by biflagellate zoospores, it have 2, unequal and and lateral flagella. Sexually reproduced by isogamous, anisogamous or oogamous.
  • Examples- Ectocarpus, Dictyota, Laminaria, Sargassum, Fucus etc.

3. Rhodophycese(also called red algae)–

  • Habitat- Found in fresh water, salty water.
  • Main pigment- It contain chlorophyll a and d and r-phycoerythrin(responsible for red color).
  • Food- Food store in form of floridean starch(similar to amylopectin) and structure like glycogen.
  • Cell wall- Composed of cellulose, pectin, and poly-sulphate-ester.
  • Reproduction- Vegetatively reproduce by fragmentation. Asexually reproduce by non-motile spores. And sexually by gametes and reproduction is oogamous and accompanied by complex post fertilisation developments.
  • Examples- Polysiphonia, Porphyra, Gracilaria, Gelidium, etc.

Bryophytes (Mosses and Liverworts)

  • Definition: Bryophytes are simple, non-vascular plants that live in moist, shaded areas. They include mosses and liverworts.
  • Location: Commonly found in hills, damp soil, and near water bodies.
  • Key Feature: They are called the “amphibians of the plant kingdom” because they live on land but need water for reproduction.

Key Structures in Bryophytes:

  • Thallus: The plant body is flat and leaf-like (thalloid) and does not have true roots, stems, or leaves.
  • Rhizoids: Root-like structures used for attachment to the surface.
  • Gametophyte: The dominant phase (haploid) of the plant that produces gametes.
  • Sex Organs:
    • Antheridium (Male): Produces biflagellate antherozoids (sperm).
    • Archegonium (Female): Produces a single egg.
  • Sporophyte: The diploid stage that forms from the zygote. It stays attached to the gametophyte for nourishment and produces spores through meiosis.

Reproduction in Bryophytes:

  • Asexual: Through fragmentation or gemmae (small multicellular buds).
  • Sexual: Involves the fusion of male and female gametes (sperm and egg) in water, forming a zygote, which grows into a sporophyte.

Importance:

  • Ecological: Bryophytes help in plant succession on rocks/soil and reduce soil erosion.
  • Economic: Sphagnum mosses are used for fuel and water retention.

Types of Bryophytes:

  1. Liverworts:
    • Habitat: Moist and shady places like tree bark, marshes.
    • Asexual reproduction: By gemmae.
    • Sexual reproduction: Male and female sex organs are on the same or different thalli (plant bodies).
    • Example: Marchantia.
  2. Mosses:
    • Habitat: Damp, shady areas.
    • Life cycle: Includes a protonema stage (filamentous) and a leafy stage (with sex organs).
    • Sexual reproduction: Antheridia and archegonia are located on the leafy shoots.
    • Example: Funaria, Polytrichum, Sphagnum.

Pteridophytes (Ferns and Horsetails)

  • Definition: First vascular plants with xylem and phloem. They include ferns and horsetails.
  • Key Feature: Dominant phase is the sporophyte (diploid), which has true roots, stems, and leaves.
  • Reproduction: They produce spores in sporangia, which develop into a gametophyte (prothallus).
  • Gametophyte: Produces male (antheridia) and female (archegonia) sex organs. Water is needed for fertilization.
  • Classification: Divided into classes like Psilopsida (e.g., Psilotum), Lycopsida (e.g., Selaginella), Sphenopsida (e.g., Equisetum), and Pteropsida (e.g., ferns).

Gymnosperms (Conifers)

  • Definition: Gymnosperms have exposed seeds (not enclosed in an ovary). Examples include pine, cedar, and cycas trees.
  • Key Feature: Seeds are “naked” because they aren’t covered by fruits.
  • Sexual Reproduction: Male and female cones produce microspores (pollen) and megaspores (ovules). Pollen grains are carried by wind to fertilize the ovules.
  • Classification: Examples include Pinus (pine), Cycas, Ginkgo.
  • Importance: Some gymnosperms, like Sequoia, are massive trees and hold ecological value.

Angiosperms (Flowering Plants)

  • Definition: Angiosperms are the largest group of plants and produce flowers and seeds enclosed in fruits.
  • Key Features:
    • Flower: Reproductive organ where male (pollen) and female (ovules) gametes meet.
    • Seed: Enclosed in a fruit, which protects the developing seed.
    • Classified into:
      • Monocotyledons (Monocots): Have one cotyledon (seed leaf), like grasses and lilies.
      • Dicotyledons (Dicots): Have two cotyledons, like roses and beans.

Major Differences in Plant Groups:

  1. Bryophytes: Non-vascular, gametophyte dominant, need water for reproduction.
  2. Pteridophytes: Vascular, sporophyte dominant, produce spores.
  3. Gymnosperms: Vascular, seeds are naked, male and female gametophytes are dependent on sporophyte.
  4. Angiosperms: Vascular, seeds enclosed in fruits, highly diverse, and have flowers for reproduction.

Competitive Exam Tips:

  • Key Points for Identification:
    • Bryophytes lack vascular tissue; their plant body is gametophyte.
    • Pteridophytes have vascular tissue and their plant body is sporophyte.
    • Gymnosperms have naked seeds and cones.
    • Angiosperms have enclosed seeds in fruits.
  • Important Processes: Understanding meiosis (spore formation), fertilization, and the alternation of generations is crucial.
  • Real-world Applications: Learn how bryophytes (like mosses) are used in ecological restoration, and gymnosperms (like pines) in timber production.

These all are the notes of chapter 3 in biology. And important questions are below HERE. *#THANKS FOR VISITING, VISIT AGAIN#* 😊

1. What is the Plant Kingdom?

  • Answer: The Plant Kingdom, also called Kingdom Plantae, includes all plants.

2. What is the Artificial System of Classification?

  • Answer: It groups plants based on visible features like color and shape, without considering their evolutionary relationships. Carl Linnaeus introduced this system in 1753.

3. What is the Natural Classification System?

  • Answer: It classifies plants based on their evolutionary relationships and genetic similarities. It was developed by George Bentham and Joseph Dalton Hooker in 1862.

4. What is the Phylogenetic Classification System?

  • Answer: This system classifies plants based on their ancestry and evolutionary relationships. It was introduced by Ernst Haeckel in 1866.

5. What are Numerical, Cytotaxonomy, and Chemotaxonomy?

  • Answer:
    • Numerical Taxonomy: Uses computers to classify plants based on many observable characters.
    • Cytotaxonomy: Classifies plants based on chromosome details like number and structure.
    • Chemotaxonomy: Uses the chemical composition of plants for classification.

6. What are algae?

  • Answer: Algae are simple, chlorophyll-containing plants found in water and moist places.

7. How do algae reproduce?

  • Answer:
    • Vegetative: By fragmentation (breaking into pieces).
    • Asexual: By producing spores like zoospores (flagellated).
    • Sexual: By the fusion of gametes, which can be:
      • Isogamous: Gametes are similar.
      • Anisogamous: Gametes are different in size (e.g., Eudorina).
      • Oogamous: Large female gamete and small male gamete fuse (e.g., Volvox).

8. What are the uses of algae?

  • Answer:
    • Fixes half of the world’s CO₂.
    • Used as food for marine animals.
    • Agar (used in jellies and ice creams) is made from algae like Gelidium.
    • Chlorella (a protein-rich algae) is used as space food.

9. Name the three main types of algae with examples.

  • Answer:
    1. Chlorophyceae (Green Algae): Examples – Chlamydomonas, Volvox.
    2. Phaeophyceae (Brown Algae): Examples – Laminaria, Fucus.
    3. Rhodophyceae (Red Algae): Examples – Polysiphonia, Gelidium.

10. What are Bryophytes?

  • Answer: Simple plants that live in moist areas. They are called the “amphibians of the plant kingdom” because they need water for reproduction.

11. How do bryophytes reproduce?

  • Answer:
    • Asexual: By fragmentation or gemmae (small buds).
    • Sexual: Male sperm from antheridium swims to female eggs in archegonium to form a zygote.

12. What are examples of Bryophytes?

  • Answer:
    • Liverworts: Marchantia.
    • Mosses: Funaria, Sphagnum.

13. What are Pteridophytes?

  • Answer: The first vascular plants (with xylem and phloem) like ferns and horsetails.

14. What is the key feature of Pteridophytes?

  • Answer: Their dominant phase is the sporophyte, which has true roots, stems, and leaves.

15. What are Gymnosperms?

  • Answer: Plants with naked seeds, like pine and cedar.

16. What are Angiosperms?

  • Answer: Flowering plants with seeds enclosed in fruits. They are divided into:
    • Monocots: One seed leaf (e.g., grass).
    • Dicots: Two seed leaves (e.g., beans).

17. What are the main differences between plant groups?

  • Answer:
    • Bryophytes: Non-vascular, need water for reproduction.
    • Pteridophytes: Vascular, produce spores.
    • Gymnosperms: Vascular, have naked seeds.
    • Angiosperms: Vascular, have seeds inside fruits.