Plant Kingdom

Hello, Readers! 

Let's have a look at the Plant Kingdom. 

Plant kingdom includes algae, bryophytes, pteridophytes, gymnosperms anda angiosperms 

ALGAE

Algae reproduce vegetatively by

fragmentation, asexually by formation of different types of spores and sexually by formation of gametes.

Depending on the type of pigment 

and stored food, algae are classified into three classes, namely Chlorophyceae, Phaeophyceae and Rhodophyceae.

Eg: Green algae (i) Volvox (ii) Chlamydomonas (iii) Chara

Brown algae (i) Laminaria (ii) Fucus (iii) Dictyota

Red algae (i) Porphyra (ii) Polysiphonia

BRYOPHYTES

Bryophytes are plants that live on land but are dependent on water for

sexual reproduction. Their body is more differentiated than that of algae. 

They possess root-like, leaf-like and stem-like structures.

The bryophytes are divided into liverworts and mosses. 

Eg: Liverworts – Marchantia, Riccia

Mosses – (c) Funaria, Sphagnum

PTERIDOPHYTES

In pteridophytes, the main plant is a sporophyte which is differentiated into true root, stem and leaves. These organs possess well-differentiated vascular tissues The sporophytes bear sporangia which produce spores. The spores germinate to form gametophytes. The gametophytes bear male and female sex organs called antheridia and archegonia, respectively. 

Eg: Ferns, Seleginela 

GYMNOSPERMS 

The gymnosperms are the plants in which ovules are not enclosed by any

ovary wall. After fertilisation the seeds remain exposed and therefore these plants are called naked-seeded plants. The gymnosperms produce microspores and megaspores which are produced in microsporangia and megasporangia borne on the sporophylls. 

Eg: Cycas, Pines 

ANGIOSPERMS

In angiosperms, the male sex organs (stamen) and female sex organs (pistil) are borne in a flower.  One male gamete fuses with egg cell

(syngamy) and other fuses with diploid secondary nucleus (triple fusion). This phenomenon of two fusions is called double fertilisation and is found only in angiosperms. The angiosperms are divided into two classes – the dicotyledons and the monocotyledons.

Eg: Peas, Rose, Neem tree etc

       Wheat, Maize, Bajra etc 

Biological Classification

Hello, readers! 

Today let's understand Classification of Living things.

Biological classification of plants and animals was first proposed by Aristotle. 

Linnaeus classified all living organisms into two kingdoms - Plants and Animals.

Robert whittaker proposed an elaborate five kingdom classification: Monera, Protista, Fungi, Plantae and Animalia. 

Monera: unicellular, prokaryotic, autotrophic or heterotrophic organisms. Eg bacteria

1. Archaebacteria: Halophiles, thermoacidophils, methanogens etc. 

2. Eubacteria: Autotrophic bacteria, heterotrophic bacteria etc.

Protista: unicellular, eukaryotic, autotrophic or heterotrophic organisms. 

1. Chrysophytes: plant like, golden algae and diatoms. 

Diatoms have soap-box like silica shells. 

2. Dinoflagellates: plant like, red, yellow, green, brown or blue cells. May have strong cellulose plates with two flagella. 

3. Euglenoids: plant like, has protein pellicle layer on cell. May have two flagella, a long and a short.

4. Slime moulds: fungus like, saprophytes, collectively called plasmodium - spores are formed for reproduction in unfavorable conditions. 

5. Protozoa: animal like, predators or parasites, 

Amoeboid protozoa, flagellated protista, ciliated protozoa and sporozoans.

Fungi:

Multicellular, eukaryotic, heterotrophic organisms. 

1. Phycomycetes: aseptate and coenocytic mycelium

2. Ascomycetes: mycelium is branched and septate, 

3. Basidiomycetes: mycelium branched and septate, 

4. Deuteromycetes: mycelium branched and septate, only asexual reproduction is discovered in them. 

Plantae: multicellular, eukaryotic, autotrophic organisms with cell wall of cellulose. Shows alternation of generation

Animalia: multicellular, eukaryotic, heterotrophic organisms without cell wall. 

Viruses, viroids, prions and lichens are not included in any of the five kingdoms. 

The Living World

Hello!

These are the important points on The Living World. 

Living organisms are self replicating, evolving and self regulating, interactive systems capable of responding to external stimuli. 

Metabolism, cellular organisation and consciousness are the defining characteristics of living things. While growth and reproduction are important characteristics but not defining characteristics of living things. 

Taxonomy includes the rules and principles for identification, nomenclature and classification of organisms. 

Binomial nomenclature is the most convenient and the most popular system. It was given by Carolus Linnaeus. 

The main taxonomic categories are: Kingdom, phylum or division, class, order, family, genus and species.

The taxonomical aids are: 

Herbarium, botanical gardens, museum, zoological parks and key.