Kingdom Plantae: General Characteristics, Nutrition, Reproduction, Alternation of Generations, Classification, Practice Problems and FAQs

Have you ever wondered why even the earliest of biologists could easily classify plants as different organisms from animals? You must be thinking, “Isn’t that obvious? They look so very different from each other.” You are right. But even then, in primitive approaches to classification, some organisms such as Euglena which share characteristics of both plants and animals were wrongly classified as plants due to their photosynthetic nature.

So who do you think drew a well-defined and clear outline around kingdom Plantae? It was Robert H. Whittaker, who in his five kingdom classification, categorised eukaryotic, multicellular photosynthetic creatures with cellulosic cell walls as plants. 

Keep scrolling down if you want to know more about these amazing creatures that make our world a better place to live.

Table of Contents

• Characteristic Feature of Plants
• Mode of Nutrition in Plants
• Reproduction in Plants
• Alternation of Generation in Plants
• Classification of Plants
• Practice Problems of Kingdom Plantae
• FAQs of Kingdom Plantae

Characteristic Feature of Plants

Plants are eukaryotic, multicellular photosynthesising organisms. However, non-photosynthetic plants do exist. Primitive plants have thallus-like bodies which are not differentiated into root, stem and leaves while more advanced plants have well-differentiated bodies.

Plants are composed of cells with cell walls made up mainly of cellulose. Cells contain special chlorophyll containing organelles known as chloroplasts. They store food in the form of starch.

Mode of Nutrition in Plants

Majority of plants have an autotrophic mode of nutrition, i.e, they can prepare their own food by the process of photosynthesis.

Some members lack chlorophyll and thus show heterotrophic modes of nutrition such as -

• Parasitic nutrition - These plants grow on other host plants and completely or partially derive nutrition from them with the help of sucking roots called haustoria, e.g, Cuscuta, Dodder, mistletoe, etc.
• Insectivorous nutrition - Some photosynthetic plants grow on soil that lacks nitrogen and hence they feed on insects to satisfy their nitrogen requirement, e.g., pitcher plant and venus fly trap.

Reproduction in Plants

Reproduction in plants can occur -

• Asexually by vegetative propagation through vegetative parts such as roots, stems or leaves.
• Sexually by means of fusion of gametes.

Alternation of Generation in Plants

They show alternation of generation, i.e., their life cycle has two phases which alternate with each other. These phases are - 

• Diploid sporophyte phase
• Haploid gametophyte phase

The gametophyte and sporophyte may have independent existence or may be dependent on the other. Depending on the length and dominance of these phases in different divisions of plants, the life cycle of plants can be of 3 types -

• Haplontic - the haploid gametophyte phase is more dominant.
• Diplontic - the diploid sporophyte phase is more dominant.
• Haplo-diplontic - the haploid and diploid phases are equally prevalent.

Classification of Plants

On the basis of presence or absence of seeds, flowers, body organisation, and vascular tissues, plants can be majorly classified into two subkingdoms -

• Cryptogamae - This sub-kingdom includes non-seed bearing plants.
• Phanerogamae - It includes seed-bearing plants.

Cryptogamae is further classified into three divisions -

• Algae

• Bryophyta

• Pteridophyta

Phanerogamae is further classified into two divisions -

• Gymnospermae
• Angiospermae

Practice Problems of Kingdom Plantae

1. A plant with a dominant sporophyte phase but a short-lived gametophyte phase can be said to have which of the following patterns of life cycles?

1. 1. Haplontic

• Diplontic

1. Haplo-diplontic
2. Diplo-haplontic

Solution: The gametophyte is the haploid phase of a plant’s life cycle and the sporophyte is the diploid phase. Based on the dominance or prevalence of the haploid and diploid phase, the life cycle in plants can be -

• Haplontic - the haploid gametophyte phase is more dominant.
• Diplontic - the diploid sporophyte phase is more dominant.
• Haplo-diplontic - the haploid and diploid phases are equally prevalent.

Thus, a plant with a dominant sporophyte and a short-lived gametophyte has a diplontic life cycle.

Hence, the correct option is b.

1. Analysis of the cell wall composition of the cells of an unknown tissue sample showed that it is primarily composed of cellulose. The tissue must have been extracted from

1. 1. a fungus
   2. an animal

• a plant

1. Both a and c are correct

Solution:  Plants are multicellular, eukaryotic, photosynthetic organisms which are composed of cells that are primarily made of cellulose. Fungal cell walls are composed of chitin and animal cells lack cell walls.

Thus, the correct option is c.

1. Seed bearing plants can be classified under which of the following sub-kingdoms?

1. 1. Bryophyta
   2. Cryptogamae
   3. Thallophyta

• Phanerogamae

Solution: The kingdom plantae is majorly divided into two subkingdoms -

• Cryptogamae - includes the divisions of non seed-bearing plants such as Thallophyta, Bryophyta and Pteridophyta.
• Phanerogamae - includes the divisions of seed-bearing plants such as Angiospermae and Gymnospermae.

Thus, correct option is d.

1. During his walk through the jungle trail, David saw a plant which had roots digging into the body of another one. What is the probable mode of nutrition of the former plant?

1. 1. Autotrophic
   2. Saprotrophic

• Parasitic

1. Insectivorous

Solution: Plants with parasitic mode of nutrition have sucking roots called haustoria which penetrate the body of the host plant and derive nutrition from it. Thus, the probable mode of nutrition of the plant which had roots digging into the body of another one is parasitic.

Hence, the correct option is c.

FAQs of Kingdom Plantae

Question 1.- State five main characteristics of kingdom Plantae.
Answer. The five main characteristics of kingdom Plantae are -

1. The members of kingdom Plantae are multicellular, eukaryotic organisms, majority of which contain chlorophyll in their cells.
2. The organisms included in kingdom Plantae have cells with walls primarily made up of cellulose.

iii. Due to the presence of chlorophyll, most members of kingdom Plantae are autotrophic in nature.

1. Plants can reproduce asexually by vegetative propagation or sexually by fusion of gametes.
2. Plants exhibit alternation of generations in their life cycle.

Question 2.- What is the major significance of the members of kingdom Plantae?
Answer. Majority of the members of kingdom Plantae possess chlorophyll pigment indifferent parts of their body which makes them capable of synthesising their own food by the process of photosynthesis. This mode of nutrition is known as autotrophic mode of nutrition and makes plants the major producers of food in an ecosystem. All other forms of life are directly or indirectly dependent on plants for their nutrition.

Question3 .- What are the five divisions of kingdom Plantae?
Answer. Kingdom Plantae is divided into the following five divisions - 

1. Algae
2. Bryophyta

III. Pteridophyta

1. Gymnospermae
2. Angiospermae

Question 4.- What is meant by alternation of generations in plants?
Answer. Life cycle of plants has two phases which alternate with each other. These phases are - 

• Diploid sporophyte phase
• Haploid gametophyte phase

This phenomenon is known as alternation of generations in plants.

Other Related Topics

Other Related Topic Of Biology

• Kingdom Animalia
• Habitat of Fungi
• Reproduction in Fungi
• Shape and Structure of Eubacteria
• Kingdom Monera
• Nutrition Respiration and Reproduction in Eubacteria