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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.
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.
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 -
Reproduction in plants can occur -
They show alternation of generation, i.e., their life cycle has two phases which alternate with each other. These phases are -
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 -
On the basis of presence or absence of seeds, flowers, body organisation, and vascular tissues, plants can be majorly classified into two subkingdoms -
Cryptogamae is further classified into three divisions -
Phanerogamae is further classified into two divisions -
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 -
Thus, a plant with a dominant sporophyte and a short-lived gametophyte has a diplontic life cycle.
Hence, the correct option is b.
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.
Solution: The kingdom plantae is majorly divided into two subkingdoms -
Thus, correct option is d.
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.
Question 1.- State five main characteristics of kingdom Plantae.
Answer. The five main characteristics of kingdom Plantae are -
iii. Due to the presence of chlorophyll, most members of kingdom Plantae are autotrophic in nature.
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 -
III. Pteridophyta
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 -
This phenomenon is known as alternation of generations in plants.