Plant Biology and Classification

It is the mouth of the capsule of the mosses which have toothed openings.

The members of a species are reproductively isolated from other species and are basic units of classification.

Roccella yields litmus solution, which is used as an indicator for acidity and alkalinity of the medium.

Roccella yields litmus solution, which is used as an indicator for acidity and alkalinity of the medium.

Thallophytes are characterised by the simple nature of their structure, i.e. undifferentiated thallus, which has no root, stem and leaf. Plants that do not have well-differentiated body design fall in this group. These plants are mostly aquatic. For example, Spirogyra, Chara, Ulothrix, Cladophora, etc.

Reason - The first level of classification among plants depends on well-differentiated distinct components of plants. For e.g. stems, roots, leaves. The next level of classification is based on the presence of special tissues for transfer of water and other substances in differentiated plant body, i.e. the presence or absence of vascular bundles. The final level of classification is based on the enclosure of seeds within fruits, i.e. the presence or absence of seed covering.  Therefore, (4) is not the criterion as cell wall is present in all plants and is made of cellulose, which makes cell wall rigid.

Reason: Kingdom Plantae is divided into 5 groups. (1) Thallophyta   e.g. Algae like Spirogyra, Chara, Cladophora (2) Bryophyta     e.g. Marchantia and Moss (3) Pteridophyta e.g. Marsilea, Ferns and Horse tails (4) Gymnosperms          e.g. Pines, Deodar  (5) Angiosperms            e.g. all flowering plants potato, tomato, Brassica (e.g. mustard)

Pteridophytes include ferns and marsilea (aquatic fern). The long-stalked leaves have four clover-like lobes and are held above water or are submerged. 

They do not have specialized tissues for the conduction of water & other substances from one part of plant body to another, i.e. they lack vascular tissues. Roots are absent in bryophytes. Instead there are root-like structures known as rhizoids.  Reason: Vascular tissue (xylem and phloem) helps in conduction of water and nutrients throughout the plant

Pteridophytes do not produce seeds. Reason: Ferns are pteridophytes. 

Reason: Flowering plants are called angiosperms. A fern is an example of pteridophyte. It does not bear flowers.

Pteridophytes have specialized tissues for the conduction of water and other substances from one part of plant to another part. They bear primitive vascular systems, i.e. evolved for the first time in pteridophytes (e.g. ferns).  Reason: Primitive - occurs at the first stage.

Mushroom belongs to the kingdom of Fungi. They are heterotrophic eukaryotic organisms as they derive their food from organic wastes. 

Reason: Thallophytes, bryophytes and pteridophytes have naked embryos that are called spores. The reproductive organs in these three groups are invisible and therefore they are called cryptogams. “Crypto” - hidden “gams” - gametes (1), (2), (3) cannot be the correct answer. The correct answer is gymnosperms. Gymnosperms - The plants of this group bear naked seeds. Therefore, they are not called cryptogams and are called phanerogams.

The first level of classification among plants depends on the well-differentiated distinct components of plants, e.g. stem, roots and leaves.