An Overview of Class 11 Biology Study Of Characteristics Of Plant Specimens And Identification Of Reasons Experiment
Introduction
Plants of the same species change in traits based on the location and individual plant, just as humans have unique faces and other physical characteristics that set them apart from other species.By looking in a reference book or reading a description, it is difficult to identify a specific plant. However, if we see the specimen in person and use a magnifying glass or microscope to check the plant's size or observe its characteristics, we will be able to identify it. By looking at archived specimens, we can see the morphological variances and identify the specimen.
Table of Contents
Aim
Apparatus Required
Theory
Procedure
Observation
Classification
Diagnostic Features
Features
Result
Precautions
Lab Manual Questions
Viva Questions
Practical Based Questions
Summary
Frequently Asked Questions
Aim
To identify and explore the morphology of various bacterial, fungal, and plant species.
Apparatus Required
Permanent Slides of Bacteria
Oscillatoria
Spirogyra
Rhizopus
Yeast
Liverwort
Preserved/Fresh Specimens of Mushroom
Lichens
Moss
Fern
Pine
One Monocotyledonous Plant(ex:maize plant)
One Dicotyledonous Plant(ex:sunflower)
Theory
The study of morphology is the examination of a species. Classification is also involved in the process of comparing an unidentified specimen to a described specimen and concluding that the two components are the same. Identification is a fundamental step in classification, and nomenclature is crucial to information retrieval.It involves a study of internal or external characteristics.
Procedure
Microscopic tools can be used to study microscopic creatures like bacteria, algae, and fungi. Write the characters after examining the permanent slides under a microscope.
The naked eye can be used to examine large-sized specimens.
Write the features of identification.
Compare the features and the observations.
Observations
The specimens are observed and their features are noted.
Bacteria
Classification
Kingdom - Monera
Class - Eubacteria
Features
Bacteria are unicellular organisms
Small size.
Organelles with membranes, such as mitochondria, nuclei, and golgi bodies, are absent.
Mesosomes(They are recognized as an integral part of the cell membrane that are found in both prokaryotic and eukaryotic cells and support the production of cell walls and DNA replication) are visible.
Flagella is present for locomotion(movement).
Bacteria
Oscillatoria
Classification
Kingdom - Monera
Division - Cyanobacteria
Class - Cyanophyceae
Diagnostic Features
Each row of cells forming Oscillatoria create unbranched filaments.
The cells are cylindrical but broader than longer.
With the exception of the apical cell, which is convex at the top, all filament cells are similar.
Features
It is a blue-green algae.
Thallus is multicellular, unbranched, and filamentous.
The cells are stacked one on top of the other.
It has a cell wall and uses photosynthesis.
The filament may have some dead cells that are visible as empty gaps.
Fresh filament specimens exhibit oscillatory movements, therefore the name Oscillatoria.
Oscillatoria
Spirogyra
Classification
Kingdom - Plantae
Division - Thallophyta
Class - Chlorophyceae
Diagnostic Features
It is green filamentous algae.
Each filament is unbranched, and the cytoplasm holds one or more ribbon-shaped spirally arranged chloroplasts.
Features
Spirogyra is free floating blue green algae.
It has no branches and feels slimy to the touch.
The filament is made up of numerous long, cylindrical cells arranged in a single row, one above the other.
Spirogyra is useful for human consumption.
Each cell contains a single, sizable vacuole.
Spirogyra
Rhizopus
Classification
Kingdom - Fungi
Division - Eumycota
Class - Zygomycetes
Diagnostic Features
They are distinguished by a body of branching mycelium made up of three different hyphae kinds.
The tips of the black sporangia are rounded.
Features
Rhizopus have mycelia(branching body).
They mainly feed on dead matter.
Well developed rhizoids are present.
It is a cosmopolitan fungi.
The hyphae are of three types-stolons,rhizoids and sporangiophores.
Rhizopus
Agaricus (Mushroom)
Classification
Kingdom - Fungi
Division - Eumycota
Class - Basidiomycetes
Diagnostic Features
Agaricus resembles an umbrella.
On the lower side of the pileus, there are gills.
Features
Mushroom is the fruiting body of Agaricus
The fungus, a saprophyte, lives in humus-rich soil .
The thallus is made up of a mass of dense, colourless hyphae that is deep.
Two components of a mature mushroom can be identified.
A pileus-like structure attached ventrally to the centre of an upright stalk or stipe made up of a mass of vertically oriented hyphae.
An annulus, which resembles a collar and is part of the young basidiocarp's covering, can be seen at the base of the stipe.
Agaricus
Yeast
Classification
Kingdom - Fungi
Division - Eumycota
Class - Saccharomycetes
Diagnostic Features
Unicellular
Nuclear envelope is present.
Features
Oval or spherical in shape, cells have no colour.
Cells create chains of buds that aid in reproduction
There is one vacuole per cell.
Each cell has a single nucleus.
They reproduce asexually by budding and sexually by spore formation.
Yeast
Liverwort
Classification
Kingdom - Plantae
Division -Bryophyta
Class - Hepaticopsida
Diagnostic Features
The sporophyte is immersed in a flat thallus that has repetitive dichotomous branching.
Features
The thallus is a flat, dorsiventrally oriented thalloid structure that develops on the substratum(surface) of the soil.
The dorsal surface of the thallus is home to tiny gemma cups, which resemble little cups. They contain the gemmae, or vegetative propagules.
Rhizoids of two types—tuberculate and smooth-walled—that are colourless, unicellular, and present on the ventral side of the thallus are present. Through their capillary function, rhizoids aid in binding and water absorption.
Liverwort
Moss
Classification
Kingdom - Plantae
Division - Bryophyta
Class - Musci/Bryopsida
Diagnostic Features
Rhizoids are long, colourless.
Rhizoid branched and separated obliquely.
Features
The Funaria thallus is made up of a thin, erect "stem" that bears tiny, oval and leaf-like structures without midribs .
The green leaves are arranged in a spiral pattern on the stem-like section.
A group of filaments anchor the thallus to the substratum rhizoids.
Rhizoids are septate, long, colourless, and entwined.
Separate branches of the body carry the reproductive organ.
Moss
Fern
Classification
Kingdom - Plantae
Division - Pteridophyta
Class - Filicopsida
Diagnostic Features
Furcate venation on the pinnate leaves.
Fresh leaves have rementa.
Features
Fern has an underground, slant developing rhizome.
A cluster of adventitious roots and scale leaves are present on the short, thick rhizome, which is also covered in the remains of leaf bases.
The aerial shoot is made up of several large compound leaves, or fronds.
From a bud, a complex leaf develops. The circinate venation of the juvenile leaf. The petiole contains a thick covering of brown hair-like structures called ramenta, and the leaf is rolled downward from the apex, much like a watch spring.
Long, complex leaves with leaflets grouped on either side of the midrib, or "rachis," measure up to 1.0 to 1.5 metres in length.
The petiole's expanded portion is called the rachis.
When young, the petiole is lengthy, cylindrical, and hair-covered.
Fern
Pine
Classification
Kingdom - Plantae
Division - Spermatophyte
Class -Gymnospermae
Diagnostic Features
perennial evergreen tree seeds are naked.
Hard and woody stem
Features
Pinus is a tall, conical tree.
There are two types of branches: (a) branches with limitless development, and (b) branches with restricted expansion.
Both varieties of branches have an abundance of membranous, scaly, brown leaves.
Scale leaf axils bear branches with restricted development. They have a cluster of long, needle-like leaves and are 2–3 cm long.
The green leaves that resemble needles are known as acicular leaves.
The dwarf branch is referred to as a spur shoot because of its needles.
In the same plant, both the male and female cones bear reproductive organs.
Pine
Monocotyledonous Plant
Classification
Kingdom - Plantae
Division -Angiosperm
Class -Monocotyledonae
Diagnostic Features
Flowers are trimerous
Seeds are enclosed in fruits
Features
Differentiated plant body with roots, stems, and leaves .
Fibrous root system
Simple or complex leaves with parallel venation.
Ovules located within the carpels.
A seed has a single cotyledon.
For instance, paddy, sugarcane, wheat, and maize.
Monocotyledon root
Dicotyledonous Plant
Classification
Kingdom - Plantae
Division - Angiosperm
Class - Dicotyledonae
Diagnostic Features
Tap root system
Embryo has two cotyledons.
Features
Taproot system .
Leaves with reticulate venation, either simple or compound.
Tetramerous or pentamerous flowers that can grow singly or in groups to create inflorescences.
Stamens and carpels are reproductive organs. Ovules are located within the carpels.
The cotyledons in seeds are two.
Example: Ground nut, lady's finger, pea, hibiscus, and gramm.
Dicot stem
Lichens
Classification
Kingdom-Fungi
Division -.Thallophyta
Diagnostic Features
Lichens have a body known as a thallus, an outside layer of fungi called a cortex, and an interior layer of fungi known as a medulla.
Features
An interaction between an alga and a fungus results in the formation of lichens.
Lichens are a fantastic way to measure the quality of the air.
Lichens can develop on many different surfaces, including rocks, trees, buildings, and soil.
The most frequent algal partners are members of the Chlorophyta or Cyanophyceae family of blue-green bacteria.
Lichen
Results
Thus the specimens are identified and their features are noted.
Precautions
Do not take out the specimens
Handle the specimens and model carefully.
Do not write or move pen on the specimens
Lab Manual Questions
1. Why does the earthworm belong to the phylum Annelida?Give one reason.
Ans: They exhibit bilateral symmetry coelomate, triploblastic, and metamerically segmented. So they belong to the phylum annelida.
2. An unlabelled slide shows filamentous structures with linearly arranged cells and blank spaces occurring intermittently.Name the specimen.
Ans: The specimen with filamentous structures with linearly arranged cells and blank spaces occurring intermittently is Oscillatoria.
3. What type of leaves are found in ferns?
Ans: Ferns' leaves are frequently referred to as fronds.Fronds consist of a petiole and a leafy blade.
4. Given only flowers of some plants, how would you classify them as monocots and dicots?
Ans: Monocot flowers have a number of parts that is divisible by three.Dicot flowers have parts that are multiple of four or five.
Viva Questions
1. What is another name of Rhizopus?
Ans: Another name of Rhizopus is bread mould.
2. Where is Oscillatoria found?
Ans: In the shallow water of lakes, ponds, ditches, and slowly moving rivers, Oscillatoria can be found.
3. Reproduction of Spirogyra takes place by which method?
Ans: Spirogyra reproduces through fragmentation, which includes cutting the filaments into smaller pieces.
4. Example of a unicellular eukaryotic organism?
Ans: The examples of unicellular eukaryotes are Yeasts and algae.
5. Give examples of yeast?
Ans: Examples of yeast are Saccharomyces cerevisiae, genus Cryptococcus.
6. What do you mean by liverworts?
Ans: A liverwort is a spore-producing, flowerless plant that produces its spores in tiny capsules.
7. What is the main difference between mosses and liverworts?
Ans: Mosses are made up of tiny, leafy arrangements that have a straightforward structure. Liverworts feature stem-attached thallus arrangements that resemble green leaves.
8. Which group does the fern plant belong to?
Ans: Fern belongs to the phylum pteridophyta.
9. Pine trees belong to which plant group?
Ans: Pine trees belong to gymnosperms.
10. What are lichens?
Ans: Lichens are a symbiotic association between an alga and fungus.
Practical Based Questions
Yeast and mushroom are different from spirogyra because they
Cannot carry out photosynthesis
Lack cellulosic cell wall
Reproduce by sexual methods
Are terrestrial as well as aquatic
Ans: A. Cannot carry out photosynthesis
Vegetative reproduction in lichens takes place by
Isidia
Soredia
Fragmentation
All the above
Ans: D. All the above
Chloroplast in spirogyra is
Spirally arranged and ribbon shaped with pyrenoids
Spirally arranged
Circular
Cup shaped
Ans: A. Spirally arranged and ribbon shaped with pyrenoids
Needle shaped structure in pinus plant is
Leaf
Shoot
Stem
Reproductive part
Ans: A. Leaf
Which of the characters is an identifying feature of gymnosperms?
Naked seeds
Rhizoids present
Chlorophyll present
Does not possess vascular bundle
Ans: A. Naked seeds
Mosses are
Monoecious
Dioecious
Both a and b
None of these
Ans: A. Monoecious
Funaria differs from Dryopteris in
Bearing seeds
Having vascular bundle
Having a dependent sporophyte
Having an independent sporophyte
Ans: D. Having an independent sporophyte
Protein body associated with storage of starch grains in spirogyra is called
Leucoplast
Amyloplast
Pyrenoid
Chloroplast
Ans: C. Pyrenoid
While locating the stem of fern, the students find that it is
Underground rhizome
Coiled like spring
Totally absent
Branched and filamentous
Ans: A. Underground rhizome
The name cyanobacteria refers to
Bacteria
Blue green algae
Yeast
Fungi
Ans: B. Blue green algae
Summary
The specimens/models/slides are identified with their morphological and diagnostic features.Identification of specimens is the important step.
FAQs on Class 11 Biology Study Of Characteristics Of Plant Specimens And Identification Of Reasons Experiment
1. What are the most important characteristics to look for when identifying a Spirogyra slide in the Class 11 practical exam?
For identifying Spirogyra, focus on these two key features:
- It is an unbranched, filamentous green alga.
- It has one or more distinct, ribbon-shaped chloroplasts arranged in a spiral within each cylindrical cell.
The presence of pyrenoids (starch storage bodies) on the chloroplasts is also a confirmatory feature frequently asked in vivas.
2. How can you distinguish between a monocot and a dicot plant specimen based on their external morphology?
To identify a plant as a monocot or a dicot, observe the following important features:
- Root System: Monocots exhibit a fibrous root system, whereas dicots typically have a tap root system.
- Leaf Venation: Monocot leaves show parallel venation (veins run parallel). Dicot leaves show reticulate or net-like venation.
- Flower Parts: Monocot flowers are usually trimerous (floral parts in multiples of three), while dicot flowers are tetramerous or pentamerous (parts in multiples of four or five).
3. From an exam perspective, what are the two main identifying features of Agaricus (Mushroom)?
The two most important features for identifying an Agaricus specimen are:
- The mature fruiting body, called a basidiocarp, is umbrella-shaped and differentiated into a stalk-like stipe and a cap-like pileus.
- On the underside of the pileus, there are numerous radiating, plate-like structures called gills, which bear the spores for reproduction.
4. How can a student differentiate between a Moss (e.g., Funaria) and a Fern (e.g., Dryopteris) specimen?
The key difference lies in their plant body structure. A Moss has a simple plant body differentiated into a stem-like axis and leaf-like structures, but lacks true roots, stems, and leaves. A Fern has a well-differentiated plant body with true roots, an underground stem (rhizome), and large, compound leaves called fronds. A crucial point for exams is that Ferns possess vascular tissues (xylem and phloem), which are absent in Mosses.
5. What is the significance of the needle-like leaves and woody cones in a Pine (Pinus) specimen?
These features are critical adaptations for survival and are important points for viva questions:
- Needle-like leaves: These minimise water loss through transpiration due to their thick cuticle and sunken stomata, helping the plant survive in xerophytic (dry or cold) conditions.
- Woody cones: The hard, woody female cones provide robust protection for the developing ovules and naked seeds from environmental damage and predation. This is a hallmark feature of Gymnosperms.
6. Why are the rhizoids found in Moss and Liverwort specimens not considered true roots?
Rhizoids are not considered true roots because they are structurally much simpler. They are filamentous outgrowths that primarily serve for anchorage. Unlike true roots, they lack vascular tissues (xylem and phloem) and do not play a major role in the absorption of water and minerals, which primarily occurs through the general plant surface in these Bryophytes.
7. What is the fundamental difference a student must observe to distinguish between a slide of Rhizopus and a filament of Oscillatoria?
The most fundamental difference is their kingdom and mode of nutrition. Rhizopus is a fungus with a body made of coenocytic (multinucleate) hyphae and is saprophytic (non-photosynthetic). In contrast, Oscillatoria is a cyanobacterium (blue-green alga), is photosynthetic, and its body is a multicellular, unbranched filament composed of prokaryotic cells. Its characteristic oscillating movement is also a key identifier.
8. What is the main purpose of studying a diverse range of plant specimens as per the CBSE Class 11 Biology 2025-26 syllabus?
Studying these varied specimens is essential to understand the evolutionary progression in the plant kingdom. By observing specimens from Algae, Fungi, Bryophytes, Pteridophytes, and Gymnosperms, students can trace the gradual development of key biological features such as:
- The transition from a simple thallus to a differentiated plant body with true roots, stems, and leaves.
- The development of vascular tissues (xylem and phloem).
- The adaptation from aquatic to terrestrial habitats.
- Changes in reproductive strategies, leading to the formation of seeds.
9. What are lichens, and what two features make them an important specimen to study?
A lichen is a unique organism resulting from a symbiotic association between an alga (the phycobiont) and a fungus (the mycobiont). Two important features to remember for exams are:
- Dual Organism: The alga performs photosynthesis to provide food, while the fungus provides structure, protection, and absorption.
- Ecological Indicators: They are known as pioneers in ecological succession on bare rocks and are highly sensitive to air pollution, especially sulphur dioxide, making them excellent bioindicators.
