Morphology of Flowering Plants - Class 11 Biology - Chapter 5 - Notes, NCERT Solutions & Extra Questions
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Extra Questions - Morphology of Flowering Plants | NCERT | Biology | Class 11
Which ones are not analogous organs?
A) Wings of a bird and wings of a butterfly
B) Eye of an octopus and eyes of mammals
C) Flippers of penguins and flippers of dolphins
D) Thorns of Bougainvillea and tendrils of Cucurbita
The correct option is D) Thorns of Bougainvillea and tendrils of Cucurbita
Homologous organs are those that share similar anatomical structures and developmental origins but can perform different functions, indicating divergent evolution. Both the thorns of Bougainvillea and tendrils of Cucurbita derive from the stem, specifically modified from axillary buds, and fulfill different roles. Therefore, they are homologous organs.
Analogous organs, on the other hand, may not be anatomically similar, but they perform similar functions, illustrating convergent evolution.
Examples of analogous organs include:
Wings of a bird and wings of a butterfly: Both are used for flying but are structurally different.
Eye of an octopus and eyes of mammals: Both serve the function of vision despite their different structures.
Flippers of penguins and dolphins: These assist in movement but are anatomically different.
Match the reasons given in column 2 to the features of cacti in column 1.
features of cacti | Reasons |
---|---|
a. spiny leaves | (i) Absorbing water from the depths of soil |
b. Thick, round fleshy stems | (ii) prevent loss of water by transpiration |
c. Deep roots | (iii) store water |
d. Closed stomata during the day | (iv) prevent animals from eating the cactus |
e. Carbon di-xoide storage during the night |
Choose the correct option.
A) a - (iv); b - (ii); c - (iv), (iii); d - (i); e - (iii), (ii)
B) a - (ii),(iv); b - (ii), (iv); c - (i); d - (iii); e - (iii), (ii)
C) a - (ii), (iv); b - (ii); c - (i); d - (iii); e - (iii), (ii)
D) a - (ii), (iv); b - (ii), (iii); c - (i); d - (ii); e - (ii)
The correct option is D:
a – (ii), (iv)
b – (ii), (iii)
c – (i)
d – (ii)
e – (ii)
Cacti exhibit several anatomical and physiological adaptations that aid their survival in arid environments:
Leaves modified to thorns minimize surface area, thereby reducing water loss through transpiration.
The stems of cacti are succulent, designed to store significant amounts of water and perform photosynthesis, since they constitute the green, visible part of the plant.
To further conserve water, cacti possess stomata that remain closed during daytime. This mechanism prevents the escape of water vapor during the hottest part of the day.
At night, cacti engage in a special kind of photosynthesis (CAM photosynthesis), where they store carbon dioxide, thus optimizing water use.
The root system is extensive, with roots penetrating deep into the soil to access water reserves.
These features altogether contribute to the high efficiency of cacti in conserving water and thriving in desert-like conditions.
In some plants, the axillary bud is modified into thorn for protection. This is an example of:
A) Aerial stem modification
B) Sub-Aerial stem modification
C) Underground root modification
D) Aerial leaf modification
The correct option is A) Aerial stem modification.
In certain plants, the axillary bud is transformed into a thorn for protection purposes. Such a modification, where the stem part above the ground level adapts to form different structures like thorns, is known as Aerial stem modification. An example of this is seen in Bougainvillea.
Meristem is seen at the tip of the stem and root.
A. Apical
B. Intercalary
C. Lateral
The correct option is A. Apical
Meristematic tissues, based on their location, are categorized into three types:
Apical meristem is found at the tip of both the stem and root, where it facilitates the primary growth by increasing the length of the plant.
Intercalary meristem is located at the internodes or at the base of the leaves.
Lateral meristem occurs along the sides of the stem and root, contributing to the secondary growth by increasing the girth of the plant.
All plants bear flowers.
A) True
B) False
The correct answer is B) False.
Not all plants bear flowers. Examples of non-flowering plants include mosses and ferns. These plants reproduce through spores instead of flowers.
Select the flowers which commonly bloom in summers:
A. Sunflower
B. Orchid
C. Lily
D. Marigold
The correct options are:
A. Sunflower
D. Marigold
Different kinds of flowers bloom in different seasons. Marigold and Sunflower typically bloom during the summer. In contrast, Lily and Orchid generally blossom during the winter season.
Which of the following is not an adaptation of a water lily?
A. Long leaf-stalks filled with air spaces.
B. Broad leaves with an oily/waxy coating.
C. Presence of stomata only on the surface facing the air.
D. Roots that are small in size.
Correct Answer: D. Roots that are small in size.
Water lilies exhibit various adaptations that enhance their survival in aquatic environments:
A. Long leaf-stalks filled with air spaces: This feature aids the leaves in floating and maintaining buoyancy on the surface of the water.
B. Broad leaves with an oily/waxy coating: This adaptation prevents the leaves from being wetted by water, helping them to remain afloat and efficiently perform photosynthesis.
C. Presence of stomata only on the surface facing the air: Stomata are only found on the upper surface of the leaves, enabling the plant to exchange gases with the air above the water surface effectively.
Option D, 'Roots that are small in size', is incorrect as it does not represent an adaptation of water lilies. In fact, water lilies typically have extensive root systems that anchor them securely in the muddy bottoms of the water bodies they inhabit.
Which of the following pairs has a single layer of petals?
A. Hibiscus, Magnolia
B. Poppy, Petunia
C. Petunia, Magnolia
D. Hibiscus, Petunia
The correct answer is D. Hibiscus, Petunia
Petals are the brightly colored, scented parts of flowers which together form the corolla. This forming layer is typically the second whorl from the outer part of a flower toward the center. Depending on their arrangement, petals can be categorized into:
Single layered: The petals are arranged in a single layer. Examples include Hibiscus, Petunia, and Periwinkle.
Double Layered: The petals are organized in two distinct layers. Examples are Poppy, Daylily, and Magnolia.
Multiple Layered: Petals are arranged in multiple, often spiral layers. Examples include Water Lily, Dahlia, and Sunflower.
Given this classification, Hibiscus and Petunia each have a single layer of petals, making option D the correct choice.
Identify the incorrect statement(s): i) Strobilanthus kunthiana is locally called 'Neelakurinji'. ii) It will most probably bloom next in the year 2030. iii) These are monocarpic. iv) They are found in plain areas of Kerala. (Correct answer +1, wrong answer -0.25)
A) Only ii is incorrect
B) Both ii and iv are incorrect
C) Only iii is incorrect
D) Only iv is incorrect
The correct option is D) Only iv is incorrect.
Strobilanthus kunthiana, also known as NeelaKurinji in the local language, primarily grows in the hilly areas of Kerala, Maharashtra, and Tamil Nadu, not in plain areas.
This plant is known for its 12-year blooming cycle. It last flowered in 2006 (September-October) and then in 2018, predicting its next blossom in 2030. The plant produces vibrant blue flowers in massive quantities, which transforms the appearance of the hills into a spectacular blue, drawing tourists.
Neelakurinji is a monocarpic plant, meaning each shrub flowers once, reproduces, and then dies. This lifecycle ensures the periodic rejuvenation of the population, with seeds taking specific periods to mature and bloom.
The mass flowering event every 12 years aids the plant's survival. It produces numerous seeds, which not only prevent complete consumption by predators but also provide an excellent opportunity for the flowers to be extensively studied and enjoyed.
Reticulate venation is found in dicot leaves, while in monocot leaves venation is of the parallel type. Biology, being a "Science of exceptions," find out any exception to this generalization.
Reticulate venation is typically a feature of dicot leaves and parallel venation is generally found in monocot leaves. However, biology often presents exceptions to such rules.
One notable exception is the presence of parallel venation in some dicot plants such as Calophyllum and Corymbium. Conversely, reticulate venation can also be observed in certain monocot plants like Alocasia and Smilax.
Which of the following is not a lateral branch of the roots?
A Tertiary roots
B Secondary roots
C Primary root
D More than one option is correct
The correct answer is C) Primary root.
The primary root is essentially the direct continuation of the radicle and develops directly from the seed. In contrast, lateral branches, such as tertiary and secondary roots, emerge from the primary root or from one another.
Hence, the primary root does not represent a lateral branch itself.
Statements: All flowers are stems. All stems are roots. Conclusions: All roots are flowers. All stems are flowers.
A) if only Conclusion I follows
B) if only Conclusion II follows
C) if either I or II follows
D) if neither I nor II follows
E) if both I and II follow
The correct answer is D) if neither I nor II follows.
Based on the given statements:
"All flowers are stems."
"All stems are roots."
We can infer through logical sequence that all flowers are also roots because they fall within the category of stems, which are said to be roots. This relationship can be visualized in a Venn diagram where the circle representing flowers is entirely within the circle representing stems, which in turn is entirely within the circle representing roots.
However, concluding "All roots are flowers" is incorrect because not all roots have to be stems; they can be roots without being stems. Similarly, concluding "All stems are flowers" is incorrect because not all stems have to be flowers; stems include all flowers but can also include other entities that aren't flowers, as depicted by the broader circle encompassing stems.
Thus neither Conclusion I nor Conclusion II is logically correct given the statements.
Phyllode in Australian Acacia is a modified:
A) leaf base
B) petiole
C) lamina
D) leaf tip
The correct answer is B) petiole.
In Australian Acacia, the leaves are typically small and have a short lifespan. Due to this characteristic, the petioles of the plant undergo modifications. They expand, become green, and assume the role of photosynthesis—a task generally performed by the leaves. These modified petioles, capable of carrying out photosynthesis and synthesizing food, are referred to as phyllodes.
Both the main stem and the branches are modified into flat green organs performing the functions of leaves are known as:
A. Cladodes
B. Phyllodes
C. Phylloclades
D. Scales
The correct answer is C. Phylloclades.
Phylloclades refer to instances where both the main stem and the branches are modified into flat green organs that perform the functions typically associated with leaves.
In the case of cladodes, it is primarily the stem branches that are modified for leaf functions. A phyllode represents a changed form, specifically a modified petiole or shoot that connects the stem to what would normally be a leaf. As for scales, they are entirely different and are known as a type of body coverage on fish and reptiles, not related to leaf function at all.
Which of the following is not a characteristic feature of entomophily?
A Sticky pollen grains
B Long and hanging stamens
C Large flowers
D Brightly colored
The correct option is B Long and hanging stamens.
Entomophily refers to pollination by insects. Examples include sunflowers and orchids. Entomophilous flowers exhibit key characteristics such as:
Large flowers.
Flowers are typically brightly colored to attract insects.
Flowers emit scent and produce nectar.
Both pollen grains and stigma are sticky in nature to facilitate pollination by insects.
However, long and hanging stamens are characteristic features of wind-pollinated (anemophilous) plants, not insect-pollinated ones. These features are adapted to enhance the likelihood of pollen being dispersed by wind.
Scutellum is a
A) food storing haploid structure in grass embryo.
B) remnant of cotyledon in maize.
C) shield-shaped and large cotyledon in grasses.
D) protective covering of plumule in grasses.
The correct answer is C) shield-shaped and large cotyledon in grasses.
The scutellum functions as a large, shield-shaped cotyledon found primarily in the seeds of monocotyledonous plants, such as grasses. It plays a critical role in the absorption of nutrients during germination.
Rhizoids have the same function as roots in flowering plants.
A) True
B) False
The correct answer is B) False.
Rhizoids and roots may seem similar because they both anchor plants, but they are fundamentally different in structure and function. Rhizoids, which are found in organisms like bryophytes and ferns, are essentially simple filaments that help secure the plant to a surface. On the other hand, roots are more complex and consist of vascular tissues which are crucial for the uptake of water and nutrients.
Radish is a modified:
A Flower
B Leaves
C Roots
D Stem
The correct option is C Roots.
The edible part of the radish is the modified root.
Which of these are components of a pistil? I: Style II: Anther III: Stigma IV: Ovary
A) I and III
B) I, III, and IV
C) II and IV
D) I, III, and IV
The correct answer is D) I, III, and IV.
The pistil is the female reproductive part of a flower and comprises three main components:
Stigma (III): where pollen lands and germination occurs.
Style (I): a tube-like structure that connects the stigma to the ovary.
Ovary (IV): the part that develops into fruits and contains ovules, which ultimately develop into seeds after fertilization.
Anther (II), on the other hand, is part of the stamen, which is the male reproductive organ of the flower, responsible for producing pollen.
Thus, the components of the pistil are Style (I), Stigma (III), and Ovary (IV).
Identify the incorrect statement with respect to angiosperms:
A. Megasporophyll is commonly woody
B. Ovules are borne on a stalk or a funiculus
C. Archegonia are absent
D. Embryo is a post-fertilization structure
The incorrect statement with respect to angiosperms is:
A. Megasporophyll is commonly woody
Archegonia are female reproductive structures present in bryophytes and some gymnosperms, but not found in angiosperms where double fertilization occurs without them.
In heterosporous plants, like gymnosperms, there are two types of reproductive organs: megaspores and microspores. The structures bearing these spores are called sporophylls: Megasporophylls for megaspores and Microsporophylls for microspores. The megasporophylls in gymnosperms have a woody nature, but in angiosperms, they evolve into more delicate structures known as carpels.
The ovules in angiosperms are attached to the ovary wall by a structure termed the funiculus.
Post-fertilization, the zygote formed through the fusion of the male and female gametes undergoes mitosis to develop into an embryo, making the embryo a definite post-fertilization structure.
Therefore, statement A, "Megasporophyll is commonly woody", is incorrect for angiosperms as their carpels (formed from megasporophylls) are not woody.
Zygomorphic flowers show bilateral symmetry.
A. True
B. False
The correct answer is A. True.
Flowers can exhibit two types of symmetry: actinomorphic and zygomorphic.
Actinomorphic flowers possess radial symmetry, meaning they can be divided into two identical halves through any radial plane passing through their center. Examples include flowers from plants like mustard, datura, and chili.
Zygomorphic flowers, on the other hand, show bilateral symmetry. This type means the flowers can be divided into two mirrored halves only along one specific vertical plane. Examples of plants with zygomorphic flowers include pea, gulmohur, bean, and Cassia. Thus, the statement "Zygomorphic flowers show bilateral symmetry" is true.
On crossing tall plants with dwarf plants, the percentage of dwarf plants in F2 generation obtained by Mendel was
(A) $25%$ (B) $40%$ (C) $60%$ (D) $75%$
The correct answer is (A) $25%$.
Mendel's experiment involved crossing tall plants (TT) and dwarf plants (tt), leading to the following genetic crosses:
Cross of tall (TT) with dwarf (tt):
$TT \times tt$
All offspring in the F1 generation are heterozygous tall (Tt).
F1 generation self-pollination to produce F2 generation:
$Tt \times Tt$
We apply a Punnett Square to determine the offspring's genotype:
$$ \begin{array}{c|c|c} & \textbf{T} & \textbf{t} \\ \hline \textbf{T} & TT & Tt \\ \hline \textbf{t} & Tt & tt \\ \end{array}$$
Analyzing the Punnett square above, we see the following genotypes:
TT (1 out of 4 or $25%$): Tall
Tt (2 out of 4 or $50%$): Tall
tt (1 out of 4 or $25%$): Dwarf
Thus, the percentage of dwarf plants (tt) in the F2 generation is $25%$.
Which of the following is a flowering plant with nodules containing filamentous nitrogen-fixing microorganism?
A) Crotalaria juncea
B) Casuarina equisetifolia
C) Cicer arietinum
D) Cycas revoluta
The correct answer is Option B: Casuarina equisetifolia.
Casuarina equisetifolia is characterized as a flowering plant that forms nodules containing filamentous nitrogen-fixing microorganisms. These microorganisms are essential as they help in fixing atmospheric nitrogen, thus enriching the soil fertility.
The standard petal of papilionaceous corolla is also called:
A Carina
B Pappus
C Vexillum
D Corona
The correct answer is C) Vexillum.
The standard petal of a papilionaceous corolla is known as the vexillum. The term "papilionaceous" describes a flower with a corolla typically comprising five petals, where a large upper petal envelops two lateral wings, and two united lower petals form the carina, as seen in flowers like peas.
Spore dispersal in Funaria takes place by the activities of:
A. Operculum
B. Sporangium
C. Capsule
D. Peristome and annulus
The correct answer is D. Peristome and annulus.
In the moss Funaria, spore dispersal is primarily facilitated by the hygroscopic movements of the peristomial teeth. These movements involve the lengthening and shortening of peristomial teeth, which help in controlling the release of spores. The inner peristome functions like a sieve, allowing only a few spores to escape at a time, ensuring a gradual dispersal.
All leaves in a plant will always be of the same size.
A) True
B) False
The correct answer is B) False.
Not all leaves on a plant are consistent in terms of size or appearance. Variations can occur in size, color, and shape. For instance, leaves exposed to more sunlight often differ in appearance compared to those in denser, shaded areas.
Which statement(s) are true about trees in hilly areas?
A) These trees are normally cone-shaped. B) They have sloping branches. C) The leaves of some of these trees are needle-like. D) All of the above.
The correct option is D) All of the above.
Trees in hilly areas are typically cone-shaped, which assists in shedding snow and rain more efficiently, preventing heavy build-ups that could lead to branch breakage.
These trees tend to have sloping branches; this configuration aids in the natural slide-off of precipitation such as snow and rain.
The leaves of some trees from hilly regions are adapted to be needle-like, which minimizes water loss and is an effective form in resisting cold and reducing snow accumulation on the leaves themselves.
Thus, all the statements given - A, B, and C - correctly describe the typical characteristics of trees found in hilly or mountainous areas.
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How is a pinnately compound leaf different from a palmately compound leaf?
A pinnately compound leaf has a number of leaflets arranged along a common axis called the rachis, which represents the midrib of the leaf (e.g., neem).
A palmately compound leaf, on the other hand, has all the leaflets attached at a common point at the tip of the petiole, similar to the fingers of a hand spreading out from the palm (e.g., silk cotton).
These distinctions are crucial for identifying and classifying plants based on their leaf morphology.
Explain with suitable examples the different types of phyllotaxy.
Phyllotaxy is the pattern of arrangement of leaves on the stem or branch. There are three main types of phyllotaxy:
Alternate Phyllotaxy: In this type, a single leaf arises at each node in an alternate manner. Examples include:
China rose
Mustard
Sunflower
Opposite Phyllotaxy: Here, a pair of leaves arise at each node and lie opposite to each other. Examples include:
Calotropis
Guava
Whorled Phyllotaxy: In this type, more than two leaves arise at a node and form a whorl. An example is:
Alstonia
Visual Examples
Alternate Phyllotaxy (China rose)
Opposite Phyllotaxy (Guava)
Whorled Phyllotaxy (Alstonia)
Define the following terms:
(a) aestivation
(b) placentation
(c) actinomorphic
(d) zygomorphic
(e) superior ovary
(f) perigynous flower
(g) epipetalous stamen
(a) Aestivation
Aestivation is the mode of arrangement of sepals or petals in a floral bud with respect to the other members of the same whorl. The main types of aestivation include valvate, twisted, imbricate, and vexillary.
(b) Placentation
Placentation is the arrangement of ovules within the ovary. The different types of placentation include marginal, axile, parietal, basal, central, and free central.
(c) Actinomorphic
A flower is actinomorphic (radial symmetry) if it can be divided into two equal radial halves in any radial plane passing through the center. Examples include mustard, datura, and chilli.
(d) Zygomorphic
A flower is zygomorphic (bilateral symmetry) if it can be divided into two similar halves only in one particular vertical plane. Examples include pea, gulmohur, bean, and Cassia.
(e) Superior Ovary
A superior ovary is a condition where the gynoecium occupies the highest position while the other flower parts are situated below it, as seen in mustard, china rose, and brinjal.
(f) Perigynous Flower
A perigynous flower has the gynoecium situated in the center and other parts of the flower are located on the rim of the thalamus almost at the same level. The ovary in such flowers is said to be half inferior, e.g., plum, rose, and peach.
(g) Epipetalous Stamen
Epipetalous stamens are stamens that are attached to the petals. An example is found in the brinjal plant.
These terms describe various anatomical and morphological characteristics of flowers, which are important for their classification and understanding their structure and function.
Differentiate between
(a) Racemose and cymose inflorescence
(b) Apocarpous and syncarpous ovary
(a) Racemose and Cymose Inflorescence
Racemose Inflorescence:
Growth: The main axis continues to grow.
Flower Arrangement: Flowers are borne laterally in an acropetal succession (youngest at the top and oldest at the base).
Example: Seen in many flowering plants like mustard.
Cymose Inflorescence:
Growth: The main axis terminates in a flower, hence growth is limited.
Flower Arrangement: Flowers are borne in a basipetal order (oldest at the top and youngest at the base).
Example: Seen in many flowering plants like jasmine.
(b) Apocarpous and Syncarpous Ovary
Apocarpous Ovary:
Carpel Arrangement: Carpels are free from each other.
Example: Seen in plants like lotus and rose.
Syncarpous Ovary:
Carpel Arrangement: Carpels are fused together.
Example: Seen in plants like mustard and tomato.
Draw the labelled diagram of the following:
(i) gram seed (ii) V.S. of maize seed
Sure, here are the labeled diagrams:
(i) Gram Seed (Dicotyledonous Seed)
(ii) V.S. of Maize Seed (Monocotyledonous Seed)
These diagrams illustrate the internal structures of both dicotyledonous and monocotyledonous seeds.
Take one flower of the family Solanaceae and write its semi-technical description. Also draw their floral diagram.
Semi-Technical Description of Solanum nigrum (makoi)
Family: Solanaceae
Vegetative Characters:
Plant: Mostly herbs or shrubs, rarely small trees.
Stem: Herbaceous, rarely woody, aerial, erect, cylindrical, branched, solid or hollow, hairy or glabrous. Underground stem in potato (Solanum tuberosum).
Leaves: Alternate, simple, rarely pinnately compound, exstipulate, venation reticulate.
Floral Characters:
Inflorescence: Solitary, axillary or cymose, as seen in Solanum.
Flower: Bisexual, actinomorphic.
Calyx: Sepals five, united, persistent, valvate aestivation.
Corolla: Petals five, united, valvate aestivation.
Androecium: Stamens five, epipetalous.
Gynoecium: Bicarpellary, syncarpous; ovary superior, bilocular, placenta swollen with many ovules, axile placentation.
Fruit: Berry or capsule.
Seeds: Many, endospermous.
Floral Formula: $\oplus \bigcap^{\top} K_{(5)} \overparen{C_{(5)}} A_{5} \underline{G}_{(2)}$
Floral Diagram:
Additional Visuals from the Chapter:
Flowering twig:
Flower:
L.S. of flower:
Stamens:
Carpel:
Describe the various types of placentations found in flowering plants.
The various types of placentations found in flowering plants are:
Marginal Placentation:
Description: The placenta forms a ridge along the ventral suture of the ovary, and ovules are borne on this ridge forming two rows.
Example: Pea.
Figure:
Label: (a) Marginal
Axile Placentation:
Description: The placenta is axial, and ovules are attached to it in a multilocular ovary.
Example: China rose, tomato, lemon.
Figure:
Label: (b) Axile
Parietal Placentation:
Description: Ovules develop on the inner wall of the ovary or on the peripheral part. The ovary is usually one-chambered, but becomes two-chambered due to the formation of a false septum.
Example: Mustard, Argemone.
Figure:
Label: (c) Parietal
Free Central Placentation:
Description: Ovules are borne on the central axis, and septa are absent.
Example: Dianthus, Primrose.
Figure:
Label: (d) Free central
Basal Placentation:
Description: The placenta develops at the base of the ovary and usually bears a single ovule.
Example: Sunflower, marigold.
Figure:
Label: (e) Basal
What is a flower? Describe the parts of a typical angiosperm flower.
What is a Flower?
A flower is the reproductive unit in the angiosperms (flowering plants) and is meant for sexual reproduction.
Parts of a Typical Angiosperm Flower
A typical flower has four different kinds of whorls arranged successively on the swollen end of the stalk or pedicel, called the thalamus or receptacle. These are:
Calyx
Corolla
Androecium
Gynoecium
Calyx and corolla are accessory organs, while androecium and gynoecium are reproductive organs.
1. Calyx
The outermost whorl of the flower.
The members are called sepals.
Generally green, leaf-like, and protect the flower in the bud stage.
May be gamosepalous (sepals united) or polysepalous (sepals free).
2. Corolla
Composed of petals.
Usually brightly colored to attract insects for pollination.
May be gamopetalous (petals united) or polypetalous (petals free).
The shape and color vary greatly and can be tubular, bell-shaped, funnel-shaped, or wheel-shaped.
3. Androecium
Consists of stamens, representing the male reproductive organ.
Each stamen has a stalk (filament) and an anther.
Anther is usually bilobed with pollen-sacs where pollen grains are produced.
May be epipetalous (attached to petals) or epiphyllous (attached to the perianth).
Stamens can be free (polyandrous) or united in various ways (monadelphous, diadelphous, polyadelphous).
4. Gynoecium
The female reproductive part, made up of one or more carpels.
Each carpel consists of three parts: stigma, style, and ovary.
Stigma: the receptive surface for pollen grains.
Style: an elongated tube connecting ovary and stigma.
Ovary: contains one or more ovules attached to a cushion-like placenta.
Carpels may be free (apocarpous) or fused (syncarpous).
After fertilization, ovules develop into seeds and the ovary matures into a fruit.
Additional Points
Floral Diagram and Floral Formula are used to summarize the floral structure.
The diagram shows the arrangement and relation of floral parts.
Define the term inflorescence. Explain the basis for the different types inflorescence in flowering plants.
Inflorescence is the arrangement of flowers on the floral axis.
Basis for Different Types of Inflorescence
Inflorescence types are primarily based on the growth of the main axis and the pattern of flower arrangement. The two major types are:
Racemose:
In this type, the main axis continues to grow, and flowers are borne laterally in an acropetal succession (youngest flowers at the tip, oldest at the base).
*Figure 5.7 Racemose inflorescence*
Cymose:
In this type, the main axis terminates in a flower, and the growth is limited. Flowers are borne in a basipetal order (oldest flowers at the tip, youngest at the base).
*Figure 5.8 Cymose inflorescence*
The arrangement allows the plant to optimize for pollination and reproductive success.
Describe the arrangement of floral members in relation to their insertion on thalamus.
The arrangement of floral members in relation to their insertion on thalamus can be described as hypogynous, perigynous, and epigynous:
Hypogynous Flowers: In these flowers, the gynoecium occupies the highest position, while the other floral parts (calyx, corolla, and androecium) are situated below it. The ovary is superior. Examples include mustard, china rose, and brinjal.
Perigynous Flowers: Here, the gynoecium is positioned in the center, and other floral parts are located on the rim of the thalamus at the same level. The ovary is half inferior. Examples are plum, rose, and peach.
Epigynous Flowers: In epigynous flowers, the thalamus grows upward, enclosing the ovary completely and fusing with it. The other floral parts arise above the ovary. The ovary is inferior. Examples are guava, cucumber, and the ray florets of sunflower.
These arrangements influence the classification and identification of the flowers.
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Comprehensive Class 11 Notes on the Morphology of Flowering Plants
Introduction to Morphology of Flowering Plants
Morphology refers to the study of the form and structure of organisms. In the context of flowering plants, morphology encompasses their various parts, which include roots, stems, leaves, flowers, and fruits. This understanding is crucial for identifying, classifying, and studying plants.
Major Parts of a Flowering Plant
The Root
Roots are vital structures in flowering plants, anchoring them in the soil and absorbing water and minerals. There are various types of root systems:
Taproot System: Found primarily in dicotyledonous plants. It features a main primary root that grows deep into the soil with lateral roots branching out.
Fibrous Root System: Characteristic of monocotyledonous plants, where the primary root is short-lived and is replaced by many roots originating from the base of the stem.
Adventitious Roots: These roots develop from parts of the plant other than the radicle. They can provide additional support, especially in plants like grass and banyan trees.
graph TD
A[Root System]
A --> B[Taproot System]
A --> C[Fibrous Root System]
A --> D[Adventitious Roots]
Regions of the Root
The root can be divided into specific regions:
- Root Cap: Protects the root tip as it pushes through the soil.
- Region of Meristematic Activity: Contains actively dividing cells.
- Region of Elongation: Cells enlarge and elongate, aiding root growth.
- Region of Maturation: Cells differentiate and mature; root hairs develop here to absorb water and minerals.
The Stem
The stem is the ascending part of the plant axis, bearing branches, leaves, flowers, and fruits. It develops from the plumule of a germinating seed. Its primary functions include:
- Spreading branches with leaves, flowers, and fruits.
- Conducting water, minerals, and food.
- In some cases, storing food, providing support, and enabling vegetative propagation.
The Leaf
Leaves are flattened lateral structures essential for photosynthesis. They develop at nodes on the stem and are classified based on their structure:
- Simple Leaf: A single, undivided leaf blade.
- Compound Leaf: Leaf blade divided into leaflets.
Venation: The arrangement of veins in a leaf:
- Reticulate Venation: Veins form a network, typical of dicots.
- Parallel Venation: Veins run parallel, typical of monocots.
Phyllotaxy: The arrangement of leaves on a stem:
- Alternate: Single leaf per node in an alternate fashion.
- Opposite: Pairs of leaves at each node.
- Whorled: More than two leaves per node.
Flower and Its Structure
Flower - A Modified Shoot
A flower is a reproductive organ formed by the transformation of the shoot apical meristem into a floral meristem. It consists of:
- Calyx: Outermost whorl, composed of sepals.
- Corolla: The colourful whorl, composed of petals.
- Androecium: The male reproductive whorl, composed of stamens.
- Gynoecium: The female reproductive whorl, composed of carpels.
graph TD
A[Flower]
A --> B[Calyx]
A --> C[Corolla]
A --> D[Androecium]
A --> E[Gynoecium]
Inflorescence
Inflorescence refers to the arrangement of flowers on a floral axis. Two main types are:
- Racemose: Flowering is acropetal, with the oldest flowers at the base.
- Cymose: Flowering is basipetal, with the oldest flowers at the top.
Classification Based on Flower Structure
Symmetry
- Actinomorphic: Radial symmetry; can be divided into two equal halves.
- Zygomorphic: Bilateral symmetry; can be divided into similar halves by only one plane.
Position of Floral Parts
Flowers can be classified based on the relative position of the calyx, corolla, and androecium in relation to the ovary:
- Hypogynous: Ovary is superior.
- Perigynous: Ovary is half-inferior.
- Epigynous: Ovary is inferior.
Seeds and Fruits
The Fruit
A fruit is a mature ovary that develops after fertilisation. Its structure can vary widely and it can be classified as either dry or fleshy. For example, mango and coconut are drupes with differentiated layers: epicarp, mesocarp, and endocarp.
The Seed
Seeds are the product of fertilised ovules and contain an embryo enclosed within a seed coat.
Dicotyledonous Seeds: They have two cotyledons and are enclosed by a seed coat comprising the outer testa and inner tegmen.
Monocotyledonous Seeds: Typically endospermic, with a single cotyledon known as a scutellum.
Special Case Study - Solanaceae Family
The Solanaceae family, also known as the potato family, is widespread and includes plants of significant economic importance:
Vegetative Characters:
- Mostly herbs, shrubs, or small trees.
- Leaves with alternate arrangement and reticulate venation.
Floral Characters:
- Bisexual and actinomorphic flowers.
- Sepals and petals often united.
- Fruits typically berries or capsules.
Economic Importance
Members of the Solanaceae family include essential food sources like potatoes, tomatoes, and spices like chilli. Some have medicinal uses, such as belladonna, and others are ornamental plants like petunias.
Placentation in Flowering Plants
Placentation refers to the arrangement of ovules within the ovary. Types include:
- Marginal: Ovules attached along the margin.
- Axile: Ovules attached to a central axis.
- Parietal: Ovules attached to the ovary wall.
- Basal: Single ovule attached at the base.
- Free Central: Ovules attached to a central column without septa.
graph TD
A[Placentation]
A --> B[Marginal]
A --> C[Axile]
A --> D[Parietal]
A --> E[Basal]
A --> F[Free Central]
Conclusion
Understanding the morphology of flowering plants is essential for classification and identification. Detailed knowledge of roots, stems, leaves, flowers, fruits, and seeds provides insight into the diverse adaptations and functions plants have developed to thrive in various environments.
Frequently Asked Questions (FAQ)
What is the morphology of flowering plants? Morphology in flowering plants refers to the study of their external structure, including roots, stems, leaves, flowers, and fruits.
What are the main functions of the stem in flowering plants? The stem supports branches with leaves, flowers, and fruits. It also conducts water, minerals, and synthesised nutrients throughout the plant and can store food.
What distinguishes a dicotyledonous seed from a monocotyledonous seed? Dicotyledonous seeds have two cotyledons, whereas monocotyledonous seeds have one. Additionally, monocot seeds often have an endosperm, which stores food for the embryo.
Why is the study of plant morphology important? Studying plant morphology aids in the identification, classification, and understanding of the diverse adaptations that plants have evolved, helping us comprehend plant biology and ecology better.
References
- NCERT Textbook for Class 11 Biology
- Additional botanical references for in-depth understanding and study
By covering these topics in a detailed manner, students can gain a comprehensive understanding of the morphology of flowering plants, as outlined in their Class 11 syllabus.
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