Case Study Questions Class 11 Biology Morphology of Flowering Plants

Case Study Questions Class 11 Biology Chapter 5 Morphology of Flowering Plants

CBSE Class 11 Case Study Questions Biology Morphology of Flowering Plants. Important Case Study Questions for Class 11 Board Exam Students. Here we have arranged some Important Case Base Questions for students who are searching for Paragraph Based Questions Morphology of Flowering Plants.

At Case Study Questions there will given a Paragraph. In where some Important Questions will made on that respective Case Based Study. There will various types of marks will given 1 marks, 2 marks, 3 marks, 4 marks.

CBSE Case Study Questions Class 11 Biology Morphology of Flowering Plants

CASE 1

In majority of the dicotyledonous plants, the direct elongation of the radicle leads to the formation of primary root which grows inside the soil. It bears lateral roots of several orders that are referred to as secondary, tertiary, etc. roots. The primary roots and its branches constitute the tap root system, as seen in the mustard plant. In monocotyledonous plants, the primary root is short lived and is replaced by a large number of roots. These roots originate from the base of the stem and constitute the fibrous root system, as seen in the wheat plant. In some plants, like grass, Monstera and the banyan tree, roots arise from parts of the plant other than the radicle and are called adventitious roots. The main functions of the root system are absorption of water and minerals from the soil, providing a proper anchorage to the plant parts, storing reserve food material and synthesis of plant growth regulators.

The root is covered at the apex by a thimble-like structure called the root cap. It protects the tender apex of the root as it makes its way through the soil. A few millimetres above the root cap is the region of meristematic activity. The cells of this region are very small, thin-walled and with dense protoplasm. They divide repeatedly. The cells proximal to this region undergo rapid elongation and enlargement and are responsible for the growth of the root in length. This region is called the region of elongation. The cells of the elongation zone gradually differentiate and mature. Hence, this zone, proximal to region of elongation, is called the region of maturation. From this region some of the epidermal cells form very fine and delicate, thread-like structures called root hairs. These root hairs absorb water and minerals from the soil.

Roots in some plants change their shape and structure and become modified to perform functions other than absorption and conduction of water and minerals. They are modified for support, storage of food and respiration. Tap roots of carrot, turnip and adventitious roots of sweet potato, get swollen and store food. In some plants such as Rhizophora growing in swampy areas, many roots come out of the ground and grow vertically upwards. Such roots, called pneumatophores, help to get oxygen for respiration.

1.) Identify incorrect statement

Statement 1 – The root is covered at the apex by a thimble-like structure called the root cap.

Statement 2 – Elongation of the radicle leads to the formation of primary root.

Statement 3 – Pneumatophores are roots come out of the ground and grow vertically upwards

Statement 4 – Root hairs absorb water and minerals from the soil.

a.) Only 1

b.) Only 3

c.) Both 2 & 3

d.) None of the above

2.) Which of the following is feature of primary roots

a.) Short lived.

b.) Originate from the base of the stem

c.) Constitute the fibrous root system.

d). All of the above.

3.) What is the function of roots?

4.) What are adventitious roots?

5.) Explain root modification and give any two example of root modification?

6.) What is pneumatophores?

Answer key

1.) d

2.) d

3.) Roots perform the following functions:

o Roots absorb water and nutrients from the soil.

o They anchor the plant firmly.

o They help in storing food and nutrients.

o Roots transport water and minerals to the plant.

4.) The roots developed from different parts of the plant other than radicle are called as the adventitious roots.

5.) Root modification – Roots in some plants change their shape and structure and become modified to perform functions other than absorption and conduction of water and minerals. They are modified for support, storage of food and respiration.

Examples,

o Tap roots of carrot.

o Adventitious roots of sweet potato, get swollen and store food.

6.) Pneumatophores – In some plants many roots come out of the ground and grow vertically upwards. Such roots, called pneumatophores, help to get oxygen for respiration.

CASE 2

The leaf is a lateral, flattened structure borne on the stem. It develops at the node and bears a bud in its axil. The axillary bud later develops into a branch. Leaves originate from shoot apical meristems and are arranged in an acropetal order. They are the most important vegetative organs for photosynthesis.

A typical leaf consists of three main parts: leaf base, petiole and lamina. The leaf is attached to the stem by the leaf base and may bear two lateral small leaf like structures called stipules. In monocotyledons, the leaf base expands into a sheath covering the stem partially or wholly. In some leguminous plants the leaf base may become swollen, which is called the pulvinus. The petiole help hold the blade to light. Long thin flexible petioles allow leaf blades to flutter in wind, thereby cooling the leaf and bringing fresh air to leaf surface. The lamina or the leaf blade is the green expanded part of the leaf with veins and veinlets. There is, usually, a middle prominent vein, which is known as the midrib. Veins provide rigidity to the leaf blade and act as channels of transport for water, minerals and food materials. The shape, margin, apex, surface and extent of incision of lamina varies in different leaves.

The arrangement of veins and the veinlets in the lamina of leaf is termed as venation. When the veinlets form a network, the venation is termed as reticulate. When the veins run parallel to each other within a lamina, the venation is termed as parallel. Leaves of dicotyledonous plants generally possess reticulate venation, while parallel venation is the characteristic of most monocotyledons.

A leaf is said to be simple, when its lamina is entire or when incised, the incisions do not touch the midrib. When the incisions of the lamina reach up to the midrib breaking it into a number of leaflets, the leaf is called compound. The compound leaves may be of two types. In a pinnately compound leaf a number of leaflets are present on a common axis, the rachis, which represents the midrib of the leaf as in neem. In palmately compound leaves, the leaflets are attached at a common point, i.e., at the tip of petiole, as in silk cotton.

Phyllotaxy is the pattern of arrangement of leaves on the stem or branch. If is of three types – alternate, opposite and whorled. In alternate type of phyllotaxy, a single leaf arises at each node in alternate manner, e.g. China rose, sun flower plants. In opposite type, a pair of leaves arise at each node and lie opposite to each other as in Calotropis and guava plants. If more than two leaves arise at a node and form a whorl, it is called whorled, e.g. Alstonia.

1.) The arrangement of veins and the veinlets in the lamina of leaf is termed as

a.) Phyllotaxy

b.) Venation

c.) Reticulate venation

d.) Parallel venation

2.) The leaf attached to the stem by the leaf base and may bear two lateral small leaf like structures termed as

a.) Petiole

b.) Lamina

c.) Stipules

d.) Pulvinus

3.) Explain different parts of typical leaf.

4.) Explain types of venation with suitable examples.

5.) Explain different types of phyllotaxy with suitable examples.

Answer key

1.) b

2.) c

3.) A typical leaf consists of three main parts: leaf base, petiole and lamina.

o Leaf base – The leaf is attached to the stem by the leaf base and may bear two lateral small leaf like structures called stipules. In monocot, the leaf base expands into a sheath covering the stem partially or wholly. In some leguminous plants the leaf base may become swollen, which is called the pulvinus.

o Petiole – The petiole help hold the blade to light. Long thin flexible petioles allow leaf blades to flutter in wind, thereby cooling the leaf and bringing fresh air to leaf surface.

o Lamina – The lamina or the leaf blade is the green expanded part of the leaf with veins and veinlets. There is, usually, a middle prominent vein, which is known as the midrib. Veins provide rigidity to the leaf blade and act as channels of transport for water, minerals and food materials.

4.) Venation is the arrangement of veins and the veinlets in the lamina of leaf is termed as venation.

o Reticulate venation – When the veinlets form a network, the venation is termed as reticulate. Leaves of dicotyledonous plants generally possess reticulate venation.

o Parallel venation – When the veins run parallel to each other within a lamina, the venation is termed as parallel, while parallel venation is the characteristic of most monocotyledons.

5.) The pattern in which the leaves are arranged on the stem is known as phyllotaxy. These are of three types:

o Alternate Phyllotaxy- The leaf arises from each node in an alternate manner. For eg. China rose, sunflower.

o Opposite Phyllotaxy- The leaves arising at each node lie opposite to each other. For eg., Calotropis

o Whorled Phyllotaxy– More than two leaves arise at each node and form a whorl. For eg., Alstonia

CASE 3

The ovules after fertilisation, develop into seeds. A seed is made up of a seed coat and an embryo. The embryo is made up of a radicle, an embryonal axis and one (as in wheat, maize) or two cotyledons (as in gram and pea).

Dicotyledonous Seed The outermost covering of a seed is the seed coat. The seed coat has two layers, the outer testa and the inner tegmen. The hilum is a scar on the seed coat through which the developing seeds were attached to the fruit. Above the hilum is a small pore called the micropyle. Within the seed coat is the embryo, consisting of an embryonal axis and two cotyledons. The cotyledons are often fleshy and full of reserve food materials. At the two ends of the embryonal axis are present the radicle and the plumule. In some seeds such as castor the endosperm formed as a result of double fertilisation, is a food storing tissue and called endospermic seeds. In plants such as bean, gram and pea, the endosperm is not present in mature seeds and such seeds are called non-endospermous.

Monocotyledonous seeds are endospermic but some as in orchids are non-endospermic. In the seeds of cereals such as maize the seed coat is membranous and generally fused with the fruit wall. The endosperm is bulky and stores food. The outer covering of endosperm separates the embryo by a proteinous layer called aleurone layer. The embryo is small and situated in a groove at one end of the endosperm. It consists of one large and shield shaped cotyledon known as scutellum and a short axis with a plumule and a radicle. The plumule and radicle are enclosed in sheaths which are called coleoptile and coleorhiza respectively.

1.) The scar on the seed coat through which the developing seeds were attached to the fruit, is termed as

a.) Hilum

b.) Micropyle

c.) Cotyledons

d.) Coleoptile

2.) Identify incorrect statement

Statement 1 – The embryo is made up of a radicle, an embryonal axis and cotyledons.

Statement 2 –Monocotyledonous seeds are endospermic but some are non-endospermic.

Statement 3 – The seed coat has two layers, the outer testa and the inner tegmen.

Statement 4 – The outermost covering of a seed is the hilum.

a.) Both 1 & 2

b.) Both 3 & 4

c.) Only 4

d.) None of the above

3.) Define seed? What are the type of seed?

4.) Write short note on seed coat?

5.) How are the seeds of monocot plant different from dicot plants?

Answer key

1.) a

2.) c

3) Seed is defined as a small embryonic “plant,” enclosed by a covering called seed coat, with some stored food materials.A seed is of two types namely,

o Monocotyledonous seed

o Dicotyledonous seed.

4.) The outermost covering of a seed is the seed coat.

o The seed coat has two layers, the outer testa and the inner tegmen.

o The hilum is a scar on the seed coat through which the developing seeds were attached to the fruit.

o Above the hilum is a small pore called the micropyle.

o Within the seed coat is the embryo, consisting of an embryonal axis and two cotyledons.

5.) Difference between monocot seed and dicot seed :

Monocot Seed

Dicot Seed

o   Only single cotyledon is present in the embryo

o   Two cotyledons are present in the embryo
o   The seed is thin and lacks food materials

o   Seed is fleshy and stores food materials

o   Presence of endosperm

o   Absence of endosperm
o   Example- Corn seed

o   Example- Bean seed

CASE 4

The flower is the reproductive unit. It is meant for sexual reproduction. A typical flower has four different kinds of whorls arranged successively on the swollen end of the stalk or pedicel, called thalamus or receptacle. These are calyx, corolla, androecium and gynoecium. Calyx and corolla are accessory organs, while androecium and gynoecium are reproductive organs. In some flowers like lily, the calyx and corolla are not distinct and are termed as perianth. When a flower has both androecium and gynoecium, it is bisexual. A flower having either only stamens or only carpels is unisexual. In symmetry, the flower may be actinomorphic (radial symmetry) or zygomorphic (bilateral symmetry). When a flower can be divided into two equal radial halves in any radial plane passing through the centre, it is said to be actinomorphic, e.g., mustard, datura, chilli. When it can be divided into two similar halves only in one particular vertical plane, it is zygomorphic, e.g., pea, gulmohur, bean, Cassia. A flower is asymmetric (irregular) if it cannot be divided into two similar halves by any vertical plane passing through the centre, as in canna. A flower may be trimerous, tetramerous or pentamerous when the floral appendages are in multiple of 3, 4 or 5, respectively. Flowers with bracts-reduced leaf found at the base of the pedicel – are called bracteate and those without bracts, ebracteate.

Based on the position of calyx, corolla and androecium in respect of the ovary on thalamus, the flowers are described as hypogynous, perigynous and epigynous. In the hypogynous flower the gynoecium occupies the highest position while the other parts are situated below it. The ovary in such flowers is said to be superior, e.g., mustard, China rose and brinjal. If gynoecium is situated in the centre and other parts of the flower are located on the rim of the thalamus almost at the same level, it is called perigynous. The ovary here is said to be half inferior, e.g., plum, rose, peach. In epigynous flowers, the margin of thalamus grows upward enclosing the ovary completely and getting fused with it, the other parts of flower arise above the ovary. Hence, the ovary is said to be inferior as in flowers of guava and cucumber, and the ray florets of sunflower.

1.) In some flowers, the calyx and corolla are not distinct and are termed as

a.) Thalamus

b.) Receptacle

c.) Perianth

d.) None of the above

2.) The flower which shows radial symmetry are termed as

a.) Zygomorphic

b.) Actinomorphic

c.) Asymmetric

d.) None of the above

3.) What is asymmetric flower?

4.) What is zygomorphic flower?

5.) Explain the types of flower?

Answer key

1.) c

2.) b

3.) If flower is irregular and cannot be divided into two similar halves by any vertical plane passing through the centre is termed as asymmetric flower.

4.) A flower can be divided into two similar halves only in one particular vertical plane, it is called as zygomorphic.

5.) A flower can be classified depending on the position of whorls- calyx, corolla, and androecium with respect to the ovary on the receptacle.

o Hypogynous

In a Hypogynous flower, the ovary is superior to the other three whorls. Here the ovary is positioned high on the thalamus and other parts are below it, e.g., tomato, tulip, brinjal, etc.

o Perigynous

In perigynous flower, the ovary is in the centre and all four whorls are almost at the same level. Here, the ovary is half superior/ inferior, e.g., rose, peach, cherry, etc.

o Epigynous

In epigynous flowers, the ovary is inferior to the other three parts. Here, the thalamus encloses the ovary inside it and the other three whorls are located above this, e.g., daffodil, cucumber, etc.

CASE 5

Androecium is composed of stamens. Each stamen which represents the male reproductive organ consists of a stalk or a filament and an anther. Each anther is usually bilobed and each lobe has two chambers, the pollen-sacs. The pollen grains are produced in pollen-sacs. A sterile stamen is called staminode. Stamens of flower may be united with other members such as petals or among themselves. When stamens are attached to the petals, they are epipetalous as in brinjal, or epiphyllous when attached to the perianth as in the flowers of lily. The stamens in a flower may either remain free (polyandrous) or may be united in varying degrees. The stamens may be united into one bunch or one bundle (monoadelphous) as in China rose, or two bundles (diadelphous) as in pea, or into more than two bundles (polyadelphous) as in citrus. There may be a variation in the length of filaments within a flower, as in Salvia and mustard.

Gynoecium is the female reproductive part of the flower and is made up of one or more carpels. A carpel consists of three parts namely stigma, style and ovary. Ovary is the enlarged basal part, on which lies the elongated tube, the style. The style connects the ovary to the stigma. The stigma is usually at the tip of the style and is the receptive surface for pollen grains. Each ovary bears one or more ovules attached to a flattened, cushion-like placenta. When more than one carpel is present, they may be free (as in lotus and rose) and are called apocarpous. They are termed syncarpous when carpels are fused, as in mustard and tomato. After fertilisation, the ovules develop into seeds and the ovary matures into a fruit. The arrangement of ovules within the ovary is known as placentation. The placentation are of different types namely, marginal, axile, parietal, basal, central and free central.

1.) Androecium is a whorl of

a.) Anthers

b.) Filaments

c.) Stamens

d.) Tepals

2.) Which of the following is the female reproductive part of the flower

a.) Androecium

b.) Gynoecium

c.) Carpel

d.) Stamens

3.) Define Staminode.

4.) Define placentation and enlist its type.

5.) Table the any 4 differences between Androecium & Gynoecium?

Answer key

1.) c

2.) b

3.) Staminode – Androecium is composed of stamens. A sterile stamen is commonly called as staminode.

4.) Placentation – The arrangement of ovules within the ovary is known as placentation. The placentation are of different types namely,

o Marginal

o Axile

o Parietal

o Basal

o Central

o Free central.

5.) Difference between androecium and Gynoecium

Androecium

Gynoecium

o   It is male reproductive structure o   It is female reproductive structure
o   Involved in the production and release of pollen grains o   Involved in the reception of pollen grains and in the formation of the pollen tube
o   It comprises Anthers and filaments o   It comprises Ovary, style and stigma
o   It is not involved in the development of seed and fruits o   Promotes the development of seeds and fruits
Updated: March 1, 2022 — 12:22 pm

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