Case Study Questions Class 11 Biology Chapter 6 Anatomy of Flowering Plants
CBSE Class 11 Case Study Questions Biology Anatomy 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 Anatomy of Flowering Plants.
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CBSE Case Study Questions Class 11 Biology Anatomy of Flowering Plants
CASE 1
The cells of the permanent tissues do not generally divide further. Permanent tissues having all cells similar in structure and function are called simple tissues. A simple tissue is made of only one type of cells. The various simple tissues in plants are parenchyma, collenchyma and sclerenchyma.
Parenchyma forms the major component within organs. The cells of the parenchyma are generally isodiametric. They may be spherical, oval, round, polygonal or elongated in shape. Their walls are thin and made up of cellulose. They may either be closely packed or have small intercellular spaces. The parenchyma performs various functions like photosynthesis, storage, secretion.
The collenchyma occurs in layers below the epidermis in most of the dicotyledonous plants. It is found either as a homogeneous layer or in patches. It consists of cells which are much thickened at the corners due to a deposition of cellulose, hemicellulose and pectin. Collenchymatous cells may be oval, spherical or polygonal and often contain chloroplasts. These cells assimilate food when they contain chloroplasts. Intercellular spaces are absent. They provide mechanical support to the growing parts of the plant such as young stem and petiole of a leaf.
Sclerenchyma consists of long, narrow cells with thick and lignified cell walls having a few or numerous pits. They are usually dead and without protoplasts. On the basis of variation in form, structure, origin and development, sclerenchyma may be either fibres or sclereids. The fibres are thick-walled, elongated and pointed cells, generally occurring in groups, in various parts of the plant. The sclereids are spherical, oval or cylindrical, highly thickened dead cells with very narrow cavities (lumen). These are commonly found in the fruit walls of nuts; pulp of fruits like guava, pear and sapota; seed coats of legumes and leaves of tea. Sclerenchyma provides mechanical support to organs.
1.) Tissue made of only one type of cell is termed as _________
a.) Simple permanent tissue
b.) Complex permanent tissue
c.) Simple Meristematic tissue
d.) Complex Meristematic tissue
2.) Identify the correct statement
Statement 1 – Cells of the parenchyma are generally isodiametric.
Statement 2 – The collenchyma occurs in layers below the epidermis.
Statement 3 – Sclerenchyma are usually dead and without protoplasts
Statement 4 – The cells of the permanent tissues do not generally divide further.
a.) Only 1
b.) Both 2 & 4
c.) Both 1 & 3
d.) All of the above
3.) Enlist the type of Simple permanent tissue?
4.) Explain Sclerenchyma.
5.) Write short note on Parenchyma?
Answer key
1.) a
2.) d
3.) There are various simple tissues in plants such as,
o Parenchyma
o Collenchyma
o Sclerenchyma
4.) Sclerenchyma are one of the simple type of permanent tissue. Sclerenchyma consists of long, narrow cells with thick and lignified cell walls. They are usually dead and without protoplasts. On the basis of variation in form, structure, origin and development, sclerenchyma may be either fibres or sclereids. The fibres are thick-walled, elongated and pointed cells, generally occurring in groups, in various parts of the plant. The sclereids are spherical, oval or cylindrical, highly thickened dead cells with very narrow cavities (lumen). Sclerenchyma provides mechanical support to organs.
5.) Parenchyma are one of the simple type of permanent tissue. It forms the major component within organs. The cells of the parenchyma are generally isodiametric. They may be spherical, oval, round, polygonal or elongated in shape. Their walls are thin and made up of cellulose. They may either be closely packed or have small intercellular spaces. The parenchyma performs various functions like photosynthesis, storage, secretion.
CASE 2
The complex tissues are made of more than one type of cells and these work together as a unit. Xylem and phloem constitute the complex tissues in plants. Xylem functions as a conducting tissue for water and minerals from roots to the stem and leaves. It also provides mechanical strength to the plant parts. It is composed of four different kinds of elements, namely, tracheids, vessels, xylem fibres and xylem parenchyma. Tracheids are elongated or tube like cells with thick and lignified walls and tapering ends. These are dead and are without protoplasm. In flowering plants, tracheids and vessels are the main water transporting elements. Vessel is a long cylindrical tube-like structure made up of many cells called vessel members. Vessel members are interconnected through perforations in their common walls. Primary xylem is of two types – protoxylem and metaxylem. The first formed primary xylem elements are called protoxylem and the later formed primary xylem is called metaxylem. In stems, the protoxylem lies towards the centre (pith) and the metaxylem lies towards the periphery of the organ. This type of primary xylem is called endarch. In roots, the protoxylem lies towards periphery and metaxylem lies towards the centre. Such arrangement of primary xylem is called exarch.
Phloem transports food materials, usually from leaves to other parts of the plant. Phloem in angiosperms is composed of sieve tube elements, companion cells, and phloem parenchyma and phloem fibres. Sieve tube elements are also long, tube-like structures, arranged longitudinally and are associated with the companion cells. The functions of sieve tubes are controlled by the nucleus of companion cells. The companion cells are specialised parenchymatous cells, which are closely associated with sieve tube elements. The companion cells help in maintaining the pressure gradient in the sieve tubes. Phloem parenchyma is made up of elongated, tapering cylindrical cells which have dense cytoplasm and nucleus. The phloem parenchyma stores food material and other substances like resins, latex and mucilage. Phloem fibres (bast fibres) are made up of sclerenchymatous cells. These are generally absent in the primary phloem but are found in the secondary phloem. At maturity, these fibres lose their protoplasm and become dead. The first formed primary phloem consists of narrow sieve tubes and is referred to as protophloem and the later formed phloem has bigger sieve tubes and is referred to as metaphloem.
1.) Xylem and phloem are examples of
a.) Meristematic tissue
b.) Simple tissue
c.) Protective tissue
d.) Complex tissue
2.) The protoxylem lies towards periphery and metaxylem lies towards the centre. Such arrangement of primary xylem is known as
a.) Exarch
b.) Endarch
c.) Inarch
d.) None of the above
3.) What are the functions of xylem and phloem?
4.) Define Protoxylem and Metaxylem?
5.) Define Protophloem and Metaphloem?
6.) Explain the composition of xylem?
Answer key
1.) d
2.) a
3.) Functions of xylem and Phloem are as follows;
o Xylem – Xylem functions as a conducting tissue for water and minerals from roots to the stem and leaves. It also provides mechanical strength to the plant parts.
o Phloem – Phloem transports food materials, usually from leaves to other parts of the plant. The phloem parenchyma stores food material and other substances like resins, latex and mucilage.
4.) The first formed primary xylem elements are called protoxylem and the later formed primary xylem is called metaxylem.
5.) The first formed primary phloem consists of narrow sieve tubes and is referred to as protophloem and the later formed phloem has bigger sieve tubes and is referred to as metaphloem.
6.) Xylem is composed of four different kinds of elements;
o tracheids
o vessels
o xylem fibres
o xylem parenchyma
Tracheids are elongated or tube like cells with thick and lignified walls and tapering ends. These are dead and are without protoplasm.
Vessel is a long cylindrical tube-like structure made up of many cells called vessel members. Vessel members are interconnected through perforations in their common walls.
Primary xylem is of two types – protoxylem and metaxylem. The first formed primary xylem elements are called protoxylem and the later formed primary xylem is called metaxylem.
In stems, the protoxylem lies towards the centre (pith) and the metaxylem lies towards the periphery of the organ. This type of primary xylem is called endarch.
In roots, the protoxylem lies towards periphery and metaxylem lies towards the centre. Such arrangement of primary xylem is called exarch.
CASE 3
The epidermal tissue system forms the outer-most covering of the whole plant body and comprises epidermal cells, stomata and the epidermal appendages – the trichomes and hairs. The epidermis is the outermost layer of the primary plant body. It is made up of elongated, compactly arranged cells, which form a continuous layer. Epidermis is usually single layered. Epidermal cells are parenchymatous with a small amount of cytoplasm lining the cell wall and a large vacuole. The outside of the epidermis is often covered with a waxy thick layer called the cuticle which prevents the loss of water. Cuticle is absent in roots. Stomata are structures present in the epidermis of leaves. Stomata regulate the process of transpiration and gaseous exchange. Each stoma is composed of two bean shaped cells known as guard cells which enclose stomatal pore. In grasses, the guard cells are dumb-bell shaped. The outer walls of guard cells are thin and the inner walls are highly thickened. The guard cells possess chloroplasts and regulate the opening and closing of stomata. Sometimes, a few epidermal cells, in the vicinity of the guard cells become specialised in their shape and size and are known as subsidiary cells. The stomatal aperture, guard cells and the surrounding subsidiary cells are together called stomatal apparatus.
The cells of epidermis bear a number of hairs. The root hairs are unicellular elongations of the epidermal cells and help absorb water and minerals from the soil. On the stem the epidermal hairs are called trichomes. The trichomes in the shoot system are usually multicellular. They may be branched or unbranched and soft or stiff. They may even be secretory. The trichomes help in preventing water loss due to transpiration.
1.) Which of the following cell regulates the opening and closing of guard cell.
a.) Epidermal cell
b.) Guard cell
c.) Subsidiary cell
d.) Trichomes
2.) Which of the following components are known as epidermal appendages.
a.) Trichomes
b.) Hairs
c.) Trichomes & Hairs
d.) Stomata
3.) Define cuticles and give its function.
4.) What is trichomes?
5.) Write short note on stomata?
Answer key
1.) b
2.) c
3.) Cuticle – The outside of the epidermis is often covered with a waxy thick layer called the cuticle.
Function of cuticle –prevents the loss of water.
4.) The cells of epidermis bear a number of hairs. Epidermal hairs present on the stem are called as trichomes.
5.) Stomata are structures present in the epidermis of leaves. Stomata regulate the process of transpiration and gaseous exchange. Each stoma is composed of two bean shaped cells known as guard cells which enclose stomatal pore. In grasses, the guard cells are dumb-bell shaped. The outer walls of guard cells are thin and the inner walls are highly thickened. The guard cells possess chloroplasts and regulate the opening and closing of stomata. Sometimes, a few epidermal cells, in the vicinity of the guard cells become specialised in their shape and size and are known as subsidiary cells. The stomatal aperture, guard cells and the surrounding subsidiary cells are together called stomatal apparatus. (Draw diagram).
CASE 4
The growth of the roots and stems in length with the help of apical meristem is called the primary growth. Apart from primary growth most dicotyledonous plants exhibit an increase in girth. This increase is called the secondary growth. The tissues involved in secondary growth are the two lateral meristems: vascular cambium and cork cambium.
The meristematic layer that is responsible for cutting off vascular tissues – xylem and phloem – is called vascular cambium. In the young stem it is present in patches as a single layer between the xylem and phloem. Later it forms a complete ring.
In dicot stems, the cells of cambium present between primary xylem and primary phloem is the intrafascicular cambium.The cells of medullary rays, adjoining these intrafascicular cambium become meristematic and form the interfascicular cambium. Thus, a continuous ring of cambium is formed.
The cambial ring becomes active and begins to cut off new cells, both towards the inner and the outer sides. The cells cut off towards pith, mature into secondary xylem and the cells cut off towards periphery mature into secondary phloem. The cambium is generally more active on the inner side than on the outer. As a result, the amount of secondary xylem produced is more than secondary phloem and soon forms a compact mass. The primary and secondary phloems get gradually crushed due to the continued formation and accumulation of secondary xylem. The primary xylem however remains more or less intact, in or around the centre. At some places, the cambium forms a narrow band of parenchyma, which passes through the secondary xylem and the secondary phloem in the radial directions. These are the secondary medullary rays
1.) The cells of cambium present between primary xylem and primary phloem is known as
a.) Interfascicular cambium
b.) Intrafascicular cambium
c.) Primary cambium
d.) Secondary cambium
2.) The cells of medullary rays, adjoining these intrafascicular cambium become meristematic and forms
a.) Interfascicular cambium
b.) Intrafascicular cambium
c.) Primary cambium
d.) Secondary cambium
3.) What is secondary growth?
4.) Define Vascular Cambium.
5.) Enlist the name of tissue involved in secondary growth?
Answer key
1.) b
2.) a
3.) The growth of the roots and stems in length with the help of apical meristem is called the primary growth. Apart from primary growth plants exhibit an increase in girth. This increase is called the secondary growth.
4.) The meristematic layer that is responsible for cutting off vascular tissues – xylem and phloem – is called vascular cambium. In the young stem it is present in patches as a single layer between the xylem and phloem. Later it forms a complete ring.
5.) The tissues involved in secondary growth are the two lateral meristems: vascular cambium and cork cambium.
CASE 5
As the stem continues to increase in girth due to the activity of vascular cambium, the outer cortical and epidermis layers get broken and need to be replaced to provide new protective cell layers. Hence, sooner or later, another meristematic tissue called cork cambium or phellogen develops, usually in the cortex region. Phellogen is a couple of layers thick. It is made of narrow, thin-walled and nearly rectangular cells. Phellogen cuts off cells on both sides. The outer cells differentiate into cork or phellem while the inner cells differentiate into secondary cortex or phelloderm. The cork is impervious to water due to suberin deposition in the cell wall. The cells of secondary cortex are parenchymatous. Phellogen, phellem, and phelloderm are collectively known as periderm. Due to activity of the cork cambium, pressure builds up on the remaining layers peripheral to phellogen and ultimately these layers die and slough off. Bark is a non-technical term that refers to all tissues exterior to the vascular cambium, therefore including secondary phloem. Bark refers to a number of tissue types, viz., periderm and secondary phloem. Bark that is formed early in the season is called early or soft bark. Towards the end of the season, late or hard bark is formed. Name the various kinds of cell layers which constitute the bark.
At certain regions, the phellogen cuts off closely arranged parenchymatous cells on the outer side instead of cork cells. These parenchymatous cells soon rupture the epidermis, forming a lens shaped openings called lenticels. Lenticels permit the exchange of gases between the outer atmosphere and the internal tissue of the stem. These occur in most woody trees.
1.) Phellogen, phellem, and phelloderm are collectively known as
a.) Periderm
b.) Phellem
c.) Phelloderm
d.) Lenticels
2.) Identify incorrect statement
Statement 1 – Lenticels permit the exchange of gases.
Statement 2 – Cork cambium is primary growth.
Statement 3 –The cells of secondary cortex are parenchymatous.
Statement 4 – Phellogen, phellem, and phelloderm are collectively known as periderm.
a.) Only 1
b.) Only 2
c.) Both 1 & 2
d.) Both 3 & 4
3.) Define cork cambium.
4.) Explain Phellem and Phelloderm?
5.) Explain lenticels and give its function?
Answer key
1.) a
2.) b
3.) As the stem continues to increase in girth due to the activity of vascular cambium, the outer cortical and epidermis layers get broken and need to be replaced to provide new protective cell layers. Hence, sooner or later, another meristematic tissue called cork cambium or phellogen develops in the cortex region.
4.) Phellogen is a couple of layers thick. It is made of narrow, thin-walled and nearly rectangular cells. Phellogen cuts off cells on both sides. The outer cells differentiate into cork or phellem while the inner cells differentiate into secondary cortex or phelloderm.
5.) Lenticels – The phellogen cuts off closely arranged parenchymatous cells on the outer side instead of cork cells. These parenchymatous cells soon rupture the epidermis, forming a lens shaped openings called lenticels.
Functions – Lenticels permit the exchange of gases between the outer atmosphere and the internal tissue of the stem.