NCERT Solutions For Class 11 | Biology | Chapter 6 | Anatomy of Flowering Plants
NCERT Solutions for Class 11 Biology Chapter 6 Anatomy of Flowering plants is the sixth chapter under Unit – 2 (Structural Organization in Plants and Animals).
Anatomy of Flowering plants helps the students understand the different kinds of tissues in a plant. Plant tissues are classified into permanent and meristematic tissues. Tissues carry out some crucial functionalities, like rendering mechanical support, assimilation of food, rendering mechanical support, photosynthesis etc.
Right from seeds, different parts of a monocot and dicot seeds, its differentiation has been covered in this article. Hope it helps students prepare for their exams in the best way possible.
1. State the locations and function of different types of meristems.
Answer – The actively dividing cell region is called meristems.
| MERISTEMS | LOCATIONS | FUNCTION |
| APICAL MERISTEMS | Tips of roots and shoot | Produce primary tissues and increase the length of plant body |
| INTERCALARY MERISTEMS | Occurs between mature tissues and besides stem nodes, | They help the growth of internodes and primary plant body |
| SECONDARY OR LATERAL MERISTEMS | Occurs in mature regions of shoots and roots, appear after primary meristems. | Produce the secondary tissues in the plant body. |
2. Cork cambium forms tissues that form the cork. Do you agree with this statement? Explain.
Answer – Yes, the cork cambium forms tissues that form the cork. The cork cambium or phellogen develops in the outer cortex region and is thick, made of narrow, thin-walled and rectangular cells. The phellogen develops cells on both sides. The outer cells of cork cambium develops into cork or phellem whilw the inner cells differentiate into secondary cortex or phelloderm. The cork is impervious to water due to suberin deposition in their cell wall.
3. Explain the process of secondary growth in the stems of woody angiosperms with the help of schematic diagrams. What is its significance?
Answer –
- The meristematic cells present between primary xylem and phloem called intrafascicular cambium have cells of medullary rays adjoining them. These cells of medullary rays become meristematic and form interfascicular cambium. A continous ring of cambium is formed.
- The cambium develops cells on both sides, where the inner cells form secondary xylem towards the pith and outer cells form secondary phloem towards the periphery.
- As the cambium is more active in the inner region, that makes the amount of secondary xylem more than secondary phloem.
- Significance– due to the continuous action of vascular cambium, the girth of the stem increases. It helps the plant to get more nutrients and water for growing leaves and giving support structure to plants.
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4. Draw illustrations to bring out the anatomical difference between
- (a) Monocot root and Dicot root
- (b) Monocot stem and Dicot stem.
Answer –
(a) Monocot root and Dicot root
Monocot root –
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Dicot root –
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(b) Monocot stem and Dicot stem
Monocot stem –
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Dicot stem –
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5. Cut a transverse section of young stem of a plant from your school garden and observe it under the microscope. How would you ascertain whether it is a monocot stem or a dicot stem? Give reasons.
Answer – Following are the characteristics to ascertain whether it is a monocot stem or dicot stem –
| DICOT STEM | MONOCOT STEM |
| The vascular bundles are found in a ring arrangement | Scattered vascular bundles are found. |
| Vascular bundle is conjoint, open and with the cells of cambium between the xylem and phloem. | Vascular bundle is conjoint, closed and with sclerenchymatous bundle sheath. The vascular bundles are scattered on the background of parachymatous cells of pith. |
| The presence of cambium shows secondary growth. | No secondary growth due to the absence of cambium. |
| Ground tissues like pith, pericycle, hypodermis, endodermis is present. The medullary rays are found between the vascular bundles. | There is absence of parenchyma in phloem. There are water contaning cavities found in the vascular bundles. |
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6. The transverse section of a plant material shows the following anatomical features
- (a) the vascular bundles are conjoint, scattered and surrounded by a sclerenchymatous bundle sheaths.
- (b) phloem parenchyma is absent.
What will you identify it as?
Answer – The given transverse section of monocot stem because they have scattered vascular bundles and phloem paranchyma is absent in them.
7. Why are xylem and phloem called complex tissues?
Answer – Xylem and Phloem are called a complex tissues because they are made up of more than one type of cell. These cells work together as a unit to perform functions. The given table shows the different types of cells present in xylem and phloem.
| ELEMENTS | |
| XYLEM | Tracheids, Vessels, Xylem fibres and Xylem parenchyma |
| PHLOEM | Sieve tubes, Companion cells, Phloem parenchyma, Phloem fibres |
8. What is stomatal apparatus? Explain the structure of stomata with a labelled diagram.
Answer – The stomatal apparatus consists of stomata, stomatal aperture and subsidiary cells.
- STOMATA– The stomata are the structures found in the epidermis of leaves. They are composed of a pain of bean-shaped or dumb-bell shaped gaurd cells enclosing stomatal pore. The stomata regulate traspiration and gaseous exchange in leaves. The outer walls of guard cells are thin while the inner walls are thick.
- STOMATAL APERTURE– The guard cells contain chloroplasts and regulate the opening and closing of stomatal aperture.
- SUBSIDIARY CELLS– They are the epidermal cells surrounding the guard cells that become specialised in shape and size.
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9. Name the three basic tissue systems in the flowering plants. Give the tissue names under each system.
Answer – The three basic tissue systems found in flowering plants are as follows-
| EPIDERMAL TISSUE SYSTEM | Epidermal cells, stomata and epidermal appdendages- trichomes and root hairs. |
| GROUND TISSUE SYSTEM | All tissues except the vascular bundle and epidermis. They are made of parachyma, sclerenchyma and collenchyma. |
| VASCULAR TISSUE SYSTEM | Complex tissues like xylem and phloem |
10. How is the study of plant anatomy useful to us?
Answer – Following are the reasons as to why the study of plant anatomy is useful to us
- To understand the adaptions of plant in different climates.
- To differentiate monocots from dicots, roots from stems and angiosperms from gymnosperms.
- To improve crop production by studying plant anatomy which helps understand the plant physiology.
- To facilitate the study of wood strength for commercial exploitation.
11. What is periderm? How does periderm formation take place in the dicot stems?
Answer –
- The phellogen, phellem, and phelloderm together are known as periderm.
- The meristematic tissue called cork cambium or phellogen develops in the cortex region to replace the broken layers of epidermis and outer cortex due to the incresing girth of the stem because of the vascular cambium.
- The cells of cork cambium are thin-walled and rectangular.
- Phellogen develops on both sides. Ther outer cells develop into cork or phellem and the inner cells develop into secondary cortex or phelloderm.
- The cork is impervious to water due to suberin deposition in their cell wall while the secondary cortex is paranchymatous.
12. Describe the internal structure of a dorsiventral leaf with the help of labelled diagram.
Answer – The dorsiventral leaf or dicotyledonous leaf in their vertical section shows three main parts, i.e. epidermis, mesophyll and vascular systems.
- Epidermis– They cover both the upper surface (adaxial epidermis) and lower surface (abaxial epidermis) of the leaf. They have conspicuous cuticle. The amount of tomata is more in abaxial epidermis than in adaxial epidermis.
- Mesophyll– The tissue present between adaxial epidermis and abaxial epidermis is called mesophyll. They are pharanchymatous and contain chloroplasts to carry out photosynthesis. It contains two types of cells, i.e. palisade parenchyma which are elongated cells arranged vertically and spongy parenchyma which are oval in shape with little intercellular spaces.
- Vascular system– The vascular bundles found in the midrib and veins are closed and conjoint. They are surrounded by the thick-walled bundle sheath cells.
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