Maharashtra Board Class 11 Biology Chapter 8 Plant Tissues and Anatomy Solutions

11th Biology Chapter 8 Exercise Plant Tissues And Anatomy Solutions Maharashtra Board

Plant Tissues And Anatomy Class 11 Exercise Question Answers Solutions Maharashtra Board

Class 11 Biology Chapter 8 Exercise Solutions Maharashtra Board

Biology Class 11 Chapter 8 Exercise Solutions

Exercise 1. Choose The Correct Option.

Question (A) Location or position of meristematic regions is divided into _____ types.
(A) one
(B) two
(C) three
(D) none of the above
Answer: (C) three
In simple words: Meristematic regions are locations of active cell division in plants, divided into three main types based on their position.

🎯 Exam Tip: Understanding the types and locations of meristematic tissues is crucial for questions on plant growth and development.

 

Question (B) Cambium is also called
(A) apical meristem
(B) intercalary meristem
(C) lateral meristem
(D) none of the above
Answer: (C) lateral meristem
In simple words: Cambium, a lateral meristem, is responsible for secondary growth and increasing the girth of the plant stem or root.

🎯 Exam Tip: Distinguish between apical, intercalary, and lateral meristems based on their function and location.

 

Question (C) Collenchyma is a type of _____ tissue.
(A) living
(B) dead
(C) living and dead
(D) none of the above
Answer: (A) living
In simple words: Collenchyma tissue provides flexible support to young plant parts and is composed of living cells.

🎯 Exam Tip: Remember the key characteristics (living/dead, cell wall thickness, function) of simple permanent tissues like parenchyma, collenchyma, and sclerenchyma.

 

Question (D) _____ is a complex permanent tissue.
(A) Parenchyma
(B) Sclerenchyma
(C) Chlorenchyma
(D) Xylem
Answer: (D) Xylem
In simple words: Xylem is a complex permanent tissue primarily responsible for water and mineral transport, unlike simple tissues such as parenchyma.

🎯 Exam Tip: Learn to differentiate between simple and complex permanent tissues and their respective functions.

 

Question (E) Mesophyll tissue is present in _____.
(A) root
(B) stem
(C) leaf<
(D) flower
Answer: (C) leaf
In simple words: Mesophyll tissue, found in leaves, is specialized for photosynthesis and consists of palisade and spongy parenchyma.

🎯 Exam Tip: Relate tissue location to its primary function, especially in key plant organs like leaves.

 

Exercise 2. Answer The Following Questions

Question (A) A fresh section was taken by a student but he was very disappointed because there were only few green and most colourless cells. Teacher provided a pink colour solution. The section was immersed in this solution and when observed it was much clearer. What is the magic?
Answer:
1. The pink coloured solution given by teacher must be a saffanin stain.
2. Saffanin is used to stain plant tissues, especially lignified tissues such as cell wall and xylem.
In simple words: Saffanin is a red stain used in botany to highlight lignified (woody) plant tissues, making structures like xylem and cell walls visible under a microscope.

🎯 Exam Tip: Knowledge of common biological stains and their specific applications in microscopy is important.

 

Question (B) While observing a section, many scattered vascular bundles could be seen. Teacher said, in spite of this large number the stem cannot grow in girth. Why?
Answer:
1. Students must have observed monocot stems.
2. It is because, monocot stem shows scattered vascular bundles.
3. In monocot stem, vascular bundles are closed i.e. without cambium.
4. Thus, secondary growth does not occur which is required for increase in girth. Hence, in spite of having large number of scattered vascular bundles, monocot stems do not grow in girth.
In simple words: Monocot stems have scattered vascular bundles that lack cambium, preventing secondary growth and an increase in stem girth, unlike dicot stems.

🎯 Exam Tip: Focus on the structural differences between monocot and dicot stems, particularly regarding vascular bundles and cambium, as these determine growth patterns.

 

Question (C) A section of the stem had vascular bundles, where one tissue was wrapped around the other. How will you technically describe it?
Answer: Concentric vascular bundle:
a. When one vascular tissue is completely encircling the other, it is called as concentric vascular bundle.
b. When phloem is encircled by xylem, it is called as leptocentric vascular bundle, whereas when xylem is encircled by phloem, it is called as hadrocentric vascular bundle.
c. When xylem is encircled by phloem on both faces, it is called as amphicribral vascular bundle. When phloem is encircled by xylem on both faces it is called as amphivasal vascular bundle.
In simple words: Concentric vascular bundles are characterized by one vascular tissue completely surrounding another, with specific types named based on which tissue encircles the other.

🎯 Exam Tip: Be precise with the terminology for different vascular bundle arrangements (conjoint, collateral, concentric, radial) and their sub-types.

 

Question (D) There were two cut logs of wood lying in the campus. One had growth rings and other didn't. Teacher said it is due to differences in their pattern of growth which is dependent on season. How?
Answer:
1. It is possible that one of the cut logs was of a tropical tree, whereas the other was of a temperate tree. Since tropical trees grow in a similar manner all year, growth rings are not apparent. Another explanation for this could be that the log which had growth rings must be of an old tree which has experience many seasons, whereas the log without growth rings must be of younger tree, that has not been subjected to seasonal changes and hence not developed prominent growth rings.
2. Growth rings are formed due cambial activity during favourable and non-favourable climatic conditions.
3. During favourable conditions, spring wood (early wood) is formed which has broader xylem bands, lighter colour, tracheids with thin wall and wide lumen, fibres are less in number, low density. Whereas, during unfavourable conditions, autumn wood (late wood) is formed which has narrow xylem band, darker in colour, lumen is narrow and walls are thick with abundant fibres, high density.
4. Spring wood and autumn wood that appear as alternate light and dark concentric rings, constitute an annual ring or growth ring.
5. These growth rings can be used to estimate the age of the tree. These are found more in older trees as compare to younger tree.
In simple words: Growth rings (annual rings) in wood indicate seasonal cambial activity, being distinct in temperate regions with varied seasons and less visible or absent in tropical regions with uniform climates.

🎯 Exam Tip: Understand the environmental factors that influence cambial activity and the formation of spring wood and autumn wood.

 

Question (E) While on the trip to Kashmir, Pintoo observed that cut portions of large trees show distinct rings, which he never found in Maharashtra. Why is so?
Answer:
1. Cut portions of large tress show distinct rings which are annual rings formed due to activity of cambium during favourable and non-favourable climatic conditions.
2. Kashmir falls under temperate region where the climatic conditions are not uniform through the year. In the spring season, conditions are favourable due to which cambium is active, whereas in autumn season, conditions are unfavourable due to which cambium is less active. This leads to formation of spring wood and autumn wood that appear as alternate light and dark concentric rings, constitute an annual ring or growth ring.
3. Maharashtra falls under tropical region where climatic conditions are favourable throughout the year. In tropical areas, continuous growth of secondary xylem occurs. Thus, trees growing in tropical regions show less or no annual rings as compared to trees in temperate region.
In simple words: Distinct growth rings are seen in temperate regions like Kashmir due to seasonal variations affecting cambium activity, while uniform climatic conditions in tropical regions like Maharashtra lead to continuous growth and less distinct rings.

🎯 Exam Tip: Relate geographical climate zones to plant growth patterns, especially the formation of annual rings in secondary growth.

 

Question (F) A student was observing a slide with no label under microscope. The section had some vascular bundles scattered in the ground tissue. It is section of a monocot stem! He exclaimed. No! it is section of fern rachis, said the teacher. Teacher told to observe vascular bundle again. Student agreed, Why?
Answer:
1. In fern rachis, the number of vascular bundles is less as compared to number of vascular bundles in monocot stem. In monocot stem, vascular bundles are numerous.
2. In fern rachis, xylem consists of only tracheids whereas in monocot stem, xylem consists of vessels (protoxylem and metaxylem) as well as tracheids. Monocot stem shows presence of lysigenous cavity just below protoxylem.
3. In fern rachis, phloem consists of only sieve cells whereas in monocot stem, phloem consists of sieve tubes and companion cells. Thus, a student must have observed these differences in the given section and agreed to teacher's statement that the given section is of fern rachis and not of monocot stem.
In simple words: Fern rachis differs from monocot stems in vascular bundle number and xylem/phloem composition (e.g., tracheids only in ferns vs. vessels+tracheids in monocots, sieve cells in ferns vs. sieve tubes+companion cells in monocots).

🎯 Exam Tip: Pay close attention to the specific anatomical features of different plant parts (like fern rachis vs. monocot stem) for accurate identification.

 

Question (G) Student found a wooden stopper in lab. He was told by an old lab attendant that it is there for many years. He kept thinking how it did not rot?
Answer:
1. Wooden stopper or cork is obtained from the phellem (cork) part of a bark.
2. Phellem (cork) is impervious in nature and does not allow entry of water due to suberized walls.
3. Due to this it does not rot and remains as it is for many years.
In simple words: Cork (phellem) is made of suberized cells, making it impervious to water and decay, which explains why a wooden stopper can last for many years without rotting.

🎯 Exam Tip: Remember the protective functions of plant tissues like cork and the chemical properties (e.g., suberin) that contribute to their durability.

 

Question (H) Student while observing a slide of leaf section observed many stomata on the upper surface. He thought he has placed slide upside down. Teacher confirmed it is rightly placed. Explain.
Answer:
1. In a dicot leaf, stomata are generally absent on upper epidermis but are present on lower epidermis. Thus, the student must have thought that he has placed slide upside down.
2. According to teacher, the section was placed rightly, thus the given section must be of monocot leaf.
3. It is because, in monocot leaf stomata are present on both upper and lower epidermis.
In simple words: Monocot leaves have stomata on both upper and lower epidermis, unlike dicot leaves where stomata are primarily on the lower surface, explaining why a monocot leaf section observed with upper stomata is correctly oriented.

🎯 Exam Tip: Understand the anatomical differences between dicot and monocot leaves, especially the distribution of stomata, for correct identification.

 

Exercise 3. Write Short Notes On The Following Points.

Question (A) Structure of stomata.
Answer:
1. Small gateways in the epidermal cells are called as stomata.
2. Stoma is controlled or guarded by specially modified cells called guard cells.
3. These guard cells may be kidney-shaped (dicot) or dumbbell-shaped (monocot), collectively called as stomata.
4. Guard cells have chloroplasts to carry out photosynthesis.
5. Change in turgor pressure of guard cells causes opening and closing of stomata, which enables exchange of gases and water vapour.
6. Stomata are further covered by subsidiary cells.
7. Stoma, guard cells and subsidiary cells form a unit called stomatal apparatus.
In simple words: Stomata are small pores on the plant epidermis, regulated by guard cells, allowing gas exchange and water vapor release, and are surrounded by subsidiary cells forming a stomatal apparatus.

🎯 Exam Tip: Focus on the structural components of the stomatal apparatus and how turgor pressure in guard cells controls its opening and closing.

 

Question (B) Write a short note on secondary growth.
OR
With the help of neat and labelled diagram explain the secondary growth in dicot stem.
Answer: Secondary growth:
1. Dicotyledonous plants and gymnosperms exhibit increase in girth of root and stem.
2. In dicot stem, secondary growth begins with the formation of a continuous cambium ring.
3. The cambium present between the primary xylem and primary phloem of a vascular bundle is called intrafascicular cambium.
4. The cells of medullary rays adjoining these intrafascicular cambium strips become meristematic (regain the capacity to divide) and form the interfascicular cambium.
5. Thus, a complete and continuous ring of vascular cambium is formed.
6. The cambium ring cuts off new cells, towards both inner and outer sides.
7. The cells that are cut-off towards pith (inner side) mature into secondary xylem and cells that are cut-off towards periphery mature into secondary phloem.
8. Generally, amount of secondary xylem is more than the secondary phloem.
In simple words: Secondary growth in dicot stems involves the formation of a continuous cambium ring from intrafascicular and interfascicular cambium, leading to increased girth by producing secondary xylem and phloem.

🎯 Exam Tip: Clearly outline the steps of secondary growth, emphasizing the role of vascular cambium and the tissues it produces.

 

Question (C) Write a short note on peculiarity of a sclerenchyma cell wall.
Answer: Peculiarity of a sclerenchyma cell wall:
1. Cell wall of sclerenchyma is evenly thickened due to uniform deposition of lignin.
2. Cell wall of sclereids is extremely thick and strongly lignified.
In simple words: Sclerenchyma cell walls are characterized by uniform and strong lignification, making them thick and rigid, especially prominent in sclereids.

🎯 Exam Tip: Highlight the unique feature of lignin deposition in sclerenchyma that provides mechanical strength to plants.

 

Exercise 4. Differentiate

Question (A) Differentiate between vascular bundles of monocot and dicot.
Answer:
1. Vascular bundle of monocot and dicot root.
2. Vascular bundle of monocot and dicot stem.
3. Vascular bundle of monocot and dicot leaf.
In simple words: The differences in vascular bundles between monocots and dicots are observed in roots, stems, and leaves, reflecting distinct anatomical organizations.

🎯 Exam Tip: For differentiation questions, provide clear, concise points for each category (root, stem, leaf) to cover all aspects.

 

Question (B) Differentiate between xylem and phloem.
Answer:

Xylem	Phloem
1. It is a dead complex tissue.	It is a living complex tissue.
2. It is composed of xylem, tracheids, vessels, xylem fibres and xylem parenchyma.	It is composed of sieve tubes, sieve cells, companion cells, phloem parenchyma and phloem fibres.
3. It is also known as wood.	It is also known as bast.
4. The cell walls are thick due to lignin.	The cell walls are thin.
5. Xylem conducts water and minerals from roots to the stem and leaves. It also provides mechanical strength to the plant parts.	It is the chief food conducting tissue of vascular plants responsible for translocation of food from leaves to other plant parts.

In simple words: Xylem conducts water and minerals and provides support, composed mainly of dead tissues, while phloem transports food and is primarily made of living tissues.

🎯 Exam Tip: Tabular differentiation is effective; ensure parallel points of comparison are used for clarity and completeness.

 

Exercise 5. Draw Neat Labelled Diagrams

Question (A) T.S. of dicot leaf.
Answer:
1. Structure of dorsiventral leaf: The mesophyll tissue is differentiated into palisade and spongy parenchyma in a dorsiventral leaf. This type is very common in dicot leaf. The different parts of this leaf are as follows:
2. Upper epidermis: It consists of a single layer of tightly packed rectangular, barrel shaped, parenchymatous cells which are devoid of chloroplast. A distinct layer of cuticle lies on the outside of the epidermis. Stomata are generally absent.
3. Mesophyll: Between upper and lower epidermis, there is chloroplast-containing photosynthetic tissue called mesophyll It is differentiated into Palisade parenchyma and Spongy parenchyma.
a. Palisade parenchyma:
Palisade parenchyma is present below upper epidermis and consists of closely packed elongated cells. The cells contain abundant chloroplasts and help in photosynthesis.
b. Spongy parenchyma:
Spongy parenchyma is present below palisade tissue and consists of loosely arranged irregularly shaped cells with intercellular spaces. The spongy parenchyma cells contain chloroplast and are in contact with the atmosphere through stomata.
ℹ️ चित्र व्याख्या (Diagram Explanation): यह एक डाइकोट पत्ती (डॉर्सिवेंट्रल पत्ती) की अनुप्रस्थ काट का चित्र है, जिसमें विभिन्न ऊतक परतें और कोशिका संरचनाएँ दर्शाई गई हैं। इसमें ऊपरी और निचली एपिडर्मिस, पैलिसेड और स्पंजी मेसोफिल कोशिकाएँ, संवहन बंडल (जाइलम और फ्लोएम के साथ) और स्टोमेटा (अभिसारी एपिडर्मिस पर) शामिल हैं। यह पत्ती की आंतरिक संरचना और प्रकाश संश्लेषण में शामिल विभिन्न परतों को समझने में मदद करता है।
4. Vascular system: It is made up of a number of vascular bundles of varying size depending upon the venation. Each one is surrounded by a thin layer of parenchymatous cells called bundle sheath. Vascular bundles are closed. Xylem lies towards upper epidermis and phloem towards lower epidermis. Cambium is absent, hence there is no secondary growth in the leaf.
5. Lower epidermis: It consists of a single layer of compactly arranged rectangular, parenchymatous cells. A thin layer of cuticle is also present. The lower epidermis contains a large number of microscopic pores called stomata. There is an air-space called substomatal chamber at each stoma.
In simple words: A dicot leaf's internal structure shows distinct upper and lower epidermises, differentiated mesophyll into palisade and spongy layers, and vascular bundles, all optimized for photosynthesis.

🎯 Exam Tip: When describing diagrams, list all key labeled parts and explain their functions concisely.

 

Question (B) T.S. of Monocot root.
Answer:
ℹ️ चित्र व्याख्या (Diagram Explanation): यह एक एकबीजपत्री जड़ की अनुप्रस्थ काट का चित्र है, जिसमें विभिन्न परतें और ऊतक संरचनाएँ दिखाई गई हैं। इसमें एपिब्लेमा, रूट हेयर, कॉर्टेक्स, एंडोडर्मिस, पेरिसाइकिल, जाइलम (प्रोटोज़ाइलम और मेटाज़ाइलम), फ्लोएम और पित्त शामिल हैं। यह जड़ की आंतरिक संरचना को दर्शाता है जो जल और खनिजों के अवशोषण और परिवहन के लिए जिम्मेदार है।
In simple words: A monocot root's transverse section features an epiblema with root hairs, a cortex, endodermis, pericycle, and radial vascular bundles with distinct xylem and phloem arrangements, and a well-developed pith.

🎯 Exam Tip: For anatomical diagrams, focus on the arrangement and characteristics of each tissue layer from the outermost to the innermost.

 

Question (C) Draw neat labelled diagrams of T.S. of dicot stem.
Answer:
ℹ️ चित्र व्याख्या (Diagram Explanation): यह एक डाइकोट तने की अनुप्रस्थ काट का चित्र है, जिसमें विभिन्न ऊतक परतें और कोशिका संरचनाएँ दर्शाई गई हैं। इसमें क्यूटिकल, एपिडर्मिस, हाइपोडर्मिस (कोलेन्काइमा), जनरल कॉर्टेक्स (पैरेन्काइमा), एंडोडर्मिस, स्टार्च ग्रेन्स, फ्लोएम, कैम्बियम, मेटाज़ाइलम, प्रोटोज़ाइलम, वुड पैरेन्काइमा और मेडुलरी किरणें शामिल हैं। यह तने की आंतरिक संरचना को समझने में मदद करता है जो पौधों को सहारा और पोषण प्रदान करता है।
In simple words: A dicot stem's transverse section includes an epidermis, hypodermis, general cortex, endodermis, medullary rays, and vascular bundles arranged in a ring, containing cambium for secondary growth.

🎯 Exam Tip: Accurately labeling the tissue layers and vascular bundle components is vital for understanding dicot stem anatomy.

 

Question 6. Write the information related to diagram given below.
ℹ️ चित्र व्याख्या (Diagram Explanation): पहला चित्र स्टोमेटा की संरचना को दर्शाता है, जिसमें माइक्रोपाइबरिल्स, स्टोमैटल छिद्र, क्लोरोप्लास्ट और गार्ड सेल शामिल हैं, जो पत्तियों में गैस विनिमय को नियंत्रित करते हैं। दूसरा चित्र मेरिस्टेमेटिक ऊतक के स्थानों को दिखाता है, जिसमें जड़ों और शूटों के शीर्ष पर एपिकल मेरिस्टेम, नोड्स पर इंटरकैलरी मेरिस्टेम और मोटाई में वृद्धि के लिए पार्श्व मेरिस्टेम शामिल हैं। ये चित्र पौधों के विकास और श्वसन के लिए महत्वपूर्ण हैं।
Answer: [Note: The labelled part can be considered as the 'region of maturation' of root apical however, the region of maturation does not contain meristematic tissue ] Classification of meristematic tissue based on its position:
1. Apical meristem:
a. It is produced from promeristem and forms growing point of apices of root, shoot and their lateral branches.
b. It brings about increase in length of plant body and is called as apical initials.
c. Shoot apical meristem is terminal in position whereas in root it is subterminal i.e. located behind the root cap.
2. Intercalary meristem:
a. Intercalary meristematic tissue is present in the top or base area of node.
b. Their activity is mainly seen in monocots.
c. These are short lived.
3. Lateral meristem:
a. It is present along the sides of central axis of organs.
b. It takes part in increasing girth of stem or root, e.g. Intrafascicular cambium.
c. It is found in vascular bundles of gymnosperms and dicot angiosperms.
In simple words: The provided diagrams illustrate the structure of stomata (for gas exchange) and the locations of different meristematic tissues (apical, intercalary, lateral) responsible for plant growth.

🎯 Exam Tip: Be prepared to interpret diagrams of plant structures and provide detailed explanations of the represented tissues and their functions.

 

Question 7. Identify the following diagrams, label it and prepare a chart of characteristics.
ℹ️ चित्र व्याख्या (Diagram Explanation): यह चित्र पौधों के ऊतकों के विभिन्न प्रकारों को दर्शाता है। 'a' जड़ का एक अनुप्रस्थ काट है, 'b' पैरेन्काइमा कोशिकाओं का एक समूह है, 'c' स्टोमेटा की संरचना है, और 'd' पत्ती की अनुप्रस्थ काट है जिसमें संवहन बंडल और मेसोफिल ऊतक दिखाए गए हैं। ये आरेख पौधों के शारीरिक संगठन के प्रमुख घटकों को उजागर करते हैं।
Answer:
1. Figure 'c'
ℹ️ चित्र व्याख्या (Diagram Explanation): यह चित्र स्टोमेटा की विस्तृत संरचना को दर्शाता है, जिसमें एपिडर्मल कोशिकाएँ, सहायक कोशिकाएँ, आंतरिक मोटी दीवार, न्यूक्लियस, स्टोमैटल छिद्र और गार्ड सेल शामिल हैं। यह गैस विनिमय और वाष्पोत्सर्जन में स्टोमेटा की महत्वपूर्ण भूमिका को उजागर करता है।
In simple words: Identifying plant tissue diagrams requires recognizing features like cell shape, arrangement, and specialized structures such as stomata, which are crucial for understanding their function.

🎯 Exam Tip: Practice identifying key anatomical structures from diagrams and recalling their functional significance and associated characteristics.

 

Question 8. Distinguish between dicot and monocot leaf on the basis of following characters.
Answer:

Characters	Dicot leaf	Monocot leaf
Stomata	Stomata are restricted to lower epidermis. Guard cells of stoma are kidney shaped.	Stomata occur on both epidermis. Guard cells of stoma are dumbbell shaped.
Intercellular space	More intercellular spaces due to presence of spongy parenchyma.	Less intercellular spaces as mesophyll is not differentiated into spongy and palisade tissue.
Venation	Reticulate venation	Parallel venation
Vascular bundle	Vascular bundles of varying size. The size of the vascular bundles is dependent on the size of the veins which vary in thickness in dicot leaf.	Vascular bundles are nearly of similar size (Except in main veins).
Mesophyll cells	Mesophyll tissue is differentiated into palisade parenchyma and spongy parenchyma.	Mesophyll tissue is not differentiated into palisade parenchyma and spongy parenchyma.

In simple words: Dicot and monocot leaves can be distinguished by differences in stomata distribution, intercellular spaces, venation patterns, vascular bundle size, and mesophyll differentiation.

🎯 Exam Tip: Create a comparative table highlighting contrasting features to clearly differentiate between monocot and dicot leaf anatomies.

 

Practical/ Project:

Question 1. Prepare detail anatomical charts with diagrammatic representation of dicot and monocot plants.
Answer: Anatomy of dicot root: The transverse section of a typical dicotyledonous root shows following anatomical features:
1. Epiblema: It is the outermost single layer of cells without cuticle. Some epidermal cells prolong to form unicellular root hairs.
2. Cortex: It is made up of many layers of thin walled parenchyma cells. Cortical cells store food and water.
3. Exodermis: After the death of epiblema, outer layer of cortex become cutinized and is called Exodermis.
In simple words: The anatomy of a dicot root includes the epiblema, cortex, endodermis with Casparian strips, pericycle, and a stele containing radial vascular bundles, all adapted for absorption and transport.

🎯 Exam Tip: Systematically describe each layer of the dicot root, detailing specific features like root hairs, Casparian strips, and the arrangement of xylem and phloem.

Anatomy Of Monocot Stem:

1. Epidermis: It is single-layered and without trichomes. 2. Hypodermis: It is sclerenchymatous. 3. Ground tissue: It consists of thin walled parenchyma cells. It extends from hypodermis to the centre. It is not differentiated into cortex, endodermis, pericycle and pith. 4. Vascular bundles: Vascular bundles are numerous and are scattered in ground tissue. Each vascular bundle is surrounded by a sclerenchymatous bundle sheath. Vascular bundles are conjoint, collateral and closed (without cambium). Xylem is endarch and shows lysigenous cavity. 5. Pith: Pith is absent.

Anatomy Of Dicot Leaf:

1. Structure of dorsiventral leaf: The mesophyll tissue is differentiated into palisade and spongy parenchyma in a dorsiventral leaf. This type is very common in dicot leaf. The different parts of this leaf are as follows: 2. Upper epidermis: It consists of a single layer of tightly packed rectangular, barrel shaped, parenchymatous cells which are devoid of chloroplast. A distinct layer of cuticle lies on the outside of the epidermis. Stomata are generally absent. 3. Mesophyll: Between upper and lower epidermis, there is chloroplast-containing photosynthetic tissue called mesophyll It is differentiated into Palisade parenchyma and Spongy parenchyma. a. Palisade parenchyma: Palisade parenchyma is present below upper epidermis and consists of closely packed elongated cells. The cells contain abundant chloroplasts and help in photosynthesis. b. Spongy parenchyma: Spongy parenchyma is present below palisade tissue and consists of loosely arranged irregularly shaped cells with intercellular spaces. The spongy parenchyma cells contain chloroplast and are in contact with the atmosphere through stomata. 4. Vascular system: It is made up of a number of vascular bundles of varying size depending upon the venation. Each one is surrounded by a thin layer of parenchymatous cells called bundle sheath. Vascular bundles are closed. Xylem lies towards upper epidermis and phloem towards lower epidermis. Cambium is absent, hence there is no secondary growth in the leaf. 5. Lower epidermis: It consists of a single layer of compactly arranged rectangular, parenchymatous cells. A thin layer of cuticle is also present. The lower epidermis contains a large number of microscopic pores called stomata. There is an air-space called substomatal chamber at each stoma.

Anatomy Of Monocot Leaf:

1.It is single layered, present on both sides of the leaf. It consists of compactly arranged rectangular transparent parenchymatous cells. Both the surfaces contain stomata. Both the surfaces have a distinct layer of cuticle. 2. Mesophyll: Mesophyll is not differentiated into palisade and spongy tissue. 3. Vascular bundle: These are conjoint, collateral and closed.

11th Biology Digest Chapter 8 Plant Tissues And Anatomy Intext Questions And Answers

Can You Recall? (Textbook Page No. 85)

Question (i) Which component brings about important processes in the living organisms?
Answer: Cell is the component that brings about important processes in the living organisms.
In simple words: Cells are the basic structural and functional units of all living organisms, performing all essential life processes.

🎯 Exam Tip: Understanding the fundamental role of cells is crucial as it forms the basis for studying tissues and organs.

Question (ii) What is tissue?
Answer: A group of cells having essentially a common function and origin is called as tissue.
In simple words: A tissue is a collection of similar cells that work together to perform a specific function in an organism.

🎯 Exam Tip: Clearly defining "tissue" helps in differentiating it from cells and organs, a common area of confusion.

Question (iii) Explain simple and complex tissue.
Answer: a. Simple tissue:
1. They are made up of only one type of cells.
2. They are found in all the plant parts.
3. They perform many functions.
4. Simple tissues in plants are Parenchyma, Collenchyma, Sclerenchyma.
b. Complex tissue:
1. They are made up of many types of cells.
2. They are found only in the vascular regions of the plant.
3. They mainly perform the function of conduction of food and water.
4. Complex tissues in plants are Xylem and Phloem.
In simple words: Simple tissues are made of one cell type performing various roles, like parenchyma for storage. Complex tissues, like xylem and phloem, consist of multiple cell types working together for specific functions such as transport.

🎯 Exam Tip: Differentiating between simple and complex tissues by cell composition and function is key for higher scores.

Question (iv) Complete the flow chart. Organisms – Organs – Cells
Answer: Organism
\( \implies \) Organ system
\( \implies \) Organs
\( \implies \) Tissue system
\( \implies \) Tissue
\( \implies \) Cells
In simple words: This flowchart illustrates the hierarchical organization of life, from the broadest level (organism) down to the most basic units (cells), showing how components combine to form increasingly complex structures.

🎯 Exam Tip: Accurately reproducing biological organizational hierarchies is a fundamental skill in biology.

Can You Tell? (Textbook Page No. 86)

Question. Enlist the characteristics of meristematic tissue.
Answer: Characteristics of meristematic tissue:
1. It is a group of young, immature cells.
2. These are living cells with ability to divide in the regions where they are present.
3. These are polyhedral or isodiametric in shape without intercellular spaces.
4. Cell wall is thin, elastic and mainly composed of cellulose.
5. Protoplasm is dense with distinct nucleus at the centre and vacuoles if present, are very small.
6. Cells show high rate of metabolism.
In simple words: Meristematic tissues are composed of young, actively dividing cells, often polyhedral, with thin walls, dense protoplasm, and high metabolic rates, found in growth regions of plants.

🎯 Exam Tip: Listing specific characteristics of meristematic tissue, such as cell shape, wall composition, and metabolic activity, earns full marks.

Can You Tell? (Textbook Page No. 86)

Question. Classify meristematic tissue on the basis of origin.
Answer: Classification of meristematic tissue on the basis of origin:
1. Promeristem / Primordial meristem:
a. It is also called as embryonic meristem.
b. It usually occupies very minute area at the tip of root and shoot.
2. Primary meristem:
a. It originates from the primordial meristem and occurs in the plant body from the beginning, at the root and shoot apices.
b. Cells are always in active state of division and give rise to permanent tissues.
3. Secondary meristem:
a. These tissues develop from living permanent tissues during later stages of plant growth hence are called as secondary meristems.
b. This tissue occurs in the mature regions of root and shoot of many plants.
c. Secondary meristem is always lateral (to the central axis) in position e.g. Fascicular cambium, inter-fascicular cambium, cork cambium.
In simple words: Meristematic tissue is classified by origin into promeristem (embryonic), primary meristem (early plant growth), and secondary meristem (later growth from permanent tissues).

🎯 Exam Tip: Differentiating between promeristem, primary, and secondary meristems by their origin and timing of appearance is crucial.

Can You Tell? (Textbook Page No. 89)

Question. Write a note on parenchyma.
Answer: Parenchyma:
1. It is a type of simple permanent tissue.
2. Cells in this tissue are thin walled, isodiametric, round, oval to polygonal or elongated in shape.
3. Cell wall is composed of cellulose.
4. Cells are living with prominent nucleus and cytoplasm with large vacuole.
5. Parenchyma has distinct intercellular spaces. Sometimes, cells may show compact arrangement.
6. The cytoplasm of adjacent cells is interconnected through plasmodesmata and thus forms a continuous tissue.
7. This is less specialized permanent tissue.
8. Occurrence: These cells are distributed in all the parts of a plant body viz. epidermis, cortex, pericycle, pith, mesophyll cells, endosperm, xylem and phloem.
9. Functions: These cells store food, water, help in gaseous exchange, increase buoyancy, perform photosynthesis and different functions in plant body.
10. Dedifferentiation in parenchyma cells develops vascular cambium and cork cambium at the time of secondary growth.
In simple words: Parenchyma is a simple plant tissue with thin-walled, living cells, often with intercellular spaces, primarily involved in food storage, photosynthesis, and gaseous exchange throughout the plant.

🎯 Exam Tip: A comprehensive note on parenchyma should cover its structure, occurrence, and diverse physiological functions in plants.

Can You Tell? (Textbook Page No. 89)

Question. Describe sclerenchyma fibres.
Answer: Sclerenchyma fibres:
1. Fibres are thread-like, elongated and narrow structures with tapering and interlocking end walls.
2. Fibres are mostly in bundles. Pits are narrow, unbranched and oblique.
3. They provide mechanical strength.
In simple words: Sclerenchyma fibers are long, slender, dead cells with thick, lignified walls that provide mechanical support and strength to the plant.

🎯 Exam Tip: Focus on the structural characteristics like shape, wall thickness, and primary function of mechanical support when describing sclerenchyma fibres.

Can You Tell? (Textbook Page No. 89)

Question. Sketch and label T.S. of phloem tissue.
Answer: T.S. of phloem tissue: Structure of phloem:
1. Phloem is a living tissue. It is also called as bast.
2. It is responsible for conduction of organic food material from source (generally leaf) to a sink (other plant parts).
3. On the basis of origin, it can be protophloem (first formed) and metaphloem (latterly formed).
4. It is composed of sieve elements (sieve cells and sieve tubes), companion cells, phloem parenchyma and phloem fibres.
2. Sieve elements:
a. Sieve tubes are long tubular conducting channel of phloem.
b. These are placed end to end with bulging at end walls.
c. The sieve tube has sieve plate formed by septa with small pores.
d. The sieve plates connect protoplast of adjacent sieve tube cells.
e. The sieve tube cell is a living cell with a thin layer of cytoplasm, but loses its nucleus at maturity.
f. The sieve tube cell is connected to companion cell through phloem parenchyma by plasmodesmata.
g. Sieve cells are found in lower plants like pteridophytes and gymnosperms and sieve tubes are found in angiosperms.
h. The cells are narrow, elongated with tapering ends and sieve area located laterally.
3. Companion cells:
a. These are narrow elongated and living.
b. Companion cells are laterally associated with sieve tube elements.
c. Companion cells have dense cytoplasm and prominent nucleus.
d. Nucleus of companion cell regulates functions of sieve tube cells through simple pits.
e. From origin point of view, sieve tube cells and companion cell are derived from same cell. Death of the one result in death of the other type.
4. Phloem parenchyma:
a. Cells of phloem parenchyma are living, elongated found associated with sieve tube and companion cells.
b. Their chief function is to store food, latex, resins, mucilage, etc.
c. The cells carry out lateral conduction of food material.
d. These cells are absent in most of the monocots.
5. Phloem fibres (Bast fibres):
a. Phloem fibres are the only dead tissue among this unit.
b. They are sclerenchymatous.
c. They are generally absent in primary phloem, but present in secondary phloem.
d. These cells have with lignified walls and provide mechanical support.
e. They are used in making ropes and rough clothes.
ℹ️ चित्र व्याख्या (Diagram Explanation): यह एक फ्लोएम ऊतक का अनुप्रस्थ काट (T.S.) दर्शाता है, जिसमें चालनी नलिकाएं, सह कोशिकाएं, फ्लोएम पैरेंकाइमा और फ्लोएम फाइबर जैसे विभिन्न घटक दिखाई देते हैं। यह चित्र इन संरचनाओं की व्यवस्था और उनके बीच के संबंध को स्पष्ट करता है, जो पौधे में भोजन के संवहन के लिए आवश्यक हैं।
In simple words: Phloem tissue, also known as bast, is a living complex tissue composed of sieve elements, companion cells, phloem parenchyma, and phloem fibers, primarily responsible for the long-distance transport of sugars and other organic nutrients throughout the plant.

🎯 Exam Tip: When asked to sketch and label, ensure all components of the phloem tissue (sieve tubes, companion cells, parenchyma, fibres) are accurately represented and labeled, along with their key structural features.

Can You Tell? (Textbook Page No. 92)

Question. Concentric vascular bundles are always closed. Describe.
Answer: 1. When one vascular tissue is completely encircling the other, it is called as concentric vascular bundle.
2. When cambium is not present between xylem and phloem, it is known as closed vascular bundle.
3. Due to absence of cambium between xylem and phloem, concentric vascular bundles are always closed.
In simple words: Concentric vascular bundles are always closed because they lack a cambium layer between the xylem and phloem, preventing any secondary growth.

🎯 Exam Tip: The presence or absence of cambium is the key factor determining whether a vascular bundle is open or closed, which is vital for understanding secondary growth.

Can You Tell? (Textbook Page No. 92)

Question. How is the structure of vascular bundles of the root?
Answer: 1. Vascular bundles of the root are radial.
2. In radial vascular bundles, complex tissues are situated separately on separate radius as separate bundle.
3. The xylem and phloem bundles are arranged alternating with each other.
In simple words: Root vascular bundles are radial, meaning xylem and phloem are arranged alternately on different radii, with separate bundles for each tissue.

🎯 Exam Tip: Emphasize the radial arrangement and separate placement of xylem and phloem in root vascular bundles.

Can You Tell? (Textbook Page No. 92)

Question. Why vascular bundles of dicot stem are described as conjoint collateral and open?
Answer: Vascular bundles of dicot stem are described as conjoint collateral and open because;
1. In dicot stem, the complex tissue is collectively present as neighbours of each other on the same radius in the form of xylem inside and phloem outside. Such type of vascular bundles are called as conjoint and collateral.
2. In dicot stem, a strip of cambium is present between xylem and phloem. Hence, it is called as open vascular bundle.
In simple words: Dicot stem vascular bundles are conjoint (xylem and phloem together), collateral (phloem outside xylem), and open (presence of cambium allowing secondary growth).

🎯 Exam Tip: The terms "conjoint," "collateral," and "open" are crucial descriptors for dicot stem vascular bundles, with the presence of cambium being key for "open."

Can You Tell? (Textbook Page No. 92)

Question. How is the arrangement of vascular bundles in dicot and monocot stem?
Answer: 1. Vascular bundle in dicot stem: Vascular bundles are conjoint, collateral, open, and are arranged in a ring. Each one is composed of xylem, phloem and cambium. Xylem is endarch. A strip of cambium is present between xylem and phloem.
2. Vascular bundle in monocot stem: Vascular bundles are numerous and are scattered in ground tissue. Each vascular bundle is surrounded by a sclerenchymatous bundle sheath. Vascular bundles are conjoint, collateral and cloused (without cambium). Xylem is endarch and shows lysigenous cavity.
In simple words: Dicot stems have vascular bundles arranged in a ring, which are conjoint, collateral, and open with cambium; monocot stems have scattered, conjoint, collateral, and closed bundles without cambium, each surrounded by a bundle sheath.

🎯 Exam Tip: Clearly contrasting the arrangement (ring vs. scattered) and the presence/absence of cambium in dicot versus monocot stems is essential for this comparison.

11th Std Biology Questions And Answers: