Anatomy Of Flowering Plants Exercises
Exercises
1. Draw illustrations to bring out the anatomical difference between
(a) Monocot root and Dicot root
(b) Monocot stem and Dicot stem
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Answer
(a)Monocot root and dicot root
TS of dicot root (Primary)
T.S of monocot root
(b)Monocot stem and dicot stem
T.S. of dicot stem
T.S. of monocot stem
2. 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.
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Answer
The dicot stem is characterised by the presence of conjoint, collateral, and open vascular bundles, with a strip of cambium between the xylem and phloem. The vascular bundles are arranged in the form of a ring, around the centrally-located pith. The ground tissue is differentiated into the collenchyma, parenchyma, endodermis, pericycle, and pith. Medullary rays are present between the vascular bundles.
T.S. of dicot stem
The monocot stem is characterised by conjoint, collateral, and closed vascular bundles, scattered in the ground tissue containing the parenchyma. Each vascular bundle is surrounded by sclerenchymatous bundle-sheath cells. Phloem parenchyma is absent and water-containing cavities are present.
T.S. of monocot stem
3. 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?
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Answer
The monocot stem is characterised by conjoint, collateral, and closed vascular bundles, scattered in the ground tissue containing the parenchyma. Each vascular bundle is surrounded by sclerenchymatous bundle-sheath cells. Phloem parenchyma and medullary rays are absent in monocot stems.
4. What is stomatal apparatus? Explain the structure of stomata with a labelled diagram.
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Answer
Stomata are small pores present in the epidermis of leaves. They regulate the process of transpiration and gaseous exchange. The stomatal pore is enclosed between two bean-shaped guard cells. The inner walls of guard cells are thick, while the outer walls are thin. The guard cells are surrounded by subsidiary cells. These are the specialised epidermal cells present around the guard cells. The pores, the guard cells, and the subsidiary cells together constitute the stomatal apparatus.
5. Name the three basic tissue systems in the flowering plants. Give the tissue names under each system.
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Answer
| No. | Tissue system | Tissues present |
|---|---|---|
| 1. | Epidermal tissue system | Epidermis, trichomes, hairs, stomata |
| 2. | Ground tissue system | Parenchyma, collenchyma, sclerenchyma, mesophyll |
| 3. | Vascular tissue system | Xylem, phloem, cambium |
6. How is the study of plant anatomy useful to us?
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Answer
The study of plant anatomy helps us to understand the structural adaptations of plants with respect to diverse environmental conditions. It also helps us to distinguish between monocots, dicots, and gymnosperms. Such a study is linked to plant physiology. Hence, it helps in the improvement of food crops. The study of plant-structure allows us to predict the strength of wood. This is useful in utilising it to its potential. The study of various plant fibres such as jute, flax, etc., helps in their commercial exploitation.
7. Describe the internal structure of a dorsiventral leaf with the help of labelled diagrams.
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Answer Dicots exhibit dorsiventral leaves. When examined, the vertical section of a dorsiventral leaf consists of three different parts, and they are
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Epidermis – It is found on the adaxial epidermis (upper surface) and the abaxial epidermis (lower surface). On the outside, the epidermis is covered with a thick cuticle. Compared to the upper surface, the abaxial epidermis comprises more stomata.
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Mesophyll – It is a tissue found in between the abaxial and adaxial epidermises. This tissue is differentiated into the palisade parenchyma and the spongy parenchyma. The palisade parenchyma is composed of tall, compactly-arranged cells, while the spongy parenchyma comprises round or oval, loosely-arranged cells possessing intercellular spaces. Mesophyll comprises of chloroplasts that carry out photosynthesis.
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Vascular system – The vascular bundles that are found in leaves are closed and conjoint, which are engirdled by thick layers of bundle-sheath cells.
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