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Class 11 Biology Chapter 5 Morphology of Following Plant
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Morphology of Following Plant
Chapter – 5
VERY SHORT ANSWER TYPE QUESTIONS
Q.1. How is the primary root formed?
Ans :- By the elongation of the radicle, primary root is formed in dicotyledonous plants.
Q.2. What is a tap-root?
Ans :- The primary root and its branches constitutes tap-root.
Q.3. In which type of plants, tap-root is seen?
Ans :- In dicotyledonous plants, tap-root is seen.
Q.4. From where does the fibrous root arise?
Ans :- Fibrous roots arise from the base of the stem.
Q.5. What are the adventitious roots?
Ans :- When roots arise from the parts of the plant other than the radicle, such roots are called adventitious roots, e.g. banyan tree.
Q.6. What is a root-cap?
Ans :- The root is covered at the apex by a thimble like structure called root-cap.
Q.7. Which region is responsible for the growth of the root in length?
Ans :- Region of elongation is responsible for the growth of the root in length.
Q.8. What are root hairs?
Ans :- The very fine and delicate, thread like structure found on the epidermal layer is called root hair.
Q.9. What are prop root?
Ans :- The roots which arise from horizontal branches of stem and hang in air are called prop root e.g. banyan.
Q.10. What are pneumatophores?
Ans :- In some plants growing in swampy areas, roots come out of the ground and grow vertically upward. Such roots are called pneumatophores, e.g. rhizophora.
Q.11. From which region does leaf arise on a stem?
Ans :- The region of a stem from which a leaf arises is the node.
Q.12. What is an internode?
Ans :- Internode are the portion between two nodes of a stem.
Q.13. Mention the name of underground stem which is modified to store foods?
Ans :- Underground stem of potato, ginger, turmeric, zaminkand, Colocasia are modified to store food.
Q.14. What are stem tendrils?
Ans :- Tendrils are slender and spirally coiled structure which develop from axillary bud and helps the plant to climb.
Q.15. What are thorns?
Ans :- Axially buds of stem may get modified into woody, straight and pointed structure called thorn.
Q.16. What is a leaf?
Ans :- The leaf is a lateral, generally flattened structure borne on a stem.
Q.17. What are the main parts of a leaf?
Ans :- The main parts of a leaf are leaf-base, petiole and lamina.
Q.18. Write one word for the green expanded part of the leaf with vein and veinlet?
Ans :- Lamina or leaf-blade.
Q.19. What is phyllotaxy?
Ans :- Phyllotaxy is the pattern of arrangement of leaves on the stem or branch.
Q.20. What is the main difference between tendril and spine?
Ans :- Tendrils are meant for climbing but spines are meant for defence.
Q.21. Write the name of reproductive organ of a flower?
Ans :- Androecium and gynoecium are the reproductive organ of a flower.
Q.22. When is a flower said ‘bisexual’?
Ans :- A flower is bisexual when both androecium and gynoecium are present.
Q.23. What is a bracteate flower?
Ans :- Flowers with bracts – reduced leaf found at the base of the pedicel are called bracteate flower.
Q.24. Define calyx and corolla.
Ans :- Calyx is the outermost whorl of the flower.
Q.25. What is placentation?
Ans :- The arrangement of ovules within the ovary is known as placentation.
Short answer type questions
Q.1. Mention the important function of a root?
Ans :- The important function of a root are –
(i) Absorption of water and minerals from the soil.
(ii) Roots gives anchorage to the plants.
(iii) Roots stores reserve food materials.
(iv) Roots helps in respiration.
Q.2. Write the names of the different regions of the root ?
Ans :- The different region of roots are –
(i) Root cap
(ii) Region of meristematic activity
(iii) Region of elongation
(iv) Region of maturation.
Q.3. Write the important functions of stem?
Ans :- Functions of stem are –
(i) It bears leaves, flowers and fruits.
(ii) It keeps the leaves exposed to sunlight for photosynthesis.
(iii) It conducts water, minerals from one part to another.
(iv) It support the plant.
Q.4. Why do roots undergo modification ?
Ans :- Root undergo modification due to the following reasons –
(i) For storage purpose e.g. tuberous root.
(ii) For mechanical support e.g. prop root.
(iii) For reproduction e.g. Dahlia.
(iv) For various physiological functions such as assimilation, respiration e.g. pneumatophores of rhizophora.
Q.5. What are the important characteristics of stem?
Ans :- The following characteristics are found in a stem –
(i) The stem develops from plumule.
(ii) It is the ascending portion of the axis of plant.
(iii) It bears leaves, fruits, seeds, buds etc.
(iv) The young stem synthesises carbohydrate.
Q.6. Write a note on modification of stem.
Ans :- Stem are also modified to perform different function for example, stem tendril which develop from axillary buds helps the plant to climb e.g. cucumber, pumpkins.
Axillary bud of stem may also get modified into woody, straight and pointed thorns e.g. in citrus, Bougainvillea. The thorn protect the plant from browsing animals.
Q.7. Describe briefly the part of a typical leaf?
Ans :- A typical leaf consists of three main parts :-
Leaf base, petiole and lamina.
Leaf base :- The leaf is attached to the stem by the leaf base.
Petiole :- It is rod-like structure supporting the lamina.
Lamina :- It is the flattened expanded green terminal portion of the leaf.
Q.8. What is venation? How many types of venation are seen in leaf ?
Ans :- The arrangement of veins and veinlets in the lamina of the leaf is termed as venation.
There are 2 types of venation seen in leaves. They are reticulate and parallel venation.
When the veinlets form a network, the venation is called reticulate. When the veins run parallel to each other within a lamina, the venation is termed as parallel.
Q.9. What is phyllotaxy? Describe its types.
Ans :- Phyllotaxy is the pattern of arrangement of leaves on the stem or branch.
Phyllotaxy is of 3 types – alternate, opposite and whorled.
In alternate type, a single leaf arise at each node in alternate manner e.g. china rose.
In opposite type, a pair of leaves arise at each node and lie opposite to each other e.g. guava.
If more than two leaves arise at a node and form a whorl, it is called whorled, e.g. Alstonia.
Q.10. Describe the modifications found in leaves?
Ans :- Leaves are modified to perform function other than photosynthesis. They are converted into tendrils for climbing as in case of peas or into spines for defence as in cactus.
Leaves of certain insectivorous plants such as pitcher plant, venus – fly trap are also modified leaves.
Q.11. What do you mean by inflorescence ? Mention its types.
Ans :- The arrangement of flowers on the floral axis is termed as inflorescence.
There are two major types of inflorescence – racemose and cymose.
In racemose type of inflorescence the main axis continues to grow, the flowers are borne laterally in an acropetal succession.
In cymose type of inflorescence the main axis terminates in a flower, hence is limited in growth. The flowers are borne in a basipetal order.
Q.12. Describe any two whorls of a flower.
Ans :- Each flowers has four whorls viz. calyx, corolla, androecium and gynoecium.
Calyx :- Calyx is the outermost whorl of the flower and the members are called sepals. Sepals are green leaf like and protect the flower in the bud stage. Calyx may be gamosepalous (sepals united) or polysepalous (sepals free).
Corolla :- Corolla is composed of petals. Petals are usually brightly coloured to attract insects for pollination. Corolla may be gamopetalous or polypetalous.
Q.13. Write a note on aestivation.
Ans :- The mode of arrangement of sepals or petals in floral bud with respect to the others members of the same whorl is known as aestivation.
The main type of aestivation are –
When sepals or petals just touch one another without overlapping, it is said to be valvate e.g. calotropis. If one margin overlap that of the next one and so on it is called twisted e.g. china rose. If the margin of petals and sepals overlap one another but not in any particular direction, the aestivation is called imbricate e.g. gulmohur. If the target petals overlap the two lateral petals which in turn overlap the other petals, this type of aestivation is vexillary e.g. bean flower.
Q.14. Write four difference between androecium and gynoecium.
Ans :- The major difference between androecium and gynoecium are –
(i) Androecium is composed of stamens whereas gynoecium is composed of carpels.
(ii) Androecium is the male reproductive organ whereas gynoecium is the female reproductive organ.
(iii) Stamen is composed of anther and filament whereas carpel is composed of stigma, style and ovary.
(iv) Stamens may be united into one bundle (monadelphous) or in two bundles (diadelphous) etc. Whereas carpel may be free (apocarpous) or fused (syncarpous).
Q.15. Describe the types of placentation with examples.
Ans :- The placentation are of different types, namely –
Marginal, axile, parietal, basal, central and free central.
In marginal placentation, the placenta forms a ridge along the ventral suture of the ovary and the ovules are borne on this ridge forming two rows. When the placenta is axial and the ovule are attached to it in a multilocular ovary, the placentation is said to be axial.
In parietal placentation, the ovules develop on the inner wall of the ovary.
When the ovules are borne on central axis and septa are absent, the placentation is called free central.
In basal placentation, the placenta develops at the base of the ovary and a single ovule is attached to it.
Q.16. Write a note on ‘fruit’.
Ans :- Fruit is a mature or ripened ovary, developed after fertilisation. If a fruit is formed without fertilisation of the ovary, it is called parthenocarpic fruit.
The fruit consists of a wall or pericarp and seeds. When the pericarp is thick and fleshy, it is differentiated into epicarp, middle mesocarp and inner endocarp.
Q.17. Draw a labelled diagram of a dicot and a monocot seed.
LONG ANSWER TYPE QUESTIONS
Q.1. Justify the statement on the basis of external feature –
(a) Underground part of a plant are not always root.
(b) Flower is a modified shoot.
Ans :- (a) Underground part of a plant are not always root can be better understood by citing an example. Ginger is the best example. Ginger grows under the ground but is not considered root because of the following reasons –
(i) Rhizome of ginger possess node and internode.
(ii) It bears dry scaly leaves at node.
(iii) It bears axillary buds from the axil of dry scale leaves and a terminal bud at the apex as in stem.
(iv) Adventitious roots develop from the nodes.
(v) When exposed to light, it becomes green.
Thus it is justified that the underground part of a plant are not always root.
Q.2. “Flower is a modified shoot” Comment.
Ans :- A flower is considered to be a modified shoot in which the leaves are modified into floral leaves (sepals and petals) and the stem is condensed with suppressed nodes and internodes as thalamus. The following facts may be cited in support of the above facts.
(a) Homology of the floral bud :-
(i) Position of floral bud is similar to that of the vegetative bud.
(ii) Sometimes floral buds are modified into vegetative buds called bulbils. Eg. Pineapple.
(b) Axis nature of the thalamus :-
(i) Sometimes the thalamus shows the development of nodes and internodes similar to that of a stem (Androphore & Gynophore)
(ii) Sometimes after bearing the floral leaves the thalamus grows further like a branch bearing foliage leaves. e.g.- Rose.
(c) Leafy nature of floral leaves :-
(i) In water lily the floral parts are leafy as they show gradual transition from sepals to carpels through petals and stamens.
(ii) The floral leaves show the same venation as observed in foliage leaves.
(d) Phyllotaxy :- The arrangement of floral parts on the thalamus is similar to the arrangement of foliage leaves on the stem.
Thus we can conclude that the thalamus is a suppressed stem and the floral parts are modified leaves.
Q.3. Differentiate between –
(a) Racemose and cymose inflorescence.
(b) Fibrous root and adventitious root.
(c) Apocarpous and syncarpous ovary.
Ans :- (a) Racemose
(i) The main axis continue to grow.
(ii) Flower arrangement is in acropetal succession.
(iii) Flowers are not aggregate.
(i) The main axis terminate in a flower.
(ii) Flower develope in basipetal succession.
(iii) Flowers are in aggregate.
(b) Fibrous root
(i) The root system formed by the adventitious root is called fibrous root.
(i) When roots arise from parts of the plant other than the radicle are called adventitious root.
(c) A carpel consists of three parts – stigma, style and ovary. When more than one carpel is present, they may be free as in lotus and rose and are called apocarpous.
They are called syncarpous when carpels are fused, as in mustard and tomato.
Q.4. Describe the structure of –
(a) Dicot seed.
(b) Monocot seed.
Ans :- (a) Structure of dicot seed :-
The outermost covering of seed is the seed coat. The seed coat has two layers, outer testa and inner tegmen. Hilum is the scar on the seed coat through which the developing seeds are attached to the fruit. Micropyle is a small pore about the hilum. Within the seed coat is the embryo which consists of an embryonal axis and two cotyledons. Cotyledon are the reserves of food materials. At the end of embryonal axis, radicle and plumule are present. In some seeds, endosperm formed as a result of double fertilisation, is a food storing tissue.
(b) Structure of monocot seed :-
Monocotyledonous seeds are endospermic but some are non-endospermic. In the seeds of cereals such as maize the seed coat is membranous. The endosperm is bulky and stores food. The outer covering of endosperm separates the embryo by a proteinous layer called aleurone layer. The embryo consists of one large and shield shaped cotyledon known as scutellum and a short axis with plumule and a radicle. The plumule and radicle are enclosed in sheath which are called coleoptile and coleorhiza.
Q.5. Take one flower of the family Fabaceaes and write its semi technical description. Also draw its floral diagram.
Ans :- Fabaceaes was earlier called papilionoideae, is a sub-family of family Leguminous. Example – pea.
Vegetative characters :- Tree, shrubs, herb, root with modules.
Stem :- Erect or climber.
Leaves :- Alternate, pinnately compound or simple, venation reticulate.
Floral Characters :-
Inflorescence :- Racemose.
Flower :- Bisexual, zygomorphic.
Calyx :- Sepals five, gamosepalous, imbricate aestivation.
Corolla :- Petals five, polypetalous, papilionaceous, vexillary aestivation.
Androecium :- Ten, diadelphous, anther, dithecous.
Gynoecium :- Ovary superior, mono carpellary, unilocular.
Fruit :- Legume, seed, one to many, non-endospermic.
Q.6. Describe with example the family Solanaceae with floral diagram.
Ans :- Solanaceae is a large family, commonly called as ‘potato family’. e.g. makoi plant (Solanum nigrum).
Vegetative characters :-
Plants mostly herbs shrubs and rarely small trees.
Stem :- Herbaceous, rarely woody, aerial, erect, cylindrical, branched, underground stem in potato.
Leaves :- Alternate, simple, rarely pinnately compound, exstipulate, venation reticulated.
Floral characters :-
Inflorescence :- Solitary, axillary or cymose as in Solanum.
Flower :- Bisexual, actinomorphic.
Calyx :- Sepals five, united, valvate aestivation.
Corolla :- petals five, united, valvate aestivation.
Androecium :- Stamens five, epipetalous.
Gynoecium :- Bicarpellary, Syncarpous, ovary superior, bilocular.
Fruits :- Berry or capsule.
Seeds :- Many, endospermous.
Q.7. Describe the different types of flower classified on the basis of position of ovary in relation to the floral leaves.
Ans :- Normally the calyx, corolla, androecium and gynoecium of a flower lie on the thalamus on their proper sequence. But in many flowers, the relative position of the first three whorls in respect to the ovary, become disturbed due to the unusual growth of the thalamus. According to the nature of thalamus and the mode of insertion of the first three floral sets with respect to the gynoecium, flowers may be hypogynous, perigynous and epigynous.
In a hypogynous flower, the ovary occupies the highest position on the thalamus, while the stamen, petals and sepals are separately inserted below the ovary. The ovary is said to be superior and rest of floral members are inferior. e.g. china rose.
In perigynous flower, the 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. The ovary here is said to be half-inferior e.g. plum, rose.
In epigynous flower, the margin of thalamus grows upward enclosing the ovary completely and getting fused with it, the other parts of the flower arise above the ovary. Hence, the ovary is said to be inferior as in flowers of guava and cucumber.
Q.8. Write the floral characters and formulae of the Liliaceae family with diagram.
Ans :- Liliaceae family is commonly called the ‘Lily Family’ is a characteristic representative of monocotyledonous plant.
Floral Characters :-
Inflorescence :- Solitary/ Cymose.
Flower :- Bisexual, actinomorphic.
Perianth :- Tepal six (3+3) often united, valvate aestivation.
Androecium :- Stamen six (3+3)
Gynoecium :- Tricarpellary, syncarpous, ovary superior, trilocular, axile placentation.
Fruit :- Capsule, rarely berry.
Seed :- Endospermous.
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