Please refer to Morphology of Flowering Plants Class 11 Biology Exam Questions provided below. These questions and answers for Class 11 Biology have been designed based on the past trend of questions and important topics in your class 11 Biology books. You should go through all Class 11 Biology Important Questions provided by our teachers which will help you to get more marks in upcoming exams.
Class 11 Biology Exam Questions Morphology of Flowering Plants
Class 11 Biology students should read and understand the important questions and answers provided below for Morphology of Flowering Plants which will help them to understand all important and difficult topics.
Very Short Answer Type Questions:
Question. Add the missing floral organs of the given floral formula of Fabaceae.
Ans. The floral formula of Fabaceae family is
Floral character of Fabaceae shows bisexual, zygomorphic, petals-five, gamosepalous, corolla-petals 5, consists of a posterior standard, two lateral wings, two anterior ones forming a keel, androecium, ten diadelphous, gynoecium-superior, ovary monocarpellay.
Question. In swampy areas like the sunderbans in West Bengal, plants bear special kind of roots called ………
Ans. Pneumatophores Roots are the organs meant for the absorption of water and minerals from the soil. Cells of roots require O2 to respire. In swampy areas, soil does not have air, so no O2 is available to them.
In such cases, roots come out of the soil shows negative geotropism and breathe after coming in contact with air, e.g., Rhizophora. Such roots are called pneumatophores respiratory roots.
Question. Name the body part modified for food storage in the following
(a) Carrot …………… (b) Colocasia ……………
(c) Sweet potato …………… (d) Asparagus ……………
(e) Radish …………… (f) Potato ……………
(g) Dahlia …………… (h) Turmeric ……………
(i) Gladiolus …………… (j) Ginger ……………
(k) Portulaca ……………
Ans. (a) Carrot — Tap root
(b) Colocasia — Stem-(corm)
(c) Sweet potato — Root
(d) Asparagus — Root
(e) Radish — Root
(f) Potato — Stem
(g) Dahlia — Adventitious root
(h) Turmeric — Stem
(i) Gladiolus — Stem
(j) Ginger — Stem
(k) Portulaca — Adventitious root
Question. In Opuntia, the stem is modified into a flattened green structure to perform the function of leaves, (i.e., photosynthesis). Cite some other examples of modifications of plant parts for the purpose of photosynthesis.
Ans. Opuntia is a xerophytic plant, in which leaves are modified into spine to reduce the rate of transpiration and they do not perform the photosynthesis at all.
So function of photosynthesis in Opuntia plant is performed by stem which is thick fleshy and flattened structure containing chlorophyll and stores food. It is known as phylloclade.
Sometimes, the stem, i.e., about one internode long modifies into a leaf like structure to carry out photosynthesis, as in Asparagus. They are present in axil of scale leaves while true
leaves are reduced to scales or spines.
Similarly in some plants, roots become assimilatory as in the case of Trapa and Tinospora.
These roots grow outside the soil, develop chlorophyll in them and perform photosynthesis.
Question. Roots obtain oxygen from air in the soil for respiration. In the absence or deficiency of O2, root growth is restricted or completely stopped. How do the plants growing in marsh lands or swamps obtain their O2 required for root respiration?
Ans. The roots of the plants (e.g., Rhizophora) growing in marshy/swamp areas become negatively geotropic. They grow vertically upwards in air, above the soil level and respire so called respiratory roots or pneumatophores.
Question. Write floral formula for a flower which is bisexual, actinomorphic sepals five, twisted aestivation, petals five valvate aestivation; stamens six, ovary tricarpellary, syncarpous, superior, trilocular with axile placentation.
Ans. Floral formula is a formula by which we can describe the flower by using some symbols.
The various symbols describing the above given conditions are as follows
Question. In aquatic plants like Pistia and Eichhornia, leaves and roots are found near ………
Ans. In Pistia and Eichhornia, in these floating plantes, the stem is like a runner where it branches to form leaves at the apex and roots below. The roots are found near the surface
of water as both the plants are hydrophytes.
Question. Reticulate and parallel venation are the characteristic of …….. and ……….. respectively.
Ans. Dicot and monocot plants All dicot plants have reticulate venation (i.e., veinlets forms network) except is Alocasia and Smilex, whereas all monocot plants have parallel venation
(veins run parallel to each other within a lamina) with the exception Calophyllum.
Question. Which parts in ginger and onion are edible?
Ans. The edible part of ginger is the modified stem rhizome which stores food material whereas in onion the edible part is fleshy leaves. In this case, the internode becomes shortened,
leaves get condensed to form a tunic and store food material.
Question. In epigynous flower, ovary is situated below the ……… .
Ans. In epigynous flower, ovary is situated below the thalamus (inferior) while the other whorls of flower like sepals, petals and androecium grows above the ovary (superior), e.g., carrot, guava, Cucurbita, sunflower, etc.
Short Answer Type Questions:
Question. Draw diagrams of a typical monocot and dicot leaves to show their venation pattern.
Ans. Venation is the pattern of distribution of veins and veinlets in the lamina of leaf. It’s pattern is different in monocot and dicot leaf.
Question. Rhizome of ginger is like the roots of other plants that grows underground. Despite this fact ginger is a stem and not a root. Justify.
Ans. Rhizome of Ginger is a type of underground modification of stem which grows horizontally underground and bear nodes, internodes and scaly leaves and buds, which gives rise to aerial shoots.
The adventitious root arises from the lower surface of nodes. It is not a root because root does not have nodes and internodes. Further the rhizome donot perform the function of roots, i.e., anchorage and absorption, rather serves as resevoir for storage of food. All these characteristics support the fact that ginger is a stem and not a root.
Question. A typical angiosperm flower consists of four floral parts. Give the names of the floral parts and their arrangements sequentially.
Ans. The four floral parts of typical angiospermic flower are
Calyx It is the outermost whorl of the flower and members are called calyx or sepals. These are usually green and are protective in function (in bud stage).
Corolla It is composed of petals, usually bright coloured to attract insects for pollination.
Androecium It is composed of stamens, the male reproductive organ. Each stamen has stalk or filament and anther (containing pollen sac and pollen grains).
Gynoecium It is the female reproductive part and made up of one or more carpels. Each carpel has stigma, style and ovary.
Question. Given below are a few floral formulae of some well known plants. Draw floral diagrams from these formulae.
Ans.
Question. Reticulate venation is found in dicot leaves while in monocot leaves venation is of parallel type. Biology being a ‘Science of exceptions’, find out any exception to this generalisation.
Ans. Reticulate venation is a characteristic of dicots and parallel venation is of monocots. But few exceptions are also seen in this generalisation parallel venation is also found in dicot plants, e.g., Calophyllum, corymbium, etc., and reticulate venation is also found in monocot plants such Alocasia, Smilax, etc.
Question. You have heard about several insectivorous plants that feed on insects.
Nepenthes or the pitcher plant is one such example, which usually grows in shallow water or in marsh lands. What part of the plant is modified into a pitcher? How does this modification help the plant for food even though it can photosynthesise like any other green plant?
Ans. In insectivorous plant, e,g., Nepenthes, the leaf lamina gets modified in the form of pitcher and anterior part of petiole coils like tendril which keeps the pitcher in a vertical direction.
Posterior part of the petiole remains flattened like a leaf. The apex of lamina forms a lid.
Pitcher contains digestive enzyme which digest the trapped insects.
All these modifications and adaptation are developed to make up the nitrogen deficiency in the plant because these plants are found in N2 deficient soil, (marshy/swamp soils)
Question. Mango and coconut are ‘drupe’ type of fruits. In mango, fleshy mesocarp is edible. What is the edible part of coconut? What does milk of tender coconut represent?
Ans. Mango and coconut are drupe fruits. They develop from monocarpellary superior ovaries and are one seeded. It is differentiated into outer thin epicarp, middle fleshy mesocarp and inner stony endocarp.
The edible part of coconut (Cocos nucifera) is endosperm. The milk of tender coconut represents the oily endosperm in liquid form. Later it gets deposited along the walls of endocarp and forms edible flesh.
Question. How can you differentiate between free central and axile placentation?
Ans. Placentation is the arrangement of ovules on the walls of ovary with the help of special kind of tissue called placenta. Plants show different types of placentation, central and axile are among them.
They have the following differences
Question. Tendrils of grapevines are homologous to the tendril of pumpkins, but are analogous to that of pea. Justify the above statement.
Ans. Homologous Organs are organs that have similar origin but they differ functionally.
Axillary bud of stem gives rise to tendril of both grapevine and pumpkins so they have same origin, i.e., homologous, whereas analogous organs are organs having different origin, but perform same function. The tendril of pea arises from the leaf and helps the plant to climb.
Hence, the origin of pea tendril is different but, its function is similar to the tendrils of grapevines.
Question. Tendrils are found in the following plants. Identify whether they are stem tendrils of leaf tendrils.
(a) Cucumber (b) Peas
(c) Pumpkins (d) Grapevine
(e) Watermelon
Ans. (a) Cucumber (Cucums sativus), have stem tendril from axillary bud.
(b) Peas (Pisum sativum) leaf gets modified into tendril for climbing.
(c) Pumpkins (Cucurbita pepo), stem tendril from axillary bud.
(d) Grape wine (Vitis), stem tendril from axillary bud.
(e) Water melon (Citrullus lanatus), stem tendril from axillary bud.
Question. Give two examples of roots that develop from different parts of the angiospermic plant other than the radicle.
Ans. In banyan tree, prop roots develop from the lower nodes of stem of banyan tree. They grow downwards and touch the soil. Prop roots are meant for support.
In sugarcane, stilt roots arise from the lower nodes of stem and enter the soil to provide strength to the plant. These protect the plant against winds.
Question. Differentiate between
(a) Bract and bracteole (b) Pulvinus and petiole
(c) Pedicel and peduncle (d) Spike and spadix
(e) Stamen and staminoid (f) Pollen and pollenium
Ans. (a) Bract and Bracteolate Bract is a leaf like structure in the axil. i.e., at the base of which flowers are borne. They can be small or scaly, green and coloured and usually single,
whereas bracteolate are bract like structures borne on the stalk of a flower.
(b) Pulvinus and Petiole Pulvinus is the leaf base, which is the proximal swollen region with which a leaf is attached to the stem. Petiole is cylindrical or sub-cylindrical stalk
which connects the leaf base with the lamina.
(c) Pedicel and Peduncle The stalk of a flower is known as pedicle, whereas the stalk of whole inflorescence is known as peduncle.
(d) Spike and Spadix In spike inflorescence, the flowers are sessile that develop on an elongated peduncle in acropetal succession, e.g., Adhatoda. The peduncle is non-fleshy. The spadix inflorescence is like spike, but it is covered by one to a few large bracts called spathes, e.g., Colocasia. The peduncle is fleshy and its opical portion is naked, i.e., without flowers.
(e) Stamen and Staminoid The male reproductive organs or microsporophylls of a flower are called stamen. A fully sterile under developed or abrtive stamen is called a staminoid, e.g., Verbascum.
(f) Pollen and Pollinium Microspore of an angiospermic flower is known as pollen. It is haploid, whereas a mass of pollen grains from the same anther constitute the pollinium as in Calotropis.
Question. The essential functions of roots are anchorage and absorption of water and minerals in the terrestrial plant. What functions are associated with the roots of aquatic plants. How are roots of aquatic plants and terrestrial plants different?
Ans. Usually the terrestrial roots show a branched network that helps in anchorage and absorption of water and minerals from soil to the plant.
While in aquatic plants, roots show modifications and deviation from their normal function.
e.g., in plants like Trapa, Tinospora the roots are green and highly branched to increase the photosynthetic area, whereas in plants like Jussiaea. They get inflated due to air project out
of water so to help the plant in floating and exchange of gases.
Difference between roots of aquatic plants and terrestrial plants are as
Question. Why is maize grain usually called as a fruit and not a seed?
Ans. The maize grain is usually known as fruit because it is infact a ripend ovary which contains a ripened ovule, e.g., a single seed. This fruit is known as caryopsis in which the pericarp is fused with the seed coat. The maize grain occurs attached to a thick cob or peduncle.
Long Answer Type Questions:
Question. Seeds of some plants germinate immediately after shedding from the plants while in other plants they require a period of rest before germination. The later phenomena is called as dormancy. Give the reasons for seed dormancy and some methods to break it.
Ans. Dormant seeds remain under non-germination conditions only for a specific period of time that may vary from days to years. This specific period is called dormancy period.
Causes of Seed Dormancy
(a) In many plants the cause of dormancy is due to the impermeability of seed coat to water, (e.g., Chenopodium, Trigonella, Meliotus) or oxygen (e.g., Brassica alba, Pyrus malus-Apple, Sinapis arvensis) or chemicals, (e.g., Xanthium)
(b) In many plants, tough (hard) seed coats are the cause of dormancy as they provide mechanical resistance to embryo growth, e.g., Capsella, Lepidium.
(c) Some seeds produce certain chemical substances, such as abscisic acid (ABA,most common), phenolic acids, coumarin, short chain fatty acid, etc. which inhibit the seed germination. These inhibitors may be present inside the fruit, (e.g., the fruit juice of tomato contains ferulic acid), in the embryo (e.g., Xanthium), endosperm, (e.g., Iris) or seed-coat, (e.g., Cucurbita)
(d) Shedded seeds like those of wheat, barley, oat etc., need an interval for ripening and gaining the ability to germinate. During the interval, the seeds produce necessary
growth hormones.
Methods of breaking dormancy are as follows
(i) Inactivation of growth inhibitors by heat or cold treatment.
(ii) Mechanical abrasions weaken the tough and impermeable seed coat.
(iii) Microorganisms present in the soil weaken and decompose hard seed coat.
(iv) Washing away of inhibitors by rain or irrigation water.
(v) Maturation of embryo.
Question. The arrangement of ovules within the ovary is known as placentation.
What does the term placenta refer to? Name and draw various types of placentations in the flower as seen in T.S. or V.S.
Ans. Placenta is a flattened, cushion like tissue on which one or more ovules are attached.
The various types of placentation seen in the flowers are described in the following table
Question. Describe various stem modifications associated with food storage climbing and protection.
Ans. The various stem modifications are as follows
Question. Stolon, offset and rhizome are different forms of stem modifications. How can these modified forms of stem be distinguished from each other?
Ans. Stem modifications Stem gets modified in different forms like stolon, offset and rhizomes.
These can be distinguished from each other in the following manner
Question. Distinguish between families – Fabaceae, Solanaceae, Liliaceae on the basis of gynoecium characteristics (with figures). Also write economic importance of any one of the above family.
Ans. The difference between the three families on the bases of charateristics of hynoecium are as follows
Economic Importance of Fabaceae
Plants of this family are the sources of pulses and edible oils. Dye is extracted from Indigofera which is a plant of this family. It serves as a source of various other products like fibres (sunnhemp), facter (Sesbania and Trifolium), ornamentals (lupin, sweet pea) and medicine (multiathi).
Question. How do you distinguish between hypogeal germination and epigeal germination? What is the role of cotyledon(s) and the endosperm in the germination of seeds?
Ans. Difference between hypogeal germination and epigeal seed sermination are as
Role of Cotyledons and Endosperm Cotyledons and endosperm contain reserved food materials. When seed imbibes water, enzymes get activated, hydrolyse reserve food material and makes it available for the germinating seed.
Question. The mode of arrangement of sepals or petals in a floral bud is known as aestivation. Draw the various types of aestivation possible for a typical pentamerous flower.
Ans. The mode of arrangement of petals or sepals in a flower bud with respect to the members of the same whorl or with each other is known as aestivation. It is of following types Valvate Margin of adjacent petals or sepals touch each other, but do not overlap, e.g., mustard (Brassica).
Twisted Regular overlapping of petals or sepals occurs in which margin of one petal overlap with the adjacent next one petal, e.g., China rose (Hibiscus rosa sinensis).
Imbricate There are five petals arranged in such a way that one petal is completely external and one petal is completely internal, three petals are partially external and partially internal, e.g., Cassia, Callistemon, Caesalpinia.
Quincuncial There are five sepals or petals of which two are completely out and two are completely inside, while one is partially out and partially in e.g., Cucurbita (Cucurbitaceae).
Vexillary It is the characteristic aestivation of corolla of family – Papilionaceae, in which corolla (petals) are papilionaceous.
The largest petal overlap the two lateral petals (wings), which in turn overlap the two smallest anterior petals (keel) e.g., Artobotrys, Polyalthea, Pisum.
Question. Sunflower is not a flower. Explain.
Ans. Sunflower is not a flower, but it is a kind of inflorescence called capitulum in which the receptacle is flattened. It bears numerous sessile and small florets. The youngest floret is
in the center and oldest lies at the periphery. Whole cluster of florets gets surrounded by bracts, known as involucre.
Two kinds of florets are recognised in sunflower
(i) Ray Florets Arranged on the rim of receptacle having distinct yellow and strap shaped petals. These florets are female, sterile and are always zygomorphic and may be arranged in one or more whorls.
(ii) Disc florets Grouped in the center, bisexual and actinomorphic.
