Answer

(b) Root Cap Zone protective covering at the root apex, secretes mucilage to soften the hard soil for the growth of root.

Zone of Meristem region of actively dividing densely packed cells resulting into root growth.

Zone of Elongation divided cells grow in size and elongate increasing the lenght of root. They cannot divide furthrer.

Root Hair Zone root hair arises and grow in this region, helps in water and mineral absorption from the soil.

Zone of Maturation the cells of root at this region are fully differentiated and mature, performing different functions of root.

• Option (a) C, B, E, A, D: This option is incorrect because it places the Zone of Elongation (E) before the Root Hair Zone (A). The Zone of Elongation should come before the Zone of Maturation (D), and the Root Hair Zone should be placed after the Zone of Elongation.

• Option (c) D, E, A, C, B: This option is incorrect because it places the Zone of Maturation (D) at the beginning, which is not correct. The Zone of Maturation should be at the end, as it is the region where cells are fully differentiated and mature. Additionally, the Root Cap Zone (C) and Zone of Meristems (B) are placed incorrectly in the sequence.

• Option (d) E, D, C, B, A: This option is incorrect because it places the Zone of Elongation (E) and Zone of Maturation (D) at the beginning, which is not correct. The Root Cap Zone (C) should be at the beginning, followed by the Zone of Meristems (B). The Root Hair Zone (A) is also placed incorrectly at the end.

Thinking Process

The arrangement of flower on the main axis of the plant is called inflorescence. Think of the different kind of flower arrangement. How do the plants put up their flower to attract the pollinating agencies?

Answer

(b) In racemose inflorescence younger flowers are born at the apex or distal end while older flowers are at the base, this type of succession is acropetal succession. Thus, the position of youngest floral but would be distal.

• (a) Proximal: In acropetal succession, the youngest flowers are found at the apex or distal end, not at the base or proximal end. Proximal refers to the part of the plant closer to the main stem or root, where older flowers are typically located in this type of inflorescence.

• (c) Intercalary: Intercalary refers to a position between the base and the apex, which is not characteristic of acropetal succession. In acropetal succession, the youngest flowers are specifically at the distal end, not interspersed between older flowers.

• (d) Anywhere: In acropetal succession, the position of the youngest flowers is not random or anywhere; it is specifically at the distal end. This organized pattern is a defining feature of acropetal succession.

Thinking Process

Gram and peas are dicot plants belonging to angiosperms. All angiosperms bear seeds. During seed development inside the embryo sac, embryo needs nourishment for its development. It is provided by endosperm. It is a product of triple fusion (3n) ploidy.

Answer

(d) Endosperm is a nourishing tissue of seed which provide nourishment to the developing embryo either before or after germination. In gram and peas, the endosperm gets used up at the time of development of seed. So, seed is non-endospermic, i.e., endosprem is not present in the mature seed.

• (a) These plants are not angiosperms: This is incorrect because gram and peas are indeed angiosperms. Angiosperms are flowering plants, and both gram and peas belong to this category.

• (b) There is no double fertilisation in them: This is incorrect because double fertilisation is a characteristic feature of angiosperms, including gram and peas. During double fertilisation, one sperm fertilises the egg to form a zygote, and the other sperm fuses with two polar nuclei to form the endosperm.

• (c) Endosperm is not formed in them: This is incorrect because endosperm is formed in gram and peas as a result of double fertilisation. However, it gets used up by the developing embryo during seed development, which is why it is not present in the mature seed.

Thinking Process

As the seed germinates, it gives rise to plumule and radicle. Radicle develops into root system. Other plant parts also can give rise to roots depending upon the need of the plants.

Answer

(c) Roots developed from parts of the plant other than radicle are called adventitious roots. They branch like tap roots and may be underground or aerial, and may develop from nodes internodes on leaves, etc.

Other options are incorrect because

Tap roots are the roots developed from the radicle of embryo and persists and grows directly into primary root.

Fibrous roots are thin, thread-like branched roots developing from base of stem. These are modifications of tap root, found in monocots.

Nodular roots are also modifications of tap roots in which roots and its branches develop small or large swalling called nodules. They help in nitrogen fixation.

• Tap roots are the roots developed from the radicle of the embryo and persist and grow directly into the primary root.

• Fibrous roots are thin, thread-like branched roots developing from the base of the stem. These are modifications of tap roots, found in monocots.

• Nodular roots are also modifications of tap roots in which roots and their branches develop small or large swellings called nodules. They help in nitrogen fixation.

Answer

(c) Venation The veins are the part of leaf which possess vascular tissues, i.e., xylem and phloem. They are meant for the conduction of water, minerals and food to and from in the leaf. The special arrangement of veins in a leaf is called as venation.

• (a) floral organs: Venation specifically refers to the pattern of veins in a leaf, not the arrangement of floral organs. Floral organs include structures like petals, sepals, stamens, and pistils, which are not related to the venation pattern in leaves.

• (b) flower in inflorescence: Inflorescence refers to the arrangement of flowers on a plant. Venation, on the other hand, is concerned with the pattern of veins in a leaf, not the arrangement of flowers.

• (d) all of them: Venation is a term that exclusively describes the pattern of veins in a leaf. It does not pertain to the arrangement of floral organs or flowers in inflorescence. Therefore, it cannot describe all of them.

Answer

(b) Orchid seed is a non-endospermic seed, i.e., endosperm is absent in it.

Endosperm is a nourishing tissue present in the seed which nourishes the developing embryo. In orchid seed endosperm is absent because it is used up during the time of seed development.

Nourishment for germinating seed is provided by the food material present in cotyledons.

Rest of the options are examples of endospermic seeds.

• Coconut: Coconut seeds are endospermic, meaning they contain endosperm which provides nourishment to the developing embryo. The liquid endosperm (coconut water) and solid endosperm (coconut meat) are present in the seed.

• Maize: Maize seeds are also endospermic. The endosperm in maize is a significant source of nutrients for the developing embryo, providing essential carbohydrates and proteins.

• Castor: Castor seeds are endospermic as well. The endosperm in castor seeds supplies the necessary nutrients to the embryo during its development.

Answer

(b) Fabaceae is a subfamily of Leguminosae which was earlier called Papilionoideae. Plants of this family are the source of pulses and edible oils. Pulses are rich in protein contents.

• Solanaceae: This family primarily includes plants like tomatoes, potatoes, eggplants, and peppers. These plants are not typically sources of pulses, which are seeds of leguminous plants.

• Liliaceae: This family consists mainly of flowering plants such as lilies, tulips, and onions. These plants are not known for producing pulses or edible oils.

• Poaceae: This family, also known as the grass family, includes cereals like wheat, rice, and corn. While these are important food sources, they do not produce pulses, which are specifically seeds from leguminous plants.

Thinking Process

Placenta is a special tissue by which ovule is attached to the ovary. It has a special kind of arrangement in the ovary which is called placentation.

Answer

(b) The placenta is attached to the developing seed near hilum. It is the scar located near the edge where seed breaks from stalk of funiculus, i.e., connecting the seed with fruit wall and placenta.

Rest of the options are incorrect as

Testa is the outer most covering of seed, micropyle is a small opening in seed coat through which water enters seed and chalaza is a tissue where nucellus and integument are joined. Nutrients from the plant travel through vascular tissue in the funiculus and outer integuments through the chalaza into the nucellus.

• Testa is the outermost covering of the seed.
• Micropyle is a small opening in the seed coat through which water enters the seed.
• Chalaza is a tissue where nucellus and integument are joined. Nutrients from the plant travel through vascular tissue in the funiculus and outer integuments through the chalaza into the nucellus.

Thinking Process

Dyes are the secondary metabolites of certain plants and are important economically.

Answer

(b) Indigofera tintoria and $T$ suffruticoga are the two plants belonging to the family-Fabaceae that produce blue indigo dye.

The other options are incorrect as

Trifolium is used as fodder.

Lupin is an ornamental plant.

Cassia is a shrub usually grown on the road side as an ornamental plant.

• Trifolium is used as fodder.
• Lupin is an ornamental plant.
• Cassia is a shrub usually grown on the roadside as an ornamental plant.

Answer

(a) It is the correct sequence of the options in the two columns.

Aleurone layer surrounds the tissue of monocot seed and morphologically and biochemically distinct from seed. It is a proteinaceous layer (surrounding the endosperm and separating embryo) which provides nutrition and helps in germination .

Parthenocarpic fruit are seedless fruit which develops without the fertilisation of egg cell present in the ovule of the plants.

The ovule cantains the female reproductive unit, i.e., embryo sac that develop into a seed after it is fertilised.

Endosperm is formed during the process of double fertilisation by the fusion of one male gamete with the two polar nuclei at the centre of the embryo sac.

• Option (b):

  • Aleurone layer (A) is incorrectly matched with “Without fertilisation” (2). The aleurone layer is related to nutrition, not fertilisation.
  • Parthenocarpic fruit (B) is incorrectly matched with “Nutrition” (1). Parthenocarpic fruits develop without fertilisation, not for nutritional purposes.
  • Ovule (C) is incorrectly matched with “Double fertilisation” (4). The ovule contains the embryo sac and develops into a seed after fertilisation, not directly related to double fertilisation.
  • Endosperm (D) is incorrectly matched with “Seed” (3). Endosperm is formed during double fertilisation, not directly a seed.

• Option (c):

  • Aleurone layer (A) is incorrectly matched with “Double fertilisation” (4). The aleurone layer is related to nutrition, not double fertilisation.
  • Parthenocarpic fruit (B) is correctly matched with “Without fertilisation” (2).
  • Ovule (C) is incorrectly matched with “Nutrition” (1). The ovule contains the embryo sac and develops into a seed after fertilisation, not for nutritional purposes.
  • Endosperm (D) is incorrectly matched with “Seed” (3). Endosperm is formed during double fertilisation, not directly a seed.

• Option (d):

  • Aleurone layer (A) is incorrectly matched with “Without fertilisation” (2). The aleurone layer is related to nutrition, not fertilisation.
  • Parthenocarpic fruit (B) is incorrectly matched with “Double fertilisation” (4). Parthenocarpic fruits develop without fertilisation, not through double fertilisation.
  • Ovule (C) is incorrectly matched with “Nutrition” (1). The ovule contains the embryo sac and develops into a seed after fertilisation, not for nutritional purposes.
  • Endosperm (D) is incorrectly matched with “Seed” (3). Endosperm is formed during double fertilisation, not directly a seed.

Thinking Process

Every plant cell require $O_{2}$ for cell respiration. The air present in between the soil particles is used up by the roots. The plant growing in water logged conditions do not get $O_{2}$ form the soil so they evolve some other mechanism to get it.

Answer

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.

Answer

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

(i) Bisexual $⚥ $

(ii) Actinomorphic $\oplus$

(iii) Sepals five $\mathrm{K}_{5}$

(iv) Twisted aestivation

(v) Petals five $\mathrm{C}_{5}$

(vi) Valvate aestivation

(vii) Stamens $A_{6}$

(ix) Syncarpus $\mathrm{G}_{(3)}$

(viii) Tricarpellary ovary $\mathrm{G}_{3}$

(x) Trilocular

(xi) Axile placentation

(xii) Floral formula would be $⚥ \oplus K_{5} C_{5} ~A_{6} G_{(3)}$

Thinking Process

Photosynthesis is performed by green parts of the plants (mainly leaves). Think of plants in which the function is performed by other plant part except leaf. It has to be green and contain chlorophyll pigment.

Answer

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.

Thinking Process

There are many plants that can grow in swamp areas like water lily, cypress trees, etc. sunderbans have halophytic mangroove forest.

Answer

Pneumatophores Roots are the organs meant for the absorption of water and minerals from the soil. Cells of roots require $O_{2}$ to respire. In swampy areas, soil does not have air, so $no_{2}$ 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.

Answer

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.

Answer

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.

Answer

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.

Answer

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.

Answer

The floral formula of Fabaceae family is

$=\% ⚥ K_{5} C_{1+2+2} A_{9+1} \underline G_{1}$

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.

Answer

Answer

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.

Thinking Process

Aquatic plants grow where plenty of water is available. These may be free floating, submerged, attached floating or attached emergent hydrophytes. Their roots possess several aquatic adaptations.

Answer

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

Answer

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.

Monocot leaf	Dicot leaf
The veins run parallel to each other within a lamina. It is called parallel venation.	Veins and veinlets form a network in the lamina. It is called reticulate venation.
Parallel venation, e.g., grasses, wheat, maize, etc., (usually found in monocots).	Reticulate venation, e.g., Hibiscus, bean, pear etc., (usually found in dicots).

Answer

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.

Answer

(i)Floral Formula $\oplus K_{(5)} C_{(5)} A_{5} G_{(2)}$ represents flowers of Solanaceae family.

(ii) Floral Formula % $\quad K_{(5)} C_{1+2+2} A_{(9)+1} G_{1}$ represents flowers of Fabaceae family.

(iii) Floral Formula $\oplus ⚥ \mathrm{K_5 C_5 A_{5+5}G_{\underline{(5)}}}$

Answer

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.

Answer

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.

Morphology of Flowering Plant

All these modifications and adaptation are developed to make up the nitrogen deficiency in the plant because these plants are found in $\mathrm{N}_{2}$ deficient soil, (marshy/swamp soils)

Nepenthes : pitcher shaped leaf

Answer

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.

Answer

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

|e.g., Dianthus, Silensa, etc, | e.g., Citrus, tomato etc.

Answer

(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.

Answer

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.

Answer

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.

Answer

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.

Answer

(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.

Long Answer Type Questions

Thinking Process

The families mainly differ from each other in their reproductive structures. Try to differentiate the above families on the basis of androecium and gynoecium.

Answer

The difference between the three families on the bases of charateristics of hynoecium are as follows

Gynoecium Characteriseies	Fabaceae	Solanaceae	Liliaceae
Carpels	Monocarpellary free, single	Bicarpellary Syncarpous	Tricarpellary syncarpous
Ovary	Superior unilocular	Superior bilocular (2-4 locular in tomato)	Superior
Ovules	Margin in two alternate rows	Many in each locular	Trilocular
Placentation	Marginal	Axile	2-many ovules in each locules
Style	Bent, single	Simple	Simple but may be united or separate
Stigma	Simple and capitate	Simple and lobe	Free or fused trilobed
Floral formula	$\mathrm{Br} % ~K_{(5)} G_{1+2+(2)}$ $A_{1+9+1} \underline G_{1}$	$-\mathrm{Br} \oplus K_{(5)} G_{5} ~A_{5} \underline G_{(2)}$	$\mathrm{Br} \oplus P_{3+3} ~A_{3+3} \underline G_{(3)}$
Diagram of gnoecium
Floral diagram
Examples	Garlic, onion, Colchicum	Potato, tomato, brinjal, datura, etc	All pulses, sunhemp, Lupin, Indigo, Cassia

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).

Thinking Process

Stem is the aerial part of plant bearing nodes, internodes, buds, flowers, fruits and seeds. Besides these functions and forms, under special conditions, it gets modified and perform many functions, e.g., storage, protection and climbing. Search out different forms of stem and its modified forms performing variety of functions.

Answer

The various stem modifications are as follows

Modification of Stem for Storage of Food
Rhizome	In this case the stem becomes underground and grows horizontally, stores food material. It bears nodes, internodes and buds which give rise to aerial shoots, e.g., ginger, banana, turmeric.
Corm	Stem is underground, grows vertically and bears nodes as well as internodes e.g. Colocasia. Corm of Colocasia
Bulb	In this case, the stem becomes underground, the internode is shortened in such a way that the leaves are condensed and these leaves become thick and fleshy and store food material e.g.,-onion. Base of scape
Tuber	This is also a special kind of stem modification, which arises at the tips of special narrow underground branches. They have nodes, internodes apical buds, scale leaf in the form of ridge. They gave no. of eyes which represent nodes. It is meant for storing food material, e.g., potato
Stem tendrils	Modification of Stems for Climbing These are found in cucurbits and grapevine. The axillary buds of the stem become elongated and spirally coiled and twine around a support for the plant to grow as the stem is weak and herbaceous.
Stem thorns	Modification of Stem for Protection These are present in the axil of leaf or apex of stem performing the function of either climbing or defence, e.g., Duranta, Calamus and also reduce transpiration.

Answer

Stem modifications Stem gets modified in different forms like stolon, offset and rhizomes. These can be distinguished from each other in the following manner

Stolon	Offset	Rhizome
The stem is a creeper. It is a long distance runner with longer and thicker internodes. Horizontal branches arise from the internodes, e.g., strawberry Colocaica.	It is like small a runnes of one internode long, but inter nodes are shorter and thicker branches arise all around the main stem usually found in rosette plants on water or ground surface. e.g., Eichhornia, Pistia.	These are stem which bear nodes and internodes, scaly leaves, axillary buds and roots arising from nodes e.g., Ginger, banana, turmeric. They are modified to store food in plants.

Answer

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.

Answer

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

Type of Placentation	Description with example	Diagram
Marginal	There is a single placenta which develops along the junction of two fused margins, e.g., pea.
Axile	Multicarpellary, syncarpous gynoecium inward growth of carpel’s margin forms a multicarpellary condition that contains an axis in the center. Placenta arises from the central axis bearing ovules, e.g., Solanum, China rose.
Parietal	The number of placenta corresponds to the number of fusing carpels. Sometimes the ovules bearing placenta grow inward to form false septa, making the ovary bilocular (e.g., mustard) or trilocular, e.g., Curcurbita.
Free central	The ovary is unilocular, and ovules are borne on the central axis, not connected to the ovary wall by a septum, e.g., Dianthus, Silensa.
Basal	The ovary is unilocular, and the single ovule is borne at the base of the ovary attached by a single placenta, e.g., sunflower, wheat.

Answer

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.

Answer

Difference between hypogeal germination and epigeal seed sermination are as

Hypogeal Seed Germination	Epigeal Seed Germination
Rapid growth and elongation of epicotyl. Cotyledons remain inside the soil. Cotyledons remain non-green, non photosynthetic	Rapid growth and elongation of hypocotyl. Seed cotyledons emerge above the soil level/ Cotyledons become green and photosynthetic
e.g., castor, beAns.	e.g., maize, rice.

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.

Answer

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.