Only II, III and IV are correct
The integument surrounds a mass of tissue called the nucellus. Tracheids of Zamia and Stangeria have scalariform pits, but other genera have multiseriate-bordered pits. Cycas ovule is with single integument which is differentiated into three layers-Outer and inner fleshy, middle stony layers. The cortex is delimited by a single- layered endodermis. Phloem consists of sieve tubes and phloem parenchyma. Orthotropous Ovule: A condition of having the ovule straight and upright with the micropyle at the apex. Content Guidelines 2. During development few micropylar cells become enlarged, which are also known as archegonial. The seeds are 45mm long and 30mm wide, ripening from green to an orange- or reddish-brown colour. 3. Archegonia are flask shaped, 1. We use cookies on our website to give you the most relevant experience by remembering your preferences and repeat visits. Answer Now and help others. He opined that these algae fix nitrogen and promote the growth of host plant. 8.14). contains a single ring of vascular bundles. It is unitegmic. Megasporophylls are compact when young but spread apart when mature. . In the centre of the cone is present a cone axis (Fig. The xylem consists of tracheids and xylem parenchyma (Fig. in length. Cones of some species of Cycas are amongst the largest cones in the plant kingdom. Not much is known about the development of megasporangium. Young plants bear more coralloid roots than the older ones. In the center, sporogenous tissues are formed which in turn form spore mother cells. It is differentiated into outer 2-3 layers of chlorophyll-containing thin-walled cells of chlorenchyma and inner 4-6 layers of thick- walled lignified cells of sclerenchyma. 1. I. 1. First of all, free nuclear division occurs and many nuclei are formed. I is correct but II is incorrect
Draw a neatly labeled diagram of chloroplast found in leaf, and its role in photosynthesis? Click Here to view all bookmarked questions of the chapter, 1. In Japan, seeds and stem of Cycas revoluta are used for preparing wine. 3. Male strobilus of Pinus, Prefer Books for Question Practice? Megasporophylls contain brown tomentose hairs. The megasporophylls of Cycas resemble foliage leaves. Pinnae are repeatedly and deeply dichotomized in C. micholitzii (Fig. Cycas revoluta and C. circinalis plants are grown for ornamental purposes in various parts of the world. With the help of a transversely expanded rhomboidai leaf base, a leaf remains attached with the stem Two rows of strong and stiff spines are present on the petiole. These cells divide into three parts the upper cell forms haustoria, the middle cell enlarges and forms a suspensor and the tip has meristematic cells which form the embryo. 8.21). Both I and II are correct and II explains I
Cytoplasm surrounds the centrally located nucleus. The starch settles down, and the clear upper liquid is drained off. 2. By clicking Accept, you consent to the use of ALL the cookies. Both I and II are incorrect but II does not explain I
Microsporangium is abaxial and arranged radially in sori. Vessels are absent. Female strobilus: Male strobilus: Gametophytic generation of Cycadales: Female gametophyte: Male gametophyte: Fertilization: Embryo development of Cycadales: Seed germination: Classification of Cycadales: Distribution of Cycadales: The members of Cycadales are mostly restricted to tropical and sub-tropical regions of the world. The rachis bears many leaflets. It is 40-45 cm long in Cycas and in Bowenia it is 5 cm long. Narrow base is attached to the cone axis with a short stalk. Identify the correct statement regarding Marchantia: 1. Hypodermis is present below the epidermis. 8.22). Droplets may exhibit taxon-Figure 1. What phylum is Zamia under? Plants with emerging megaspo-rophylls were selected within each of the locationsinFeb.2004. 2. 3. It grows in wild state in Japan, China and Taiwan and is widely cultivated in several parts of the world, including India. The stem is thick, woody and usually un-branched. The stem is thick cylindrical and unbranched. Stopes (1904) has worked on the vascular supply of Cycas seed. In all cycads, the microsporophylls are arranged spirally about a cone axis; in all cycads but Cycas, megasporophylls are similarly arranged. Name the types of nitrogenous bases present in the RNA. 2. II and III only
Branching in stem (Fig. III. The cortex is wider in comparison with the normal root. 1 female strobili, 2 Seeds with wings C On each megasporophyll of the female strobilus two seeds can develop following fertilization. Members of this order are mostly inhabitants of tropical and subtropical regions. In a vertical section the leaflet is differentiated into a swollen midrib portion and two lateral wings (Figs. Female gametophyte: Old generation
C. revoluta (native of Japan) is the most common cultivated species in Indian gardens. Only II is correct
Cork cells are dead and remain filled with subenn. Endodermis is followed by multilayered pericycle. Male cones are oblong to ovoid, bearing a short peduncle. More than 7,00,00,00,000 microspores per cone may be present. genus: cycas. Cross section. 3. 3-6 archegonia are present in the female gametophyte near the archegonial chamber. Development of young sporophyte within tissue of the megasporangium. Can cockroaches be fused together with their Brain Juice? The term embryophytes is an appropriate synonym for plants. Advertisement cookies are used to provide visitors with relevant ads and marketing campaigns. 4. Female strobilus of Pinus
In T.S. These are also arranged in horseshoe shapes. 8.44). Each megasporophyll has (a) bract scale and (b) ovuliferous scale which bears 2 ovules on the ventral side. 3. Female strobilus of Cycas 2. In Dioon, the edule suspensor is 70 mm long. 2. Megasporophylls are ovate-lanceolate with many small teeth. Reproductive organs are borne on antheridiophores and archegoniophores that arise from the apical notches of male and female thalli respectively. II. The terminal part of Ceratozamia is depressed. Microspore is the first cell of the male gametophyte having haploid number of chromosomes. 8.25). Megasporangium is also called an ovule. Cycas ovule is simple, sessile and Orthotropous. 1. 8.27A). A small shrub with a trunk of about 40 cm long. 8.16). Ovules are terminal. Megasporophylls sterile blade is as broad as long with usually only 2 ovules. It is because of the fact that the apical meristem is used up during the development of the male cone. This cookie is set by GDPR Cookie Consent plugin. The cookie is set by the GDPR Cookie Consent plugin and is used to store whether or not user has consented to the use of cookies. Cells of the cortex remain filled with starch. 8.42A) and C. rumphii (Fig. In the apical portion of the nucellus forms a nucellar beak. droplets.23,25,34 This remarkable female strobilus behavior represents a system that would be interesting to study in relation to specicity of pollinator attraction, diversity of sugar rewards, and cycad phy-logeny. The megasporophylls remain covered by many yellow or brown-coloured hairs. Mesophyll is well-developed and remains differentiated into palisade and spongy parenchyma. The female Cycas strobilus is comprised of a loose assemblage of individual megasporophylls. It cuts cork towards outer side and secondary cortex towards inner side. Phylum: Ginkgophyta. 8.26). Involute vernation
With the separation of suspensor cells, embryonal cells also get separated. Pant (1953) observed that usually the megasporophylls in Cycas are produced only once in a year. the rachis reveals the following structures from outside within: Epidermis is the outermost layer of the rachis consisting of thick-walled cells. There are multiple small vacuoles in each cell. But according to Chaudhary and Akhtar (1931) the alga is mainly responsible for the formation of these large intercellular spaces. It is used in the preparation of starch and alcoholic drinks. We use cookies to ensure that we give you the best experience on our website. 2. 8.32). The most common method of vegetative propagation in Cycas is by bulbils. is a specialist pollinator of Cycas micronesica. The crushed primary phloem is present in the form of dark streaks outside the secondary phloem. The male strobili are typically about 0.4-0.8 in (1-2 cm) in diameter and form on the . Numerous vascular bundles remain arranged in a ring. Leaflets are narrow and linear. The male cone is terminal while the megasporophylls are produced in succession with the leaves at the top of the stem. Casparian steps are present in the barrel-shaped cells of the endodermis. 3. 1. Thallus is dorsiventrally flat. The sclerotesta consists of lignified thick-walled cells. Its upper part has a leaflet in which ovules are present. Xylem and phloem bundles in the roots are radially arranged, i.e. The nucellar beak force grows into the micropyle. Multicellular rhizoids help in anchorage and absorption of water through their capillary action. Vascular bundle is one, and present in the midrib region of the leaflet. [4] It is cultivated in Fiji and Vanuatu. Phloem is present alternately with xylem groups and consists of sieve tubes and phloem parenchyma. In Macrozamia denisonii, the largest cone was found which is 60-80 cm long. Genus: Ginkgo biloba. The portion of the midrib in between the palisade layer and lower hypodermal region is filled with parenchymatous cells. A homosporous life history occurs in nearly all bryophytes and in most pteridophytes. Cycas ovule is with single integument which is differentiated into three layers-Outer and inner fleshy, middle stony layers. Female strobilus of Cycas
Only I, II and III
Some of the cells of the outermost cortical region start to become meristematic and function as cork cambium. This will permanently delete All Practiced Questions. It also occurs on Christmas Island, an Australian territory in the Indian Ocean 300km (190mi) south of Java, in Australia's Top End (Darwin), and in Western Australia. Development of young sporophyte within tissue of the megasporangium. In T.S. In haplo-diplontic life cycle, alternation of generations is marked and mitosis occurs in both haploid and diploid phases. I. 4. The age of the plant can be calculated by counting the number of crowns of leaves and megasporophylls which are produced every year. The gametophytes of vascular plants have become smaller and simpler, 1. 8.33) are flat, leaf-like, woody and brown-coloured structures with narrow base and expanded upper portion. Here we will see the structure and organization of Female Reproductive Structures. 8.41 A). Its trunk ranges from 1.5 to 2.5 metres in length. The basal cell in the tetrad is the functional megaspore. The vascular bundles show different structure at different levels of rachis starting from the base up to the apex, especially with regard to their diploxylic nature. Prior to the anatomical studies of the stem of Cycas revoluta by Brongniart (1829), the Cycas was actually considered a palm. The decoction of young red seeds of C. circinalis is used as a purgative and emetic. They are known as Cycad ferns, being the earliest seed-producing plants, showing fern-like appearances. Upper epidermis is a continuous layer while the continuity of the lower epidermis is broken by many sunken stomata. C. circinalis, if allowed to grow undisturbed, may attain an age of 100 years or even more. Spore mother cell divides by meiosis to form 4-microspores. The functional megaspore of Gymnosperms is better called as Embryo-sac. document.getElementById( "ak_js_1" ).setAttribute( "value", ( new Date() ).getTime() ); BotanyZoologyBiochemistryCell & Molecular BiologyBiotechnologyBioinformaticsBiophysicsPlant PhysiologyPhysiology & EndocrinologyImmunologyMicrobiologyGeneticsEmbryologyEvolutionEcologyResearch MethodologyBiostatisticsPhysics for BiologistsChemistry for Biologists. 1. It is 10-18 meters in length like Dioon spinulosum. Later, the ventral canal nucleus gets disappeared. 8.27B). I. Micro sporophylls bear two elongated sac like structures at the base on the ventral side called pollen sacs. I, II III and IV are correct, All the following regarding Dryopteris are true except:
[3], The trunk of the cycad contains a starchy pith from which sago can be prepared by drying, grinding and washing. On its upper as well as lower sides are present irregularly distributed sunken stomata. In the beginning, Cycas is monoxylic, i.e. Pollen tube acts like a haustorium. Large compound leaves called fronds
During pollination, a drop appears in micropyle. Megaspore represents the first stage of female gametophytic generation. Get NEETprep's Unique MCQ Books with Online Audio/Video/Text Solutions via Telegram Bot. Its trunk reaches up to 4 metres while the leaves attain a length of 1-2 metres with 50 to 100 or more pairs of leaflets. Which of the following is not true for the green alga Spirogyra? Seeds germinate when they are kept in moist soil. 4. In Dioon, ovules get destroyed due to failure of pollination. Normally, there are four leaf traces which form the vascular supply to the leaf. Two types of leaves are present in Cycas. Performance cookies are used to understand and analyze the key performance indexes of the website which helps in delivering a better user experience for the visitors. Which part of the male reproductive system store the sperm? Their function is to fix the plant in the soil and to absorb water and other minerals. The secondary xylem consists of radial rows of tracheids separated by parenchymatous cells. Medullary rays in Dioon are one cell thick and while in Cycas it is 6-7 cells thick. Give an example. Antheridia are club shaped
The centrifugal xylem is present and is separated from the parenchyma (secondary xylem). I and II only
Companion cells are absent. Female strobilus of Cycas
A great phylogenetic significance has been attributed to the transfusion tissue by Worsdell (1897). In the wide zone of parenchymatous cortex there are present many intercellular spaces. The number of pinnae varies in different species. This is the Part 6 of the Lecture Notes Series in Cycas. Centrifugal xylem is much reduced and present in the form of two patches lying one on each side of the protoxylem elements of centripetal xylem. But opting out of some of these cookies may affect your browsing experience. tip has meristematic cells which form the embryo. The megasporangia are better-called OVULES. Micropyle: a small opening in the surface of an ovule. K. R. Sporne (1965) has distributed Cycadales in two families namely; D. Bierhost (1971) divided living Cycadales into three families, which are; Your email address will not be published. [2][3], The cycad's range is centred on the Maluku Islands, extending northwards to Sulawesi, eastwards to New Guinea, and westwards to Java and southern Borneo. Neck cells are two in number. Several perpendicularly attached microsporophylls are arranged around the cone axis in closely set spirals. Well-developed medullary rays traverse through the so-formed secondary vascular tissue. But opting out of some of these cookies may affect your browsing experience. Only I
At the time of their entrance in the petiole, the leaf trace bundles subdivide and form many petiole bundles. This represents the accessory transfusion tissue or secondary transfusion tissue. Traces are diploxylic which has centripetal and centrifugal xylem. Antheridia are club shaped
Explain with suitable example. This cookie is set by GDPR Cookie Consent plugin. The leaf traces remain scattered in the cortical region of the stem and constitute the vascular supply to the leaves from the main vascular cylinder. 3. The phloem is located outside the xylem and consists of sieve tubes and phloem parenchyma.
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