Plant Kingdom

Q: Short Answer.Each plant or group of plants has some phylogenetic significance in relation to evolution: Cycas, one of the few living members of gymnosperms is called the 'relic of the past'. Can you establish a phylogenetic relationship of Cycas with any other group of plants that justifies the above statement?

Cycas is considered a 'living fossil' because it is the only living species in the family Cycadaceae. All other species of this family are now extinct. This plant is often considered as the plant of the Old World; which means it is found only at those places which can be associated with some of the oldest rocks in the world. Due to these reasons; it is called the 'relic of the past'. Moreover, the Cycas plant shows more resemblance to Pteridophytes than Gymnosperms. This shows the phylogenetic relationship between Pteridophytes and Gymnosperms.Some of the characters of Cycas which indicate this are as follows :Seeds are shed when the embryo is still mature. In other gymnosperms; seeds are shed only when the embryo is mature.The megasporophylls appear like leaves.In spite of the presence of pollen tubes, male gametes are flagellate.The leaf base is persistent.It shows circinate ptyxis venation like the pteridophytes.

Q: SrCharactersPlant group IPlant group IIPlant group IIIPlant group IV 1.AutotrophicYesYesYesYes2.TerrestrialNoYesYesYes 3.Presence of vascular tissueNoYesYesNo 4.Flower producedNoNoYesNoShirin had been on a holiday to Ooty. In her school, she has studied the interesting world of plants. On the day of her return, she collected four groups of plants I, II, III, and IV. She carefully noted some of their details and arranged the information in the form of a table as given below. She asked her teacher how to identify which group is of pteridophytes. Take a look at the data and suggest which of the groups could be of Pteridophytes and why?

The pteridophytes are the terrestrial vascular plants which have body differentiated into roots, stem, and leaves. These are the first plants to have vascular tissues. The plants possess chlorophyll pigments, which help to perform photosynthesis and so they are autotrophic. These plants reproduce through spores as they don't have flowers.Thus, the correct answer is option B.

Q: How is double fertilization significant to angiosperms and how has this event led to the successful evolution of angiosperms?

Angiosperms are the most abundant plants on this Earth and their greater rate of survival is often attributed to double fertilization. The reasons are as stated below:Double fertilization results in two products - zygote and endosperm.It increases the chances of polyembryony and this provides better survival opportunities to the plant.Endosperm is responsible for nourishment of the developing embryo and thus ensures proper growth of the embryo.Viability of seeds also increases as a result of double fertilization.

Q: A multicellular, filamentous alga exhibits a type of sexual life cycle in which meiotic division occurs after the formation of the zygote. The adult filament of this alga has:

Many algae show haplontic life cycle. In this case, the dominant phase is the free-living gametophyte. Sporophytic generation is represented by single-celled zygote. Meiosis in zygote results in the formation of haploid spores, e.g. Spirogyra and Chlamydomonas.So, the correct answer is 'Haploid vegetative cells and haploid gametangia'

Q: Why is double fertilization not observed in gymnosperms despite them being seeded plants?

In gymnosperms, ovaries are absent and thus seeds are present in the cones. The male and female gametophytes are present inside cones. These produce pollen and egg respectively. Through wind pollination, the pollen grains are transferred to the female cones. One of the two sperm cells produced in the pollen fuse with the egg to form the zygote. The other one degenerates. The zygote develops inside the female cone. Nourishment is provided by endosperm derived from the female gametophyte. So, the process of double fertilization is not observed in gymnosperms, though they are seeded plants.

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Cycas is known as 'relic of past'. Why so? Check the given question to get the answer.

Short Answer.
Each plant or group of plants has some phylogenetic significance in relation to evolution: Cycas, one of the few living members of gymnosperms is called the 'relic of the past'. Can you establish a phylogenetic relationship of Cycas with any other group of plants that justifies the above statement?

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Can you identify the division of kingdom Plantae by a list of characteristics of a particular plant? Check the given question.

Sr	Characters	Plant group I	Plant group II	Plant group III	Plant group IV
1.	Autotrophic	Yes	Yes	Yes	Yes
2.	Terrestrial	No	Yes	Yes	Yes
3.	Presence of vascular tissue	No	Yes	Yes	No
4.	Flower produced	No	No	Yes	No

Shirin had been on a holiday to Ooty. In her school, she has studied the interesting world of plants. On the day of her return, she collected four groups of plants I, II, III, and IV. She carefully noted some of their details and arranged the information in the form of a table as given below. She asked her teacher how to identify which group is of pteridophytes. Take a look at the data and suggest which of the groups could be of Pteridophytes and why?

Plant group I

Plant group II

Plant group III

Plant group IV

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Angiosperms are the most abundant plants on this earth. They posses a unique feature, double fertilization. How do you think, the success of angiosperms is can be attributed to double fertilization?

How is double fertilization significant to angiosperms and how has this event led to the successful evolution of angiosperms?

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A member of plant kingdom has the dominant, free-living, photosynthetic gametophyte phase. Can you identify the ploidy of cells and type of life cycle for this member? The given question can have an answer.

A multicellular, filamentous alga exhibits a type of sexual life cycle in which meiotic division occurs after the formation of the zygote. The adult filament of this alga has:

Haploid vegetative cells and diploid gametangia

Diploid vegetative cells and diploid gametangia

Diploid vegetative cells and haploid gametangia

Haploid vegetative cells and haploid gametangia

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Gymnosperms and angiosperms are the two plant divisions that possess seeds. So do you think, double fertilization will be possible in gymnosperms also?

Why is double fertilization not observed in gymnosperms despite them being seeded plants?

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