Short Answer TypeA hill station city had abundance of different species of lichens a few years back. Since it has turned a busy tourist spot very few lichens are found there.
(a)What could be the possible reason for this?
(b) What measures are to be taken to conserve lichens?
Long Answer TypeBriefly, explain the pattern of lifecycle followed by
a. All bryophytes
b. All pteridophytes
With the help of a schematic diagram describe the haplo-diptontic life cycle pattern in plants
In a sexually reproducing plant, there is an alternation of generation between a haploid and a diploid phase of plant bodies.
The haploid plant body is termed gametophyte while the diploid plant body is called sporophyte.
The gametophyte produces gametes by mitosis while the haploid spores are produced by sporophyte following meiosis (reduction division). Two gametes fuse together to produce a zygote which develops into the diploid sporophyte. In a haplodiplontic life cycle pattern, such as in bryophyta or pteridophyta both the phases of life are multicellular.
However, in bryophytes, the gametophytes are small, photosynthetic, independent and represent dominant phase. The partly or totally dependent, the sporophyte is physically attached to the gametophyte. The (n) spores dispersed by sporophyte germinate into individual gametophytic plants.
In pteridophytes, the 2n (diploid) phase is dominant, well organized, independent while the haploid phase though also free-living and independent is short lived and photosynthetic.
In both of these groups of plants the mobile male gametes, antherozoid produced by sex organ antheridium, travel to archegonium (bearing an egg cell) via the medium of water. The egg cell is nonmotile. The reproduction is oogamous.
One Word AnswersThe plant body in higher plants is well differentiated and well developed. Roots are the organs used for the purpose of absorption. What is the equivalent of roots in the less developed lower plants?
Short Answer TypeHeterospory i.e., formation of two types of spores – microspores and megaspores is a characteristic feature in the life cycle of a few members of pteridophytes and all spermatophytes. Do you think heterospory has some evolutionary significance in plant kingdom?
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 as the ‘relic of past’. Can you establish a phylogenetic relationship of Cycas with any other group of plants that
justifies the above statement?
In which plant will you look for mycorrhiza and coralloid roots? Also, explain what these terms mean.
Long Answer TypeLichen is usually cited as an example of ‘symbiosis’ in plants where an algal and a fungal species live together for their mutual benefit. Which of the following will happen if algal and fungal partners are separated from
each other?
a. Both will survive and grow normally and independent from each other.
b. Both will die
c. Algal component will survive while the fungal component will die.
d. Fungal component will survive while algal partner will die.
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