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Evolution of sex in algae : An overview  In plants, asexual and sexual reproduction are the two main modes of reproduction. Asexual reproduction does not entail sex and does not involve the fusing of any kind of cell or gamete. Spores are a unique form of cell that reproduces in this manner. Every one of these spores has the ability to grow into a new plant. In contrast, when two cells, or gametes, combine during sexual reproduction, a zygote is created that eventually grows into a new plant. Without fusing, individual gametes are normally unable to create new plants. Origin of sex:  The most primitive algae, such as those belonging to the Cyanophyceae (Myxophyceae) family, such as Gloeocapsa and Chroococcus, reproduce by fusion, whereas Oscillatoria, Nostoc, and Anabaena, among others, reproduce vegetatively through the division of a small group of cells known as hormogonia, which subsequently gives rise to new plants through additional division. Certain Cyanophyceae members ...

  Classification and Distribution of Gymnosperm in India  Phanerogams are the collective term for gymnosperms and angiosperms (phanero = exposed, gams = sex organs or spermatophytes; sperma = seed). • Plants with bare seeds are known as gymnosperms. The ovules in gymnosperms are openly visible both before and after fertilization. They are not contained by the ovarian wall. of contrast, the ovule or ovules of angiosperms are entirely encased within a structure known as the ovary. For this reason, only naked seeds are produced in gymnosperms instead of fruits, but in angiosperms, seeds are produced inside fruits. • Coulter and Chamberlain (1910) divided gymnosperms into 7 orders. Some of the orders are extinct today.  The seven orders are as follows:  1. Cycadofilicales (extinct)  2. Bennettitales (extinct)  3. Cycadales (Mesozoic to present day)  4. Cordaitales (extinct)  5. Ginkgoales (Palaeozoic to present day)  6. Coniferales (Palaeozoic ...

  Mutation and types of mutagens  A single base change may result in a helpful adaptation, a catastrophic genetic disease, or no effect at all. What causes mutations, and how do they affect a species' future?A single base change may result in a helpful adaptation, a catastrophic genetic disease, or no effect at all. What causes mutations, and how do they affect a species' future? A genetic sequence can change by a mutation. Mutations can involve modifications as minor as the replacement of a single nucleotide base, or building block of DNA, with a different nucleotide base. Larger mutations, on the other hand, can impact numerous genes on a chromosome. In addition to substitutions, DNA sequence insertions, deletions, and duplications can also result in mutations. Certain mutations are inherited when they are inherited from a parent who carries them through the germ line, which is when the mutation is carried by an egg or sperm cell. Somatic mutations are another type of nonher...

  Watson and Crick Model of DNA  Many people think that in the 1950s, English physicist Francis Crick and American biologist James Watson discovered DNA. This is not the situation in actuality. Rather, Swiss chemist Friedrich Miescher discovered DNA for the first time in the late 1860s. Then, in the decades that followed Miescher's discovery, a number of studies conducted by other scientists—most notably,  Phoebus Levene and Erwin Chargaff—uncovered more information about the DNA molecule, including its main chemical constituents and the ways in which they interacted with one another. Watson and Crick may never have come to their ground-breaking conclusion in 1953—that the DNA molecule exists as a three-dimensional double helix—without the scientific groundwork laid by these pioneers. https://educationtechbysapna.blogspot.com/2024/04/structure-and-function-of-cyphellae-and.html The year 1869, albeit little known to most, was a turning point in the history of genetics stud...

  Structure and Function of Cyphellae and cephalepodia in Lichens      Cyphellae ( photobionts)   are smooth- surfaced depression in the thallus of lichen and are responsible for exchange of the gases.  A minute, rimmed, cup-like depression or pore, found in lichens of the genus Sticta, which is visible in the lower surface of the thallus as a small white pit.               cephalepodia  (Mycobiont)   A number of lichens have an alga as the major photobiont but with a cyanobacterium present as a minor photobiont in discrete pockets and such pockets are called cephalepodia.  The basic structure of a lichen is like that of the popular peanut butter cup candy. A layer of photobionts (the peanut butter) is held within a matrix of fungal fibers or hyphae (the chocolate). This allows the photobionts access to sunlight as well as protection from drying out. https://educationtechbysapna.blogspot.com/2024/03/gly...

  Lichens  The word Lichen derives from the Greek Leichen (tree moss, lichen, lichen - like eruption on skin".  A lichen is not a single organism. They are found in a symbiotic, mutually beneficial relationship. The combination of an alga with a fungus creates lichen. The fungus is the main component of lichen.  Lichens  are composed of several organisms from three different kingdoms: fungi, plants, and bacteria.  Lichens are not single organisms but an intimate symbiosis of fungi, most often an ascomycete, and a photosynthetic alga or cyanobacterial species.  The association of these separate organisms is often referred to as a mutualistic relationship, defined as two or more organisms living in a mutually beneficial arrangement.  Most often the symbiosis association includes a second photosynthetic partner (Photobiont) but only one fungus (mycobiont) per lichen.  Spribille  et al . have rewritten this dogma by identifying lichen involv...