Q.explain the following terms in simple language.....
Asked by deepitapai | 26th Oct, 2008, 03:59: PM
Deoxyribonucleic acid (DNA) is a type of nucleic acid that contains the genetic instructions used in the development and functioning of all known living . It is the genetic material in the nuclei of all cells. DNA is composed of purine (adenine and guanine) and pyrimidine (cytosine and thymine) bases, each connected through a ribose sugar to a phosphate backbone.
Inflorescence is the characteristic arrangement of flowers on a stem. Spikes, racemes, umbels, whorls, panicles, cymes, and corymbs are common types of inflorescences.
Germ cells are the reproductive cells of the body i.e. the ova or eggs and sperms. They contain only half (haploid) the usual number of chromosomes that other cells contain.
Double fertilisation is seen in flowering plants. One sperm nucleus unites with the egg to form the diploid zygote, from which the embryo develops, and the other unites with two polar nuclei to form the triploid, primary endosperm nucleus. Since 2 fertilisations are taking place simultaneously, this type of fertilisation is called double fertilisation.
Zygote is the diploid (2n) cell resulting from the union of two gametes i.e. the male and female gamete in sexual reproduction.
Chromosome is a threadlike linear strand of DNA and associated proteins in the nucleus of eukaryotic cells that carries the genes and functions in the transmission of hereditary information. Chromosomes can change their conformation and degree of compaction throughout the cell cycle. During interphase, the major portion of the cycle, chromosomes are very long and extremely thin. However, during cell division, the chromosomes become compacted into shorter and thicker structures that can be seen under the microscope.
Answered by | 26th Oct, 2008, 06:31: PM
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