Class name Subject Book title Chapter number Content Created at
Class XII Biology Biology 4 the F g1neration while at the F 2tage both the traits were expressed in the proportion 3:1. The contrasting traits did not show any blending at eit...
Class XII Biology Biology 4 is convenient (and logical) to use the capital and lower case of an alphabetical symbol to remember this concept of dominance and recessiveness. (D...
Class XII Biology Biology 4 possible gametes are written on two sides, usually the top row and left columns. All possible combinations are represented in boxes below in the sq...
Class XII Biology Biology 4 to dominate over the other allele t or ‘dwarf’ character. It is thus due to this dominance of one character over the other that all the F are tall ...
Class XII Biology Biology 4 can easily be analysed to predict the genotype of the test organism. Figure 4.5 shows the results of typical test cross where violet colour flower ...
Class XII Biology Biology 4 or was in-between (incomplete dominance). But, in the case of co-dominance the F genera1ion resembles both parents. A good example is different typ...
Class XII Biology Biology 4 the example of ABO blood grouping also provides a good example of multiple alleles? Here you can see that there are more than two, i.e., three alle...
Class XII Biology Biology 4 round shaped seeds. Here can you tell which of the characters in the pairs yellow/ green colour and round/wrinkled shape was dominant? Thus, yellow...
Class XII Biology Biology 4 = 9 Round, Yellow : 3 Wrinkled, Yellow: 3 Round, Green : 1 Wrinkled, Green Based upon such observations on dihybrid crosses (crosses between plants...
Class XII Biology Biology 4 types of genotypes and phenotypes are formed? Note them down in the format given. Can you, using the Punnett square data work out the genotypic rat...
Class XII Biology Biology 4 pairing and separation of a pair of chromosomes would lead to the segregation of a pair of factors they carried. Sutton united the knowledge of chr...
Class XII Biology Biology 4 of non-parental gene combinations (Figure 4.11). Morgan and his group also found that even when genes were grouped on the same chromosome, some gen...
Class XII Biology Biology 4 account the influence of environment. Human skin colour is another classic example for this. In a polygenic trait the phenotype reflects the contri...
Class XII Biology Biology 4 trace a specific nuclear 69 structure all through spermatogenesis in a few insects, and it was also observed by him that 50 per cent of the sperm r...
Class XII Biology Biology 4 composition; Among the males an X-chromosome is (c) In many birds, female has a pair present but its counter part is distinctly dissimilar chromoso...
Class XII Biology Biology 4 these are the autosomes. A pair of X-chromosomes are present in the female, whereas the presence of an X and Y chromosome are determinant of the ma...
Class XII Biology Biology 4 the males produce sperms by mitosis (Figure 4.13), they do not have father and thus cannot have sons, but have a grandfather and can have grandsons...
Class XII Biology Biology 4 is evident that control crosses that can be performed in pea plant or some other organisms, are not possible in case of Figure 4.13 Symbols used in...
Class XII Biology Biology 4 in question is dominant or recessive. Similarly, the trait may also be linked to the sex chromosome as in case of haemophilia. It is evident that t...
Class XII Biology Biology 4 of a female becoming a haemophilic is extremely rare because mother of such a female has to be at least carrier and the father should be haemophili...
Class XII Biology Biology 4 of this phenylalanine is accumulated and converted into phenylpyruvic acid and other derivatives. Accumulation of these in brain results in mental ...
Class XII Biology Biology 4 Similarly, Turner’s syndrome results due to loss of an X chromosome in human females. Failure of cytokinesis after telophase stage of cell division...
Class XII Biology Biology 4 sex Suchanindividualhasoverallmasculinedevelopment, chromosome composition in humans : however, the feminine development (development of breast, i....
Class XII Biology Biology 4 form known as ‘Punnett Square’. The factors (now known as gene) on chromosomes regulating the characters are called the genotype and the physical e...
Class XII Biology Biology 4 This helped in understanding the mutational basis of genetic disorders. Down’s syndrome is due to trisomy of chromosome 21, where there is an extra...