The brain loses 5-10 percent of its weight between the ages 20 & 90.
Ionizing radiation, for example X-rays, gamma rays and alpha particles
Correct answer: Option D- DNA ligase
Explanation: In option A, thymine is a nucleotide, so it is present throughout the replication process, wherever it is required. It is added to the newly formed DNA. In option B, Helicase enzyme is active during initiation and elongation stage, as it facilitates the opening of the winded DNA strands. Option C is nucleotidase and it has no role in DNA replication. So, the correct answer is DNA ligase, which is option D.
The okazaki fragments formed during DNA replication are sealed at the end. And in this step, DNA ligase is used. It catalyzes the formation of phosphodiester bond between the nucleotides of okazaki fragments. So it is the last active molecule of the process.
The only way for gases to diffuse in and out of the leaf is through small openings on the bottom of the leaf, the stomata.
Cross pollination is the transfer of pollen of different species to stigma of different species of plants.
Cross pollination results in healthy, viable and diverse plants.
Mendel observed that traits could either be dominant or recessive.
Blended traits or incomplete dominance is the condition in which dominant allele could not produce its trait alone instead blending with recessive allele takes place giving new phenotype to progeny.
Explanation:
In cross pollination pollen transfer takes place from anthers to stigma. In Mendelian genetics the anthers of the plant was removed because it has both male and female parts on same plant so that self pollination does not take place.
The importance of cross pollination is that it creates diversity in the plant species since the traits having different alleles are combined to form the progeny plant. The offspring are healthier and high quality seeds are found.
Mendel observed that traits are either dominant or recessive in general. It was observed that when homozygous parents were crossed, the progeny in F1 generation always had dominant trait. The recessive trait only appeared when F1 generation offspring were self pollinate.
Blended traits or incomplete dominance appear when alleles get blended and exhibit the traits in phenotype. The phenotype appeared will not be matching with either parents.
The example is a white coloured flower is crossed with red colour flower the resultant colour of the flower is pink. It shows that dominant allele red is not completely dominant and gets blended with white colour.
