(i) Name the scientist who suggested that the genetic code should be made of a combination of three nucleotides.
(ii) Explain the basis on which he arrived at this conclusion.
(i) George Gamow suggested that the genetic code should be made up of a combination of three nucleotides.
(ii) He proposed that if 20 amino acids are to be coded by 4 bases, then the code should be made up of three nucleotides. 43 = 64 (42 = 16), which is less than 20. So, the codon was proposed to be triplet.
What is menstrual cycle? Which hormones regulate menstrual cycle?
Fill in the blanks:
(a) Humans reproduce __________. (asexually/sexually)
(b) Humans are__________. (oviparous/viviparous/ovoviviparous)
(c) Fertilization is __________ in humans. (external/internal)
(d) Male and female gametes are __________. (diploid/haploid)
(e) Zygote is __________. (diploid/haploid)
(f) The process of release of the ovum from a mature follicle is called__________.
(g) Ovulation is induced by a hormone called the __________.
(h) The fusion of male and female gametes is called _____________.
(i) Fertilisation takes place in _____________.
(j) Zygote divides to form _____________which is implanted in uterus.
(k) The structure which provides vascular connection between fetus and uterus is called ____________.