No, predators do not only kill the old and sick prey. They will go after any of the prey, including the strong ones and the children. The reason they often go after the old and sick prey is because they're easier to pick off, whether they are on their own or in a pack. Predators will go after any one of the members of their prey, but prefer the old and/or sick as it requires less energy.
The seasonal movement of animals from one place to another (usually occurs in species with ability to flight and in large amount
Natural selection is a specific mechanism of evolution in which the heritable traits help an organism to survive and reproduce successfully. answer B
Theoretically it is the Chargaff's rule which entails that the ratio of purines and pyrimidines are 1. So following that rule you can solve this question.
G (purine) = C (pyrimidine) and
A (purine) = T (pyrimidine)
So G + C would be 28% and hence
A +C would be 72% i.e. 36% each.
Please note that their are certain modified bases besides these four are also there including methyl Cytosine, Methylated Adenine. But htese modification does not violate the Chargaff's rule and they follow standard Watson Crick base pairing.
The substance like iodine 131 is used as in medicine which
can help produce various images of organs and tissues. This substance is called
as a tracer. Iodine 131 is a radioactive isotope which is also used to monitor
thyroid gland functioning, to locate tumours in the liver or brain, and also
treat thyroid cancer.
