NameMatriculation numberQuestion 1 [2.5 marks]a.Firstly, the fox cubs that have just started to crawl, open their eyes and started showing affection tohumans by breathing heavily, wagging their tails, and howling. This shows that tameness is expressedin the fox’s genes and the tame behaviour is inbuilt.Secondly, in an experiment with cross-fostering, where aggressive subs were given to tame mothersand vice versa, the mother’s behaviour does not influence that of the cub. This shows that thedifference in tame and aggressive foxes lies largely with their genes. They also transferred embryosfrom aggressive mothers into tame mothers, but the results showed that the genes for aggressivenesscannot be changed or kept and preserved for the next generation.b.i)Red blood cells and haemoglobin were eliminated from the genetic makeup of the icefish.Globin genes that encode the haemoglobin protein were different in the icefish’s DNA when comparedto other fishes. A mutation wrecked the globin genes in icefish and since haemoglobin was no longernecessary to icefish, the mutation was not eliminated.ii)Anti-freeze genes.50 million years ago, the water around Antarctica were once a temperate 10 degrees Celsius.However, this changed 34 million years ago when the Drake Passage opened as Antarctica brokeaway from South America. This led to a continuous current circulating the new continent isolating thesurrounding waters and keeping its temperatures to -1.8 degrees Celsius. Therefore, the Notothenioidsand anti-freeze evolved to ensure the survival of the species.These anti-freeze traits came from genes. The ancestral genes were accidentally duplicated and whileone copy remained the same, the other accumulated mutations, that eventually gave the gene a newfunction which was to make anti-freeze proteins.c.DNA evidence can tell us that our lineage goes back several million years before the Olduvai fossils.DNA evidence cannot tell us when and where the traits that distinguish us from chimps – likebipedality, first emerged. In this case, only fossils and their ancient environments can address thosequestions.
