Hsc Biology: Questions And Answers

HSC BIOLOGY TOPIC 2: BLUEPRINT OF LIFE
HSC BIOLOGY TOPIC 2: BLUEPRINT OF LIFE

1) Evidence of evolution suggests that the mechanisms of inheritance, accompanied by selection, allow change over many generations. 1.1.1 Outline the impact of evolution of plants and animals of: * Changes in physical conditions in the environment * Changes in chemical conditions in the environment * Competition for resources 1.1.2 Outline the impact of evolution of plants and animals of: * Changes in physical conditions in the environment * Changes in chemical conditions in the environment * Competition for resources

Evolution is the change in a population
Australia separated from the Gondwana early in the age of mammals. During Australia’s isolation, natural selection occurred so that the koala, a mammal, is unique to Australia and can’t be found anywhere else.
Baobab trees have different species in Australia and Madagascar. They are probable descended from a common Gondwanan ancestor.
Comparative Embryology:
Comparative embryology involves studying the embryo development of different species. For example, when comparing the embryos of vertebrates, they often look similar and are difficult to distinguish from each other. This implies that vertebrates come from a common ancestor.

Comparative anatomy:
Comparative anatomy is the study of structures such as bones and organs found in different groups. A pentadactyl limb (the five-fingered limb found in birds, mammals and reptiles) is often studied in comparative anatomy. It shows that these groups had a common ancestor and adaptive radiation (or divergent evolution) has modified the limb.
The genes in each haploid cell are combinations of the parental genes. Crossing over (synapsis) occurs when homologous chromosomes exchange genetic material. It introduces genetic variation.
Chromosomes are made of DNA. Genes are coded within the DNA on the chromosomes. During division each chromosome (which therefore includes the genes) makes a complete copy of itself. The new chromosome is attached to the original chromosome by a centromere. In the initial division of meiosis the homologous chromosomes line up in matching pairs and one of each pair of homologous chromosomes moves into a new cell. Next the duplicated chromosomes separate to single strands resulting in four sex cells that are haploid, (ie contain half the chromosome number of the original cell).
The genes are located on the chromosomes. They are duplicated during the first stage of meiosis and are then randomly assorted depending on which chromosomes from each pair enters which new haploid cell during the first and second