spicynuggets
Question 1/
The key point that is need to be noted is that the modern human group that is hypothesised by the "Out of Africa Hypothesis which migrated out of Africa ~ 100,000 ya and reached Asia ~ 70,000 years ago before moving down through South-east Asia and into Australia 50,000 years ago. It can be concluded that Aboriginals were part of this group of Homo Sapiens.
Question2/
VCAA expects you know the adaptations C3/C4/CAM plants have and how it aids them to survive in their respective environments. It is not clear in how much depth they are looking for in this new study design, so here is my guide on what they could be expecting.
C3 plants are the normal types of plants that are adapted to a variety of temperatures and levels of humidity.
They convert CO2 into 3 carbon compound called PGA and then into glucose.
C4 plants are adapted to much hotter environments. We know that Rubisco, enzyme responsible for the Calvin cycle, has increased affinity of O2 as substrate as temperatures increase, cause photorespiration and reducing photosynthetic efficiency. In order to combat this issue, the light dependant stage is separated from the light independent stage so that the O2 produce in light dependent stage does not come in contact with Rubisco. Therefore, the Calvin Cycle occurs in bundle sheath cells, deep in the leaf tissue, away from the stomata and the light dependent stage occur in the mesophyll cells. This means CO2 is converted into malic acid before being transported into the bundle sheath cells as bundle sheath cells don't have access to the stomata.
CAM plants are adapted to dry climates and hence they are specialised to conserve H2O.
To do this, they only open their stomata at night, in order to let in CO2. The CO2 is stored as malic acid in the cells large vacuole. When it is day time, the stored CO2 is release from malic acid and can be used to power photosynthesis without having to open their stomata during the day.
This helps the CAM plants be much more efficient (up to 90%) in conserving water than C3 plants.
