Biology

Describe how increased concentrations of atmospheric carbon dioxide may change coral reef ecosystems

Will cause more co2 to dissolve into the ocean, leading to more carbonic acid and hence hydrogen carbonate ions to to form and dissociate, the end result of which is increasing numbers of hydrogen ions in the sea, increasing the acidity. Ocean acidification hinders coral reefs' ability to create their exoskeletons, as the reduced conc of carbonate ions in the water limit their access to the necessary materials. Additionally, the calcium carbonate exoskeletons of corals can be weakened and dissolve. This can result in a reduction in biodiversity and negatively impact autotrophs in the ecosystem.

Explain how populations change by natural selection

Sexual reproduction and mutations causes there to inherintly be variation within a population. When something different occurs in the environment, such as a drought, or when overproduction of offspring occurs more than the carrying capcity can hold, competition increases for the limited available resources. This means the weaker adapted organisms will die and the ones with favourable characteristics are more likely to survive. These survivors go on to breed successfully and pass their heritable traits to the next generation. Over time, these advantageous alleles/traits become more common in the population.

2 types of natural carbon sinks

fossil fuels

forests

data based question - fishes and lakes

aii. respire and breathe out co2

b. there is significantly more variation of species in the subtropical lakes, and theres a greater number of individuals per m2 in subtropical lakes

ci. the mean length of fish in the subtropical lake is smaller, both have fishes of variable lengths

cii. 1.9 cm

di. subtropical

dii. less energy available for piscivores as they are a higher trophic level

diii. theres more food under the submerged plants

e. In subtropical lakes the number of species increases with higher water transparency, and in temperate water the water transparency doesnt affect the number of species/stays the same

f. some species may die out as they dont adapt to the warmer waters