How does Fixism explain the diversity of living things?
(4 marks) Fixism claims that species were created the way they are now, given that they do not change. Therefore, the diversity we find today is the diversity that has always existed. c.
Explain why two very different species such as birds and butterflies can have similar wings, responsible for the same function. Which evidence of evolution is it? (4 marks)
Given that both species must adapt to the same environment, they end up developing similar structures. It is an example of convergent evolution.
According to Darwin, why do individuals compete against each other? What are the consequences of this constant competition? (4 marks)
The cause is the lack of resources in an environment and the consequence is that only the fittest (better adapted) will survive.
Compare the theory of punctuated equilibrium with Neo-Darwinism and neutralism. What are their similarities and differences? (5 marks)
They are all evolutionary theories. Punctuated equilibrium and Neo-Darwinism are different because the former claims that evolutionary changes happen fast and are very sudden; the latter claims that the process is slow and gradual. Neutralism proposes that most mutations are neither advantageous nor disadvantageous given that natural selection does not affect them.
Name four barriers that can lead to genetic isolation (4 marks):
- Geographical barriers
- Sexual barriers
- Physiological barriers
- Chromosomal barriers
- Ethological barriers
Differentiate, with examples, between abiotic and biotic factors (4 marks).
Abiotic: The non-living chemical and physical factors in an environment (which affect ecosystems). E.g., Temperature, pH, salinity, humidity, wind, etc. Biotic: The living components of an environment which affect an ecosystem. E.g., Disease (pathogens), competition, predation, mate availability, etc.
Define biomass (2 marks).
Biomass is the total dry weight of organic matter in organisms or ecosystems. (i.e., the entirety of all biologically produced organic matter - carbohydrates, proteins, etc.)
Explain, using an example, the difference between the habitat and the ecological niche of a species (3 marks).
One example would be a lion. Its natural habitat is the African Savannah, and its ecological niche is its role as a hunter.
What would happen if an ecosystem did not have bacteria and fungi? And what if it did not have autotrophic organisms? (4 marks)
- In the first scenario, dead organic matter would not be recycled and turned into inorganic compounds. As a result, after a period, plants would not have enough nutrients. - In the second scenario, there would not be any primary producers and, as a result, life would not be possible.
Outline the formation of oil and natural gas (5 marks).
Oil and natural gas form as the result of the decay of marine organisms on the ocean floor. Sediments are deposited on top of the organic matter, creating anoxic conditions that prevent decomposition. The compacted and heated organic matter forms oil and gas, which accumulates within porous rocks.