B2d

Question 1

What is Charles Darwin’s theory of evolution?

Answer 1

• survival of the fittest/natural selection
• organisms in a species show wide variation and have to compete for limited resources in an ecosystem
• the organisms that are best adapted would be more successful competitors and would be more lightly to survive, reproduce and pass on the adaptions to their offspring
• less well adapted organisms are less likely to survive and pass on their characteristics
• over time, successful adaptions become more common in the population and the species changes–it evolves

Question 2

What new discoveries have helped to develop the theory of natural selection?

Answer 2

• Darwin didn’t know why new characteristics appeared or how they passed on beneficial adaptations
• this was due to DNA being yet to be discovered
• we now know that adaptions are controlled by genes, new adaptions arise because of mutations, adaptions are passed on through genes

Question 3

How can reproductive isolation be caused by geographical isolation?

Answer 3

• a physical barrier divides a species, e.g. a river changes its course
• the two new populations are unable to mix
• different mutations create different new features in the two groups
• natural selection take place
• the conditions on each side will be slightly different, so the beneficial features will be different
• eventually, the two populations have such different features that they can not breed together to produce fertile offspring
• they have become reproductively isolated and the two groups are separate species

Question 4

Why do people disagree with Darwin?

Answer 4

• goes against religious believes, it was a plausible explanation for our own existence without the need for a ‘creator’
• Darwin couldn’t explain why new, useful characteristics appeared or how they were inherited

Question 5

What was Lamarck’s theory of evolution?

Answer 5

• Lamarck argued that if an organism used a characteristic a lot then it would become more developed
• he believed acquired characteristics could be passed to offspring
• people later concluded that acquired characteristics don’t have genetic basis, they can’t be passed on to the next generation

Question 6

Why is the theory of natural selection widely accepted?

Answer 6

• the theory was debated and tested independently by a wide range of scientists, no one has found conclusive evidence that the theory is wrong
• the theory offers a plausible explanation to many observations of animals and plants (physical characteristics and behavioural patterns)