B1.8 Evolution Flashcards
1
Q
How are living things related (evolutionary relationships)?
A
- Species with similar characteristics often have similar genes as they share a common ancestor, so they’re closely related. They often look very alike and tend to live in similar types of habitat e.g. whales and dolphins
- Occasionally, genetically different species might look alike too. E.g. dolphins and sharks look pretty similar as they’ve both adapted to living in the same habitat. But they’re not closely related- they’ve evolved from different ancestors.
- Evolutionary trees show common ancestors and relationships between organisms. The more recent the common ancestor, the more closely related the two species.
2
Q
What are interaction of organisms (ecological relationships)?
A
- If we see organisms in the same environment with similar characteristics (e.g. dolphins and sharks) it suggests they might be in competition (e.g. for the same food source).
- Differences between organisms in the same environment (e.g. dolphins swim in small groups, but herrings swim in giant shoals) can show predator-prey relationships (e.g. dolphins hunt herrings).
3
Q
How does natural selection explain how evolution occurs?
A
- Charles Darwin’s theory:
- Individuals within a species show variation because of the difference in their genes.
- E.g. some rabbits have big ears and some have small ones.
- Individuals with characteristics that make them better adapted to the environment have a better chance of survival and so are more likely to breed successfully.
- E.g. big-eared rabbits are more likely to hear a fox sneaking up on them, and so are more likely to live and have millions of babies.
- The genes that are responsible for the useful characteristics are more likely to be passed on to the next generation.
- E.g. all the baby rabbits are born with big ears.
4
Q
How can evolution occur due to mutation?
A
- Most of the time mutations have no effect, but occasionally they can be beneficial by producing a characteristic.
- This characteristic may give the organism a better chance of survival.
- The beneficial mutation is more likely to be passed on to future generation by natural selection.
- Over time, the beneficial mutation will accumulate in a population e.g. some species of bacteria have become resistant to antibiotics due to a mutation
5
Q
Why did people not agree with Darwin?
A
- It went against common religious beliefs about how life on Earth developed.
- Darwin couldn’t give a good explanation for why these new, useful characteristics appeared or exactly how individual organisms passed on their beneficial characteristics to their offspring.
- There wasn’t enough evidence to convince many scientists, because not many other studies had been done into how organisms change over time.
- Mechanism of inheritance and variation was not known until after 50 years the theory was published.
6
Q
What was Lamarck’s theory of evolution?
A
- Lamarck (1744-1829) argued that if a characteristic was used a lot by an organism then it would become more developed during its lifetime.
- E.g. if a rabbit used its legs to run a lot (to escape predators), then its legs would get longer.
- Lamarck believed that these acquired characteristics would be passed on to the next generation.
- E.g. the rabbit’s offspring would have longer legs.
7
Q
How can scientists develop different hypotheses from similar observations?
A
- Scientists came up with different hypotheses to explain similar observations.
- Scientists developed different hypotheses because they had different beliefs or they have been influenced by different people.
- E.g. Lamarck and Darwin both had different hypotheses to explain how evolution happens in the end.
8
Q
What is Darwin’s theory of evolution?
A
- Natural selection:
- All species of living things have evolved from simple life forms that first developed more than three billion years ago.
9
Q
Who came up with the idea of natural selection?
A
•Charles Darwin.
10
Q
When was genes and mutation discovered?
A
•They weren’t discovered until 50 years after Darwin’s theory was published.
11
Q
What is the only way to find out whose hypothesis is right?
A
•To find evidence to support or disapprove each one.
12
Q
Why is Lamarck’s theory rejected?
A
- The experiments didn’t support his hypothesis.
- E.g. if you dye a hamster’s fur bright pink, its offspring will still be born with the normal fur colour the new characteristic won’t have been passed on.
13
Q
How did the discovery of genetics support Darwin’s idea?
A
- It provided an explanation of how organisms born with the beneficial characteristics can pass them on (i.e. via their genes).
- There’s so much evidence for Darwin’s idea that it’s now accepted hypothesis (a theory).
14
Q
What is classification?
A
•Studying the similarities and differences between organisms allows us to classify living organisms into animals, plants and microorganisms.
15
Q
What is classification used for?
A
- It helps us to understand evolutionary and ecological relationships.
- Models allow us to suggest relationships between organisms.
