Biology revision

What is biodiversity?

Biodiversity is the variety of all living things and their interactions. It changes over time as extinction occurs and new species evolve. 

Define evolution

The process by which organisms change over generations due to genetic variation, natural selection, and other mechanisms.

How does biodiversity relate to evolution?

Biodiversity is a result of evolution, as genetic variation and natural selection lead to the emergence of new species over time.

What is a scientific theory?

A well substantiated explanation of some aspect of the natural world that is acquired through the scientific method and repeatedly testing through observation and experimentation.

Why do scientific theories sometimes change or get rejected?

New evidence or better explanations can lead to modifications or rejection of previously accepted theories.

What are Darwin’s 5 points of natural selection?

1. Variation exists in populations.

2. More offspring are produced than can survive.

3. Competition for limited resources.

4. Survival of the fittest (best-adapted individuals reproduce).

5. Gradual change in species over time.

What causes variation in a population?

Mutations, sexual reproduction, gene flow, and environmental factors.

What are the 4 stages of speciation?

Variation	Variation between individuals exists and new variation is introduced by random mutations.
Isolation	Population is split into two. The two new populations are isolated and cannot interbreed Isolation can be caused by geographic separation, and time, behavioural, reproductive and ecological differences.
Selection	The two populations experience different selection pressures. Examples of selection pressures include the availability of food, predators, climate, habitats and disease.
Time	After a very long time (thousands of years) the two populations can no longer interbreed. They are two separate species.

Provide an example of speciation

Darwin’s finches in the Galápagos Islands evolved different beak shapes due to different food sources.

Why is the fossil record incomplete?

Many organisms don’t fossilize, fossils are destroyed over time, and some habitats favor fossilization more than others.

How does the fossil record support evolution?

It shows transitional forms and a progression of life forms over geological time.

Describe the 5 key points of natural selection

1. Variation – There are genetic differences within the population 

 

2. Birth rate – More offspring are produced than survive 

 

3. Inheritance – The traits must be inherited, that is coded in the organisms DNA. 

 

4. Selection – Some of the variations are more favourable than others. Favourable traits help individuals survive and reproduce.  

 

5. Time – The frequency of traits in the population changes over time

What is the difference between convergent and divergent evolution?

Convergent: The process where two or more species evolve to have similar characteristics as a result of similar environments (not a common ancestor)

Divergent: The process where two or more species diverge from a common ancestor due to different selective pressures, becoming more dissimilar over time

What are homologous structures?

Structures that are similar in related organisms because they were inherited from a common ancestor, but adapted for different purposes

What are analogous structures?

Structures that have similar functions due to similar environmental pressures in unrelated organisms

How does the pentadactyl limb support evolution?

This suggests that many vertebrates descended from the same common ancestor. Although the limbs of crocodiles, birds, whales, horses, bats and humans all look very different they share the same five fingered bone structure. This shows a common ancestral structure adapted for different functions in different species.

What is comparative biochemistry?

Comparative biochemistry is the study of similarities and differences in the molecules of living organisms.  These molecules include, proteins, DNA and RNA.

What is LUCA?

The Last Universal Common Ancestor

What disproves Lamarck’s theory of evolution?

He argued that if a characteristic was used a lot by an organism then it would become more developed. These "developed" characteristics would be passed on to the next generation. This theory was disproven by August Wiesmann, he cut off the tails of 22 generations of mice, continually allowing them to breed with each other. All the offspring were born with tails. 

What is artificial selection?

The process where humans identify desirable traits in plants and animals. They only select those organisms who have the desirable trait to breed together. 

How does artificial selection differ from natural selection?

In natural selection, it is nature that selects the desirable trait. Whereas, in artificial selection, it is humans that select the desirable trait.

What are optimal conditions for fossil formation?

Rapid burial, lack of oxygen, and the presence of minerals

How does embryology support evolution?

Similar early developmental stages in different species suggest common ancestry

What are vestigial organs?

Structures that have lost their original function (e.g., human appendix, whale pelvic bones).

What is a ubiquitous protein?

Ubiquitous proteins are proteins which are present in all species that carry out the same function. Animals from the same species will have identical acid sequences within the same protein. While the same protein may exist and serve the same function in different species, they may have different amino acids arranged in a different order.

How does biogeography support evolution?

Similar species are found in geographically close regions, indicating shared ancestry and adaptation

Give an example of a modern animal with a scattered distribution.

Marsupials (e.g., kangaroos in Australia, opossums in the Americas) due to continental drift.

who made this

bob