Biology Unit 1-5 (no 4) Flashcards Preview

Biology Mocks > Biology Unit 1-5 (no 4) > Flashcards

Flashcards in Biology Unit 1-5 (no 4) Deck (446)
Loading flashcards...
1

What is a species?

A species is a group of organisms that share common physical characteristicsMembers of the same species are capable of breeding together to produce viable offspring

2

What is evolution?

Evolution is the cumulative change in the heritable characteristics of a population

3

What happens in speciation?

Evolution can lead one species to diverge into two separate species. One species can gradually diverge into separate species by evolution

4

What do fossils tell us about evolution?

- Fossils demonstrate gradual change in physical characteristics of a species - Fossils demonstrate species extinctionFossils record the gradual change in the characteristics of a species over long periods of time

5

What is a homologous structure?

A homologous structure is a physical characteristic shared by related species

6

What does the pentadactyl limb tell us about mammals?

All mammals are descended from a common ancestor The genetic code is universal. This provides evidence that all living species share common ancestors.

7

Outline the difference between artificial and natural selection.

Artificial selection:Organisms are selected for a purpose (better tasting food crops, smarter sheepdogs, faster racehorses)Artificial selection is carried out by humansNatural selection:Organisms are not selected for a purpose… instead the focus is on survivalNatural selection is driven by environment

8

How does artificial selection demonstrate evolution?

Selective breeding of domesticated animals (pets) shows this because they have evolved through human selection

9

What is a cline?

A cline is a gradation in one or more characteristics within a species.

10

Outline five types of evidence which support thetheory of evolution by natural selection

? fossils/paleontological: fossilized horse ancestors/other evidence? homologous structures: pentadactyl limb/vertebrate embryos/other? Selective breeding of domesticated animals shows that artificial selection can cause evolution? recent observed evolution: resistance to antibiotics/melanistic (dark color) insects in polluted areas/other recent example? geographic distribution: ring species/other evidence from geographical distribution? biochemistry: cytochrome c/other biochemical evidence

11

What explains similarities in structure when there are different function?

Evolution of homologous structures by adaptive radiation explains the similarity even when they have different functions.

12

What is adaptive radiation?

When organisms come from the same origin, like from an ancestor that had a pentadactyl limb, and they become different because they perform different functions.

13

What is a convergent evolution?

Organisms that have had different origins and have become similar because they perform the same or a similar function.

14

Give evidence from patterns of variation.

Example: human skin colour as evidence for evolution: • People with darker skin colour have evolved in places with high UV light --> protect them from cancer • People with lighter skin colour have evolved in places with low UV light --> helps them to generate enough Vitamin D

15

What is gradual divergence?

Continuous variation across the geographical range of related population matches the concept of gradual divergence.

16

Does the continuous range in variation match the belief that species were created as distinct types of organisms?

No it does not. Continuous range in variation is not constant or unchanging. It provides evidence for evolution and origin of species by evolution.

17

How did melanistic insects evolve?

Dark varieties of typically light coloured insects are called melanistic. The most famous example is the peppered moth which developed the melanistic variety in polluted industrial areas for better camouflage (change in natural environment)

18

Why do living organisms face a struggle for survival?

1. All species have great potential fertility2. Population sizes show long term stability3. Environmental resources are limitedLiving organisms have to compete with other members of their species in order to survive

19

Why do living organisms face a struggle for survival?

1. All species have great potential fertility2. Population sizes show long term stability3. Environmental resources are limitedLiving organisms have to compete with other members of their species in order to survive

20

What do members of a species show?

Living organisms show an enormous range of variation. No two living organisms are ever truly identical, even if they are genetic clones

21

Only under what condition can natural selection occur?

Natural selection can only occur if there is variation among members of the same species.Adaptations are characteristics that make an individual more suited to survive in its environment and successfully reproduce.

22

What promotes genetic variation?

Independent assortment, Meiosis, Gene Mutation and sexual reproduction

23

How does natural selection lead to evolution?

1. Individuals that are better adapted tend to survive and produce more offspring while the less well adapted tend to die or produce fewer offspring2. individuals that reproduce pass on characteristics to their offspring3. natural selection increases the frequency of characteristics that make individuals better adapted and decreases the frequency of other characteristics leading to changes within the species

24

Explain how the use of antibiotics has led to the evolution of resistant bacteria

- members of a population of the same species show variation- some organisms are more likely to survive due to selective advantage- these variations may be genetically controlled/heritable- these genes are most liekly to be passed on to offspring - this can change the characteristic of the population- bacteria can noramlly be killed by antibiotics- anti biotics impose a selection pressure - if few bacteria have natural resistance to the antibioticthey will survive- if the resistance is heritable they will pass it on their offspring- they will reproduce/evolve to form bacterial colonies resistant to antibiotics.

25

Explain how the use of antibiotics has led to the evolution of resistant bacteria

- members of a population of the same species show variation- some organisms are more likely to survive due to selective advantage- these variations may be genetically controlled/heritable- these genes are most liekly to be passed on to offspring - this can change the characteristic of the population- bacteria can noramlly be killed by antibiotics- anti biotics impose a selection pressure - if few bacteria have natural resistance to the antibioticthey will survive- if the resistance is heritable they will pass it on their offspring- they will reproduce/evolve to form bacterial colonies resistant to antibiotics.

26

Briefly explain Darwin`s theory of evolution.

• Species tend to produce more offspring than the environment can support• the consequence of the potential overproduction of offspring is a struggle for survival• Mutation, meiosis and sexual reproduction cause variation (different characteristics) between individuals in a species.• Adaptations are characteristics that make an individual suited to its environment.• Individuals that are better adapted tend to survive and produce more offspring while the less well adapted tend to die or produce fewer offspring.• Individuals that reproduce will pass on characteristics to their offspring.• This selective "pass on characteristics" is called natural selection.• Natural selection leads to change in allele frequency.• Characteristics acquired during the lifetime of an individual (Eg. Learned skills) are not heritable. Therefore, it does not affect evolution.

27

What is an acquired characteristic?

An Acquired characteristic is a change that happens to an organism during its lifetime. These types of characteristics do not affect DNA and are not heritable.

28

Discuss evidence against the theory of evolution by inheritance of acquired characteristics.

? This is an incorrect theory stating that characteristics acquired during the lifetime of an individual can be passed on to next generation.? Acquired characteristics example: giraffes reach for leaves on tall tree, therefore their neck becomes longer, over many generations, giraffes have long neck.? This theory is incorrect because it relies on phenotypic inheritance, not genotypic inheritance /somatic changes cannot be passed on? example: if tail cut off rat -- offspring still have tails? cannot be repeated experimentally since very many generations would be necessary? also mutations would have to be eliminated in such anexperiment -- impossible

29

Explain with an example of natural selection causes progressive change.

Darwin collected finches which varied in sizes and shapes of their beaks.Beaks characters and diet are closely related, when one changes the other does also. Medium ground finch can eat large and small seeds whereas small finch can only eat small seeds.Daphne Major absence of small ground finch so... When eating small seeds the medium ground finch was smaller in body and beak size. When there was a shortage, the larger beaked individuals survived.Variation in beak and body size is mostly due to genes but the environment has some effect. The proprtion of the variation due to genes is called heritability.

30

What is progressive change?

Natural selection increases the frequency of characteristics that make individuals better adapted and decreases the frequency of other characteristics.