Evolution and Classfication

Question 1

Define species?

Answer 1

• a group of organisms that can interbreed to produce fertile offspring

Question 2

Two examples of the most bio diverse ecosystem?

Answer 2

• tropical rainforest

* coral reefs

Question 3

3 main causes of extinctions?

Answer 3

• loss of habitat
• competition from introduced species
• over hunting by humans

Question 4

Additional factors that threaten species?

Answer 4

• deforestation
• pollution
• drainage of wetland

Question 5

Why might the loss of species in a rainforest may be a serious problem for humans?

Answer 5

• because the plants are a source of chemicals that can be used for medicine

Question 6

Describe what is meant by genetic bottleneck?

Answer 6

• lack of biodiversity within a species - all individuals have very similar genetic makeup

Question 7

Define species conservation?

Answer 7

• the planned preservation of wide life e.g zoo

Question 8

What is evolution?

Answer 8

• process by which new species are formed from pre existing ones over a very long period of time

Question 9

Charles Darwin?

Answer 9

• whilst visiting Galapogos Island, he studied small birds = finches. The island was new so any species must have reached there from mainland 600miles away
• finches are unable to fly so Darwin suggested that one species of finch flew there by help of prevailing wind
• no other birds on the island so there was large supply of food for finch. He noticed each islands finch has different beaks which was adapted to the different types of food
• Darwin proposed that over time, different species of finch had developed from single common ancestor and the beak developed over time was specialised to feed on particular food source = adaptive radiation

Question 10

Natural selection?

Answer 10

• There is over-population of a particular species
• there is competition between members of the same species to survive
• Individuals that are better adapted to the environment are more likely to outcompete others in the population
• These individuals are more likely to survive and reproduce
• These individuals then reproduce and pass on the favourable characteristics (genes) to their offspring

Question 11

What is palaeontology?

Answer 11

• the study of plants and animals from the geological past - represented by fossil remains
• fossils = the preserved remains, impressions/ traces of plants, animals and other organisms that lived millions of years ago

By arranging extinct animals and plants into geological sequence, it is possible to suggest how one group may have evolved into another.

Question 12

What is mass extinction?

Give examples of mass extinction

Answer 12

• occurs when large proportion of known species become extinct within a short period of time
• e.g dinosaurs - 65million years ago
• marine invertebrates- 250million years ago

Question 13

Theories for dinosaurs becoming extinct?

Answer 13

• drop in temperature which they couldn’t survive bc of the large amounts of food they needed to stay alive
• meteor crashed into earth blocking sun, plants couldn’t photosynthesise leading to mass starvation

Question 14

What is taxonomy/classifcation?

Answer 14

• taxonomy is the scientific study of the diversity of living organisms
• the sorting of living organisms into groups of a manageable size ( classifcation)
• each type of group in the classifcation hierarchy is called a taxon and organisms share some basic features
• scientists classify organisms based on evolutionary relationships - to identify relationship they look at similarities and differences

Question 15

What do scientists examine?

Answer 15

• physical similarity : insects have mouth parts of a similar pattern even if foods different

• DNA composition : organisms with common ancestors have closely related DNA
- comparisons of DNA bases by DNA HYBRIDISATION allows scientists to look for similarities/differences

Question 16

The bonobo chimpanzee is closet living relative to human. How can scientists decide humans are more closely related to chimp than cow?

Answer 16

• isolate DNA from chimp/cow
• compare DNA sequences using DNA hybridisation/genetic fingerprinting methods and look for % similarity in DNA
• if DNA is smaller = closely related

Question 17

Hierarchical system?

Answer 17

• one where large groups are divided into smaller groups?

Question 18

Define biodiversity?

Answer 18

• is a measure of the number of species on the planet

Question 19

What are the seven different taxons?

Answer 19

• Kingdom : largest taxanomic group - prokaryotes, protoctista, plants, fungi, animals
• Phylum : a group of similar classes e.g chordstes
• Class : a group of similar order
• Order : a group of similar family
• Family : a group of similar genera
• Genus : a group of similar species
• Species : a group of organisms that can interbreed to produce fertile offsprings

Question 20

Why are humans called Homo sapiens in the binomial system?

What is the advantage of having a binomial system worldwide?

Answer 20

• because the first name tells you the genus, the second tells you the species

Advantage:
• no confusion
• no ambiguity

Question 21

Kingdom, Phylum, Class?

Answer 21

Kingdom : Animalia
Phylum: arthropod ( invertebrates )
Class: insects, crustaceans, arachnids, myriapods

Kingdom : Animalia
Phylum: Annelids ( invertebrates )
Class : earthworms, lugworms, leeches

Kingdom : Animalia
Phylum : Chordates ( vertebrates)
Class : Mammals, Reptiles, Fish, Amphibians, Birds

Question 22

Phylums?

Answer 22

• Annelids: they have a segmented body visibly seen as rings. Body is divided internally into septa and filled with fluid. Have a thin permable skin and closed circularly system. The brain and nervous system are primitive

• Athropods: body divided into segments - head, thorax, abdomen. Legs are paired/jointed. Spiders have 4 pairs , crustaceans have 10-20, centipedes have many. They have open circulatory system. Hard exoskeleton made of chitin ( for support, protection of organs, prevention of water loss ).
Disadvantage of exoskeleton: fixed in size and doesn’t grow with animal

• Chordate:

• Fish : have scales fins and gills, eggs fertilised in water
• Amphibians: moist skin, jelly coated eggs which are fertilised in water. Juveniles have gills, adults have lungs
• Reptiles : dry scaly skin, lungs for G.E, eggs laid on land/ protected by leathery shells
• Birds : body covered in feathers, lungs and lay eggs with hard shells
• Mammals : give birth to young, have lungs and feed young on milk

Question 23

The mammal class is further subdivided into two groups?

Answer 23

• Marsupials e.g. kangaroo: Young are born at a very immature state and develop in the female’s pouch.
• Placentals: Young undergo considerable development in the mother’s womb, and receive nourishment via the placenta before they are born.

Question 24

Endothermic/ exothermic?

Answer 24

• Chordates: birds and mammals are endothermic - they regulate body temp
- amphibians, fish, reptiles are exothermic

Question 25

What is a homologus feature?

Answer 25

• a feature that has different functions in different organism but is similar in structure so may have had a common origin

Question 26

What is analogous?

Answer 26

• when you have the same function but different structure

• sometimes animals have common features but it’s not due to them coming from common ancestors but adapted to similar environments

Question 27

Biochemical techniques to confirm evolutionary relationship?

Answer 27

1. Separation of chemical substances
   - too look for sims and diffs in sequence is carried out by chromatography
2. DNA base sequence analysis
   ELECTROPHORESIS
   - DNA sequence can be analysed by DNA hybridisation and DNA fingerprinting to compare sequences of bases i.e look @ sims and differences
3. Amino acid sequence analysis
   - two closely related species will have similar biological molecules e.g if the amino acid sequence within proteins are analysed/compared you can look for sims+diffs