Biology Flashcards
How was the hyracotherium different to modern horses?
A hydrawhatever was a small mammal with 4 toes at the front and 3 at the rear/back. It had low-crowned teeth. It’s characteristics are those of a forest-dwelling animal. A modern horse (Equus) that has hooves and is larger then it’s ancestor
How are organisms classified?
All living organisms are classified based on very basic, shared characteristics. Organisms within each group are then further divided into smaller groups that are based on more detailed similarities .
List 3 animals that are closely related
3 animals that are not closely related
Horses, donkeys, zebra
Cats, jellyfish, bats
What is the relationship between the DNA of two organisms and how closely they are related?
To be related all organisms must be similar in structure
What are homologous structures? Give examples
Characteristics that have the same basic structure but not necessarily the same function in related species. (related)
Human hand, bat wing
What are analogous structures? Give examples
Structures that look similar on genetically different organisms. (Not related)
Sharks and dolphins
Define artificial selection
The process by which we choose to breed organisms with desirable characteristics
What are the two main methods of selective breeding
Cross-breeding - mating or hybridising two different species
Inter-breeding - To breed with another species
Describe Natural Selection
And environmental factor that acts on a population, and have more offspring then others
What is a selective agent?
An environmental factor that acts on a population
Give examples of biotic and physical factors
Biotic - Predication (predictors), competition and infection (living things)
Physical - temperatures, soil conditions, rainfall and fires (environmentally based)
Name 3 animals that have become extinct
Dodos, mammoth, Tasmanian tiger
Define variation
Natural differences n population caused by differences in genes
Describe how the pepper moth provides evidence for natural selection
The pepper moth exists in 2 forms, the normal coloured white with black specks, the other, a mutation, a black colour. In cities, black peppered moths were most common. In rural areas, white were more common. Birds such as the fly catcher and nuthatch were the natural selective agents that preyed on moths
Define the theory of evolution
Proposes that all species are related.
What are two tests to see if two animals are the same species?
Whether it can interbreed and can it create fertile offspring (both under natural conditions)
How are species prevented from interbreeding
Isolation - prevention by a mechanism
Define speciation
The process by which one species splits into two or more separate species. Responsible for the formation of any new species that appear on the fossil record.
List steps for speciation
Variation
Isolation
Selection
Define isolation and give examples
Formation of new species, stops one difference in a population in reaching another population
Examples: geographical and climate barriers
Define mutation
A change to the base sequence caused by a mistake that happens when DNA is copied
Two examples of transitional forms
Archaeopteryx and anchiornis (small groups of dinosaurs that had feathers)
What is required for evolution to occur
Speciation
Natural selection
Homologous and analogous structures
Biotic and physical factors
Define species distribution
A map of all the places species occur
