Flashcards in B1 Topic 1 - Variation Deck (33)
What are the five kingdoms that all living things are divided into?
Animals, plants, fungi, protoctists and prokaryotes
What are the main characteristics of plants?
Are autotrophs (produce their own food by photosynthesis)
Cells have cells walls which support cells
What are the main characteristics of animals?
Heterotrophs (can't make their own food)
Don't have cell walls or chlorophyll
What are the main characteristics of fungi?
Saprophytes (eat dead organisms and decaying material)
Have cell walls but no chlorophyll
What are the main characteristics of protoctists?
What are the main characteristics of prokaryotes?
Briefly explain the binomial system.
Gives all living organisms a two part name
First refers to the genus and the second refers to the species
Name some advantages of the binomial system.
Targeting conservation efforts
What are the two causes of variation?
Genes and the environment
Define continuous variation.
Give some examples.
When the variable being recorded has no distinct categories and is more like a range.
Height, weight, hand span
Define discontinuous variation.
Give some examples.
When there are two or more distinct categories and no intermediates.
Blood type, hair colour, eye colour
How are polar bears adapted to live in the Arctic?
Compact bodies so less heat loss
Thick layer of blubber for insulation
Thick coat traps layers of air
Greasy fur repels water to prevent cooling by evaporation
Big feet to spread weight on snow which stops them from sinking
White fur to match surroundings - snow...
A slow and continuous change of organisms from one generation to the next.
Briefly explain natural selection.
1. Individuals not all the same due to mutations.
2. Populations have to compete for limited resources e.g. Food or water.
3. Individuals with better characteristics are more likely to survive long enough to reproduce and pass on these characteristics.
4. Offspring of this individual are better adapted and can pass it on to their offspring as well.
5. Some individuals are less well adapted and are therefore less likely to pass on their genes.
6. Over time, there are more better adapted individuals compared with the lesser adapted ones.
Speciation is when a population of the same species become so different that they can no longer produce fertile offspring.
Explain how speciation occurs?
One part of a population becomes isolated from the rest, maybe by a physical barrier. If the conditions on each side happen to be different, each group will evolve to suit its own area. After millions of years, the two populations will have adapted so much that they will no longer be able to have fertile offspring.
What is hybrid?
When two different species interbreed.
What is a species?
A species is a group of organisms with similar characteristics that can breed to make fertile offspring.
List the different classifications for organisms, starting with 'Kingdom'.
Kingdom, Phylum, Class, Order, Family, Genus, Species
(King Philip Came Over For Good Soup)
What is a hybrid?
A hybrid is the offspring of two organisms that come from different species. The hybrid is usually infertile.
Why aren't viruses classified in the binomial system?
Viruses don't have all the characteristics of a living organism and so scientists are still debating as to whether they are alive or not.
Describe the main characteristics of the phylum a Chordata.
All the species in this phylum are vertebrates, meaning that they have a spine to support their body structure.
State some methods that organisms:
Inhaling through lungs, absorption through gills, diffusion through skin
External fertilisation (fish), internal fertilisation (mammals), oviparous (lay eggs), viviparous (live young)
Homeothermic (warm-blooded, generate own heat), poikilothermic (cold-blooded, use sun or other sources to warm up the blood)
Explain evolution with respect to variation, over-reproduction, struggle for existence, survival, organisms inheriting characteristics from their parents and changes in the proportion of individuals which are better adapted to their environment.
Even organisms from the same species have slight variations due to small mutations in their DNA. Occasionally, these mutations may give an organism a better chance of surviving until it reaches reproductive maturity.
This organism will then have a greater chance of mating to have many offspring. By having many offspring, more of the babies will also carry the beneficial adaptation and a higher number of those better adapted will survive long enough to pass the genes down to the next generation.
As well as the better adapted organisms increasing in numbers, the weaker organisms in that species will have their chances of survival lowered due to changes in environment that the better adapted organisms are better adapted to.
Eventually, after millions of years and generations, the proportion of organisms that are better adapted will greatly outnumber the original species until the old species becomes 'extinct'.
What is genetic variation?
Genetic variation is the difference in the alleles between individuals in a population or species.
A section of DNA that codes for a characteristic.
Chromosomes are long strand of genes, which are made up of DNA.
The dominant allele is the gene which actually controls the characteristic.
The allele which does not have any impact on the organism but that can still be passed on to its offspring.