Variation And Genes Flashcards
What are the 2 types of variation
- genetic variation
- environmental variation
What is genetic variation
- caused by differences in genotype
- which then affects it’s phenotype
- these differences are inherited
What is environmental variation
- interactions with the environment having an influence on an organisms phenotype
- e.g. plant being yellow is it doesn’t photosynthesise properly
What is a mutation
- rare,random change to DNA that can be inherited
- mutations occur continuously
- a gene becomes altered, producing a genetic variant
What does mutation effect
- As the gene codes for the sequence of amino acids that make up a protein, gene mutations sometimes lead to changes in the protein that it codes for
- resulting on an influence on the organisms phenotype
What is the theory of evolution
All of today’s species have evolved from simple life forms that first started to develop over 3 billion years ago
How to answer a question about evolution/natural selection resulting non a higher population of mutated animals
- variation arises in population due to a mutation from reproduction
- The mutation gives the organism an advantage — more likely to survive
- Therefore they’re more likely to reproduce and pass on this gene
- overtime making it more common in the population
What is speciation
- when phenotypes have changed so much that they become reproductively isolated from the original species
Why might a species become extinct
- environmental changes (e.g. destruction of habitat)
- A new predator kills them all
- A new disease kills them all
- Can’t compete with another species for food
- A catastrophic event happens, killing them all (e.g. volcano)
What is selective breeding
- humans artificially select plants or animals to breed for desired characteristics
What are some examples of why we might selectively breed
- Animals to produce more meat or milk
- Crops with a resistance to disease
- Dogs with a good, gentle temperament
- decorative plants with big or unusual flowers
Describe the process in selective breeding
- select organisms with the desired characteristics
- breed them
- select the best of the offspring, and continue breeding
- continue over several generations, making the characteristic stronger and stronger
What is the draw back to selective breeding
- reduces gene pool
- can lead to inbreeding
—> which leads to health problems - reduction in number of different alleles, so a new disease can wipe them all out because there’s less chance of there being any resistant alleles
What is genetic engineering
- transferring genes responsible for a desirable characteristic from one organism to another, so that it has the desirable;e characteristic
Describe the process of genetic engineering
- useful gene is isolated from one organism’s genome using enzymes and is inserted into a vector
- the vector is usually a virus or bacterial plasmid (depending on the organsim it’s transferring to)
- when the vector is introduced to the target organism, the useful gene is inserted into its cells
- the organism then develops with desired characteristic, coded for by the gene
What are some of the worries with genetic engineering
- accidentally create unplanned problems which get passed onto future generations
What are the pros to genetic modification
- increases yield for crops = more food
- helps people who lack nutrients in developing nations
- is already being used for crops in some places without any problems
What are the cons to genetic modification
- can affect the No. of wild flowers and insects that live in crops — reducing farmland biodiversity
- we don’t fully understand side effects to eating GM crops
- herbicide resistant may get picked up by naturally occurring weeds from GM crops, creating super weed
What are the 3 ways fossils will form
- From gradual replacement by minerals
- From casts and impressions
- From Preservation in place where no decay happens
How are fossils formed from gradual replacement by minerals
- Things like teeth, shells and bones that don’t decay easily, are buried
- eventually they are replaced by minerals when they decay, forming a rock-like substance, shaped like the OG
- surrounding sediment also turns to rock, but fossil stays distinct inside the rock
How are fossils formed form casts and impressions
- organisms buried in soft clay
- it hardens around organism and the organisms decays. Leaving a cast
- impressions form when things like footprints are pressed into theses soft materials
How are fossils formed from preservations in places where no decay happens
- in amber and tar pits, there’s no oxygen or moisture = decay microbes can’t survive
- In glaciers, it’s too cold = decay microbes can’t survive
- In peat bogs, it’s too acidic = decay microbes can’t survive
Why can’t we tell how life began
- lack of evidence
- soft bodied animals decays too quickly to be fossilised
- some important fossils might’ve been destroyed by geological activity
What is classification
- By Carl Linnaeus in 1700s
- groups living things according to their characteristics and the structures that make them up
What are the different groups in classification
- Kingdom
- Phylum
- Class
- Order
- Family
- Genus
- Species
What’s the pneumonic to remember the different groups of dividing organisms
Keep pond clean or frogs get sick
Why has classification improved over time
- microscopes improved = more knowledge of biochemical processes
- Carl Woese proposed 3 domain system
Explain the 3 groups in the 3 domain system
- ARCHAEA: primitive bacteria, found in extreme places (e.g. hot springs or salt lakes)
- BACTERIA: true bacteria (e.g. E.coli). The have biochemical differences to archaea
- EUKARYOTA: fungi, plants, animals, protists
Explain how the Binomial system works
- two part Latin name
- first part: Genus with capital letter
- second part: Species
- e.g. Homo Sapiens
