Genes and Selection Pressures
What is an environmental selection pressure? Provide and example.
Factors within the environment that influence the survivability of a species within that particular environment
What is genetic drift? Name the two types.
Changes to a population’s allele frequency due to sudden and random occurrences.
Bottleneck Effect and Founder Effect
What is selective breeding?
The changing of a population’s gene pool by humans changing/removing alleles through controlling breeding of animals or plants.
Which artist wrote the following songs:
“Flowers,” “Used to Be Young,” “Wrecking Ball”?
Miley Cyrus
Which artist wrote the following songs:
“Espresso,” “Feather,” “Nonsense”?
Sabrina Carpenter
What is allele frequency and how do you calculate it?
The proportion of certain alleles in a gene pool
Allele frequency = number of particular allele ÷ total number of alleles in the population
Describe gene flow
Introduction or removal of alleles between populations through either migration or inbreeding
•Migration into a population = immigration (addition of alleles)
•Migration out of a population = emigration (removal of alleles)
•Interbreeding occurs when individuals temporarily enter a population to breed, changing the gene pool
How does selective breeding affect genetic diversity?
Selective breeding reduces genetic diversity
•There is an increase in frequency of selected alleles
•Can cause human-induced bottle neck
Which artist wrote the following songs:
“As It Was,” “Late Night Talking,” “Watermelon Sugar”?
Harry Styles
Which artist wrote the following songs:
“Misery Business,” “Still Into You,” “The Only Exception”?
Paramore
How does natural selection affect genetic diversity? Explain why
It reduces genetic diversity due to only those with advantageous alleles surviving and passing on their alleles
How do you determine if two individuals are of the same species?
They are able to breed with each other and produce viable and fertile offspring.
Explain why antibiotic resistance is a public health issue and how humans can cause resistance.
Antibiotic resistance in bacteria has led to existing antibiotics no longer being effective.
Resistance can develop due to:
•People not finishing their antibiotics treatment, which means not all pathogenic bacteria are killed and they then have more time to mutate
•Using antibiotics when it isn’t necessary, which can make normal flora resistant to antibiotics
•Widespread use of antibiotics
Which artist wrote the following songs:
“Save Your Tears,” “Blinding Lights,” “Take My Breath”?
The Weeknd
Which artist wrote the following songs:
“Picture to Burn,” “Long Live,” “Style”?
Taylor Swift
Describe the four factors that facilitate natural selection using an example
Variation, selection pressure, selective advantage and heritability
Outline three types of isolation and describe how they can lead to speciation
Three of:
Geographical – individuals may not be able to interact with each other due to separation by barriers (e.g. body of water).
Ecological – individuals may inhabit different ecological niches or habitats so they do not interact with each other.
Temporal – the time of the day or year when individuals are ready to breed may differ.
Behavioural – the type of mating behaviours, such as mating call, of individuals may vary.
Structural – the physical characteristics of individuals may drastically vary, physically preventing breeding.
Gamete mortality – the sperm may be unable to penetrate the ovum for fertilisation.
Zygote mortality – fertilisation may occur and a zygote may be formed, however, it will not survive.
Hybrid sterility – a viable offspring may be formed and may survive until adulthood, but will not be fertile.
What is the difference between antigenic drift and antigenic shift?
•Antigenic drift: small gradual changes to genes that code for surface antigens. Initially memory cells can recognise the virus but as changes accumulate the memory cells can no longer recognise it
•Antigenic shift: sudden significant changes to genes that code for surface antigens. This occurs due to viral recombination - when two or more viruses combine when infecting the same host and form a new subtype
Which artist wrote the following songs:
“Purple Rain,” “When Doves Cry,” “Kiss”?
Prince
Which artist wrote the following songs:
“Jolene,” “9 to 5,” “Coat of Many Colors”?
Dolly Parton
Silent mutation - change in DNA that does not affect amino acid sequence
Missense mutation - change in DNA that changes the amino acid produced
Nonsense mutation - change in DNA causes STOP codon to be produced
Frameshift insertion - DNA base inserted and shifts all codons
Frameshift deletion - DNA base is deleted shifting all codons
Describe the two types of speciation using Galapagos Finches and Howea Palm Plants as examples.
The Galapagos islands have a variety of different finch species – it is thought this is due to allopatric speciation. As the islands are separated by ocean and have different food sources (different selection pressures). Those suited to their ecological niche on their island survive and passed on genes. The finches have different beak types due to the different food sources. These genetic differences accumulated and formed new species of finches on each island
The two Howea palm species formed as a result of different soil types acting as a selection pressure (sympatric speciation). Howea belmoreana inhabits neutral/acidic soil whilst Howea forsteriana inhabits alkaline soil called calcarenite. Howea forsteriana diverged from the original palm species after is colonised the alkaline soil. This produced physiological differences such as differing flowering times which meant the two species could no longer interbreed. Genetic differences accumulated over time and a new species was formed.
Describe how antibiotic resistance arises via natural selection
A population of bacteria has individuals resistant to an antibiotic as well as individuals susceptible to the antibiotic.
Exposure to an antibiotic serves as an environmental selection pressure.
A selective advantage is conferred to bacteria with resistance to the antibiotic.
Bacteria resistant to the antibiotic are able to continue replicating and pass on the allele for resistance to other bacteria via bacterial conjugation, increasing its allele frequency.
Which artist wrote the following songs:
“Born in the U.S.A.,” “Dancing in the Dark,” “The River”?
Bruce Springsteen
Which artist wrote the following songs:
“Angel Eyes,” “The Visitors,” “I Wonder (Departure)”?
ABBA