Biology Flashcards
What is an allele?
Alleles are variations of a gene
What is a dominant allele?
The allele that is always SEEN
What is a recessive allele?
The allele that is hidden
What is dominant allele represented by?
Capital letters
What is a recessive allele represented by?
Lowercase letters
When are dominant alleles seen?
ALWAYS
When are recessive alleles seen?
When there are 2 recessive alleles OR when there are NO dominant alleles
What is a genotype?
A genotype is an individual’s genetic makeup. (Alleles)
What is a phenotype?
A phenotype is what an individual looks like
What does homozygous mean?
It means an individual has TWO identical alleles
What does heterozygous means?
It means that an individual has two different alleles
What does a Punnett square show?
The percentage chance of an offspring’s phenotype and genotype
Is “B’ dominant or recessive?
Dominant
Is “f” dominant or recessive?
Recessive
Is BB homozygous or heterozygous?
Homozygous
Is Mm homozygous or heterozygous?
Heterozygous
R is Red and r is White that phenotype is Rr?
Red
R is Red and r is white. What phenotype is RR?
Red
What sex chromosomes represent a male
XY
What sex chromosomes represent a female
XX
IF a disease is recessive. Is this male affected, unaffected or a carrier? XbY
Affected
If a disease is recessive. Is this male affected, unaffected or a carrier? XBY
Unaffected
If a disease is recessive. Is this female affected, unaffected or a carrier? XbXb
Affected
If a disease is recessive. Is this female affected, unaffected or a carrier? XBXb
Carrier
If a disease is recessive. Is this female affected, unaffected or a carrier? XBXB
Unaffected
What does a square represent in a pedigree?
Male
What does a circle represent in a pedigree?
Female
What does a shaded shape mean in a pedigree?
A person affected by a disease
What does an unshaded shape mean in a pedigree?
A person that is unaffected OR a carrier
If a line connects two shapes in a pedigree what does this mean>
They matedh
What is a mutation?
A permanent change in the DNA sequence
What do mutations create in a population?
New alleles OR new variations of genes
What is a gene pool?
The sum of different alleles in a population
What is allele frequency?
The frequency/percentage of one allele in the population
What is a mutagen?
A substance that increases the rate of mutationsW
What are 3 main mutations?
Radiation, Chemicals and UV light
What is an example of a radiation mutagen?
X-rays
What is an example of a chemical mutagen?
Tobacco
What is an example of a UV mutagen?
The sun’s rays
What is Co-dominance?
When TWO dominant alleles are both expressed in an individual. This creates patches in coloring. Eg. White dog + brown dog = Brown and white spotted dog
What is a carrier?
A person who does not show a disease/have a disease… however, carries it in their DNA and can pass it onto their children.
What are the 3 stages of natural selection?
- Variation
- Selection pressure
- Adaptation
What are the 3 stages of speciation
- Variation
- Isolation
- Selection
What is variation>
The amount of different alleles in a population. Eg. Humans can have brown eyes, blue eyes, green eyes.
What is a selection pressure
A change in the environment that causes an allele to have an advantage. EG. predation
What is adaptation?
When the “fitter” allele in a population becomes more common and allows organisms to be BETTER adapted to survive in their environment.
What is isolation?
The separation of one population into two or more for a long period of time preventing them from mating with other populations.
What are the 2 types of isolation?
- Geographical
- Climatic
What is geographical isolation?
When a land feature separates individuals in a population. Eg. Temperature
What is an example of speciation?
-Squirrel population in America had varying arm lengths.
-The grand-canyon isolated/separated the population into 2 groups.
-The south side squirrel population adapted to tall trees and got longer arms.
-The north side squirrel population adapted to flat rocky surface and got short arms for running fast.
-Two new species formed from one.
What is an example of natural selection?
-The peppered moth has 2 variations: dark and light.
Coal production coated trees with black soot.
-The dark moths camouflaged with the black soot avoiding predators.
-Light moths were eaten.
-The frequency of dark moths became more common.
-Dark coloured moth are better adapted to survive in their environment.
What is artificial selection?
When humans deliberately breed organisms to get desirable traits in offspring.
What is crossbreeding?
Breeding two organisms with different desirable traits to combine them and get both in the offspring.
What is inbreeding?
Breeding related organisms together to emphasise a desirable trait in offspring.
What is evolution?
The permanent change in allele frequency in a population
What is the theory of evolution?
The theory that all organisms originate from a common name ancestor
What 2 types of evolution are there?
- Convergent
- Divergent
What is convergent evolution?
When two organisms have similar structure with the same function, NOT because of common ancestor. Due to common selection pressure (environment). EG. Fin or shar and dolphin
What is an analogous structure?
A characteristic that 2 different species have for the same function, NOT because of common ancestor. Due to common selection pressure (environment).
What is divergent evolution?
When two organisms have similar structure that have been adapted for different function, THese structures come from a common ancestor. EG. Forearm of cat and human
What is a homologous structure?
A structure that is the same in multiple species however has different functions. These come from a common ancestor that now has NO function
What is a vestigial structure?
A characteristic in an organism that they have from an ancestor that now has NO function
What are 4 pieces of evidence supporting evolution?
- Fossils
- Embryo similarities
- Comparative anatomy
- DNA analysis
How do fossils support evolution?
Finding fossils and using carbon dating to age them have provided an evolutionary timeline showing small changes in one species from their ancestors to current date.H
How does embryology support evolution?
Vestigial structure in organisms suggests that they are passed on from ancestors and are no longer needed. EG. Wisdom teeth in humans have been from our herbivore ancestors
How does DNA analysis support evolution?
Similarities in proteins in DNA suggest that different species are closely related. More similarities = more closely related.
Eg. Chimpanzees and humans share similarities in DNA.