Genetics and Variation Flashcards
Chromosomes in the Human body
46 chromosomes- arranged in 23 pairs
In each pair, there are two copies of a gene
What are Dominant Genes?
One gene will override the other gene
They are genes expressed in both homozygous and heterozygous condition
eg. brown hair genes> blonde hair genes
Alleles can be…
Recessive or Dominant
What is the use of Punnet Squares?
Punnet squares are the simplified way of expressing what possibility of variation of genes can be made.
Where is a cell’s genetic material found?
Genetic material is found in the nucleus.
What is the shape of DNA?
Double Helix
What does each gene code for?
Each gene codes for an inherited characteristic.
What are alleles?
Different forms of the same gene
Continuous Variation is…
variation with no limit for the population eg. height
Line graphs are used to plot this kind of data
Discrete Variation is…
variation with distinct groups eg. hair/eye colour
Evolution is…
the process that organisms have developed from earlier forms of life
Extinction is…
the complete disappearance of a species from Earth
What is a fossil?
A fossil is the remains or impression from a prehistoric organism embedded in rock and preserved in petrified form
Heterozygous is…
two different alleles eg. Aa
Homozygous is…
two copies of the same allele eg. aa
Inherited variation is…
variation caused by inherited genes from the offspring’s parents
What is an invertebrate?
An animal without a backbone
What is natural selection?
The process where organisms better adapted to their environment survive to breed and pass on their genes.
Recessive is…
characteristics only expressed in the homozygous condition
Phenotype is…
physical appearance due to your genotype
How do fossils form?
- Impression
- Preservation
- Mineral replacement
Preserved organisms form when…
amber is secreted and catches animals and plant matter in its resin. Amber is the prehistoric remains of the tree resin keyword- cretaceous ambers
Only 1% of bones become…
fossils
Factors for fossilisation: Body Type…
fossilisation prefers animals with hard parts like bones, shells and teeth
Factors for fossilisation: Exposure…
fossilisation requires dead animals to be buried rapidly, near or in water… or in arid deserts where wind buries the animals
What happens to fossils that aren’t buried quickly enough?
Animals left out in the open will be erased through the process of decalcification, erosion and corrosion
Factors for fossilisation: Sediment…
Dry sand or alkaline mud is a good place for fossil formation
Factors for fossilisation: Petrification…
Bones are completely dissolved but leave fossil stone photocopies
Example of things that living organisms compete for are…
- food
- territory
- water
- mates
- space
- light
- mineral’s ion
The smallest group in natural selection system is…
species
Genetic Variation…
is caused by DNA mutation and occurs between species, passed from parents to offspring through reproduction
Examples of what causes extinction are…
- rapid environmental changes
- new predators
- new disease
- competition
- catastrophic events
