First Test Flashcards
Define natural selection
the process whereby organisms better adapted to their environment tend to survive and produce more offspring.
Evolution
Change in the characteristics of a species over many generations
An example of natural selection
In a habitat there are red bugs and green bugs. The birds prefer the taste of the red bugs, so soon there are many green bugs and few red bugs. The green bugs reproduce and make more green bugs and eventually there are no more red bugs.
Crossed breeding
Selective breeding by combining a desirable feature of one individual with another in the offspring
Phenotype
The observable characteristics eg tall
Genotype
The allele information eg Tt
What is dominate disease
this occurs when a person has one disease allele but it over powers the other normal gene. The person is affected by the disease.
Recessive disease
This occurs only when two of the abnormal gene are present (homozygous). One from each parent.
Define heterozygous
Heterozygous- allele information that is different. Eg Aa
Define homozygous
Homozygous- allele information that is the same. Eg aa or AA
Define carrier
Carrier- the person that has a specific trait and carries it to someone else in their family.
Define true breeding
Pure bred an organism that always pass down similar traits
Define gene
A section of DNA that codes for a particular characteristic.
