Key Area 4 Flashcards
What is said to happen when organisms that can breed with each other breed?
If they reproduce offspring that are fertile (can also reproduce) they are said to belong to the same species.
What is said to happen when organisms that cannot breed with each other or do breed?
Organisms that cannot breed with each other, or do breed, produce infertile (sterile) offspring are said to be members of different species.
A characteristic which shows continuous variation can be ……..
A characteristic which shows continuous variation can be measured.
What are characteristics that show continuous variation controlled by?
Characteristics which show continuous variation are controlled by many genes (polygenic).
Does continuous variation have distinct groups?
There are no distinct groups e.g height in humans.
What can continuous variation be affected/influenced by?
Continuous variation can be affected by your environment (your body mass is affected by diet).
What can continuous variation be represented by?
Continuous variation is represented by a histogram (bar graph where all bars touch) or a line graph.
What is variation?
Variation is the differences that occur between individuals of the same species.
What are examples of variation in humans?
- Ability to tongue roll
- Height
What are examples of variation in plants?
- Leaf length
- Flower colour
What is discrete variation?
A characteristic which shows discrete variation can be represented by a number of distinct groups e.g. eye colour and tongue rolling ability.
Characteristics which show discrete variation are controlled by what?
Characteristics which show discrete variation are controlled by only one gene - single gene inheritance.
What is discrete variation represented by?
Discrete variation is represented by a bar chart or pie chart.
What are genes?
Genes are units of inheritance that control characteristics.
What is genetics?
Genetics is the study of inheritance.
How many copies of each gene do we inherit from our parents?
We inherit one copy from each of our parents.
What are alleles?
Different versions of the same gene.
What is the genotype?
The alleles which an organism possesses.
What is the genotype represented by?
The genotype is represented using letters:
- A capital letter - dominant
- Lower case - recessive
What is the phenotype?
The phenotype of an organism is its physical characteristics or appearance.
What are the genotypes and phenotypes determined by?
These are determined by the genetic information inherited from both of its parents and the influence of environmental factors.
What do different alleles have?
Different alleles have different “strengths” or dominance.
What does the term dominant mean?
Some alles only need one copy to be present - these are dominant.
What does the term recessive mean?
Some alles need two copies to be present - these are recessive.
