B 9.1 Why organisms are different Flashcards
(12 cards)
What is variation?
Differences in characteristics between individuals of the same species.
What are the two main causes of variation?
Genetic factors and environmental factors.
What is genetic variation caused by?
Differences in the genes inherited from parents, usually due to sexual reproduction.
What is environmental variation caused by?
Differences in conditions such as diet, lifestyle, climate, or injuries.
Give an example of a characteristic caused by both genes and the environment.
Body mass (affected by inherited metabolism and diet/lifestyle).
What is a mutation?
A random change in the DNA of a gene.
How can mutations affect an organism?
They may have no effect, cause a small change, or rarely result in a new characteristic.
Do mutations always affect the phenotype?
No — most mutations do not change the organism’s appearance or function.
What is meant by phenotype?
The observable characteristics of an organism.
What is meant by genotype?
The genetic makeup of an organism — the combination of alleles it has.
How does sexual reproduction contribute to variation?
It mixes genes from both parents, producing genetically unique offspring.
Why is variation important in a population?
It increases the chance that some individuals will survive changes in the environment.
