Biology - inheritance, Variation and Survival Flashcards
What is DNA?
A list of chemical instructions found in the nucleus of the cell, these instructions are about how to build an organism.
What are the two ways which we gain our characteristics?
Inheritance from genes and from the environment.
How many chromosomes do human body cells have?
46 (23 pairs)
What is variation of an organism?
How there are differences between organisms of the same species because of differences in their genes
What is continuous variation? Give examples
Variation over a range of values. You can draw a distribution curve from the value. Examples are height, weight, skin colour
What is discontinuous variation? Give an example
Variation where features take only certain values. Example is the blood group of someone
What is natural selection?
Variation in a population means that some organisms may have characteristics which help them to survive longer. This increased survival rate increased the chance that they will reproduce and pass on these advantageous genes. So over time, this advantageous gene becomes more common.
Why might a change in environment endanger a species?
That species is well-adapted to that environment, so a change to that environment may mean they do not have the necessary characteristics to help them survive in that environment.
Why is it important to help preserve animals?
Humans may rely on these animals for food, medicine and clothing etc. If one species becomes extinct this can have a knock on effect for the other species in that ecosystem.
What is a habitat?
The environment which an organism lives in.
How did giraffes end up with long necks?
Long necks are advantageous to help them eat from tall trees, therefore the giraffes with the longest necks are better adapted to survive and will be more likely to reproduce and pass on those genes.
