2.8 Flashcards
What did Gregor Mendel discover? What did he research on?
Genetics using pea plants
Why were pea plants a good system to use?
Pea plants have lots of clearly inherited features:
- flower colour
- height
- pod shape
Pea plants reproduce quickly so he could so thousands of experiments
He could control how pollen passes from one pea to another
What experiment did Mendel do with the peas? What were the results? What did he conclude?
Crossed pure breeding purple plants with pure breeding white plants.
Offspring flower was not a blend it was purple.
Purple was dominant and white was recessive.
Why wasn’t his woke accepted at the time?
He was a monk lot a scientist
He published in an obscure journal
Science believed all features blend
Chromosomes had not been discovered
What are fossils?
Preserved remains of organisms that died many years ago
How do fossils form?
When decay cannot happen (too cold, no oxygen, too dry)
Hard parts of organisms do not decay easily (bones)
If decay happens slowly and flesh can be replaced by minerals
Preserved traces such as footprints are preserved
What are the problems with describing the early environments organisms? Why is this?
We don’t know how life started because
Hardly any fossils from around the time because
-animals were soft bodied
-earth movements destroyed early fossils
How is extension caused?
New predators New diseases Better competition Catastrophes Climate change
What do new species form from?
Existing species
How do new species form?
Isolation - when groups separate and changes into new species
Natural selection- changes their alleles
How is every member of a group different ?
Genetic variation
Describe the process of natural selection.
If allele allows organism to survive it will have a bigger chance of reproducing and being passed on.
Beneficial allele will spread through population
Why aren’t scientists certain of how life began?
Not enough valid evidence
What are the three ways fossils are formed?
- Hard body parts replaced by minerals as they decay
- Parts of animals or plants which don’t decay preserved in amber/ peat bogs/ tar pits/ ice
- Cast or impressions of footprints covered by sediment to become rock
