Topic 3-Organ Systems Flashcards
How can fossils be formed from gradual replacement by minerals ?
things like teeth, shells and bones don’t decay easily so can last ages when buried. They’re eventually replaced by minerals ,forming a rock like substance shaped like the original hard part. The fossil stays distinct inside rock and eventually are dug up.
How can fossils be formed from casts and impressions ?
Fossils can form when an organism’s buried in a soft material like clay. The clay hardens around it and the organism decays,leaving an impression when it hardens.
How can fossils be formed from preservation in places where no decay happens ?
because conditions aren’t sutiable for microbes to work. e.g glaciers are too cold and peat bogs are too acidic.
What 3 things can fossils found in rock layers tell us ?
- what it looked like
- how long it existed, deeper the rock ,older it is
- how it evolved from studying the similarities and differences between fossils in differently aged rocks.
Why is the fossil record incomplete ?
- very few dead plants or animals actually turn into fossils. most just decay away
- body parts like soft tissue then to decay away completely
- there are fossils yet to be discovered.
What is the pentadactyl limb ?
- the limb has 5 digits
- Mammals , reptiles and amphibians have the limb
- in these species , the limb has similar bone structure but different functions.
How does the pentadactyl limb provide evidence for evolution ?
the similarity in bone structure provides evidence that species with a pentadactyl limb have all evolved from a common ancestor that had this limb. If they’d all evolved from different ancestors, it’‘d be highly unlikely that they’d share a similar bone structure.
How can you measure the growth of organisms ?
by its height,length,width or circumference
by its mass including all the water in its body ( wet mass )
by its mass with no water in its body ( dry mass ) but the organism has to be dead.
How do animals and plants develop ?
cell differentiaion, the process of cells becoming specialised for its job
cell division by mitosis
cell elongation , where a plant expands and grow.
How do animals grow ?
by cell division. They grow when they’re young until they reach full growth. When animals are young cells divide at a fast rate but when they become an adult , most cell division is for repair , the cells divide to replace old or damaged cells
