Inheritance variation and evolution
Explain how the fossil in the diagram above may have formed.
(snake is) covered in sediment / mud or sinks into the mud 1
(then) the soft parts decay / are eaten or bones / hard parts do not decay 1
(so) minerals enter bones or bones are replaced by minerals
P+Mt Qs 7/10/20
The different types of rat snake have evolved from similar ancestors. The rat snakes have evolved to to
suit their environments. Explain how the Japanese rat snake evolved to be different from the Texas rat
snake
statements:
• there are lots of different colours of snakes
• some shades of green are closer to the colour of the environment (in Japan) than others
• survivors (in each generation) will breed and produce offspring
explanations:
• different colours are controlled by different genes / alleles / are caused by mutations
• being green means they are best suited to grassy / green environments
• being green means they are camouflaged
• those that are camouflaged best will be able to catch more food
• those that are camouflaged best will be able to avoid being eaten
• survivors’ offspring will inherit the genes / alleles / mutation for the shade of green colouration
Scientists have found other fossils of the ancestors of modern birds, but the fossil record is very
incomplete. Suggest two reasons why there are gaps in the fossil record.
conditions not right for fossilization
ignore references to soft-bodied
• geological activity has destroyed fossils / has destroyed evidence
allow a named / described example − eg vulcanism / earth movements / erosion
• fossils not yet found allow description of why not yet found
Explain how the fossil in the diagram above may have formed.
(snake is) covered in sediment / mud or sinks into the mud 1
(then) the soft parts decay / are eaten or bones / hard parts do not decay 1
(so) minerals enter bones or bones are replaced by minerals
P+Mt Qs 7/10/20
The different types of rat snake have evolved from similar ancestors. The rat snakes have evolved to to
suit their environments. Explain how the Japanese rat snake evolved to be different from the Texas rat
snake
statements:
• there are lots of different colours of snakes
• some shades of green are closer to the colour of the environment (in Japan) than others
• survivors (in each generation) will breed and produce offspring
explanations:
• different colours are controlled by different genes / alleles / are caused by mutations
• being green means they are best suited to grassy / green environments
• being green means they are camouflaged
• those that are camouflaged best will be able to catch more food
• those that are camouflaged best will be able to avoid being eaten
• survivors’ offspring will inherit the genes / alleles / mutation for the shade of green colouration
Scientists have found other fossils of the ancestors of modern birds, but the fossil record is very
incomplete. Suggest two reasons why there are gaps in the fossil record.
conditions not right for fossilization
ignore references to soft-bodied
• geological activity has destroyed fossils / has destroyed evidence
allow a named / described example − eg vulcanism / earth movements / erosion
• fossils not yet found allow description of why not yet found
