Question

Give reasons--

1]thorns of bounvillea plant and tendril of passiflora plant considered homologous organ

2]oldest fossils are found in the bottom layers and recent fossils in the top layers of sedimentary rocks

Answer 1

1. Thorns of bounvillea plant and tendril of passiflora plant considered as a homologous organ because both grow over the stem means have similar origin but different function tendril for clinging the stem and thorns for defence.
2. Oldest fossils are found in the bottom layers and recent fossils in the top layers of sedimentary rocks because oldest fossil is a fossil of organism that die first and hence get burried inside the soil first and as the time passed the burried remains of that organism get deeper and deeper due to the accumulation of soil layers over it. Organisms that die later will get burried over the layer of previous fossils or in the top layer of soil.