Question
Describe the various evidences from palaeontology which support organic evolution.

Answer

The evidence for organic evolution are as follow:
i. Fossils/Paleontology evidence: Fossils of earliest life are scanty and only of prokaryotes mostly. Eukaryotes developed later
оп.
ii. Disparity between fossils: Present-day organisms seem to be related to the fossils of the quaternary period but differ from those of the tertiary period. Fossils of the quaternary period are similarly related to the tertiary period but differ from the ones
of the Cretaceous period. These differences are due to changes in the form, structure, and habits of organisms due to evolution.
iii. Extinct organisms: Lots of organisms existed on earth for some time and then got extinct like dinosaurs, toothed birds, pteridosperms, giant horsetails, ancestors of man, etc. Extinction happened due to many factors. Some of the extinct forms have left their modified descendants (Man, modern-day Horse) while others have perished without leaving any descendants (Pteridosperm, Dinosaurs).
iv. Missing Links: These are transitional or intermediate forms between two groups of organisms which occur only in the fossil state. E.g., Seymouria, a missing link between amphibia and reptilia.
v. Plant vs Animal Fossils: Ancestral animals have left more fossils as compared to plants evidently due to the presence of slow decaying harder structures in their exoskeleton and endoskeleton.

Need a full question paper?

Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.

Start Generating Free

Similar questions

Can a child have blood group O if his parents have blood group ‘A’ and ‘B’. Explain.
Do all the gametes formed from a parent organism have the same genetic composition? Analyse the situation with the background of gametogenesis and provide suitable explanation.
Can you list 10 recombinant proteins which are used in medical practice? Find out where they are used as therapeutics (use the internet).
i. Describe the arrangement of nuclei and cells in a mature embryo sac of a typical angiosperm.
ii. Explain the devices the flowering plants have developed to prevent the following types of pollination:
1. Prevents both autogamy and geitonogamy
2. Prevents autogamy, but not geitonogamy
With a suitable diagram, describe the organisation of mammary gland.
Give an account of post transcriptional modifications of a eukaryotic mRNA.
  1. Name the respective forms in which the malarial parasite gains entry into
  1. Human body and
  2. Body of female Anopheles.
  1. Name the respective hosts and the sites in their body, where the sexual and asexual reproduction of malarial parasite occur.
  2. What is meant by:
  1. Addiction
  2. Dependence with reference to drugs/ alcohol?
What are ecological pyramids? Mention its limitations.
Distinguish between asexual and sexual reproduction. Why is vegetative reproduction also considered as a type of asexual reproduction?
Explain the development of a secondary oocyte (ovum) in a human female from the embryonic stage upto its ovulation. Name the hormones involved in this process.OR
When does oogenesis start in humans? Name the three hormones and their sources, linked with oogenesis. How do they influence the process of oogenesis? Explain.