The forelimbs of four vertebrates are shown in the diagram shown above.
(a) What type of evolution is exhibited by the similarity among these organs in those organisms?
(b) What are such organs known as?
(c) What do they indicate?

Fill in the blanks in the following statements, with the time period [as million years ago (mya)] of evolution of various life forms on the earth.
(a) The first non-cellular forms of life, i.e., giant organic molecules like RNA, proteins, etc. could have originated _______________________.
(b) About _______________ the first cellular forms of life appeared on the earth; slowly single-celled forms became multicellular forms.
(c) By the time of _______________ invertebrates were formed.
(d) Jawless fish probably ev-olved around _______________.
(e) Sea weeds and a few plant species existed probably around_______________ ; the first organisms that invaded land were plants.
(f) About _____________ fish with stout and strong fins that could move on land and go back to water were present; they were called lobefins.

Read the passage and answer the questions that follow:
(i) Fish with stout and strong fins existed about 350 mya; they could move on land and go back into water.
(ii) Reptiles dominated the earth for about 200 million years.
(iii) Some land reptiles went back into water and evolved into fish-like reptiles.
(iv) The land reptiles of that period were dinosaurs; they disagpeared suddenly from the earth.
(a) Name the fish that could move on land and go back into water. What did they evolve into?
(b) Give an example-ofthe fish-like reptiles. Mention the time period when they were evolved.
(c) Name the largest of the dinosaurs. When did the dinosaurs suddenly disappeared?

A few stages and their respective time period in the evolutionary history of human beings are mentioned in the flow-chart given below. Answer the questions that follow, as asked.


(a) Name the two primates.
(b) Name two places where the fossils were discovered.
(c) Name the ancestor.
(d) Name the hominid.

(a) Identify the respective animal to which each of the following skulls, A, Band C belongs. Which two among them resemble more closely?
(b) Name the (I) ape-like and (ii) man-like primates that existed 15 million years ago.