EXERCISES

Q1. Explain antibiotic resistance observed in bacteria in light of Darwinian selection theory.
Answer: Antibiotic resistance in bacteria is a good example of Darwin’s theory of natural selection.
In a large group of bacteria, some may naturally have small changes in their genes that make them resistant to an antibiotic. When the antibiotic is given, most bacteria die, but the resistant ones survive. These surviving bacteria then multiply and pass on the resistance to their offspring.
After some time, almost all bacteria in the population become resistant. This shows that in nature, only those organisms that are best suited to their environment survive and reproduce, which is what Darwin called “survival of the fittest.”

Q2. Find out from newspapers and popular science articles any new fossil discoveries or controversies about evolution.
Answer: Example Areas for Discussion:

• Fossil Discoveries (Hominin Evolution): New discoveries in Africa (like those in Ethiopia and Tanzania) frequently change the accepted timelines and relationships within the human evolutionary tree — for example, new species of Homo or Australopithecus that challenge the linear model of human evolution.
• Controversies: The debate surrounding ‘missing link’ fossils (like Archaeopteryx) continues, with new interpretations of their anatomy challenging the view that they are perfect transitional forms. There is also an ongoing scientific discussion regarding whether “saltation” (single-step large mutation, proposed by de Vries) plays a more significant role than previously thought in some evolutionary changes, as opposed to Darwin’s gradualism.

Q3. Attempt giving a clear definition of the term species.
Answer: A species is a group of organisms that can naturally interbreed to produce fertile offspring and are reproductively isolated from other such groups. In simple terms, members of the same species can mate and have young ones that can also reproduce, while different species cannot. Over time, variations and adaptations within a population may lead to the formation of new species, a process known as speciation.

Q4. Try to trace the various components of human evolution (hint: brain size and function, skeletal structure, dietary preference, etc.)
Answer:

Q5. Find out through internet and popular science articles whether animals other than man have self-consciousness.
Answer: Self-consciousness involves the capacity for introspection and the ability to recognize oneself as an individual entity distinct from the environment and other individuals. In behavioral biology, self-consciousness (or self-recognition) is often tested using the Mirror Self-Recognition (MSR) test.
Animals that have shown evidence of self-recognition include great apes (chimpanzees, orangutans, gorillas), dolphins, orcas, and elephants. The evolution of man is the most successful story with language skills and self-consciousness.

Q6. List 10 modern-day animals and using the internet resources link it to a corresponding ancient fossil. Name both.
Answer:

Q7. Practise drawing various animals and plants.
Answer: This is a request for a physical and you can practise drawing various animals and plants by yourself.

Q8. Describe one example of adaptive radiation.
Answer: Adaptive radiation is the process of evolution of different species in a given geographical area starting from a point and literally radiating to other areas of geography (habitats).

Example – Darwin’s Finches: Darwin observed many varieties of small black birds on the Galapagos Islands. He believed that all these varieties evolved from a common seed-eating ancestor. Over time, as the birds adapted to different food sources and habitats, their beaks changed in shape and size. Some developed beaks suitable for eating insects, while others became better for feeding on fruits or seeds. This process of evolution from one common ancestor into different species adapted to various ecological roles is called adaptive radiation.

Q9. Can we call human evolution as adaptive radiation?
Answer: Human evolution is not an example of adaptive radiation. Adaptive radiation means one ancestor gives rise to many species adapted to different environments, like Darwin’s finches. Human evolution, however, followed a single, continuous line of development with gradual changes such as larger brains and upright walking. It is therefore considered progressive evolution, not adaptive radiation.

Q10. Using various resources such as your school library or the internet and discussions with your teacher, trace the evolutionary stages of any one animal, say horse.
Answer: The evolution of the horse (Equus) is a classic example showcasing directional selection and gradual evolution in response to major environmental changes, particularly the spread of grasslands.