Q. 1) Explain antibiotic resistance observed in bacteria in light of Darwinian selection theory.
Ans: According to Darwinian selection theory that the members of a population who have inheritable variations, each generation produces many more offsprings than can possibly survive and some individuals have adaptive characteristics that enable them to survive and reproduce better than other individuals. This resulted in an increasing proportion of individuals to have adaptive characteristics in succeeding generations which in turn results in a population adapted to that particular environment.
The phenomenon of antibiotic resistance observed in bacteria can be very well explained in terms of Darwinian selection theory. In a population of bacteria, some bacteria already have inheritable variations in the gene responsible for resistance towards a specific antibiotic. When such a mixed population of bacteria is exposed to that specific antibiotic, those who are sensitive to it die but those with the genetic variation for antibiotic resistance, survive in the presence of that antibiotic. This antibiotic resistance trait is passed on to the next generation. When the next generation bacteria are also exposed to the antibiotic the bacteria which have inherited the trait are able to survive and those who may have and slowly, the population of such bacteria increases and the entire population, over the time, becomes resistant to that particular antibiotic.
Q. 2) Find out from newspapers and popular science articles any new fossil discoveries or controversies about evolution.
Ans: Fossils are preserved remains or traces of animals, plants or other organisms that existed a long time ago in history. They give us very important clues about the life forms that existed millions of years ago. Also, a lot has been understood in terms of origin and evolution of various groups of animals based on a study of different fossils found at different locations across the world.
Few examples:
Dinosaur fossils have been known about for millennia. The Chinese considered them to be dragon bones, while Europeans believed them to be the remains of giants and other creatures killed by the Great Flood. The first dinosaur species to be identified and named was Iguanodon, discovered in 1822 by the English geologist Gideon Mantell, who recognised similarities between the fossils and the bones of modern iguanas.
- The discovery of a rare human skull in October 2013 sparked an evolution controversy. Researchers discovered the fossilised skull of an early human relative in Dmanisi, Georgia. It is said to be the most complete skull ever of the early Homo genus. They say it could represent a single evolving Homo erectus lineage that came out of Africa and spread into Europe and Asia, a conclusion that is still controversial.
- Archaeopteryx fossil has been a classic textbook example of a species in evolutionary transition, displaying features that are a part bird, part reptile. However, scientists have reclassified it based on a newly discovered fossil of a two-legged feathered creature in China as a feathered dinosaur.
Q. 3) Attempt giving a clear definition of the term species.
Ans: Species can be defined as a group of the reproductively isolated population that interbreed to produce fertile offspring and share phenotypic similarities.
Q. 4) Try to trace the various components of human evolution.
Ans: Human evolution has been a lengthy process of change by which human originated from ape-like ancestors. Scientific evidence shows that the physical and behavioral traits shared by all people originated from ape-like ancestors and evolved over a period of approximately six million years.
(Tabular content exactly as in PDF – brain size, posture, skeletal structure, dietary preference and features of Dryopithecus, Ramapithecus, Australopithecus, Homo habilis, Homo erectus, Neanderthal man, Homo sapiens fossilis and Homo sapiens sapiens.)
Q. 5) Find out through internet and popular science articles whether animals other than man have self-consciousness.
Ans: Self-consciousness means having conscious knowledge of one's own character, feelings, motives and desires and imagining how others might perceive us. It extends right up to having self-conscious emotions like pride or shame. It is a measure of intelligence.
Of the hundreds of animals tested so far, only 10 animals have been proven to have any measurable degree of self-awareness. They are Humans, Orangutans, Chimpanzees, Gorillas, Bottlenose Dolphins, Elephants, Orcas, Bonobos, Rhesus Macaques and European Magpies.
Q. 6) List 10 modern-day animals and link them to corresponding ancient fossils.
Ans:
- Dog – Leptocyon
- Horse – Eohippus
- Elephant – Mastodons
- Crocodile – Protosuchus
- Bird – Archaeopteryx
- Camel – Protylopus
- Crocodile – Sarcosuchus
- Fish – Ostracoderms
- Whale – Protocetus
- Giraffe – Palaeotragus
Q. 7) Describe one example of adaptive radiation.
Ans: Adaptive radiation is the rapid development of many new species from a single ancestral species. One of the best examples of adaptive radiation is Galapagos finches. Darwin observed diversity in finches which evolved from a single species adapting to different food habits.
Q. 8) Can we call human evolution as adaptive radiation?
Ans: No, human evolution cannot be called adaptive radiation. It occurred slowly over millions of years and is an example of anagenesis.
Q. 9) Trace the evolutionary stages of horse.
Ans: The evolutionary history of horse shows increased body size, reduction of toes, strengthening of back, development of brain and durable grinding teeth. The lineage started with Hyracotherium (Eohippus) and evolved through Miohippus, Merychippus and Pliohippus to modern Equus.
Q. 10) Practise drawing various animals and plants.
Ans: Select a few plants and animals that you find comparatively easy to draw and label. Practise on these diagrams to make them neat, clear and precise. Labelled diagrams of goat and banana tree are given in the textbook.