Answer - 11 : - In a pollination of plant species, geographical isolation is usually not a major factor as no new trait will become part of the genetic makeup in a self-pollinating plant species. However, there are some possibilities of some environmental changes which could result in some variations.

Question - 12 : - Will geographical isolation be a major factor in the speciation of an organism that reproduces asexually? Why or why not?

Answer - 12 : - In the case of asexually reproducing organisms, geographical isolation can’t be considered a factor. This is due to the fact that meiosis does not occur during asexual modes of reproduction.

Question - 13 : - Give an example of characteristics being used to determine how close two species are in evolutionary terms.

Answer - 13 : - Let us take the instance of humans and chimpanzees. Chimpanzees are able to express a wide range of emotions – such as busting out in laughter or smiling – this trait was once thought to be a feature exclusive to humans. The smile can be linked to the activation of the brain’s limbic system – where the orbicularis oculi muscle involuntarily contracts and raises the cheeks, forming wrinkles around the eyes. This implies that the smile is a true and genuine smile. Interestingly, this type of reflex has a name – the Duchenne smile. Moreover, research has shown that chimpanzees share 98.6% of our DNA – This means that humans and chimpanzees shared a common ancestor eons ago. It is important to also note that chimpanzees are the closest living relatives to humans.

Question - 14 : - Can the wing of a butterfly and the wing of a bat be considered homologous organs? Why or why not?

Answer - 14 : - The wing of a butterfly and the wing of a bat cannot be considered homologous organs as they do not share a common ancestor. Even though both structures aid in flying, they have evolved separately. To prove this, the wings of a butterfly are composed of two chitinous membranes, whereas wings of a bat are composed of bony skeleton, complete with blood vessels. Hence, these aren’t homologous organs but rather analogous organs.

Question - 15 : - What are fossils? What do they tell us about the process of evolution?

Answer - 15 : - Fossils are the preserved remains of animals or plants or other organisms that died out millions of years ago. These fossils tell us about a lot of extinct animals and also give insights into how evolution might have occurred. Fossils can be used to understand how an organism would have lived and what it may have looked like. More importantly, we can correlate with fossils as well as extant organisms to understand their relationships. For instance, scientists were able to recover protein sequences from a dinosaur called the T-rex, which confirmed its avian lineage. This means birds are the extant relatives of (avian) dinosaurs. Moreover, the pattern of fossil distribution gives us an idea of the time in history when various species were formed or become extinct.

Question - 16 : - Why are human beings who look so different from each other in terms of size, color and looks said to belong to the same species?

Answer - 16 : - While human beings do vary in color and general appearance, their genetic makeup is identical to any other human. One of the speculations put forth for our drastic changes is due to evolutionary pressure – where the need to be easily recognized pushed us towards having widely different faces.

Question - 17 : - In evolutionary terms, can we say which among bacteria, spiders, fish and chimpanzees have a ‘better’ body design? Why or why not?

Answer - 17 : - Body designs are the result of environmental needs and pressure. Hence, we can’t conclude that one organism has a better body compared to another. For instance, fish have evolved a streamlined design as it is best suited for an aquatic environment. On the other hand, a spider or a chimpanzee might be ill-equipped to survive in such aquatic environments.

Question - 18 : -
A Mendelian experiment consisted of breeding tall pea plants bearing violet flowers with short pea plants bearing white flowers.

Answer - 18 : -

The progeny all bore violet flowers, but almost half of them were short. This suggests that the genetic make-up of the tall parent can be depicted as

(a) TTWW

(b) TTww

(c) TtWW

(d) TtWw

Answer

Correct answer – (c)

TtWW might be the genetic makeup of the tall parent. Since half the progenies are short, this implies that the parent plant also will have a collection of short genes; all progenies bore violet flowers, further suggesting that violet color is dominant over white.

Question - 19 : - An example of homologous organs is

Answer - 19 : -

(a) Our arm and a dog’s fore-leg.

(b) Our teeth and an elephant’s tusks.

(c) Potato and runners of grass.

(d) All of the above.

Answer

Correct answer – (d)

Homologous organs have the same origin as each of the above organs, but different functions. Homologous organs can be defined as the organs of various animals having similar basic structure but different functions. For example, a whale’s flippers, a frog’s forelimbs, and man have the same basic structures but perform different functions, which is why they are called homologous organs.

Question - 20 : - In evolutionary terms, we have more in common with

Answer - 20 : -

(a) A Chinese school-boy.

(b) A chimpanzee.

(c) A spider.

(d) A bacterium.

Answer

Correct answer – (a)

Humans and chimpanzees are related since they belong to the identical order (Primates) and same family, (Hominidae). However, a school-boy, regardless of the ethnicity is still a Homo sapien

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