1. “Human being is said to be a moving museum of vestigial organs”. How can you support this statement?
A. 1. During the course of evolution, some organs remain in organisms. For example, appendix in the digestive system.
2. In human beings it has no role to play in the process of digestion but it is useful in herbivores.
3. Such type of organs which are not useful in animal are called “vestigial organs”.
4. There are nearly 18 vestigial organs in human beings.
5. That’s why human being is said to be a moving museum of vestigial organs.
2. How does the creation of variations in a species promote survival?
A. Variations occur due to sexual reproduction and also due to inaccurate copying of DNA. Depending on the nature of variations, different individuals would have different kinds of advantages. For example, bacteria variants which can withstand heat have better chances to survive in a heat wave non-variant bacteria having no capacity to tolerate heat wave. Thus, variations in a population of a species help in survival of a species.
3. How do Mendel’s experiments show that traits may be dominant or recessive?
A. The trait which appears in all the members of F1 generation and also in 75% numbers of F2 generation obtained by self fertilization of F1 generation is dominant character.The trait which does not appear in F generation but after self-fertilization of F1 generation, reappears in 25% of F2 generation is known as recessive.
4. How do Mendel’s experiments show that traits are inherited independently?
A. Mendel crossed pure breeding tall plants having round seeds with pure breeding short plants having wrinkled seeds. The plants of F1 generation were all tall with round seeds indicating that the traits of tallness and round seeds were dominant. Self breeding of F1 yielded plants with characters of 9 tall round seeded, 3 tall wrinkled seeded , 3 short round seeded and one short wrinkled seeded. Tall wrinkled seeded and short round seeded plants are new combinations which can develop only when the traits are inherited independently.
5. Why are the small numbers of surviving tigers a cause of worry from the point of view of genetics?
A. The small number of members in a population of tigers do not allow large number of vari ation to occur which are essential to survival of the species. A deadly disease or calamity may cause death of all the tigers. The small number of tiger also indicates that existing tiger variants are not well adopted to the existing environment and may extinct soon.
6. Can the wing of a butterfly and the wing of a bat be considered homologous organs? Why or why not?
A. The wing of a butterfly and the wing of a bat are similar in function. They help the butterfly and the bat in flying. Since they perform similar function, they are analogous organs and not homologous.
7. What are fossils? What do they tell us about the process of evolution?
A. Fossils are the remains of organisms that once existed on earth.They tell us about the development of the structures from simple structured to complex structured organisms. They tell us about the phases of evolution through which they must have undergone in order to sustain themselves in the competitive environment.
8. 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?
A. Species is a group of organisms that are capable of interbreeding to produce a fertile offspring. Skin color, looks, and size are all variety of features present in human beings. These features are genetic but also environmentally controlled. Various human races are formed based on these features. All human races have more than enough similarities to be classified as same species. Therefore, all human beings are a single species as humans of different color, size, and looks are capable of reproduction and can produce a fertile offspring.
9. A study found that children with light colored eyes are likely to have parents with light-colored eyes. On this basis, can we say anything about whether the light eye color trait is dominant or recessive? Why or why not?
A. This information is not sufficient. For considering a trait as dominant or recessive, we need data of at least three generations. This data is about only two generations.
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