EXERCISES
1. A Mendelian experiment consisted of breeding tall pea plants bearing violet flowers
with short pea plants bearing white flowers. The progeny all bore violet flowers
but almost half of them were short. This suggests that the genetic make-up of the
a tall parent can be depicted as
(a)TTWW
(b)TTww
(c)TtWW
(d)TtWw
Ans:-(c)TtWW
2 An example of homologous organs is
(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.
Ans:-(d)all of the above
3. In evolutionary terms, we have more in common with
(a)a Chinese school-boy.
(b)a chimpanzee.
(c)a spider.
(d)a bacterium.
Ans:- (a) a Chinese school-boy.
4. 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?
Ans:-For considering an attribute as dominant or recessive, we’d like knowledge of a minimum of 3 generations. This knowledge is regarding solely 2 generations. The fogeys may be homozygous for the attribute resulting in the presence of the same trait in youngsters. This doesn’t support that the given attribute is dominant.
5. How are the areas of study – evolution, and classification – interlinked?
Ans:- Evolution and classification are interlinked with each other. Classification is the most important term to explain evolution. Classification is based on the similarities and dissimilarities between species or among organisms. More closer the characteristics are, the more closer is the evolution and more chances are to remain in the same group of classification. Thus evolution and classification are interlinked with each other.
6. Explain the terms analogous and homologous organs with examples.
Ans:- Homologous organs are those organs that have similar structure styles but perform different functions. For example:- Hands of humans and wings of bats
Analogous organs are those organs that have different structures but perform similar functions. For example :- The wings of birds and insects.
7. Outline a project which aims to find the dominant coat color in dogs.
Ans:- Do it yourself.
8. Explain the importance of fossils in deciding evolutionary relationships.
Ans:- Fossil gives evidence about:-
(a) The organisms that lived way back like the fundamental quantity throughout that they lived, their structure, etc.
(b) Biological process development of species i.e., line of their development.
(c) Connecting links between 2 teams. As an example, feathers gift in some dinosaurs implies that birds are terribly closely associated with reptiles.
(d) That organism evolved earlier and later.
(e) Development of complicated body styles from straightforward body designs.
9. What evidence do we have for the origin of life from inanimate matter?
Ans:- Miller and Urey experiment.
10. Explain how sexual reproduction gives rise to more viable variations than asexual
reproduction. How does this affect the evolution of those organisms that reproduce
sexually?
Ans: Variation occurs among the individuals during reproduction whether organisms multiply asexually or sexually. In asexual reproduction involves single parent and large number of individuals are formed after many generations. All these individuals would be similar. However, there would be only very minor differences between them due to small inaccuracies in DNA copying.
The sexual reproduction generates greater diversity. This is so because sexual
reproduction involves two parents and every offspring receives some characters of father and some characters of the mother. Since different offsprings receive a different combinations of characters of their parents, they show distinct variations among themselves as well as from their parents.
During sexual reproduction, the variations caused by –
i) Chance of separation of chromosomes during gamete formation.
ii) Crossing over during meiosis.
iii) Chance coming together of chromosomes during fertilization.
iv) Alterations in genetic material.
11. How is the equal genetic contribution of male and female parents ensured in the
progeny?
Ans: In sexual reproduction male and female gametes are required. The male gamete or sperm and female gamete or ovum are produced in meiosis cell division and every daughter cell receives haploid (n) number of chromosomes of the mother cell. So gametes possess a half the number of chromosomes. For example, the human cell consists of 46 number of chromosomes but gametes possess 23 number of chromosomes. During sexual reproduction the sperm and ovum fuse together and form a zygote and it contains 46 chromosomes from where a new individual will be produced through a series of embryonic development. Thus the pregnancy receives an equal genetic contribution of male and female parents.
12. Only variations that confer an advantage to an individual organism will survive in
a population. Do you agree with this statement? Why or why not?
Ans:- It is agreeable that only variations that confer an advantage to an individual organism will survive in a population. All variation does not necessarily provide an equal chance of survival to an organism in the environment. Survival chances highly depend on the nature of variations. For example- variation leading to the increase of heat-resistant bacteria is beneficial to the bacteria for its survival when it finds itself in a condition where suddenly there is an increase in the temperature of its habitat above the optimum temperature required for survival.
