Heredity and Evolution: Class 10 Science Q&A · Page 2
47 free answers on Heredity and Evolution (Science) for Class 10 students, across CBSE, ICSE and State boards.
Question & Answer
Questions
- ScienceClass 10CBSE
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?
Solution: Sexual reproduction causes a lot of viable variations because of the following reasons: (a) Error in copying of DNA (though it was rare) (b) Random segregation of paternal and maternal chromosomes at the time of sex cell formation. (c) Exchange of genetic material between homologous chromosomes during the formation of gametes. (d) Accumulation of variations occurred because of reproduction over generation after generation, and choice naturally
- ScienceClass 10CBSE
What evidence do we have for the origin of life from inanimate matter?
Solution: The evidence on the origin of life from inanimate matter was provided by Stanley L. Miller and Harold C. Urey’s experiment, which was conducted in 1953. They created an artificial environment which was reminiscent of the early earth’s atmosphere – it contained ammonia, hydrogen and other gases which were thought to have existed during primordial earth. This concoction of gases was kept at a temperature slightly below 100 ° C. Additionally, spark
- ScienceClass 10CBSE
Explain the importance of fossils in deciding evolutionary relationships.
Fossils give evidence about: (a) The organism and their paleobiology (b) Even the behaviour of an organism can be deduced to some extent (for example, palaeontologists) have unearthed a site with more than 10,000 skeletons of a dinosaur called Hadrosaurus. This implies that the dinosaur lived in herds. (c) Fossils also provide insight into the evolutionary history of animals and plants (for instance, palaeontologists have discovered that whales had evolved from goat-si
- ScienceClass 10CBSE
Outline a project which aims to find the dominant coat colour in dogs.
Dogs have a certain set of genes that govern coat colour. There are a minimum of eleven known sequence series (A, B, C, D, E, F, G, M, P, S, T) that influence the colour of a dog. A dog inherits one copy from each of its parents. As an example, within the B series, a dog is genetically black or brown. Assume that one parent is homozygous black (BB), whereas the other parent is homozygous brown (bb). In this case, all the offspring are going to be heterozygous (Bb). Since black
- ScienceClass 10CBSE
Explain the terms analogous and homologous organs with examples.
Solution: Homologous organs are those organs that have the basic structural design as well as the origin; however, they serve different functions. For example, the forelimbs of humans and the wings of bats are anatomically similar. Analogous organs are those organs that have a different structural design as well as origin; however, they perform similar functions. For example, the wings of birds and insects.
- ScienceClass 10CBSE
How are the areas of study – evolution and classification – interlinked?
Classification and evolution are two related fields of biology. Evolution pertains to how organisms evolve, and classification deals with finding out how two species are related to each other. For example, evolution and fossil evidence point to the fact that Australopithecus afarensis is considered one of our earliest ancestors. And classification tells us that Australopithecus afarensis belongs to the genus Homo, which is also the same genus as modern hu
- ScienceClass 10CBSE
A study found that children with light-coloured eyes are likely to have parents with light-coloured eyes. On this basis, can we say anything about whether the light eye colour trait is dominant or recessive? Why or why not?
Solution: Knowledge of at least 3 generations is required to find if an attribute is dominant or recessive. Hence, it is not possible to identify if the given trait is dominant or recessive.
- ScienceClass 10CBSE
In evolutionary terms, we have more in common with (a) A Chinese schoolboy (b) A chimpanzee (c) A spider (d) A bacterium
Solution: Correct answer – (a) Humans and chimpanzees are related since they belong to the identical order (Primates) and the same family (Hominidae). However, a schoolboy, regardless of ethnicity, is still a Homo sapien.
- ScienceClass 10CBSE
An example of homologous organs is (a) Our arm and a dog’s foreleg (b) Our teeth and an elephant’s tusks (c) Potato and runners of grass (d) All of the above
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 structures but different functions. For example, a whale’s flippers, a frog’s forelimbs, and a man have the same basic structures but perform different functions, which is why they are called homologous organs.
- ScienceClass 10CBSE
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 makeup of the tall parent can be depicted as (a) TTWW (b) TTww (c) TtWW (d) TtWw
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 colour is dominant over white.
- ScienceClass 10CBSE
In evolutionary terms, can we say which among bacteria, spiders, fish and chimpanzees have a ‘better’ body design? Why or why not?
Solution: 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.
- ScienceClass 10CBSE
Why are human beings who look so different from each other in terms of size, colour and looks said to belong to the same species?
Solution: While human beings do vary in colour 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 recognised pushed us towards having widely different faces.
- ScienceClass 10CBSE
What are fossils? What do they tell us about the process of evolution?
Solution: 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 r
- ScienceClass 10CBSE
Can the wing of a butterfly and the wing of a bat be considered homologous organs? Why or why not?
Solution: 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 the wings of a bat are composed of a bony skeleton, complete with blood vessels. Hence, these aren’t homologous organs but rather analogous organs.
- ScienceClass 10CBSE
Give an example of characteristics being used to determine how close two species are in evolutionary terms.
Solution: 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. In
- ScienceClass 10CBSE
Will geographical isolation be a major factor in the speciation of an organism that reproduces asexually? Why or why not?
Solution: 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.
- ScienceClass 10CBSE
Will geographical isolation be a major factor in the speciation of a self-pollinating plant species? Why or why not?
Solution: In the pollination of plant species, geographical isolation is usually not a major factor, as no new trait will become part of the genetic makeup of a self-pollinating plant species. However, there are some possibilities of some environmental changes which could result in some variations.
- ScienceClass 10CBSE
What factors could lead to the rise of a new species?
Solution: Factors that would result in a new species are as follows: (a) Mutation (b) Genetic drift (c) Natural selection (d) Geographical isolation (e) Generative isolation for prolonged periods (f) Environmental factors on the isolated populations (g) Quantum of genetic variant transmissible from one generation to the following generation
- ScienceClass 10CBSE
Why are the small numbers of surviving tigers a cause of worry from the point of view of genetics?
Solution: As the size of the tiger population decreases, the genetic pool of the species decreases too. This results in a limitation on the variations which will be introduced within the genetic makeup of the tigers. This lack of variation will result in serious implications. For example, if an illness spreads within the tiger population, it can potentially wipe out the whole population, possibly causing their extinction.
- ScienceClass 10CBSE
Why are traits acquired during the lifetime of an individual not inherited?
Solution: Traits acquired during a lifetime cannot be inherited by successive generations as the changes do not reflect in the DNA of the germ cells. For instance, a football player cannot pass on his skills to his offspring as they are limited to non-reproductive cells only.