GENETICS AND HEREDITY: SHORT ANSWER TYPE QUESTIONS Class 10th CHAPTER 14 JKBOSE/NCERT
SHORT ANSWER TYPE QUESTIONS
Question 1. If a trait ‘A’ exists in 10% of the population of an asexually reproducing species and a trait ‘B’ exists in 60% of the same population, which trait is likely to have arisen earlier?
Ans: Trait ‘B’ is likely to have arisen earlier because it exists in a higher percentage (60%) of the population compared to trait ‘A’ (10%). The higher frequency of trait ‘B’ suggests that it has had more time to accumulate and spread through the population.
Question 2. How does the creation of variation in a species promote survival?
Ans: The creation of variation in a species promotes survival because it increases the chances of some individuals possessing traits that are better suited for their environment. When the environment changes or presents challenges, individuals with advantageous variations have a higher probability of surviving and reproducing, passing on their beneficial traits to the next generation. This leads to the adaptation and evolutionary success of the species.
Question 3. How is the sex of a child determined in human beings?
Ans: In human beings, the sex of a child is determined by the combination of sex chromosomes inherited from the parents. Females have two X chromosomes (XX), while males have one X and one Y chromosome (XY). The father’s sperm determines the sex of the child, as it carries either an X or a Y chromosome.
Question 4. Out of the two parents, mother and father, whose genetic combination plays a role in determining the sex of a newborn in humans and why?
Ans: The father’s genetic combination plays a role in determining the sex of a newborn in humans. This is because the father’s sperm carries either an X or a Y chromosome, which determines whether the child will be female (XX) or male (XY). The mother’s eggs always carry an X chromosome.
Question 5. What are the different ways in which individuals with a particular trait may increase in a population?
Ans: Individuals with a particular trait may increase in a population through various ways:
a) Natural selection: If the trait provides a survival advantage, individuals with that trait are more likely to survive, reproduce, and pass on the trait to the next generation.
b) Genetic drift: In small populations, random fluctuations in allele frequencies can lead to the increase of individuals with a particular trait by chance.
c) Gene flow: If individuals with the trait migrate and interbreed with other populations, they can introduce the trait and increase its frequency in the new population.
d) Mutation: New genetic variations can arise through mutations, leading to individuals with a new trait that may increase in frequency over time.
Question 6. Why are traits acquired during the lifetime of an individual not inherited?
Ans: Traits acquired during the lifetime of an individual are not inherited because they do not alter the genetic material (DNA) that is passed on to offspring. Acquired traits result from environmental influences or experiences that affect the phenotype but do not change the genotype. Inheritance is based on genetic information contained in the DNA, which is passed on from parents to offspring.
Question 7. Why are the small numbers of surviving tigers a cause of worry from the point of view of genetics?
Ans: The small numbers of surviving tigers are a cause of worry from a genetic perspective because they exhibit reduced genetic diversity. With a small population size, there is a higher risk of inbreeding and the loss of genetic variation.
Question 8. Give an example of characteristics being used to determine how close two species are in evolutionary terms.
Ans: An example of characteristics used to determine how close two species are in evolutionary terms is the similarity of DNA sequences.
Question 9. How are the areas of study—evolution and classification—interlinked?
Ans: Evolution and classification are interlinked because classification systems are based on the principles of evolutionary relationships. By studying the similarities and differences in traits among organisms, scientists can classify them, such as species, genera, families, etc. This classification reflects the evolutionary history and genetic relatedness among organisms. Evolution provides the framework for understanding the diversity of life and forms the basis for organizing organisms into different taxonomic groups.
Question 10. Can the wing of a butterfly and the wing of a bat be considered – homologous organs? Why or why not?
Ans: The wing of a butterfly and the wing of a bat cannot be considered homologous organs. They are analogous organs because they have similar functions (flight) but different evolutionary origins.
Question 11. What are fossils? What do they tell us about the process of evolution?
Ans: Fossils are the preserved remains, impressions, or traces of ancient organisms. They provide tangible evidence of past life on Earth. Fossils can tell us about the process of evolution by documenting the existence of different species that lived in the past and revealing the changes in their characteristics over time. They provide a record of intermediate forms and transitional species, showing the gradual changes and diversification of life forms.
Question 12. Explain the importance of fossils in deciding evolutionary relationships.
Ans: The evidence for the origin of life from inanimate matter is supported by experiments such as the Miller-Urey experiment. This experiment demonstrated that complex organic molecules, including amino acids, could be synthesized from simple inorganic molecules under conditions that simulated the early Earth’s atmosphere. The formation of these organic molecules provides evidence that the building blocks of life could have arisen from non-living materials through natural chemical processes.
Question 13. How is the equal genetic contribution of male and female parents ensured in the progeny?
Ans: The equal genetic contribution of male and female parents is ensured through sexual reproduction. In sexual reproduction, the genetic material from both parents combines during fertilization to form the genetic makeup of the offspring. Each parent contributes half of the genetic material, with the male parent providing sperm carrying genetic information and the female parent providing eggs containing genetic information. This equal contribution helps maintain genetic diversity and the mixing of genetic traits in the progeny.
Question 14. 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?
Ans: Human beings, despite their differences in size, colour, and looks, are considered to belong to the same species because they can interbreed and produce fertile offspring. The ability to reproduce and have viable offspring is one of the key criteria for defining individuals as members of the same species. While human populations may display phenotypic variations, they are still genetically compatible and share a common gene pool.
Ans: Question 15. In evolutionary terms, can we say which among bacteria, spiders, fish and chimpanzees have a better body design? Why or why not?
Ans: In evolutionary terms, it is not possible to determine which among bacteria, spiders, fish, and chimpanzees have a better body design. Each of these organisms has evolved unique adaptations that suit their specific environments and lifestyles. What may be considered a better body design depends on the specific selective pressures and ecological niches that organisms face. Evolution does not aim for an ultimate or superior body design but rather favours traits that increase an organism’s fitness and survival in its particular environment.
Question 16. 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: No, variations that confer an advantage to an individual organism will not be the only ones to survive in a population. While advantageous variations increase the likelihood of survival and reproductive success, the persistence of other variations is also possible. The survival of variations depends on various factors such as environmental changes, genetic drift, and complex interactions between organisms. Additionally, what may be advantageous in one environment or situation may not be advantageous in another, and the balance of traits in a population can change over time.