Question 1. What is heredity?

Ans: Heredity refers to the passing on of traits from parents to offspring through genetic information contained in the DNA.

Question 2. What are acquired traits? Do they inherit to the next generation?

Ans: Acquired traits are characteristics or features that an organism develops during its lifetime as a result of environmental influences or experiences. These traits are not inherited and are not passed on to the next generation.

Question 3. What is speciation?

Ans: Speciation is the process by which new distinct species arise from existing species.

Question 4: List any two factors that could lead to speciation.

Ans: Two factors that could lead to speciation are:

a) Geographic isolation: Physical barriers, such as mountains or bodies of water, can separate populations, restricting gene flow and promoting genetic divergence.

b) Reproductive isolation: Mechanisms or barriers that prevent interbreeding between different populations, such as differences in mating behaviours, breeding seasons, or genetic incompatibilities.

Question 5. Define variations.

Ans: Variations refer to the differences or variations that exist among individuals of the same species. These variations can be observed in traits such as appearance, behaviour, or physiological characteristics.

Question 6. What is the role of variations in evolution?

Ans: Variations play a crucial role in evolution. They provide the raw material for natural selection to act upon. Variations increase the chances of individuals having certain traits that may be advantageous in their environment, allowing them to better survive and reproduce. Over time, these advantageous variations can accumulate in a population, leading to the evolution of new traits and species.

Question 7. What is the role of natural selection in evolution?

Ans: Natural selection is a fundamental mechanism of evolution. It refers to the process by which individuals with traits that are favourable to their environment have a better chance of surviving and reproducing, passing on their advantageous traits to the next generation. Natural selection acts on the genetic variations present in a population, favouring traits that increase fitness and adaptability while reducing the prevalence of less advantageous traits.

Question 8. What do you mean by phenotype and genotype?

Ans: Phenotype refers to the observable physical characteristics or traits of an organism, which are influenced by both genetic and environmental factors. Genotype, on the other hand, refers to the genetic makeup of an organism, specifically the combination of alleles (different forms of genes) it possesses.

Question 9. Define genetic drift.

Ans: Genetic drift is a random process that can occur in small populations, leading to changes in the frequency of alleles from one generation to the next.

Question 10. What is DNA? Where is it found in a cell?

Ans: DNA (deoxyribonucleic acid) is a molecule that carries the genetic instructions necessary for the development, functioning, and reproduction of all known living organisms. It is found in the cell nucleus of eukaryotic cells and the cytoplasm of prokaryotic cells.

Question 11. Who gave the hypothesis that evolution took place due to natural selection?

Ans: The hypothesis that evolution took place due to natural selection was proposed by Charles Darwin and Alfred Russel Wallace. They independently proposed the theory of natural selection in the mid-19th century.

Question 12. What is the contribution of J.B.S Haldane?

Ans: J.B.S. Haldane was a British scientist known for his contributions to the field of population genetics. He made significant advancements in understanding the role of genetic variation in evolution, particularly through his work on the mathematical modelling of population genetics and the estimation of genetic parameters.

Question 13. Who experimentally proved that complex organic molecules originated from simple inorganic molecules in the remote past?

Ans: Stanley Miller and Harold Urey conducted the Miller-Urey experiment in the 1950s, which provided experimental evidence that complex organic molecules, including amino acids, could be synthesized from simple inorganic molecules, simulating the conditions believed to be present on early Earth. This experiment supported the hypothesis that the building blocks of life could have originated from non-living materials through natural processes.

Question 14. As per recent evidence where did the human species, Homo sapiens originate?

Ans: Recent evidence suggests that the human species, Homo sapiens, originated in Africa. Fossil and genetic studies indicate that modern humans evolved in Africa and then migrated to other parts of the world, leading to the colonization of different regions.

Question 15. A couple has six sons and a daughter. The husband thinks that he produces more y-bearing sperm. Is his thinking right?

Ans: No, the husband’s thinking is not necessarily right. The sex of a child is determined by the combination of sex chromosomes inherited from the parents. While sperm cells carry either an X or a Y chromosome, it is random and not influenced by the thinking or preference of the father. The chance of conceiving a son or a daughter is approximately equal, assuming no specific medical conditions affect the sex ratio.

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